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Water Stress Management contains the invited lectures and selected oral and poster presentations of the 11th International Symposium on the Properties of Water (ISOPOW), which was held in Queretaro, Mexico 5-9 September 2010. The text provides a holistic description and discussion of state-of-the-art topics on the role of water in Biological, Chemical, Pharmaceutical and Food systems within a frame of an integrated approach and future trends on the subject. Different points-of-view about the state of water and phase transitions in a variety of substrates are presented.

ISOPOW is a non-profit scientific organization whose activities aim at progressing the understanding of the properties of water in food and related biological systems and the exploitation of this understanding in improved raw materials, products and processes in the food, agro food or related industries. The first Symposium was organized in Glasgow, Scotland in 1974. Since then, ISOPOW meetings have promoted the exchange of knowledge between scientists involved in the study of food materials and scientists interested in water from a more basic point of view and the dialogue between academic and industrial scientists/technologists.

Inhaltsverzeichnis

Frontmatter

The State of Water and Its Impact on Pharmaceutical Systems: Lipid-Based Drug Delivery Systems and Amorphous Solids

Physicochemical properties relevant to aqueous pharmaceutical formulations such as drug solubility and stability have clearly been a focal point of research for many decades. As a result, pharmaceutical scientists have access to a large body of knowledge that provides a framework for understanding the properties of drugs in aqueous solution, such as the kinetics and mechanisms of their degradation, solubility as influenced by ionizable substituents and various solution equilibria, etc. However, most drug products are manufactured, stored, and most frequently administered as solid formulations (e.g., tablets, capsules, suppositories, polymer implants, transdermal patches) rather than as aqueous solutions or suspensions. For these nonaqueous systems, the state of current understanding of the equilibria and kinetics that govern performance is less advanced. Recently, interest in various nonaqueous delivery systems has been increasing because, as drug potency has received greater emphasis during the selection of new drug candidates, the lead compounds emerging from these selection processes tend to be more lipophilic and less water soluble. Consequently, a variety of amorphous or lipid-based delivery systems such as self-emulsifying or self-microemulsifying lipid dispersions often administered in soft gelatin capsule form for oral delivery are now being considered for commercialization. Similarly, various types of colloidal or nanoparticle formulations (e.g., nanosuspensions, solid-lipid nanoparticles, liposomes, micelles, polymeric micelles) in which the drug is suspended as a nano-sized particle or incorporated into a lipid particle have become increasingly attractive as possible vehicles for enhancing the bioavailability of orally administered drugs having poor water solubility, controlling drug release, enabling intravenous injection of nearly insoluble compounds, reducing side effects after intravenous administration, and in some cases providing enhanced permeability and retention in tumor tissue for the treatment of cancer.

B. D. Anderson

Food Preservation by Nanostructures-Water Interactions Control

Understanding structure–function properties in food systems has led to possibilities of food preservation by managing product structural features so that water and nutriments are subjected to various levels of physical immobilization, thus reducing reactivity and allowing a better control of product stability. In this chapter it is noted that to achieve this, it is necessary to induce in the solid matrix of the product the formation of micro–nano cavities, fissures, and pores into which water and other substances will strongly (and tightly) bound. Important thermodynamic characteristics of the system control this reduction in mobility and entropy control of food matrix-liquid is aimed to achieve the task. Also, principles and practical applications of such processes are discussed as well as structural features-appraisal methodologies.

E. Flores-Andrade, E. Azuara-Nieto, C. I. Beristain-Guevara, A. Monroy-Villagrana, D. I. Téllez-Medina, L. A. Pascual-Pineda, L. Alamilla-Beltrán, G. F. Gutiérrez-López

Water and Food Appearance

Food appearance depends not only on its chromatic characteristics (hue, saturation) and luminosity but also on the spatial distribution of light inside the food material, which determines appearance aspects such as transparency and gloss.

M. P. Buera, A. E. Farroni, L. M. Agudelo-Laverde

Maillard Reaction in Limited Moisture and Low Water Activity Environment

Maillard reaction is a nonenzymatic browning reaction that involves the reaction of carbonyl groups, primarily reducing sugars with free amino groups which cause the changes of chemical and physiological properties of proteins (Labuza and Saltmarch 1981). It results in the development of complex mixtures of colored and colorless reaction products which range from flavor volatiles (low molecular weight compounds) to melanoidins, a series of brown pigments with high molecular weights (Carabasa-Giribet and Ibarz-Ribas 2000; Martins and Van-Boekel 2005); these effects could be either desirable or undesirable. Browning and the formation of aroma are desired in baking, roasting, or frying, while it is undesirable in the foods which have a typical weak or other color of their own such as browning in the products of condensed milk, white dried soups, tomato soup, etc. and generation of off-flavors in food during storage. Besides, Maillard reaction can also have negative effects on nutritional values such as the losses of essential amino acids, as well as the formation of mutagenic compounds (Belitz et al. 2004).

C. W. Wong, H. B. Wijayanti, B. R. Bhandari

Carbohydrates and Proteins as Nonequilibrium Components of Biological Materials

Carbohydrates and proteins form the main hydrophilic phases in biological materials. Water solubility and formation of glass-like structures at high solids contents are well-known properties of carbohydrates, particularly of low molecular weight sugars (White and Cakebread 1966). Natural biological materials, including foods, often contain carbohydrates mixed with proteins and other hydrophilic substances in their aqueous phase.

Y. H. Roos

Low-Temperature Mobility of Water in Sugar Glasses: Insights from Thermally Stimulated Current Study

Molecular mobility in sucrose and sorbitol glasses, containing 35–1 % w/w water, is studied using thermally stimulating current method. Low-temperature dipole relaxation, Tgw, is observed in the temperature range of −125 to −155 °C and assigned to the rotational mobility of water molecules. From the concentration dependence of the Tgw, two regions are identified, i.e., intermediate water region (35–10 % w/w water), and low water region (less than 10 % w/w water). The results of this investigation, combined with earlier NMR (Girlich and Ludemann, Z Naturforsch 1994, 49c: 250) and neutron scattering (Chou et al, J Phys Chem B 2012, 116: 4439) studies, indicate that water molecules in sugar glasses form clusters at the intermediate water contents, whereas unclustered water molecules prevail at higher solute/lower water concentrations.

S. Ewing, A. Hussain, G. Collins, C. Roberts, E. Shalaev

Functional Behavior of Different Food Components as Affected by Water and Physical State

The presence of water in foods, and the vast number of roles that water plays, is an old and well-researched topic. There are countless interactions in which water impacts the food chain, starting from irrigation of crops, harvested raw materials, storing and processing, and finished goods properties such as shelf life, microbiological quality and safety, functional properties, palatability and profitability, to name a few.

A. Marabi, L. Forny, A. Gianfrancesco

Effect of Different Components of Edible/Biodegradable Composite Films on Water Relationships in the Polymer Matrix

Films and coatings based on edible/biodegradable hydrocolloids have received special attention in the last few years as an alternative to preserve foods with several possibilities: to maintain sensory and nutritional properties or microbial stability, to reduce moisture losses or mechanical damage, to improve food appearance (especially gloss), to add different food ingredients such as color or aroma compounds, to incorporate bioactive compounds such as antimicrobials or antioxidants, and to reduce the use of plastic packaging. Films or coatings must be transparent, flavorless, and odorless and they must have adequate water vapor permeability and selective permeability to gases and volatiles. They must not represent a health risk and be low cost (Krochta and de Mulder-Johnston 1997; Tharanathan 2003).

