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2008 | Buch

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Food Materials Science

Principles and Practice

herausgegeben von: José Miguel Aguilera, Peter J. Lillford

Verlag: Springer New York

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik"

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Über dieses Buch

Food Materials Science provides the science behind structuring processes for foods and applications in food product design. The first in its field, the book is an invaluable reference.

The creation of added value from raw food materials is a legitimate aspiration of the modern food industry. Adding value to foods requires knowledge of what the consumer wants and creating products that satisfy the demand. Quality, convenience and safety are the major drivers of the modern food industry.

Food manufacture is about producing billions of units of standardized products which must be cheap, nutritious, safe and appealing to the consumer’s taste. Food products are complex multicomponent and structured edible materials that nevertheless must comply with the laws of physics and fundamentals of engineering sciences. In the last 20 years the design of food products with specific functionalities has advanced significantly by the application of scientific knowledge from disciplines such as polymer physics, colloidal and mesoscopic physics, materials science and new imaging and probing techniques borrowed from chemistry, biology and medicine. Our knowledge of the relationship between microstructure, processing, and macroscopic properties continues to increase as the science of food materials advances at a fast pace.

This book is intended to those interested in viewing food technology as a way to preserve, transform and create structures in foods and the related materials science aspects of it. It attempts to present a unified vision of what today is considered to be food materials science and some derived applications. The book may be used as a text in a course in food materials science at the senior or graduate level or as a supplement text in an advanced food technology course. It will also serve as a reference book for professionals in the food industry.

Inhaltsverzeichnis

Frontmatter

Fundamentals

Chapter 1. Why Food Materials Science?

For centuries, mankind has hunted and farmed its food supply. For an equal amount of time, someone has had to convert these raw materials to an edible state, most of which required processing, since apart from fruits and nuts, most biological materials are not easily eaten and digested by Homo sapiens. In the hands of an expert, such as a the Cordon Bleu chef, this processing has been developed into an art form, using the intrinsic properties of the raw materials to create colours, textures and flavours for our delectation and nutrition. Furthermore, the methods and materials have been codified into millions of recipes, which are available to everyone.

José Miguel Aguilera, Peter J. Lillford, Heribert Watzke

Chapter 2. The Composite Structure of Biological Tissue Used for Food

Natural materials are all hierarchical composites composed of a relatively small number of basic materials. Commonly, the composite will be based on fibres that can support tensile loads (a fibre is defined as at least 100 times longer than wide) in a matrix that holds the fibres together and passes force, by shear, between the fibres. The fibres can be arranged parallel (the “preferred” orientation) or helically around a cylinder, or semi-randomly or random like a felt. This fibre-matrix composite is arranged in a series of structures of cascading size and complexity, giving a wide range of properties to the final structure, since at each level in the hierarchy the various components can be structured in different ways and stabilized to different degrees. This is the basic framework that nature has given us. At various stages in the chain of preparation of food both the materials and the structures can be modified to make their texture, flavour and nutritional characteristics more acceptable. This involves selection and breeding of the organisms, and preparation and cooking of what they yield. Wider considerations will require the selection and breeding to have minimal environmental impact (“sustainability”) and the products to be entirely used or recycled.

Julian F. V. Vincent

Chapter 3. Food Polymers

This chapter discusses food biopolymers, their mixtures and the origins of their functionality. These subjects are of fundamental importance for a number of reasons. Most food polymers are functional components of living organisms and are consumed as either living organisms or ingredients from former living organisms. Structure–function relationships of biopolymers are essential to create life. Only the emergence of life implied the emergence of a demand for food. It is also of interest to discuss behavioural differences of biopolymers in biological and food systems and between biopolymers and synthetic polymers. The origins of biopolymer functionality are therefore of interest for application in the food industry (Tolstoguzov 2000, 2002).

Vladimir Tolstoguzov

Chapter 4. The Crystalline State

From the snap, gloss and texture of chocolate to the shelf life of frozen foods, crystalline microstructure plays a very important role in the texture, appearance, shelf life and overall quality of many foods. The total amount of crystalline phase in a food, as well as the size distribution and shape of the crystals within the food, can affect the physical properties of the product. Furthermore, some materials in food can crystallize in different polymorphic forms so that control of polymorphic transformations may also be necessary.

