Valorisation of Agro-industrial Residues – Volume II: Non-Biological Approaches

Conversion of lignocellulosic biomass into reducing sugar has contributed to an alternative use of lignocellulose source, especially in the production of value-added products such as amino acids, biofuels, and vitamins. In the bioconversion process, pretreatment of lignocellulosic biomass is important to enhance the accessibility of enzyme hydrolysis, thus increasing the yield of reducing sugar. Lignocellulosic biomass has a very complex arrangement of structure that needs a proper study in pretreatment and enzymatic hydrolysis process to obtain an optimum yield of reducing sugar. This chapter discusses chemical and enzymatic pretreatment methods that are commonly applied to effectively modify the chemical structures of lignocellulosic biomass. Acid pretreatment using dilute sulfuric acid (H₂SO₄) is the most commonly employed for chemical pretreatment while sodium hydroxide (NaOH) is the most commonly applied for alkaline pretreatment because of its ability to delignify biomass. Then, enzymatic hydrolysis of lignocellulosic biomass for the production of reducing sugar is discussed in detail. The kinetics and optimization of hydrolysis which are the key parameters that determine the yields of reducing sugar are also presented. The right pretreatment method combined with an efficient hydrolysis process will ensure successful conversion of lignocellulosic biomass into reducing sugar, thus providing a sustainable production of reducing sugar from biomass for various applications.

Antioxidants can be extracted from mangosteen peel with ethanol as solvent using microwave assisted extraction (MAE) efficiently and economically. The mangosteen peel antioxidant can be used to inhibit the biodiesel B20 oxidation. The microwave power gives a great factor of antioxidant conversion in mangosteen peel extraction. At 35 min and 300, 450, 600 W, the antioxidant conversions obtained were 15.45, 17.00, 18.33%, respectively. The total phenolic concentration was about 156–202 mg GAE/g. In addition, the extraction kinetic can be quantitatively described by antioxidant diffusivity from inside the solid to the solid’s surface and antioxidant mass transfer from the solid’s surface into solution with diffusion coefficient (D _e) of 2.81 × 10⁻¹¹, 3.42 × 10⁻¹¹, 3.8 × 10⁻¹¹ cm²/s, mass transfer coefficient (k _c) of 6.36 × 10⁻⁸, 8.97 × 10⁻⁸, 1.05 × 10⁻⁷ cm/s for 300, 450, 600 W, respectively, and Henry equilibrium constant (H) of 0.032. In the oxidation, the mangosteen extract antioxidant can improve 26.32% of the oxidative stability of biodiesel B20. Theoretically, the performance of mangosteen peel extract antioxidants in biodiesel B20 oxidation can be evaluated from its oxidation kinetic which can be approached using the pseudo-homogeneous first-order model. The reaction rate constant follows the Arrhenius equation with activation energy (E _a) of 54.34 and 56.27 kJ/mol as well as collision factors (A) of 348,711 1/min, for the oxidation of biodiesel B20 and the mixture of biodiesel B20 and mangosteen peel extract antioxidant, respectively. The activation energy of the mixture of biodiesel B20 and mangosteen peel antioxidant was higher, so that the mixture of biodiesel B20 and antioxidant is more difficult to oxidize.

Global industrialization has led to an enhanced production and use of enzymes and value-added products in various industrial sectors. As the demand for a cleaner and safer environment is inevitable in this twenty first century, better utilization of wastes for the production of value-added products has also been improved. Different bioprocesses are being used for the utilization of different agro-industrial residues for their transformation into useful products. The nature of substrate used is a major limiting factor in all fermentation processes. Cashew apple and its by-products are a new and promising substrate for bioprocessing as they are rich in carbohydrates, minerals, vitamins, amino acids, carotenoids, phenolics, organic acids, and antioxidants. Although 10–30 t/ha of cashew apples are accumulating globally, 90–94% have been discarded after harvesting the nut. Only 10% is commercially used for the preparation of wine, jam, juice, and ice cream and these products are hardly exported. Bioprocessing with cashew apple has wide variety of applications in different fields including bioethanol production, microbial production of enzymes, dextransucrase production as a preservative in food industry, production of biosurfactants, etc. Considering less cost, rich nutritional contents, and availability of cashew apple and its by-products, they can be exploited more as a promising substrate for the different fermentation processes.