A. Chiralt, P. Talens, F. M. Monedero, M. J. Fabra

Glass Transition Observed with Cross-Linked Dextrans Containing a Small Amount of Water

Many biological systems and foods take on a gelling state in their ordinary condition. Gels consisting of various polymers are also used in the pharmaceutical and medical industries. Thus, it is of practical importance to characterize the polymer network in gels in order to understand their physical properties. Moreover, it is necessary to rationalize freezing and/or freeze-drying processes of the gels on the basis of scientific fundamentals for the preparation of frozen and freeze-dried products (Franks 1986). For differential scanning calorimetry (DSC) studies conducted from this standpoint, it was found by one of the present authors that water in polymer gels sometimes remains partially unfrozen during cooling below −50 °C and freezes during subsequent heating (rewarming) (Murase et al. 1982, 1986). The occurrence of ice crystallization during rewarming, especially that observed with a cross-linked dextran, depends on the density of cross-links, as well as on water content and cooling rate. The density of cross-links is presumably related with the flexibility of polymer chains and water diffusivity through the polymer network in gels (Murase and Watanabe 1989; Ruike et al. 1999).

N. Ijima, N. Murase

Sensorially and Instrumentally Detected Antiplastizicing Effect of Water in Cornflakes

Textural properties are key drivers for food acceptability (Chauvin et al. 2008). In low-moisture cereal foods, quality depends mainly on textural attributes like crispness (Fontanet et al. 1997). Water is one of the most important factors affecting texture of low-moisture foods, and its effect has been extensively studied (Labuza et al. 1970; Roos et al. 1996; Peleg 1998; Jacoby and King 2001; Lewicki 2004; Castro-Prada et al. 2009). It is also known that water affects glass transition temperature (Chen et al. 1997), which is widely used in assessing stability (Roos 2010). In order to measure water mobility in complex and heterogeneous systems, nuclear magnetic resonance spectroscopy has been widely used (Chinachoti et al. 2006). On the other hand, in low-moisture starchy food, other processes that take place at glassy state, such as physical aging and toughening, could affect textural properties (Suwonsichon and Peleg 1998; Chang et al. 2000; Chung and Lim 2004).

A. E. Farroni, S. Guerrero, M. P. Buera

Characterization of a Hydrate–Dehydrate System with Critical Transitions in the Typical Range of Processing and Storage Conditions

The use of water in pharmaceutical processing, along with the ubiquitous presence of water in the environment make the study and characterization of pharmaceutical hydrates a subject of particular interest to the quality of the in-process material as well as on the performance of the final product. Many drug compounds produce crystalline hydrates. The temperature and humidity conditions used during the processing, handling and storage of pharmaceutical products has an important effect on the dynamics of hydration and dehydration pertaining to hydrate formation. The key to such dynamics is the energetics of the interaction of water with the drug molecule in forming the hydrate. Such an effect can be probed in practice through studies of hydration as a function of temperature and water activity. We present a case study where the energetics of hydration are such that the system can turn into one of three crystalline forms by small changes in temperature or relative humidity, near the typical ambient conditions. The example illustrates how characterization techniques can be integrated to create a phase diagram showing the conditions leading to different hydrated or dehydrated forms.

A. D. Otte, R. Pinal

Viscoelastic Sorption Behavior of Starch and Gluten

The migration of gasses and liquids through (bio) polymers plays an important role in numerous applications and processes like, e.g., drying and (re)wetting of foods and food ingredients, packaging, and controlled release. A good understanding of the transport mechanisms is therefore of great importance to control these processes. The transport of solvents through (bio) polymers is a complex process and involves diffusion due to water concentration gradients, swelling, shrinkage, and relaxation of the polymeric matrix. Often also transitions between the glassy, rubbery, and/or viscous states of the polymer system are involved. Here we report on a theoretical and experimental study of water transport in biopolymer films of starch and gluten.

M. B. J. Meinders, L. Oliver

Molecular Weight Effects on Enthalpy Relaxation and Fragility of Amorphous Carbohydrates

Many food processing techniques such as dehydration, concentration, extrusion, and freezing produce amorphous foods that can be stored below their glass transition temperature (Wungtanagorn and Schmidt 2001). Below glass transition temperature (

T

g

), amorphous food constituents exist in a thermodynamically unstable nonequilibrium and disordered state. Isothermal storage/aging of glassy amorphous food components results in structural relaxations that achieve a more stable equilibrium state over extended time periods (Struik 1978). Since the equilibrium state is a low energy state, some of the energy is lost/relaxed in the nonequilibrium glassy amorphous state during isothermal storage of food components. This energy can be recovered in the form of enthalpy during the reheating of the glassy system by using a differential scanning calorimeter, since physical aging is a reversible process. The enthalpy recovered during reheating of the aged material system is a measure of the system’s molecular mobility at the selected aging temperature (Gupta et al. 2004). Structural relaxation in the glassy state of amorphous food components during isothermal storage/aging is also known as enthalpy relaxation/physical aging. Many macroscopic properties of glassy materials, such as volume, enthalpy, refractive index, electrical conductivity, and viscosity, change during physical aging (Struik 1978). The changes in macroscopic properties may adversely affect the physicochemical stability during the isothermal storage of low water amorphous foods and food constituents (Farahnaky et al. 2008).

R. M. Syamaladevi, G. V. Barbosa-Cánovas, S. J. Schmidt, S. S. Sablani

Effect of Dehydration Conditions on the Bulk and Surface Properties of the Resulting Dehydrated Products

This study investigated the effects of dehydration conditions on the surface morphology and melting point of the resulting anhydrous product. The hydrate of thymine, theophylline and cytosine hydrate, were prepared and then dehydrated under various heating temperature conditions. The bulk properties and surface morphology of the hydrate and dehydrated samples were characterized using x-ray powder diffraction (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). It was found that although different heating temperatures gave the same solid state of processed samples, they displayed significant impact on the melting point and surface morphology of the samples.

Y. Zhang, M. T. Carvajal

Moisture Sorption Isotherms of Foods: Experimental Methodology, Mathematical Analysis, and Practical Applications

Knowing the moisture content of a product is insufficient to predict its stability, making it necessary to also know its water activity (

a

w

), a thermodynamic property describing the interactions between water molecules and the food matrix. Moisture sorption isotherms, i.e., the relationship between moisture content and

a

w

at constant pressure and temperature describing the sorption process of water molecules into a specific material, are useful when identifying optimal food dehydration and storage conditions. Moisture sorption properties affect physicochemical and biological phenomena such as enzymatic degradation, microbial activity, food microstructure, sensory quality deterioration, nutrient losses, and other changes limiting the shelf life of food products. Some of these phenomena are associated with water mobility, which is also related with the phase transitions from a “glass” or amorphous to a “rubbery” state. Glass transition is a second order phase transition associated with time, temperature, and moisture content. When fresh foods are dried, water removal leaves behind an amorphous material. A desirable final product moisture level is one that corresponds to a glass transition temperature (

T

g

) higher than the product storage temperature. Therefore, knowing

T

g

helps in setting the food storage and/or process conditions required to retain textural properties and to predict the shelf life of low and intermediate moisture content foods.

C. Caballero-Cerón, J. A. Guerrero-Beltrán, H. Mújica-Paz, J. A. Torres, J. Welti-Chanes

Understanding Cryopreservation of Oyster Oocytes from a Physical Chemistry Perspective

Cryopreservation applies to the freezing, storage (usually long-term) at a very low temperature, thawing, and successful recovery of living cells. There are seven basic steps in cryopreservation protocols: sample collection, maintenance of collected material in extender solutions, quality assessment, refrigerated storage, freezing, thawing, and viability assessment (Tiersch 2000). Cell viability can be affected at any of these steps, although most damage occurs due to exposure of cells to high concentrations of intra- and extracellular solutes or due to intracellular ice formation (IIF) during cooling and/or thawing. It has been suggested that the growth and propagation of intracellular ice crystals cause cell death through disruption of the cell membrane. Extracellular ice has also been shown to cause mechanical damage of cells (Sterling 1968; Rubinsky et al. 1990). The formation of extracellular ice also increases solute concentration in the remaining unfrozen matrix (Mazur et al. 1972; Pegg 2002), which leads to additional stress such as solute toxicity (Mazur et al. 1972) and causes cells to shrink osmotically (Lovelock 1953; Steponkus et al. 1983). The consequences of the freezing process on a cell are represented schematically in Fig. 1.

