Health-promoting effects of a dietary fiber concentrate from the soybean byproduct okara in rats

Quality characteristics and volatile compounds of plant-based patties supplemented with biji powder

Biji (okara or soybean curd residue), a by-product of soybean processing, contains proteins. In this study, control plant-based patties were compared with patties supplemented with biji powder (5, 10, 15, and 20 g). Increasing the amount of biji added to patties was found to be favorably associated with increased water-holding capacity, decreased cooking loss, and reduced diameter and thickness. Texture profile analysis revealed trends of increased hardness, springiness, cohesiveness, and chewiness which were proportional to the inclusion of biji powder. The volatile compounds in plant-based patties supplemented with biji were analyzed using HS-SPME-Arrow-GC/MS. Notably, benzaldehyde, nonanal, and 2-heptanone, which are undesirable flavors, were detected at significantly lower levels in patties supplemented with biji. Therefore, biji can serve as a supplementary ingredient to enhance the texture and flavor of plant-based patties.

Quantification of the environmental impact arising from the utilization of whole and defatted Okara in fermentative and dehydration processes

Okara is the insoluble pulp that remains after the grinding and filtration of soybeans during the production of soymilk and tofu. As it retains a noteworthy quantity of nutrients, there has been an increasing emphasis in the utilization of this residue for the development of sustainable processes. This study focused on assessing the environmental impact of employing okara as a medium for fermenting and dehydrating probiotic bacteria at laboratory scale. The evaluation was carried out using the Life Cycle Assessment (LCA) methodology, considering the entire process lifecycle. Whole okara and defatted okara were used as culture media for Lactiplantibacillus plantarum CIDCA 83114, followed by dehydration (either freeze-drying or spray-drying) and subsequent storage. For the purpose of comparison, both scenarios (whole and defatted okara) were evaluated using 1 kg of dehydrated final product for storage, as functional unit. Based on experimental results, the conservation of the received okara and the dehydration-storage (e.g., freezing and freeze-drying) phases were identified as the most significant environmental hotspots responsible for the most substantial impacts of the processes. The use of LCA facilitated the measurement of the environmental effects linked to the reutilization of okara as an agro-industrial residue, thus providing quantitative support when engineering its sustainable valorization.

Sensory and physicochemical properties of biscuit produced from blends of whole wheat, soy okara and tigernut residue flours

Biscuits are popular ready to eat, cheap and convenient food products that are consumed globally. Supplementation of wheat flour with inexpensive staples from other cereals, legumes, roots and tubers will help in improving the nutritional quality of wheat products. Therefore, this study investigated the sensory and physicochemical properties of biscuits produced from blends of whole wheat, soy okara and tigernut residue flours. The sensory qualities of the twelve whole wheat, soy okara and tigernut residue flour biscuits at p < 0.05 ranged from 5.36 to 7.68 (color), 5.60-7.64 (appearance), 4.48-7.96 (mouthfeel), 4.28-7.76 (aroma), 3.96-8.32 (taste), 3.64-8.20 (crunchiness), 3.56-7.56 (crispiness), and 5.08-8.36 (overall acceptability). Physical, proximate and mineral analysis were carried out on the best five biscuit samples containing 100:0:0 (MVP), 60:20.98:19.02 (ISP), 50.75:39.25:10 (JAR), 53.79:22.57:23.64 (GEN) and 56.32:27.39:16.29 (XEC) whole wheat, soy okara and tigernut residue flours respectively. The physical analysis showed that diameter (38.13-38.17 mm), height (37.73-37.76 mm) and thickness (6.10-6.17 mm) were not significantly different, but the weight (7.30-7.73 g), spread ratio (5.73-6.10 mm) and breaking strength (600-643 g) significantly (p < 0.05) differed among the biscuit samples. The proximate composition of the biscuits ranged from; ash (1.70-1.90%), moisture (4.00-5.70%), fiber (7.00-11.30%), fat (16.20-17.30%), protein (6.50-12.00%), carbohydrate (56.94-59.20%) while mineral content ranged from; magnesium (122.00-134.00 mg/100 g), sodium (16.00-28.00 mg/100 g), calcium (12.00-24.00 mg/100 g), iron (2.30-3.50 mg/100 g) and phosphorus (100.00-121.00 mg/100 g). The study showed that substitution of wheat flour with soy okara and tigernut residue flour at a ratio of 60:20.98:19.02 yielded the most acceptable biscuits in all the sensory attributes assessed. This implies that biscuits produced from this composite blend contain sufficient amounts of protein, fat, fiber and carbohydrate. Hence, they can serve as relief for malnutrition.