Environmentally sustainable and cost-effective alternatives for the control of plant pathogens and plant pests are required in the current scenario because of the development of agrochemical resistance in targeted pathogens, as well as the negative impacts of chemical pesticides on public health and the environment. Therefore, biological control agents (BCAs), such as fungi, are an attractive input to replace hazardous pesticides and offer great potential for field application. Agro-industrial bioprocessing generates large quantities of waste, such as straw, pulp, leaves, husk, and bagasse, which poses serious environmental problems worldwide. Effective use, added value, and bioconversion of these materials via bio treatment for the production of fungal BCA have received considerable attention in recent years. Many researchers have succeeded in using cheap agro-residues for the mass production of fungal biological control agents, mainly using SSF technology. The fermented substrate can be used directly for field application and the difficulties with downstream processing and product formulation are excluded. Among the microorganisms present in the rhizosphere, Beauveria bassiana, Verticillium lecanii, Metarhizium anisopliae, Paecilomyces spp., Trichoderma harzianum, Trichoderma viride, Trichoderma asperellum, Trichoderma virens, etc. are the most commonly used fungal biological control agents. Coffee husk is reported to be an excellent agricultural residue for the growth of Trichoderma spp. and Paecilomyces spp. Many aspects of the use of agricultural by-products in solid-state fermentation remain to be exploited for the production of bioactive compounds, green chemicals, biopesticides, etc., as well as for the development of more economically feasible processes.

Water pollution due to textile industrial wastewater discharge has become one of serious issues especially in developing countries, including Indonesia. The wastewater has a dangerous impact on the surrounding environment and living things including animals and human, since it contains some heavy metals, which have a tendency to accumulate in nature and do not decompose by nature. Accumulation of these heavy metals in the human body until certain level could cause some diseases. Therefore, this wastewater has to be treated first before safely discharged into the environment. One of the most promising methods to remove these heavy metals from the wastewater is by adsorption process. In the recent years, there have been a trend to utilize biomass or agro-industrial wastes based adsorbent due to their availability (abundant in nature), minimal effort, and biodegradability. The use of agro-industrial wastes to produce biomass-based activated carbon for removal of heavy metals in textile industrial wastewater could become one of the best promising alternatives to solve wastewater problem from textile industry as well as waste from agro-industry. This chapter focuses on the preparation, physical characterization, and adsorption properties of several bio-based activated carbon made of agro-industrial wastes.

Since the 1980s the energy demand has been increasing steadily, including diesel fuel. On the other hand the oil reserve in the world was increasingly limited because of being the product that could not be renewed. Therefore, effort was carried out to look for the alternative fuel that could be renewed and environment friendly. The alternative energy from new renewable energy is a solution to reduce the dependence of fossil energy. The renewable energy consists of the energy of water, wind, biomass or biofuels, solar energy, ocean energy, and geothermal energy. One of the biofuels is biodiesel. Biodiesel is diesel fuel which is made from vegetable oil by transesterification. The abundance of glycerol will result in declining sales value of glycerol as a by-product of the biodiesel plant. It should be anticipated to improve the usefulness of glycerol both in terms of quantity and its variants. The increasing usefulness of glycerol will result in the higher price of glycerol that will increase the profitability of biodiesel plants. Among the usefulness of glycerol investigated is as an ingredient in pharmaceutical products, polyether, emulsifiers, fabric softener, stabilizers, preservatives in bread, ice cream, cosmetic ingredients, a propellant binder, and others. This chapter explains the utilization of glycerol to produce triacetin as bioadditive and polyglycidyl nitrate (PGN) as a propellant binder. Triacetin is used to increase octane number of fuel and improve the biodiesel’s performance. Propellant binder consists of two kinds of non-energetic polymers and polymer energetic. The most energetic polymer is PGN. The focus of this chapter is to determine each step of reactions, operating conditions of process and the results of products.