Richard W. Hartel

Chapter 5. The Glassy State

The physical state of materials is often defined by their thermodynamic properties and equilibrium. Simple one-component systems may exist as crystalline solids, liquids or gases, and these equilibrium states are controlled by pressure and temperature. In most food and other biological systems, water content is high and the physical state of water often defines whether the systems are frozen or liquid. In food materials science and characterization of food systems, it is essential to understand the physical state of food solids and their interactions with water. Equilibrium states are not typical of foods, and food systems need to be understood as nonequilibrium systems with time-dependent characteristics.

Yrjö H. Roos

Chapter 6. Rubber Elasticity and Wheat Gluten Proteins

Many materials exhibit elastic behaviour when a stress is applied, the material returning to its original dimensions after the stress has been removed. In crystalline and glasslike solids the elastic limits rarely exceed 1%. In contrast, true elastomers are able to undergo large elastic deformations, that is, to stretch and return to their original state in a reversible way and without breaking. Such elastomeric materials are polymers consisting of long flexible chainlike molecules These chains are capable of undergoing considerable molecular motion, unlike in crystalline solids where only limited atomic movement is permitted. The energy involved in the deformation of elastomers is stored and on removal of the stress this energy is recovered. This latter stage is therefore passive in that it does not require energy input. The degree to which an elastomer is “ideal” is determined by how much of the stored energy is recovered, with some systems being more efficient than others.

A. S. Tatham, P. R. Shewry

Chapter 7. State Diagrams of Food Materials

The physical/chemical states and the thermal transitions of food materials determine the process conditions, functionality, stability and overall quality, including the tex-ture, of the final food products. Carbohydrates and proteins—two major biopolymers in various food products—can exist in an amorphous metastable state that is sensi-tive to moisture and temperature changes (Cocero and Kokini 1991; Madeka and Kokini 1994, 1996). The physical states of components in a biopolymer mixture determine the transport properties, such as viscosity, density, mass and thermal dif-fusivity, together with reactivity of the material.

Didem Z. Icoz, Jozef L. Kokini

Chapter 8. Nanotechnology in Food Materials Research

Nanotechnology is an enabling science and technology that allow scientists and engineers to manipulate, measure, formulate, synthesize, and control nanostructured materials and devices so that novel properties and functions can be achieved. The term “nano” corresponds to dimensions in the order of 10-9. Therefore, one nanometer (nm) means one-billionth meter. According to the U.S. National Nanotechnology Initiative (www.nano.gov), the length scale of nanotechnology is in the range of 1–100 nm. More importantly, nanotechnology implies (1) novel phenomena, properties, and functions at nanoscale; and (2) the ability to manipulate matter at the nanoscale in order to change those properties and functions.

Jooyoung Lee, Xiaoyong Wang, Chada Ruengruglikit, Zafer Gezgin, Qingrong Huang

Chapter 9. Assembly of Structures in Foods

From a physical point of view, a natural way to describe a system is to define the macroscopic physical state it is in, that is, the solid, liquid or the gas state. These three states are differentiated from one another by the degree of order between the atoms or the molecules (a common denominator being constituents). The order is highest within a solid (where there exists a regular stacking) and lowest in a gas (where the probability of finding a neighbour of one constituent is only dependent, isotropically, on the density of the gas, which must be an average quantity) (de Gennes and Prost 1993). Systems composed of one type of atoms may even exhibit all three phases, depending on temperature and pressure. Another possible state is the liquid crystal state (de Gennes and Prost 1993), which, at least in one direction, exhibits liquidlike order and anisotropy.

E. van der Linden

Chapter 10. Solid Food Foams

The words “cell” and “cellular” came to English (via French) from the Latin cella, a store room or chamber. In modern usage, they have several very different meanings. The two that are pertinent to food structure and texture have to do with the cells in edible tissues of plants, fungi and animals or with the open spaces, filled with air or another gas, enclosed by a liquid or solid matrix that forms the cell walls.

Maria G. Corradini, Micha Peleg

Chapter 11. Probing Food Structure

The relationship between a food’s structure and its properties/functionalities is of fundamental interest in food materials science. The great expectation is to relate the functionality of a food material to the physico-chemical characteristics of its ingredients and their geometric arrangement (i.e., structure formation). Functionalities of interest are either of chemical (e.g., flavor release from a given matrix), physical/ mechanical (e.g., shelf life, sensory) or biological nature (e.g., nutrient bioavailability). Currently we are far from being able on a routine basis to relate food structures to functionality, and only in rare cases is it possible to establish a direct relationship (Renard et al. 2006). Recent examples are ice crystal size and fat destabilization in ice cream and its effects on texture and melting properties (Muse and Hartel 2004) as well as sugar particle size in chocolate and its influence on the rheological properties of the chocolate mass (Servais et al. 2002).

