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Cereal Processing By-Products Within the Biorefinery Concept
Cereal grains comprise the principal component of human diet for thousands of years and therefore their processing represents a big asset of the food production chain. Wheat, rice, oat, barley and corn processing via dry and wet milling, pearling and malting includes complex procedures that generate an important amount of by-products that differ in their physical state and chemical composition.
Cereal processing by-products represent abundant and low-cost resources of phytochemicals (e.g. carbohydrates, proteins, dietary fibre, lipids, vitamins, polyphenols, inorganic and trace elements) with potential nutraceutical and pharmaceutical applications. To this line, their re-utilization and upgrade to high added-value applications is a great challenge towards the sustainable development of the agro-food sector for the years to come.
Oat processing and the alternative options
The target compounds and substrates are plenty and have been covered adequately through the whole book. Oat, its processing by-products and healthy components is a typical example of the available valorization and upgraded choices. Oats possess high amounts of water soluble fibers and particularly β-glucan (e.g. 2.2-7.8 g/100 g) as well as proteins (11-20 g/100 g). Their nutritional advantages in spite of diabetes and the control of blood cholesterol level have been attributed to the contained β-glucan.
To this line, the attribution of cereal β-glucan as functional ingredient has increased the interest concerning their incorporation in food formulations. Oat grains have been subjected to amylase hydrolysis (converting starch, carbohydrates and dietary fibers to maltose and β-glucan) in order to develop nondairy products. This process is monitored via enzyme kinetics modeling that optimizes the viscoelastic behavior of hydrolysates and simulates biodegradation processes of multienzymatic system based on cultures, e.g. hydrolysis of starch wastes.
Carbohydrate hydrolysis generates a drink that is consumed alternatively to milk products due to the lactose intolerance and cholesterol content issues of human populations, and a by-product (oat mill waste), which is usually dried and utilized as animal feed. The latest is rich in proteins and β-glucan that could be recovered using extraction and membrane technologies and utilized further in different applications, e.g. to replace fat of yoghurt and cheese.
Other cereal processing by-products
Similar examples exist for other cereal processing by-products, too. Wheat and rye bran contain arabinoxylans which contribute to a reduction of the blood glucose, while oat bran. Corn bran is one of the best sources of ferulic acid (an antioxidant compound), compared to other cereals, fruits and vegetables. γ-oryzanols found in rice bran and oil have 10-fold higher antioxidant properties than tocopherols.
All these phytochemicals could be recovered and delivered to consumers as natural substitutes for synthetic pharmaceutical products and artificial additives (colors, antioxidants, emulsifiers, stabilizers, etc.) thus preventing the potential adverse effects associated with the consumption of the latter. Up to now, numerous cereal processing by-product derived ingredients have appeared on the market, e.g. Oat Fiber Plus Tablets (Now Foods), Stabilized Rice Bran (NutraBio), Life Extension NK Cell Activator (Swanson Health Products), Gama Oryzanol (Swanson Health Products) and Promitor Soluble Fiber (Tate & Lyle).
The vast majority of cereal products consumed worldwide are made from refined grain, and thus there is a need to develop more functional foods and nutraceuticals from cereal processing by-products in order to assure the delivery of health beneficial compounds to final consumers and sustainability of the related industry.
The biorefinery concept
Distillers’ Dried Grains with Solubles (DDGS), the major by-product of bioethanol and distillery plants, constitutes a by-product of heterogeneous nature that could be used as a starting raw material within a biomass-based biorefining strategy for the production of several high added-value compounds. Such a process might necessitate the selection of an intermediate product of the DDGS process as a starting material, with the view of recovering target compounds and increasing the quality of final DDGS as feed ingredient.
The availability of these products in the market could counterbalance capital investment and processing costs. However, the need for more industrial research coupled with detailed process economics was is imperative before leading to commercial realization and exploitation.
Biorefineries are more conceptually at the moment, e.g. there are a limited number of biorefining technologies that have been demonstrated at commercially relevant scales, but the current studies suggest that it is possible to be realized following integrated systems and approaches. They comprise the concept of the 2020s, but there is work to do and it is essential that businesses are supported at all stages.
Future biorefineries will most likely be developed from existing industries by optimization of side streams, or by combination of existing processes. Most of the reports conducted related to the future projections and market implementation of wheat bran byproducts.
Multiple biofuels production from wheat bran increase the efficiency of material and energy can apparently be more economical process for biomass utilization as well as the technological and nutritional functionality of bran can be improved.
Sustainable Recovery and Reutilization of Cereal Processing By-Products addresses topics associated with the sustainable management of cereal manufacturing. Emphasis is placed on current, advisable practices, general valorization techniques of cereal processing by-products, and the functional properties of healthy cereal by-product components that lead to target applications in foods and nutraceuticals. General valorization techniques of cereal processing by-products include focus on wheat bran, distillers’ dried grains -based within the biorefinery concept, and different techniques for the separation, extraction, recovery and formulation of valuable compounds, including proteins, arabinoxylans, and beta-glucan.
- Addresses topics associated with sustainable management of cereal manufacturing
- Places emphasis on current, advisable practices
- Presents general valorization techniques of cereal processing by-products
- Highlights the functional properties of healthy cereal by-product components that lead to target applications in foods and nutraceuticals
Over the last years, Food Waste Recovery Group has organized a series of workshops (e.g. the 2nd one comes on 2nd of July in Stuttgart), teaching activities (webinars, e-course etc) and books targeting food waste recovery processing and industrial techniques, describing tools for the implementation of innovations in the food industry, exploring the effect of emerging and non-thermal technologies on nutraceuticals and functional foods development, as well as highlighting the sustainable solutions for the management of specific food processing by-products from the olive, grape and coffee industry.
Charis M. Galanakis is an interdisciplinary scientist with a fast-expanding work that balances between food and environment, industry, and academia. His research targets mainly the separation and recovery of functional macro- and micromolecules from different food by-products, as well as their implementation as additives in food and other products. He is the coordinator of Food Waste Recovery Group of ISEKI Food Association (Vienna, Austria) and R&I director of Galanakis Laboratories (Chania, Greece).
He serves as an editorial board member and subject editor of Food and Bioproducts Processing and Food Research International, and he has edited 9 books with Elsevier.Follow Dr. Galanakis via Twitter – @CharisGalanakis, LinkedIn or ResearchGate.
Join the Food Waste Recovery Group on LinkedIn or the Food Waste Recovery Page on Facebook.
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Food Science & Nutrition
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