M. H. Lim, L. F. Siow, L. Salinas-Flores

The Role of Water in the Cryopreservation of Seeds

Plant genetic resources are vitally important for human beings and the sustainability of the planet. Biodiversity conservation is the practice of protecting and preserving the abundance and variety of all species (Lambardi et al. 2004; Walters 2006). Neotropical ecosystems are submitted to constant pressure by human activity; in these ecosystems the number of plants at risk of genetic depletion or extinction and the loss of important genetic resources is continuously increasing. Preservation of plant biodiversity avoids the risk that species and plant varieties may become extinct, producing a definitive loss of their genetic variability. Preservation of plants only in field collections is risky, as valuable germplasm can be lost (genetic erosion) because of pests, diseases, and adverse weather conditions.

N. E. Zaritzky

Water Activity and Microorganism Control: Past and Future

The influence of water or moisture content of foods on shelf-life has been recognized since early ages; most primitive cultures found a convenient way to reduce moisture content in foods to a level that prevents or delays microbial spoilage, such as drying, salting, and adding sugars. In some cases, the spoilage of products subjected to these procedures has also been referred to in the following ways: halophilic bacteria can grow in salted products; osmophilic yeasts may ferment sugar in preserved foods; and some dried foods can be spoiled by xerophilic molds (Mossel 1975). Substantial interest in the influence of water activity (

a

w

) on food product quality and stability, promoted by empirical observations between total moisture content and product stability, began during the middle of the last century. Scott (

1957

) introduced the concept of

a

w

as a quantitative approach to define the influence of moisture content on microbial response in foods. Microbiologists recognized that

a

w

, rather than moisture content, controlled microbial response, as well as sporulation and/or toxin production (Jay et al. 2005). The relationship between

a

w

and food-borne microorganisms has been the topic of study by food researchers over the past several decades (Christian 2000; Chirife 1995; Lenovich 1987). Microbiologists have investigated how microorganisms respond under different conditions of temperature, pH, additives, atmosphere composition, and

a

w

(Hocking and Pitt 1987; Beuchat 1996). The influence of

a

w

in microbial death, survival, sporulation, and toxin production in food has been extensively studied by food microbiologists (Lenovich 1987; Beuchat 1983, 1987; Hocking and Christian 1996; Gutierrez et al. 1995). The

a

w

principle has been included in various government regulations, with the recognition that control of

a

w

as an important critical control point for risk analysis, as defined by the HACCP concept, sets up

a

w

limits on food products.

A. López-Malo, S. M. Alzamora

On Modeling the Effect of Water Activity on Microbial Growth and Mortality Kinetics

The effect of moisture on the growth of different kinds of bacteria, yeasts, and molds in or on foods has traditionally been depicted in the form of a rate vs. water activity (

a

w

) plot. The rate curve of each organism type begins (or ends) at a point along the

a

w

-axis. At lower

a

w

levels, presumably, the particular type of organism does not grow, i.e., its growth rate is zero. While such plots can and have been successfully used to identify safe water activities for food storage, for example, they do not always tell the whole story. One reason is that the borderline between growth and no growth is rarely sharp. Another reason is that a plot of this kind does not fully reveal what happens above the marked water activity threshold. Moreover, in many foods, water activity control is accompanied by a drying process, in which case the temperature history may affect the type or number of organisms remaining in the food, and/or the introduction of a complementary agent such as salt or chemical preservative. To deal with these aspects of microbial growth inhibition, it is necessary to develop a kinetic model of growth whose parameters account for the role of all pertinent factors that affect a food’s biological stability and that of their interactions. The same can be said about chemical and physical changes that inevitably occur during food preservation, especially when heat is involved. Such changes are of two kinds: degradation, notably the loss of freshness and nutrients, or synthesis, notably the accumulation of Maillard reaction products, but also other compounds that impart off flavor. Water activity, and factors such as pH and salt concentration, affect the heat resistance not only of microorganisms, including bacterial spores, but also of enzymes. The subject has been amply studied and there is a large body of literature covering its various aspects.

M. Peleg, M. G. Corradini, M. D. Normand

Importance of Halophilic and Halotolerant Lactic Acid Bacteria in Cheeses

Water plays a significant role in cheese texture and in bacterial metabolism and consequently is very important for the events that occur during cheese ripening. The influence of water content and water activity (

a

w

) on cheese quality is very complex, due to changes in chemical composition during the continuous ripening of the product. Salt, along with pH, water activity, and redox potential, helps to minimize spoilage and prevents the growth of pathogens and spoilage organisms in cheese. This dairy product contains different low molecular weight compounds which are partly produced during ripening or, as in the case of salt, are added during manufacturing. These low molecular soluble compounds are mainly responsible for the water activity in cheeses.

G. Melgar-Lalanne, F. Morales-Trejo, Y. Rivera-Espinoza, H. Hernández-Sánchez

Influence of Water Activity and Molecular Mobility on Peroxidase Activity in Solution

Water is one of the most critical components in foods and biological systems because it affects several physicochemical properties of these systems with effects on their chemical and enzymatic stability (Bell 2007).

G. Sacchetti, L. Neri, G. Bertolo, D. Torreggiani, P. Pittia

Phase Transitions in Sugars and Protein Systems: Study of Stability of Lysozyme in Amorphous Sugar Matrices

In the last decades, development of products resulting from the application of molecular biology and biotechnology has demonstrated accelerated progress; as a result, the use of biological products such as proteins and enzymes has increased considerably in the food and pharmaceutical industry (Wanh 2000). Since most of these biomolecules, particularly enzymes, are extremely sensible to changes in temperature, pH, ionic force, and water concentration, scientists in these fields are in constant search of new methodologies and techniques to improve their stability. In industrial processes, biomolecules are obtained in aqueous solutions; however, in this medium their shelf life is relatively short. A remarkable improvement in the stability of protein based drugs has been obtained when these biomolecules are taken to a dry state; unfortunately, the freeze drying or spray-drying processes (which are the most common used techniques to obtain dry protein) expose these molecules to extreme conditions that cause a considerable decrease in their activity (Passot et al. 2005; Liao et al. 2004; Hinrichs et al. 2001; Heller et al. 1999).

L. M. Martínez, M. Videa, F. Mederos, Y. de Moral, M. Mora, Cristina Pérez

An Exhaustive Study on Physicochemical and Structural Changes During Drying of Apple Discs

Dehydration is one of the most employed techniques in the preservation and development of foods. Water is a vital component in the structural preservation and functional integrity of vegetable tissues. As a consequence of its removal during convective air drying, great physicochemical changes in biopolymer composition and spatial conformation are presented, inducing disarrangements and/or destruction of the natural structure, shrinkage, changes in water and biopolymer mobility and distribution, changes in thermal transitions, color changes, and modification in mechanical properties, among others. These characteristics have been identified as the most important properties associated with modifications in quality properties of fruits (Chapman 1994; Krokida et al. 1998, 2000; Ruan and Chen 1998).