Soybean Processing Wastes: Novel Insights on Their Production, Extraction of Isoflavones, and Their Therapeutic Properties

Soybean processing waste (SPW) has potential as a sustainable source of phytochemicals and functional foods. A variety of phytochemicals, nutrients, and minerals have been characterized from SPW using various analytical methods. SPW utilization strategies may provide a new way to increase production of bioactive compounds, nutritional supplements, and cosmetic ingredients. SPW has the potential for value-added processing, to improve commercial use, and to lower environmental pollution through proper use. Okara, a byproduct generated during soybean processing of tofu and soy milk, is rich in dietary fiber, isoflavones, and saponins. Isoflavones, an important class of biologically active compounds owing to their multifunctional and therapeutic effects, are extracted from SPW. Further, studies have shown that okara has potential prebiotic and therapeutic value in lowering the risk of noncommunicable diseases. Therefore, in this review, we focus on several extraction methods and pharmacotherapeutic effects of different SPWs. Their effective uses in functional foods, nutraceuticals, and health applications, as biocatalysts, and as value-added resources have been discussed.

Changes of High-Purity Insoluble Fiber from Soybean Dregs (Okara) after Being Fermented by Colonic Flora and Its Adsorption Capacity

In order to explore the changes and properties of high-purity insoluble dietary fiber from okara (HPIDF) after entering the colon and be fermented by colonic flora, fermented high-purity insoluble dietary fiber (F-HPIDF) was obtained by simulated fermentation in vitro by HPIDF and colonic flora from C57BL/6 mice. For exploring the differences of HPIDF and F-HPIDF, the changes of structure (SEM. FTIR, XRD, particle size, specific surface area, monosaccharide composition) and adsorption properties (water, oil, heavy metal irons, harmful substances) of HPIDF/F-HPIDF were explored. The results showed that F-HPIDF had a higher water-holding capacity (19.17 g/g), water-swelling capacity (24.83 mL/g), heavy metals-adsorption capacity (Cd²⁺: 1.82 μmol/g; Pb²⁺: 1.91 μmol/g; Zn²⁺: 1.30 μmol/g; Cu²⁺: 0.68 μmol/g), and harmful substances-adsorption capacity (GAC: 0.23 g/g; CAC: 14.80 mg/g; SCAC: 0.49 g/g) than HPIDF due to the changes of structure caused by fermentation. In addition, with the fermentation of HPIDF, some beneficial substances were produced, which might be potential intestinal prebiotics. The study of F-HPIDF strengthens the speculation that HPIDF may have potential bioactivities after entering the colon, which proved that okara-HPIDF may have potential functionality.

Structure/function relationships of bean polysaccharides: A review

Beans are a rich source of high quality protein and oil, and have attracted increasing interest from both nutrition researchers and health-conscious consumers. This review aims to provide a foundation for the future research and development of bean polysaccharides, by summarizing the sources, structure, and functions of bioactive bean polysaccharides. Structure/function relationships are described, for biological activities, such as immunological, antioxidant and anti-diabetes. This will provide useful guidance for further optimization of polysaccharide structure and the development of bean polysaccharides as a novel functional material.