Martin Michel, Laurent Sagalowicz

Structuring Operations

Chapter 12. Structure–Property Relationships in Foods

Structure–property relationships, the connection between the structure and the way a product behaves, is central to materials science and product engineering and design. For example, understanding the relationship between structure and specific physical properties is crucial for ultimately designing advanced materials and nanomaterials. For traditional engineering materials, finding structure–property relationships is somewhat easier than for foods because specific properties are well defined (e.g., strength, electrical conductance, etc.), measured with precise instruments and usually intrinsic to the structure of the final product. Also, the microstructures involved are those of more or less homogeneous materials (simple as it may appear, they do not contain water!) and are required not to change appreciably with time.

José Miguel Aguilera, Peter J. Lillford

Chapter 13. Structuring Water by Gelation

Gels are of central importance for most semisolid food products. A gel can contain more than 99% water and still retain the characteristics of a solid. The network structure will determine whether the water will be firmly held or whether the gel will behave more like a sponge, where water is easily squeezed out. The gel structure will also have a major impact on the texture as well as diffusion of water and soluble compounds. Many food matrixes are based on colloidal gels such as yoghurts, cheeses, many desserts, sausages etc (see also Chapters 19 and 20). In whole foods, there is often a combination of colloidal structures and fragments of biological tissues or gel structures in combination with particles, emulsion and foam structures. This level of complexity of composite food structures will not be dealt with here.

Anne-Marie Hermansson

Chapter 14. Bubble-Containing Foods

The presence of bubbles in a number of food products, such as bread, champagne, ice cream and beer, has dominated our perception of product quality. Novel bubble-containing products occupy a greater proportion of supermarket shelf space. The inclusion of bubbles in foods permits the creation of very novel structures while offering lighter alternatives in terms of calories. Manufacturers generally find that most products manage to gain a positive market image by highlighting bubbles. Consumers also associate such products with health and luxury. It is generally recognised that the mechanisms governing the formation and stability of such structures are very complicated, because the recipes often contain a number of ingredients that undergo very complex interactions during processing as well as storage. At the same time, there is also recognition of the fact that these complex interactions between ingredients have not been adequately researched. A significant body of published information exists on the formation of porous structures in bread and their relation to the processes adopted to mix the dough (Chiotellis and Campbell 2003; Martin et al. 2004). However, such studies in relation to the whole range of other bubble-containing food products such as cakes, creams used in biscuits, ice cream, and so on, are very sketchy. This chapter describes the formation of bubble-containing food structures, particularly focusing on products other than bread, and aims to develop the relationship between process variables and the structure characteristics, and to explore the interplay between structure and mouth-feel.

K. Niranjan, S. F. J. Silva

Chapter 15. Emulsions: Principles and Preparation

Emulsions are mixtures of fluids that are immiscible. Usually one fluid is present as small droplets in another phase. There are emulsions of oil in water, called oil-inwater emulsions (abbreviated as O/W), but also emulsions of water in oil (W/O). The droplet phase is called the dispersed phase, the surrounding phase the continuous phase. Emulsions are important in a great diversity of products.

Remko M. Boom

Chapter 16. Processing of Food Powders

The development of formulation engineering concepts in food manufacturing and the demand for diversity in food products has driven a substantial market increase for food ingredients. Most ingredients are supplied in powder form and therefore a better understanding of dispersed solid food systems is important both for food ingredient manufactures and food producers.

Lilia Ahrné, Alain Chamayou, Koen Dewettinck, Frederic Depypere, Elisabeth Dumoulin, John Fitzpatrick, Gabrie Meesters

Chapter 17. Fat Crystal Networks

Fats and oils are comprised primarily of triacylglycerides (TAGs). TAGs consist of a glycerol (1, 2, 3-trihydroxypropane) backbone with three fatty acids esterified to the three alcohol groups at specific locations referred to as sn-1, sn-2, and sn-3 (Figure 17.1). Fatty acids differ based on chain length, saturation, trans- or cis-bonds, branching, as well as any combination of the aforementioned (Small 1986).