S. M. Casim, M. F. Mazzobre, S. M. Alzamora

Defining High and Low Spray Drying Temperatures for Aloe vera Gel

Spray drying is widely used in the food industry to obtain products in the form of powder (Masters 1991; Filková and Mujumdar 1999; Nijdam and Langrish 2005; Roustapour et al. 2006; León et al. 2010). Three types of modes of contact between drying air and the food product can be found: parallel (co-current), counter-current, or mixed (fountain). The latter is a combination of parallel and counter current flow patterns, which implies that the already dry material comes into contact with drops being sprayed, favoring the formation of agglomerates. In turn, the formation of agglomerates raises the rehydration capacity of the final product (Masters 1991; Vega et al. 2001; Peighambardoust et al. 2011). Although spray drying is a common method used for drying thermolabile materials, there are few reports about the dehydrating conditions used for

Aloe vera

industrial processing. This plant is widely used in the pharmaceutical, cosmetological, and food areas because of the beneficial effects it provides as a functional ingredient in food and cosmetic products (Simal et al. 2000). However, it has been reported that when gel obtained from the

Aloe vera

leaf is subjected to thermal processing, changes in its components and functional properties, such as wettability, water retention, and oil adsorption capacity, among others, can occur (Eshun and He 2004; García et al. 2010). Aloe gel contains 98.5 % water, and the remaining solid material consists of polysaccharides, fat, and water-soluble vitamins, minerals, enzymes, phenolic compounds, and organic acids (Bozzi et al. 2007; Eshun and He 2004; Hamman 2008). Several studies have focused on assessing the physical, chemical and functional changes caused by

Aloe vera

gel processing conditions, especially during dehydration through convective drying (Simal et al. 2000; Femenia et al. 2003; Miranda et al. 2009; García et al. 2010; Gulia et al. 2010). However, to date there is limited data regarding the effect that spray drying temperature has on the physical, calorimetric, and functional characteristics of

Aloe vera

. Therefore, the objective of this study was to evaluate the effect of spray drying temperatures on obtaining

Aloe vera

gel in powder form.

I. N. García-Luna, J. Porras-Saavedra, F. Vergara-Balderas, J. Welti-Chanes, G. F. Gutiérrez-López, L. Alamilla-Beltrán

Mexican Plum (Spondias purpurea L.) Moisture Sorption Properties

Fresh fruits, no matter where they come from, are perishable products due to their high moisture content. Some fruits are protected with an external thick peel or film that allows them to remain fresh for a long time if they are appropriately handled. However, other fruits, even though they have a thick peel, have very short growing periods. This is the case of prickly pear, mamey, litchi, pitaya or pitahaya, black and yellow sapote, and Mexican plum, just to mention a few. Pitaya or pitahaya and Mexican plum possess a delicate peel that may allow the fruit to remain fresh for a very short time, after which the peel can become dry or be broken due to dryness or overripening. All of these fruits grow in Mexico because of the microclimates that exist throughout the country. Therefore, to take advantage of these fruits that last for a short time or because of overproduction, it is necessary to apply or use conventional and/or new processing technologies to deliver new or processed fruit products to domestic and overseas consumers.

J. A. Guerrero-Beltrán, F. Ruiz-Hernández, J. Welti-Chanes

Antioxidant Activity of Microencapsulated Capsicum annuum Oily Extract Obtained by Spray Drying

There is great interest today in development of food additives obtained from vegetables and fruits, due to the presence of phytochemicals and the potential use of these substances as functional ingredients. Chiles are used in the manufacture of condiments and food formulations because of their pigmentation and flavor. In addition to its provitamin and antimicrobial properties (Acero-Ortega et al. 2005), Capsicum has shown antioxidant activity because of its content of polyphenolic compounds and carotenoids. Carotenoid consumption has been associated with a lower risk of developing chronic degenerative diseases (Matsufuji et al. 1998; Dutta et al. 2005). In some studies, certain carotenoids were identified in the fruits of dry chile (

Capsicum annuum

L. grosum Sendt), such as β-carotene, α-carotene, β-cryptoxanthin, zeaxanthin, lutein, capsanthin, capsorubin, and criptocapsina (Collera-Zúñiga et al. 2005). Carotenoids can be extracted from chile’s natural matrix in order to use their properties as phytochemicals; however, due to the unsaturated nature of chile’s molecular structure, once carotenoids are extracted, they can be modified by isomerization and subsequent oxidative degradation, resulting in the loss of antioxidant activity with formation of fractions carotenoids called apocarotenoids (Maoka et al. 2001).

A. Y. Guadarrama-Lezama, L. Alamilla-Beltrán, E. Parada-Arias, M. E. Jaramillo-Flores, G. F. Gutiérrez-López, L. Dorantes-Álvarez

Physical–Chemical Properties and Microstructure of Agave Powders Obtained by Spray Drying

In Mexico, the

Agave

plant is an important economic and cultural resource, representing great native biodiversity due to the taxonomic diversity of the species within its territory, such as the

Agave angustifolia

Haw. Agave plants contain sugars and fructooligosacharides (FOS) as reserve polymers with special characteristics that allow diversification of its use in foods (García-Mendoza 2002; Madrigal and Sangronis 2007).

M. F. Fabela-Morón, J. Porras-Saavedra, R. Martínez-Velarde, A. Jiménez-Aparicio, M. L. Arenas-Ocampo, L. Alamilla-Beltrán

Stabilization and Controlled Release of Invertase Through the Addition of Trehalose in Wet and Dried Alginate-Chitosan Beads

The stability and controlled release of certain active substances (such as flavors, drugs, enzymes, essential oils, etc.) can be achieved through encapsulation. Ionically cross-linked hydrogels such as alginate- or alginate-chitosan-CaCl

2

beads were proposed as suitable materials for encapsulation systems (Deladino et al. 2008; Han et al. 2008). Alginate beads coated with chitosan were used for encapsulation and release of different proteins (Coppi and Iannuccelli 2009; Zhou et al. 2010). Direct interaction between them forms beads with improved mechanical properties associated with reinforcement of bead structure due to chitosan binding to free alginate sites by cooperative ionic bounds (Deladino et al. 2008).

P. R. Santagapita, M. F. Mazzobre, M. P. Buera

Rheology and Stability of Citral/Sugar Microemulsions

Microencapsulation of hydrophobic flavors is of great importance in the flavoring and food industries, since solid or liquid microencapsulated food flavors exhibit good chemical stability and a controlled release. Spray drying is generally used to produce flavor powders in a short time (Gharsallaoui et al. 2010). As an initial step for drying, oil flavors must be emulsified. It is possible to form emulsions that are kinetically stable for a reasonable period of time by including substances known as emulsifiers and/or thickening agents prior to homogenization (McClements 1999). The choice of a wall material for microencapsulation by spray drying is very important for encapsulation efficiency and microcapsule stability. The carrier material should dissolve easily and be water soluble, bland, and inexpensive, have good oil-emulsifying and droplet-stabilizing properties, exhibit low solution viscosities at high solids levels, and have excellent film-forming properties and form amorphous powders upon drying. Carrier systems are usually formulated by combining a number of water-soluble components (carbohydrates, gums, and proteins) (Gharsallaoui et al. 2010). It is well known that, among other factors, the type of carrier governs flavor retention during the spray-drying process (Thijssen 1971); for this reason, disaccharides are sometimes included in commercial formulations to improve retention characteristics.