Immunobiotic Feed Developed with Lactobacillus delbrueckii subsp. delbrueckii TUA4408L and the Soymilk By-Product Okara Improves Health and Growth Performance in Pigs

Lactobacillus delbrueckii subsp. delbrueckii TUA4408L is able to differentially modulate the innate immune response of porcine intestinal epithelial cells triggered by TLR4 activation. This strain also has a remarkable ability to grow on plant substrates. These two immunological and biotechnological characteristics prompted us to evaluate whether the soymilk by-product okara fermented with the TUA4408L strain can serve as an immunobiotic feed with the ability to beneficially modulate the intestinal immunity of piglets after weaning to improve their productivity. Our in vivo studies demonstrated that the administration of immunobiotic TUA4408L-fermented okara feed significantly increased piglet growth performance and meat quality. These positive effects were associated with the ability of the TUA4408L-fermented okara feed to beneficially modulate both intestinal microbiota and immunity in pigs. The immunobiotic feed improved the abundance of the beneficial bacteria Lactobacillus and Lactococcus in the gut of pigs, reduced blood markers of inflammation, and differentially regulated the expression of inflammatory and regulatory cytokines in the intestinal mucosa. These findings indicate that the immunobiotic TUA4408L-fermented okara feed could be an economical and environmentally friendly option to improve the growth performance and immune health of pigs.

Prebiotic Impacts of Soybean Residue (Okara) on Eubiosis/Dysbiosis Condition of the Gut and the Possible Effects on Liver and Kidney Functions

Okara is a white-yellow fibrous residue consisting of the insoluble fraction of the soybean seeds remaining after extraction of the aqueous fraction during the production of tofu and soymilk, and is generally considered a waste product. It is packed with a significant number of proteins, isoflavones, soluble and insoluble fibers, soyasaponins, and other mineral elements, which are all attributed with health merits. With the increasing production of soy beverages, huge quantities of this by-product are produced annually, which poses significant disposal problems and financial issues for producers. Extensive studies have been done on the biological activities, nutritional values, and chemical composition of okara as well as its potential utilization. Owing to its peculiar rich fiber composition and low cost of production, okara might be potentially useful in the food industry as a functional ingredient or good raw material and could be used as a dietary supplement to prevent varied ailments such as prevention of diabetes, hyperlipidemia, obesity, as well as to stimulate the growth of intestinal microbes and production of microbe-derived metabolites (xenometabolites), since gut dysbiosis (imbalanced microbiota) has been implicated in the progression of several complex diseases. This review seeks to compile scientific research on the bioactive compounds in soybean residue (okara) and discuss the possible prebiotic impact of this fiber-rich residue as a functional diet on eubiosis/dysbiosis condition of the gut, as well as the consequential influence on liver and kidney functions, to facilitate a detailed knowledge base for further exploration, implementation, and development.

The anti-lipidemic role of soluble dietary fiber extract from okara after fermentation and dynamic high-pressure microfluidization treatment to Kunming mice

The present study was conducted to evaluate the anti-hyperlipidemia ability of the dietary fiber extracted from okara in mice fed a high cholesterol diet. The dietary fiber was extracted from okara by combining fermentation with dynamic high-pressure microfluidization. An animal model was established to test the hypothesis that soluble dietary fiber, insoluble dietary fiber and total dietary fiber inhibit the fatty liver could be related to the total lipids and cholesterol including total cholesterol, triglyceride, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol in the serum. Compared with mice fed with simvastatin, mice fed dietary fiber can significantly reduce their serum total cholesterol, low-density lipoprotein cholesterol, triglyceride, and atherogenic index whereas no significant effect on high-density lipoprotein cholesterol was observed. Dietary fiber lowered a high level of liver total cholesterol and triglyceride. The dietary fiber extracted from okara might play an important role in the prevention of hyperlipidemia in high cholesterol mice and could be used as a natural supplement to a high cholesterol diet of functional food, due to the suppression of liver lipid synthesis.