The disposal of a large number of waste materials results in high costs for the food industry and can have a negative environmental impact. Metabolites, such as phenolic compounds, fibers, and proteins obtained from vegetable by-products or waste biomass could be used as ingredients in the formulation of new functional foods. Argentine native fruits (chilto, algarrobo, and mistol) were used as food (edible fleshy fruits, sweets, flours, juices, pulp, and beverages) by different local communities and some of them have now been industrialized. In fact, fruit industrial processing has, as a consequence, the production of large amounts of wastes, mainly peels or skin, pomace, and seeds. Phenolic enriched extracts (benzoic and cinnamic acids and derivatives; phenylpropanoid acids; C-glycosyl flavones; anthocyanins, among others) obtained from Argentinean native fruit wastes were able to modulate the metabolism of lipids and carbohydrates in the gastrointestinal tract (GT) through enzymes inhibition (lipase, amylase, and glucosidase), regulate oxidative processes and inflammatory pathologies, so these extracts could be considered functional ingredients. Furthermore, these phenolic extracts were used to develop zein matrix microcapsules and coating structures based on zein fibers that could be optimized to food package. Proteins and protein hydrolysates obtained from carob tree seeds were also antioxidants and inhibitors of pro-inflammatory enzymes and improve vascular function in a rabbit model of high fat diet-induced metabolic syndrome. Thus, Argentinean native fruit wastes have the potential to be a novel renewable, sustainable, and low-cost raw material for the production of several value-added products.

Agricultural and crop residues serve as a renewable source for the production of bioethanol and other value-added chemicals. The residue which is left out after harvesting chili from chili plants constitute chili postharvest residue (CPHR). It is an abundant, inexpensive, and readily available source of renewable lignocellulosic biomass. Presently this is considered as a waste and disposed by burning after harvest. Hence this could be a viable biomass for second-generation biofuel production as well as for the production of other value-added products like biopolymer and industrial enzymes. Similar to other lignocellulosic biomass, chili postharvest residue also requires some kind of pretreatment for better enzymatic saccharification of cellulose by enzymes. The objective of the present study was to evaluate pretreatment liquor as well as the enzymatically saccharified biomass for second-generation biofuel, xylanase and biopolymer production.

Indonesia is among the top ten sugarcane-producing countries in the world. Among the important sugarcane-based industry is bioethanol production. Bioethanol is recently experiencing significant growth due to the increase in need of renewable energy. However, this industry faces a challenge since it produces a huge amount of liquid waste, namely vinasse. The production of 1 L of bioethanol generates 12 L of vinasse. Vinasse is pollutant due to its high value of chemical oxygen demand (COD) and biological oxygen demand (BOD), high salt content, unpleasant odor, high acidity, and dark color. Therefore, it should be treated before releasing to the environment. However, pretreatment of vinasse is not economical. The more feasible way to handle vinasse is shifting it into valuable product. Vinasse contains nutrients which are necessary for improving soil fertility and useful for plant fertilization. There are some methods to convert vinasse to organic fertilizer. This chapter shows one case study of formulating vinasse with filter cake of sugar factory, and agricultural wastes to produce liquid organic fertilizer (LOF). LOF was synthesized via anaerobic fermentation of vinasse in the presence of promoting microbes and formulation of fermented vinasse with filter cake, lead tree leaves, and banana peel to produce LOF. The LOFs were characterized to determine the values of organic C, C/N ratio, and the contents of N, P, and K elements. LOFs were applied on the tomato plant to enhance plant growth. The more advanced process of vinasse valorization is converting it into slow release solid organo-mineral fertilizer (SR-OMF).

Lignocellulosic biomass has been recognized as a sustainable feedstock for the production of renewable energy and bio-products. Various technologies including biochemical and thermochemical have been developed and applied for the conversion of the oil palm biomass. Thermochemical processes (i.e., combustion, pyrolysis, gasification, and liquefaction) could be the more economically feasible option to convert the lignocellulosic biomass quickly with lower cost compared to biochemical process due to high recalcitrant level of lignocellulosic biomass toward microbial degradation. Pyrolysis is one of the predominant technologies for lignocellulosic biomass conversion into valuable end products. This chapter provides an overview on the palm oil industry, oil palm biomass and current management scenario, pyrolysis process, parameters that influence the pyrolysis process, and the effect of these parameters on the pyrolysis product yield. The potential applications of pyrolytic products from oil palm biomass were also comprehensively addressed.