N. Sosa, C. Schebor, O. E. Pérez

Response Surface Methodology to Assay the Effect of the Addition of Proteins and Hydrocolloids on the Water Mobility of Gluten-Free Pasta Formulations

In gluten-free pasta formulation (suitable for those suffering from celiac disease), the influence of each constituent has a major importance on the final product quality, especially water and hydrocolloid contents used to replace the gluten matrix. Gluten-free doughs are mixed dispersed systems; the dispersion medium contains several types of dispersed particles, with two main construction materials—polysaccharides and proteins. Four levels of structural hierarchy in dispersed food systems can be distinguished: submolecular, molecular, supermolecular, and macroscopic. Structural functions of a biopolymer depend upon its place in the structural hierarchy of the product (Tolstoguzov 2000).

V. J. Larrosa, G. Lorenzo, N. E. Zaritzky, A. N. Califano

Effects of a w Reduction and Type of Sugar in Rheological Behavior, Water Mobility, and Structural Changes in Apples

Osmotic dehydration is an operation that is commonly used to obtain minimally processed high-moisture fruits with characteristics close to those of fresh fruits. Many mechanisms are involved in mass transfer of solutes inside the product with an opposite flux of water, but also physical, micro-, and macrostructural modifications occur that influence interactions between water, structure, chemical compounds, and the mechanical behavior of fruits (Alzamora et al. 2000).

S. Vicente, A. Nieto, S. M. Alzamora

Effect of Water Content on Thermo-Physical Properties and Freezing Times of Foods

For the prediction of temperature change in different foodstuffs during freezing and thawing processes, accurate estimation of the thermo-physical properties of the product is necessary, such as specific heat, density, freezable water content, enthalpy, and initial freezing temperature. These data allow the adequate design and optimization of equipment and processes. Water is a main component in all foods and greatly influences the behavior of these properties, depending on its concentration. During the freezing process, which involves the phase change of water into ice, the specific heat, thermal conductivity, and density undergo abrupt changes due to the latent heat release. This complex process does not have an analytical solution and it can be described as a highly nonlinear mathematical problem. Many difficulties arise when trying to numerically simulate the freezing process, especially when using the finite element method (FEM), which is especially useful when dealing with irregular-shaped foodstuffs. Several techniques have been applied to consider the large latent heat release when using FEM. One traditional method is the use of the apparent specific heat, where the sensible heat is merged with the latent heat to produce a specific heat curve with a large peak around the freezing point, which can be considered a quasi-delta-Dirac function with temperature (depending on the amount of water in the food product) (Pham 2008). However, this method usually destabilizes the numerical solution. Implementation of the enthalpy method, which can be obtained through the integration of the specific heat with temperature (Fikiin 1996; Comini et al. 1990; Pham 2008; Santos et al. 2010), and the Kirchhoff function, which is the integral of the thermal conductivity, allows the reformulation of the heat transfer differential equation into a transformed partial differential system with two mutually related dependent variables

H

(enthalpy) and

E

(Kirchhoff function) (Scheerlinck et al. 2001). These functions,

H

and

E

versus temperature, are smoother mathematical functions compared to the specific heat, thermal conductivity, and density versus temperature, avoiding inaccuracies and/or divergence of the numerical method. Even though it brings great advantage to the resolution of the problem, with the simultaneous enhancement of the computational speed of the program, this transformation of variables is not widely used in the literature. Unleavened dough and cooked minced meat were selected due to their significant difference in water content in order to explore the performance of the computational code written using the enthalpy-Kirchhoff formulation. Another important reason is because cooked minced meat and dough are both present in several ready-to-eat meals, therefore contributing valuable information to food processors interested in optimizing cooling and freezing operating conditions of semi- or fully processed goods. The objectives of this work are (1) to experimentally determine by differential scanning calorimetry (DSC) the thermo-physical properties of dough and cooked minced meat in the freezing range: specific heat as a function of temperature, bound water, heat of melting, initial freezing temperature, etc.; (2) to develop and validate a finite element algorithm to simulate the freezing process in regular and irregularly shaped foodstuffs; and (3) to introduce appropriate equations of the thermo-physical properties in the numerical program to assess the effect of total water content, bound water, and surface heat transfer coefficient on freezing times in an irregular food system.

M. V. Santos, V. Vampa, A. N. Califano, N. E. Zaritzky

Influence of Fluid Concentration on Freezing-Point Depression and Thermal Conductivity of Frozen Physalis Juice

The physalis (

Physalis peruviana

l.), member of the family

Solanaceae

and the genus

Physalis

spp., consists of more than 80 varieties; their main characteristic is that their fruits are locked inside a sepal in bucket form. This fruit, originally from the South American Andes, is the best known species of this genus. It is also characterized by its high sugar content and significant amount of vitamins A, B, and C, as well as iron and phosphorus, which could be considered as medicinal properties (Puente et al. 2010). Colombia is the main producer of physalis, followed by South Africa. Colombian physalis is characterized as having a more pronounced color and higher sugar content, making it more appealing in the market. At present, various processed products from the physalis are available, including jams, jellies, raisins, and candies covered in chocolate, juices, nectars, and pulps. According to the National Research Council, the juice of overripe physalis has a high pectinase content, making it an excellent raw material to prepare jams and derivative products, with low production costs (Ministerio de Agricultura y Desarrollo Rural 2009).

J. Telis-Romero, G. I. Giraldo-Gómez, H. A. Villa-Vélez, D. M. Cano-Higuita, V. R. N. Telis

Freezing Rate Effect on Thermal Transition of Blueberries

World blueberry consumption has risen mainly because of its health benefits (Nicoletta et al. 2008), such as low calories and the presence of anticancer and antioxidant compounds that prevent various diseases, which is why blueberries have become an important component of a healthy diet (Yrjo et al. 1996). Chile is the biggest producer of blueberries in South America and the largest exporter to northern markets (Federación de Productores de Fruta de Chile 2009; Frederick 2009). Blueberries are small blue fruits from the genus

Vaccinium

, with high nutritional value and potential anti-disease effects, but with a short shelf life of about 20 days under refrigeration conditions at a temperature close to 0 °C (Yommi and Godoy 2010). Due to its short shelf life, conservation methods such as freezing are required. The effect of freezing rates on fruit quality and their optimal conditions are strongly dependent on the type of food.

P. Díaz-Calderón, O. Henríquez, J. Enrione, S. Matiacevich

Glass Transition Temperature of Some Thai Fruits Using Differential Scanning Calorimetry: Influence of Annealing and Sugar Composition

Glass transition is a nature of second-order time-temperature-water dependent transition, which is generally characterized by a discontinuity in physical, mechanical, electrical, thermal, and other properties of a material. In the case of complex multicomponent mixtures, such as foods, the discontinuity occurs in a range of temperatures. The most common method used to determine glass transition temperature (

T

g

) is differential scanning calorimetry (DSC), which detects the change in heat capacity (

C

p

) that occurs over the transition temperature range (Roos 1995; Rahman 2004).

S. Charoenrein, N. Harnkarnsujarit, N. Lowithun, K. Rengsutthi

Effect of Emulsifier on Complex Formation and In Vitro Digestibility of Gelatinized Potato Starch

It is known that amylose and lipid compounds form a helical inclusion complex in gelatinized starch. The complex formation has attracted much attention because of impact on retrogradation (Tufvesson et al. 2001), in vivo (Holm et al. 1983) and in vitro (Guraya et al. 1997; Crowe et al. 2000) digestibility, and rheological properties (Kaur and Singh 2000; Gelders et al. 2006) of gelatinized starch.

K. Kawai, S. Takato, K. Kajiwara

Influence of Alcohols and Polyols on the Behavior of Aqueous Solutions of β-Lactoglobulin at pH 5.5

Protein native conformation is controlled by molecular interactions among protein and solvent molecules and intramolecular interactions between protein functional groups. Several factors affect these interactions, such as changes in temperature, pressure, pH, ligand concentration, or solvent modifications caused by the presence of different substances.