Diet complexity and l-threonine supplementation: effects on growth performance, immune response, intestinal barrier function, and microbial metabolites in nursery pigs

The aim of this study was to investigate the effects of diet complexity and l-Thr supplementation level on the growth performance, immune response, intestinal barrier function, and microbial metabolites in nursery pigs. Thirty-two weaned pigs (body weight 7.23 ± 0.48 kg) were randomly assigned to dietary treatments in a 2 × 2 factorial arrangement based on diet complexity (complex or simple) and dietary Thr content. The complex diet contained fish meal, plasma protein, and dried whey to mimic a conventional nursery diet. The simple diet was formulated with corn, wheat, and soybean meal and did not contain any animal products. l-Thr was supplemented to each diet to supply either 100% (STD Thr) or 115% (SUP Thr) of the NRC (2012) requirement for standardized ileal digestible Thr. Pigs were individually housed and fed experimental diets ad libitum for 14 d. Diet complexity, dietary Thr content, and their interactions were considered the main effects. Pigs fed the simple diet had greater (P < 0.05) plasma interleukin (IL)-10 and IL-6 concentrations compared with those fed the complex diet on days 7 and 14, respectively. Simple diet-fed pigs tended to show greater (P < 0.10) expression of genes encoding for tumor necrosis factor-α, claudin-1, and zonula occludens-1 in the jejunum compared with complex diet-fed pigs. The simple diet-fed pigs had greater (P < 0.05) concentrations of NH3-N in the jejunum digesta than did complex diet-fed pigs. The SUP Thr increased (P < 0.05) villus height and goblet cell (GC) density in villi and crypts in the jejunum and deepened (P < 0.05) crypts in the proximal colon. The SUP Thr resulted in the upregulation (P < 0.05) of occludin gene expression and a tendency toward the downregulation (P = 0.10) of IL-6 gene expression in the jejunum. Interactions (P < 0.05) between diet complexity and l-Thr supplementation level were observed in GC density in the crypt, NH3-N concentration in the jejunum, and the contents of acetate, propionate, and total volatile fatty acids in the colon. In conclusion, feeding a simple diet to nursery pigs resulted in systemic and intestinal inflammation. The SUP Thr diet did not normalize the simple diet-induced inflammation but improved gut integrity. SUP Thr seems to have greater benefits with a simple diet than with a complex diet. Therefore, SUP Thr in a simple diet could be a beneficial nutritional strategy for enhancing gut health.

Valorisation of By-Products from Soybean (Glycine max (L.) Merr.) Processing

In recent years, increased awareness of the health benefits associated with consuming soy-based foods, knowledge of milk-related allergies and a move towards more sustainable food production have led to an increase in the number of available soy-based products. The biggest producers in the world, the USA, South America and China, are from the Pacific region. This enormous production is accompanied by the accumulation of related by-products, in particular, a substance that is known as okara. Okara is a paste that is rich in fibre (50%), protein (25%), fat (10%), vitamins and trace elements. Its proper use would lead to economic advantages and a reduction in the potential for polluting the environment. Its high fibre content and low production costs mean that it could also be used as a dietary supplement to prevent diabetes, obesity and hyperlipidaemia. Chemical or enzymatic treatment, fermentation, extrusion, high pressure and micronisation can all increase the soluble fibre content, and thus improve nutritional quality and processing properties. However, the product also degrades rapidly due to its high moisture content (70-80%), which makes it difficult to handle and expensive to dry by conventional means. The aim of this paper is therefore to thoroughly study the existing literature on this subject in order to develop a general protocol for okara exploitation and valorisation. A cost/benefit analysis could drive the design of eco-friendly, sustainable protocols for the preparation of high-value nutritional products.

Feeding the Outer Bran Fraction of Rice Alters Hepatic Carbohydrate Metabolism in Rats

Dietary intake of fiber-rich food has been reported to contribute to multiple health benefits. The aim of the current study is to investigate the effects of a diet containing the outer bran fraction of rice (OBFR), which is rich in insoluble fiber, on the intestinal environment and metabolite profiles of rats. Fourteen 8-week-old male Sprague–Dawley rats were divided into a control group and an OBFR group. For a period of 21 days, the control group was fed a control diet, while the OBFR group was fed a diet containing 5% OBFR. Metabolomics analysis revealed drastic changes in the cecal metabolites of the rats fed the OBFR diet. Furthermore, in the plasma and liver tissue, the concentrations of metabolites involved in pyruvate metabolism, the pentose phosphate pathway, gluconeogenesis, or valine, leucine, isoleucine degradation were changed. Concordantly, the OBFR diet increased the expression of genes encoding enzymes involved in these metabolic pathways in the livers of the rats. Collectively, these results suggest that the OBFR diet altered the concentrations of metabolites in the cecal contents, plasma, and liver, and the hepatic gene expressions of rats, and that this may have mainly contributed to carbohydrate metabolism in the liver.