Michael A. Rogers, Dongming Tang, Latifeh Ahmadi, Alejandro G. Marangoni

Chapter 18. Extrusion

Extrusion is a manufacturing process, common in many industries. As a unit operation it can be regarded simply as a shaping process where infinitely long fibres or semi-continuous anisotropic structures are formed, from a block or compacted dispersion. In the metals and plastics industry both “hot drawing” and “cold drawing” are performed. Both of these are known in the kitchen, where the equivalent of “hot drawing” is the formation of cheese fibres in a fondue, and “cold drawing” is the piping of icing sugar as cake decoration, or pasta production from dough. Forming into appealing shapes has also become part of the processing repertoire of ice cream, chocolate and dairy products.

Peter J. Lillford

Polyphasic Food Systems

Chapter 19. Structuring Dairy Products by Means of Processing and Matrix Design

Dairy products can be classified in terms of their base structures as either gels (such as yoghurt and cheeses), emulsions (such as milk, cream or butter), or foams (such as whipped cream or whipped desserts). Many dairy products (such as ice cream), however, are comprised of more than one structural property, that is, they may contain features of a gel, an emulsion and a foam next to each other.

Ulrich Kulozik

Chapter 20. Structured Cereal Products

This chapter describes the importance of cereals and their products and the various structures that can be produced from them. It shows how cereals have been, and continue to be, the main source of nutrition for much of the world, and how the development of structure in foods such as bread has provided improved sensory texture, appearance and palatability to these foods.

B. J. Dobraszczyk

Chapter 21. Structured Meat Products

After an animal has been slaughtered, the objective is to maximise the conversion of the carcass to safe edible foodstuff. As a result, mankind has experimented empirically and created a host of meat products. Their classification depends on the initial raw materials, type of processing and characteristics of the final product. So, a first classification is between entire pieces (i.e., cooked meat pieces, hams, etc.); coarse comminuted meats (burgers and reformed or restructured meat); and minced meats (i.e., sausages). Types of processing include cooking, salting (curing), drying, fermentation, and almost any combination of these that provides protection against microbial spoilage and yet offers an edible texture and flavour (Flores and Toldrá 1993). As a result, a wide variety of products are obtained.

Milagro Reig, Peter J. Lillford, Fidel Toldrá

Chapter 22. Structured Chocolate Products

It is believed that Mayas, 2600 years ago, were already drinking chocolate. At this time, chocolate was consumed in America as a sweet and spicy beverage, seasoned with chilli pepper, vanilla and pimiento. The beverage was expensive and thus reservedto elites, and cocoa was even often used as a currency. The story of chocolate begins in Europe with the discovery of America and Christopher Colombus brought some chocolate back to Spain for Queen Isabella, but Hernando de Soto introduced it much more broadly.

B. J. D. Le Révérend, S. Bakalis, P. J. Fryer

Chapter 23. Edible Moisture Barriers for Food Product Stabilization

The reduction of mass transfer between a food product and its surrounding atmosphere by coating the entire product with an edible material is an extremely old practice, already used in the twelfth century in China (fruit waxing), and in England during the sixteenth century (meat larding) (Kester and Fennema 1986). Today, controlling mass, and more specifically moisture transfer, still remains an important challenge to maintain the quality of fresh or processed products, such as fruits, meats and seafood products. In ready-to-eat composite foods, the limitation of internal moisture transfer between components is also of major concern. It has gained in importance as consumers’ demand for this kind of convenient product has increased. Moisture transfer from the “wet” to the “dry” component of these products affect the physical properties, especially texture, and chemical composition of the food system, and consequently its quality and shelf-life (Katz and Labuza 1981).

C. Bourlieu, V. Guillard, B. Vallès-Pamiès, N. Gontard

Chapter 24. Encapsulation of Bioactives

Food bioactives are physiologically active components in food or dietary supplements of plant or animal origin that have a role in health beyond basic nutrition. The addition of bioactive components to foods, particularly those foods that are consumed as part of the normal diet of target populations, offers opportunities for improving the health and well-being of consumers. The interest of the food industry in these functional foods has resulted in the development of a new generation of food products with enhanced levels of food components that have potential health benefits (Schmidl and Labuza 2000; Hilliam 2000; Heasman and Mellentin 2001; Augustin and Clarke 2004).

M. A. Augustin, L. Sanguansri

Backmatter

Titel: Food Materials Science
herausgegeben von: José Miguel Aguilera
Peter J. Lillford
Verlag: Springer New York
Electronic ISBN: 978-0-387-71947-4
Print ISBN: 978-0-387-71946-7
DOI: https://doi.org/10.1007/978-0-387-71947-4

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