G. I. Giraldo, C. M. Romero

Effects of Protein Conformational Modifications, Enthalpy Relaxation, and Interaction with Water on the Solubility of Milk Protein Concentrate Powder

Milk protein concentrate (MPC) powder is produced from skim milk by ultrafiltration/diafiltration followed by spray drying. It contains varying amounts of protein up to 85 % (w/w). The use of MPC as a food ingredient is increasing worldwide due to its favorable functional properties and high nutritional value. However, MPC gradually loses solubility upon storage. Generally it is believed that the loss of solubility is linked with conformational modification of protein molecules during processing and storage. Besides, other factors like enthalpy relaxation of amorphous MPC powder during storage and interaction with water may have detrimental effects on the solubility of MPC upon ageing. This review highlights some underlying molecular mechanisms of protein denaturation that induce solubility loss in MPC powder.

E. Haque, B. R. Bhandari

Active Edible Films Based on Modified Corn Starch for Food Applications

The lifestyle of consumers along with the desire to consume naturally healthy beneficial products has increased the demand for production of fresh produce. Minimally processed fruits and vegetables deteriorate over time, either by means of microbial activity or by physicochemical reactions with the food environment. Therefore, the food industry is investigating ways to protect the integrity and quality of their products by developing better packaging technologies that can maintain or improve the quality attributes of fresh produce, as well as extend their shelf life and ensure the microbiological stability.

T. Arredondo-Ochoa, Y. M. Márquez-Hernández, B. E. García-Almendárez, C. Regalado

Influence of Moisture Content and Temperature on the Stability of a Dehydrated Probiotic Dairy Product Containing Bifidobacterium infantis or Lactobacillus acidophilus

Since the beginning of the twentieth century, there has been growing interest in the health benefits provided by probiotic bacteria (Trebichavský and Šplíchal 2006). A variety of subjects of interest revolve around this theme, such as the mechanisms of action of probiotic bacteria in providing therapeutic effects, the research of probiotic microorganisms, and the development of new probiotic products.

G. Trujillo-de Santiago, C. Rojas-de Gante

Effect of Relative Humidity on Shrinkage and Color Changes in Dehydrated Strawberry

Dehydrated fruits are prone to discoloration during storage. Many natural pigments are unstable in dried fruits, and brown pigments can be formed. The rate of physical and chemical changes in dried vegetables and food models is slow in the glassy state. At temperatures above the glass transition, in addition to decreasing viscosity and increasing rate, other changes such as crystallization and structural collapse affect the rate of discoloration (Karmas et al. 1992). Diffusion-controlled chemical reactions are particularly dependent on translational diffusivity of the reactants (or on the viscosity of the matrix material) and are thus susceptible to the physical state of the system (Slade et al. 1995). It has been shown that matrix collapse caused by storage above the glass transition temperature (

T

g

) or by mechanical compression and porosity (Burin et al. 2004; White and Bell 1999) affected browning rates, indicating that besides water content, system structure plays a relevant role.

L. M. Agudelo-Laverde, N. Acevedo, C. Schebor, M. P. Buera

Effect of Blanching and/or Osmotic Dehydration on Texture and Rheological Properties of Apple Tissue

Texture is a key quality attribute that is critical in determining the acceptability of raw and processed fruits. Texture and rheological properties of biological tissues depend on the contribution of different levels of structure and their chemical and physical interactions. Heating process and mass transfer during osmotic dehydration of fruit tissues take place simultaneously, with complex physical and structure modifications that influence and produce specific rheological behaviors and sensory responses.

A. B. García Loredo, S. Guerrero, S. M. Alzamora

Water Activity Depression of Tejocote Fruit (Crataegus pubescens) Using Osmotic Solutions and Pressure Gradients

Tejocote is a native fruit to Mexico. Peeled tejocote is commonly preserved by cooking it in sucrose solutions and packed in hot sterilized jars. Such process involves moisture removal and solute impregnation, whose overall effect reduces water activity of the product. The objective of this work is to determine the effect of syrup concentration and processing time on aw of osmodehydrated tejocote, at ambient temperature. Peeled tejocote was subjected to dehydration impregnation with vacuum pulse of 50 cmHg for 3 min and 0.5–5 days of immersion in sucrose solutions (30–50 %), using the response surface methodology. A significant model (

p

 < 0.01) was obtained to describe aw of osmodehydrated tejocote, as a function of the studied variables. Important aw depression was achieved (0.930) after 3 days of processing. Studied osmotic dehydration conditions allowed to reduce aw of peeled tejocote, to levels that would enhance its stability.

A. Valdez-Fragoso, J. Welti-Chanes, H. Mújica-Paz

Prediction Approach to the Glass Transition Temperature of Amorphous Carbohydrate Polymer

Most of carbohydrate polymers exist, at least partially, in an amorphous state, and thus, glass transition occur during dehydration/rehydration and cooling/heating processing. Since various physical properties are changed drastically by the glass transition (Levine and Slade 1988; Roos 1995; Le Meste et al. 2002), it is important to understand the glass transition temperature (

T

g

).

K. Kawai, K. Fukami, P. Thanatuksorn, C. Viriyarattanasak, K. Kajiwara

Effect of Sugars on the Release of Aroma Compounds in Model Systems

Kinetic and thermodynamic mechanisms control the rate of release and the concentration of volatiles in the vapor phase in equilibrium with a food. Chemical nature of the aroma compounds, composition, and structure of foods are main characteristics that influence the transfer of aroma compounds within the foods and their release (Seuvre et al. 2006; Cayot et al. 2008). Besides the intrinsic characteristics of aroma and food matrix and the environmental factors, interactions occurring between volatile and nonvolatile compounds (in particular those with food macromolecules like proteins, hydrocolloids, and carbohydrates) are major factors that limit the release of volatiles, and thus their perception, as demonstrated by many studies in this field.

P. Pittia, P. Piccone, M. Martuscelli

Wetting Behavior of Chitosan Solutions on Blueberry Epicarp With or Without Epicuticular Waxes

Edible coatings can prevent microbial spoilage and quality loss of blueberries due to mass transfer (e.g., moisture, gases, aroma compounds, etc.). The protection of blueberry (and in foods in general) by edible coatings depends on controlling the wetting of the coating solutions, which affects the adhesion and the thickness of the film (Park 2002). Indeed, the thickness of edible coatings is an important parameter since it directly affects the biological properties and the shelf-life of blueberries. The central parameter that characterizes the wetting of a blueberry epicarp is the equilibrium contact angle (CA) (Israelachvili 1992). By convention, the CA is the angle,

θ

, at which a liquid–vapor interface meets the solid surface. Surface free energy (SFE) of blueberry epicarp can be obtained using different approaches. All of these methods are based on CA measurements of different sessile liquid drops with known surface tension deposited on the blueberry epicarp, but discrepancies have been shown in the obtained results (Etzler 2006). One of the main methods for the determination of SFE is the “acid–base” theory of van Oss, Chaudhury, and Good (vOCG) (van Oss et al. 1986, 1988).

O. Skurtys, P. Velásquez, F. Osorio

Influence of Brine Concentration on Moisture and NaCl Transport During Meat Salting

In meat brining, the concentration of brine could affect both water and NaCl transport and, consequently, the total length of the treatment and the final quality of the product. In the present work, the kinetics of water and NaCl transport during the brining of pork loin slices in different brine concentrations (50, 100, 150, 200, 240 and 280 kg/m3) were determined (5±1 °C). In the case of moisture content, the brine concentrations of under 200 kg/m3 led to significant (p < 0.05) sample hydration. Close to this concentration, no net water transport took place, and above it, samples were dehydrated. As regards the evolution of NaCl content, the higher the concentration of brine used, the greater the NaCl content in the sample. The identified effective moisture diffusivity showed a tendency to decrease when the brine concentration rose, changing from positive (hydration) to negative values (dehydration). For NaCl, the identified effective diffusivity remained constant with brine concentration (1.90±0.28) 10

–10

m

2

/s.