Oral Administration of Okara Soybean By-Product Attenuates Cognitive Impairment in a Mouse Model of Accelerated Aging

The microbiota-gut-brain axis has attracted increasing attention in the last decade. Here, we investigated whether okara, a soybean by-product rich in dietary fiber, can attenuate cognitive impairment in senescence-accelerated mouse prone 8 (SAMP8) mice by altering gut microbial composition. Mice were fed either a standard diet, or a diet containing okara (7.5% or 15%, w/w) for 26 weeks. In the memory test, the 7.5% okara-fed mice showed a longer step-through latency and the 15% okara-fed mice had a short escape latency compared with control mice. The 15% okara-fed mice displayed decreased body weight, increased fecal weight, and altered cecal microbiota composition compared with the control group; however, there was no significant difference in the serum lactic acid and butyric acid levels among these mice groups. The 7.5% okara-fed mice had significantly higher NeuN intensity in the hippocampus compared with control mice. Furthermore, a decrease in inflammatory cytokine TNF- and an increase in brain-derived neurotrophic factor (BDNF) was observed in the 7.5% okara-fed group. The expression of synthesizing enzyme of acetylcholine was increased by the okara diets, and the acetylcholine level in the brain was higher in the 7.5% okara-fed group than in the control. These suggest that oral administration of okara could delay cognitive decline without drastically changing gut microbiota.

Effect of oat and soybean rich in distinct non-starch polysaccharides on fermentation, appetite regulation and fat accumulation in rat

Consumption of non-starch polysaccharides (NSP) is associated with reduced risk of obesity. This study aimed to compare the effects of cereals (oats) and legumes (soybean), rich in different classes of NSP, on appetite regulation and fat accumulation in rats. Soy pectin fermented more efficient than cereal arabinoxylan in rats. Soy pectin and oat β-glucan were utilized mainly in the caecum of rats. Only small amount of maltodextrin, cello-oligosaccharides and xylo-oligosaccharides were detected in the digesta. Caecal fermentation of soy pectin produced significantly higher concentration of short chain fatty acids (SCFAs) compared to the control. Retroperitoneal (RP) fat-pad weight was significantly lower for rats fed with soybean meal enriched diet than for controls. An inverse correlation between rat RP fat-pad weight and concentration (and proportion) of butyrate was observed. Consumption of soy pectin and oat β-glucan enriched foods to produce targeted SCFAs in vivo could be a potential strategy to lower fat mass accumulation and a potential tool to manage obesity.

Protease technology for obtaining a soy pulp extract enriched in bioactive compounds: isoflavones and peptides

This work presents a new bioprocess process for the extraction of bioactive components from soy pulp by-product (okara) using an enzymatic technology that was compared to a conventional water extraction. Okara is rich in fiber, fat, protein, and bioactive compounds such as isoflavones but its low solubility hampers the use in food and fertilizer industry. After the enzymatic attack with endoproteases half of the original insoluble proteins were converted into soluble peptides. Linked to this process occured the solubilization of isoflavones trapped in the insoluble protein matrix. We were able to extract up to 62.5% of the total isoflavones content, specially aglycones, the more bioactive isoflavone forms, whose values rose 9.12 times. This was probably due to the increased solubilization and interconversion from the original isoflavones. In conclusion, our process resulted in the formulation of a new functional product rich in aglycones and bioactive peptides with higher antioxidant potency than the original source. Therefore, we propose that the enzymatic extraction of okara bioactive compounds is an advantageous tool to replace conventional extraction.