C. Ozuna, J. A. Cárcel, J. V. García-Pérez, R. Peña, A. Mulet

Relationship Between Electrical Conductivity and Water Activity of Starch-Water Composites

When electrical conductivity (EC) is studied in food hydrocolloids, such as starch, molecular structure is important because conductivity depends on the interaction of water with charged carboxyl group or hydroxyl groups (Marcotte et al. 1998). Several authors have found that EC of starch-water composites increases with temperature and decreases during starch gelatinization (Wang and Sastry 1997; Karapantsios et al. 2000; Li et al. 2004). This behavior is explained considering granule swelling, increase of viscosity, and reduction of the area for starch particle movement. Decreasing water content in the material decreases EC (Lewicki Piotr 2004).

E. Morales-Sánchez, M. L. Reyes-Vega, M. Gaytán-Martínez, J. D. Figueroa-Cárdenas, G. Velázquez

Water Content, a w, and Enzyme Activity (Xaa-Prolyl-Dipeptidyl Aminopeptidase) During the Germination Process of Cocoa Beans (Theobroma cacao L.)

Cacao seeds demonstrate epigeal (or epigeous) germination in which the hypocotyl elongates and forms a hook, pulling rather than pushing the cotyledons and apical meristem through the soil. Once it reaches the surface, it straightens and pulls the cotyledons and shoot tip of the growing seedlings above the ground (Bewley 1997). After the cocoa seeds are removed from the fruit they germinate rapidly, 4–6 days after planting. The root and the hypocotyle emerge first, which causes the cotyledons to elevate above the substrate (10 or 15 days after planting). The cotyledons then open and expose the plumule, which begins to grow at the same time as the root, but it is much smaller. The first phase of growth is completed with the maturation of the first leaves (López-Andrade 2003). This means that germination commences with the uptake of water by dry seed imbibition and is completed when a part of the embryo, usually the radicle, extends to penetrate the structures that surround it (Bewley 1997).

M. L. Sánchez-Mundo, M. X. Quintanilla-Carvajal, C. Bautista-Muñoz, G. F. Gutiérrez-López, M. E. Jaramillo-Flores

Water Fraction Effect in the Rheological Behavior of Jalapeño Pepper Pulp

Rheological characteristics of jalapeño pepper pulp as a function of the water fraction at 30 °C were investigated. Jalapeño pepper pulp was analyzed in a rheometer with concentric cylinder geometry under controlled shear rate and temperature. Flow curves were obtained in duplicate with shear rate ramps from 1 to 442 s

–1

. The studied range of water fraction was from 0.54 to 0.76. Five empirical non-Newtonian models were fitted to experimental data of jalapeño pepper pulp. The shear stress increased with increasing shear rate and decreasing water fraction. Jalapeño pepper pulp behaved as a pseudoplastic fluid and the Herschel-Bulkley and Sisko models described well the shear stress – shear rate behavior, with coefficients of determination about 0.99. The yield-stress, consistency index and behavior index for Herschel-Bulkley model increased as the water fraction of the jalapeño pepper pulp decreased.

F. Santoyo, J. Viganó, J. Telis-Romero

Study of Water Quality Through Hydro-Chemical Signature in León, Guanajuato, Mexico

The aquifer system of Valle de León (VL) is a free aquifer that consists mainly of sedimentary Tertiary rocks of lacustrine origin (Fig. 1). This valley presents different hydraulic conductivity stratifications that store water with various chemical and isotopic characteristics, so this water represents its different origins. According to the most recent census (Instituto Nacional de Estadística y Geografía, INEGI), VL has a population of 1,436,480 inhabitants, living in 11 population centers; it is the region’s most important industrial corridor and is included in one of Mexico’s most productive agricultural zones. VL covers approximately 687 km

2

surrounded by higher altitude topographic zones. The water supply of the population is mainly groundwater. This comes from deep wells, which are located mostly in irrigation zones but also in urban and rural zones of VL.

S. A. Cortés, G. A. Lozano, J. Pérez

Calorimetric and Thermogravimetric Analysis of Agave tequilana Weber Fibers

Agave tequilana

crop waste provides lignocellulosic material that can be exploited through the surface treatment of the fibers, such as by soaking in acid-alkali media, which allows for the separation of water-soluble components such as pectins, sugars, and fructooligosaccharides from insoluble components such as hemicellulose and lignin fibers. This treatment also improves the properties of the fibers in terms of their thermal stability and tensile strength, which is necessary for developing composites because it allows for the removal of impurities such as waxes, pectin, and minerals, increasing the fibers’ surface area (Ben Sghaier et al. 2012; Rosli et al. 2013). The objective of this research was to characterize lignocellulose fibers from

A. tequilana

Weber by calorimetric and thermogravimetric techniques.

C. De Dios-Naranjo, R. Mora-Escobedo, G. F. Gutiérrez-López, J. Solorza-Feria, A. Flores-Morales, H. Yee-Madeira, L. Alamilla-Beltrán

Study of Allspice Fluidized Bed Drying (Pimenta dioica L. Merrill) by Biochemical and Structural Analysis

Allspice (

Pimenta dioica

L. Merrill) is a spice native to Southern Mexico that can be used in different ways, from the pharmaceutical industry to the food industry, and it is well known for its flavoring properties from antiquity to today (Macía 1998). Allspice contains a number of antioxidants, which has caught the attention of researchers in this field.

A. E. Carpinteyro-Díaz, I. Anaya-Sosa, M. T. Cruz y Victoria, T. Santiago-Pineda

Refined Hemisphaericin Stabilization by Microencapsulation with Arabic Gum and Spray Drying

Hemisphaericin, the protease from the fruits of

Bromelia hemisphaerica

, is found as a complex of nine multiple molecular forms, identified by isoelectric points distributed over a pH range from 3.5 to 9.0 (Garduño et al. 1974). Cortés-Vázquez et al. (2008) have reported the purification and characterization of hemisphaericin-C, a 24 kDa cationic protease with primary substrate specificity of dual type. On the other hand, several studies on industrial applications for hemisphaericin have been carried out successfully, including fish protein solubilization, beer chill proofing, malt adjunct hydrolysis, plant protein functional property improvement (Briones-Martínez et al. 1994), and antioxidative peptide production from whey proteins (Palma-Rodríguez 2008).

L. A. Reyes, M. I. Cortés-Vázquez, M. C. Oliver-Salvador, J. Yáñez-Fernández, R. Briones-Martínez

Salt Crystallization in Chitosan Films as Affected by Solvent pH and Moisture Content

Chitosan (CH) is a cationic biopolymer used as a matrix to develop edible films and coatings for food applications. When developing chitosan-based film-forming dispersions and films, CH is usually dissolved in aqueous acetic acid solutions (pH = 3.8); sodium hydroxide is often added to increase the pH of the solvent, thus preventing film solubilization at high relative humidity conditions, which can cause changes in the solvent properties (pH and ionic strength) affecting the structure and properties of the obtained films. This is particularly significant for chitosan, since its conformation in solution greatly depends not only on structural parameters like the degree of acetylation and chain length, but also on solution parameters such as ionic strength, solvent, temperature, and pH (Sorlier et al. 2002). During film drying, changes in solvent properties occur in line with water evaporation: increase in ionic strength, change in pH, and conformational modifications in the polymer chain. Moreover, when sodium hydroxide is added to chitosan-based film-forming dispersions, sodium-acetate tri-hydrate salts can crystallize, since these are oversaturated when the film reaches determined water content, depending on molecular mobility, which in turn is greatly affected by film moisture content.

M. Vargas, C. González-Martínez, A. Chiralt

Water Antiplasticization Effect in Biscuits as Affected by Glucose and Sucrose Addition

Water is the most effective plasticizer in food matrices, decreasing glass transition temperature (Tg) and mechanical resistance and determining a softening effect with concentration increase.

P. Pittia, G. Di Teodoro, G. Sacchetti

Physicochemical Characterization of Regional Breads Produced in the Northern Mountains of Puebla State, Mexico

Water exists in foods in free and bound forms; only unbound water is available for microbial growth and biochemical reactions (Prior 1979; Troller 1980). Measurement of unbound water is termed water activity (

A

w

) and is defined as the ratio of partial vapor pressure of water in the air to the vapor pressure of water vapor in saturated air at the same temperature (Scott 1957). This measurement is numerically equal to the relative humidity at equilibrium expressed as a fraction. Techniques for measurement of

A

w

have been reviewed by Prior (1979) and Troller and Christian (1978). In addition, two collaborative studies have compared the various methods (Labuza et al. 1976; Stoloff 1978). Bread is one of the oldest food products consumed by humans. There is clear evidence of its use by different civilizations since prehistoric times. Bread has been a popular product because of its nutritious properties, and this product uses common ingredients as salt, sugar, and yeast (Serna 1996). Bread is a basic food made with cereals, usually in the form of flour, and liquid means, usually water. One of the greatest differences in bread production is the addition of leavening. Bread can be identified by very different names according to its form, weight, color, texture, etc., and the way in which it is presented in different countries as well as in different localities. In Mexico, baking product consumption is high, where approximately 750 varieties of sweet bread exist (CANAIMPA 2007).

N. Güemes-Vera, S. Soto-Simental, M. I. Reyes-Santamaria, J. F. Hernández-Chávez

Structural Relaxation of Salmon Gelatin Films in the Glassy State

The unique property of gelatin to form networks and induce plasticity and elasticity is considered beneficial in the preparation of biopolymer-based packaging materials. However, its use in food products has been limited by some religious groups (Gudmundsson 2002). Gelatins from marine sources have emerged as an alternative, although they are different from mammalian collagen in terms of their biochemical constituents and therefore in their functional properties. It has been shown that cold-water fish collagen can have a lower content of amino acids (~16–18 %) (Gilsenan and Ross-Murphy 2000). Joly-Duhamel et al. (2002) established a positive correlation of the concentration of amino acids, proline (Pro) and hydroxyproline (Hyp), with the melting temperature of native collagen (helix to coil) and gelatin molecular weight with renaturation temperature (coil to helix), suggesting an important effect of biochemical composition on the structure stability of the gel network. An aspect that has not been explored in detail for marine gelatin is the structural stability of these systems at temperatures below their glass transition temperature (

T

g

). Early studies in glassy carbohydrates by Noel et al. (1999) described the ageing kinetics of maltose in the glassy state in terms of an overshoot in heat capacity on consecutive heating runs using a differential scanning calorimeter (DSC). Badii et al. (2005) evaluated the kinetics of enthalpic relaxation of bovine gelatin state as a function of the difference between ageing temperature and

T

g

. In their later work, the same authors quantified the enthalpic relaxation of the same model system by DSC, correlating enthalpic values with an increase in the elastic modulus (

E

) obtained by mechanical spectroscopy. Work by Lourdin et al. (2002) described the mechanical relaxation of amorphous potato starch in the glassy state, obtaining characteristic relaxation parameters by the application of the Kohlrausch–Williams–Watts (KWW) model (Eq. 1). Anderssen et al. (2004) discussed the KWW equation in terms of a spectrum of relaxation times describing the ageing of a polymer. The KWW is an equation that can quantitatively describe the kinetics of the relaxation process toward an absolute relaxed state (Anderssen et al. 2004):

ϕ

t

=

exp

t

τ

0

β

$$ \phi (t)= \exp \left[-{\left(\frac{t}{\tau_0}\right)}^{\beta}\right] $$

where

φ

is the relaxation function,

t

is time,

β

(0 < 

β

 ≤ 1) is the width of the relaxation time distribution spectrum, and

τ

0

is the characteristic relaxation time, being dependent on temperature and material structure.

J. Enrione, C. Sáez, D. López, O. Skurtys, C. Acevedo

Relationship Between Raw Material Characteristics and Dehydration Parameters of Vegetables Dried Using a New Kind of Solar Dryer

In the last few years, an increasing demand for innovative products in response to changing lifestyles has led to a strong increase in out-of-home food consumption. Consumers are also becoming more interested in consuming healthy, natural, and tasty foods because of their positive role in the treatment of a certain type of chronic degenerative diseases (Bazzano et al. 2002). Dried food products constitute an important sector of innovative snacks, in particular fruits and vegetables (F&V)-based products.

G. Bertolo, A. Maestrelli, M. Della Campa

Caking Process and Microstructural Changes of Wall Materials Used in Spray-Drying Process

Microencapsulation process is applied to protect the core material or active agent against environmental factors and helps resist brittle material processing conditions improving flavor, aroma, stability, nutritional value, and appearance. Microencapsulation applications are found in agricultural, pharmaceutical, food, cosmetics, and fragrance industries (Madene et al. 2006). The retention of the active agent in this process is governed, among other factors, by type of wall material, so its selection is an important step. The most commonly used materials include carbohydrates such as maltodextrin (MD) and gum arabic (GA) and proteins such as whey and soy protein isolate (SPI) (Madene et al. 2006; Matalanis et al. 2011). During microencapsulation process, the final products are in the form of powder containing individual microparticles, agglomerates, or both. The food powders containing amorphous carbohydrates could experiment physical changes as stickiness and caking when the powder is exposed to temperature above the powder’s glass transition temperature (

T

g

). This temperature is a function of the moisture content and water activity (

a

w

) of the powder (Foster et al. 2005; Schebor et al. 2010). At the

T

g

, the viscosity of amorphous materials decreases significantly, allowing greater molecular mobility, which has effect in sticky behavior (Foster et al. 2005). The caking of food powders is an unwanted and very common problem that occurs during processing, handling, and storage. The particles of amorphous powders may progressively be deformed until they stick to each other and, eventually, form great agglomerates (Saragoni et al. 2007). This phenomenon is affected by microstructure and hygroscopicity; however, other facts are reported as decisive like stress, humidity, and temperature for caking mechanism and caking kinetics (Hartmann and Palzer 2011). The caking phenomenon reduces the product quality and functionality, rehydration, dispersibility, and the shelf life and increases deterioration of organoleptic quality and the formation of lumps and agglomerates (Lipasek et al. 2012). Microscopy techniques have been applied to analyze powder microstructure, identifying useful factors to describe changes observed during processing and storage (Guadarrama-Lezama et al. 2014).

J. Porras-Saavedra, E. Palacios-González, J. Yáñez-Fernández, M. F. Mazzobre, M. P. Buera, L. Alamilla-Beltrán

Food Matrix Structure Quality Preservation: Water Removal Operation Conditions Control During Convective Drying

Food product development (FPD) is a systematic task with the objective of generating new products by either modifying any existing or producing a new and original one. Driven by consumers’ expectations, new knowledge, globalization, and shorter product cycles, among others, companies must survive in a dynamic and often unpredictable markets characterized by high levels of competitiveness (De-Greef et al. 2014).

H. Necoechea-Mondragón, D. Y. Morales-Delgado, E. Parada-Arias, M. Cornejo-Mazón, D. I. Téllez-Medina

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