Application of transglutaminase for quality improvement of whole soybean curd

To improve the quality of whole soybean curd (WSC), effects of compound coagulants consisting of calcium chloride (CaCl₂) and transglutaminase (TGase) were investigated. The results showed that TGase modified the water distribution and reduced the cooking loss of WSC, accompanying with increased water holding capacity. The bloom value of WSC was upgraded as the TGase concentration increased. Although certain sensory parameters showed different scores in groups, the overall acceptability of 1500 ppm group was the highest. TPA test suggested that hardness, springiness and chewiness were promoted by TGase significantly. Smooth appearance of WSC was observed, resulting from the transformation of microstructure. Protein subunits of 7Sα', 7Sα, 7Sβ, 11SA3, 11S acidic, and 11S basic proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, band intensity of protein subunits declined at storage and cooking phase, indicating that crosslinking of proteins was still in progress. In conclusion, the addition of TGase improved the quality of CaCl₂-induced WSC and could be used to facilitate the production of this new type of soybean product.

The impact of fruit and soybean by-products and amaranth on the growth of probiotic and starter microorganisms

The ability of different fruit by-products, okara, and amaranth flour, to support the growth of probiotic and non-probiotic strains was evaluated. The tests were conducted with three commercial starter cultures (Streptococcus thermophilus), ten probiotic strains (seven Lactobacillus spp. and three Bifidobacterium spp. strains), and two harmful bacteria representative of the intestinal microbiota (Escherichia coli and Clostridium perfringens). In vitro fermentability assays were performed using a modified MRS broth supplemented with different fruits (acerola, orange, passion fruit, and mango), and soy (okara) by-products or amaranth flour. Orange and passion-fruit by-products were the substrates that most promoted the growth of bacterial populations, including pathogenic strains. On the other hand, the acerola by-product was the substrate that showed the highest selectivity for beneficial bacteria, since the E. coli and Cl. perfringens populations were lower in the presence of this fruit by-product. Although the passion fruit by-product, okara, and amaranth stimulated the probiotic strains, the growth of the pathogenic strains studied was higher compared to other substrates. Different growth profiles were verified for each substrate when the different strains were compared. Although pure culture models do not reflect bacterial interaction in the host, this study reinforces the fact that the ability to metabolize different substrates is strain-dependent, and acerola, mango, and orange by-products are the substrates with the greatest potential to be used as prebiotic ingredients.

Okara: A Nutritionally Valuable By-product Able to Stabilize Lactobacillus plantarum during Freeze-drying, Spray-drying, and Storage

Okara is a nutritionally valuable by-product produced in large quantities as result of soymilk elaboration. This work proposes its use as both culture and dehydration medium during freeze-drying, spray-drying, and storage of Lactobacillus plantarum CIDCA 83114. Whole and defatted okara were employed as culture media for L. plantarum CIDCA 83114. The growth kinetics were followed by plate counting and compared with those of bacteria grown in MRS broth (control). No significant differences in plate counting were observed in the three media. The fatty acid composition of bacteria grown in whole and defatted okara showed a noticeable increase in the unsaturated/saturated (U/S) fatty acid ratio, with regard to bacteria grown in MRS. This change was mainly due to the increase in polyunsaturated fatty acids, namely C18:2. For dehydration assays, cultures in the stationary phase were neutralized and freeze-dried (with or without the addition of 250 mM sucrose) or spray-dried. Bacteria were plate counted immediately after freeze-drying or spray-drying and during storage at 4°C for 90 days. Freeze-drying in whole okara conducted to the highest bacterial recovery. Regarding storage, spray-dried bacteria previously grown in whole and defatted okara showed higher plate counts than those grown in MRS. On the contrary, freeze-dried bacteria previously grown in all the three culture media were those with the lowest plate counts. The addition of sucrose to the dehydration media improved their recovery. The higher recovery of microorganisms grown in okara after freeze-drying and spray-drying processes and during storage was ascribed to both the presence of fiber and proteins in the dehydration media, and the increase in U/S fatty acids ratio in bacterial membranes. The obtained results support for the first time the use of okara as an innovative matrix to deliver L. plantarum. Considering that okara is an agro-waste obtained in large quantities, these results represent an innovative strategy to add it value, providing a symbiotic ingredient with promising industrial applications in the development of novel functional foods and feeds.

Determination of soluble dietary fibre content of Okara treated with high hydrostatic pressure and enzymes: a comparative evaluation of two methods (AOAC and HPLC-ELSD)

ABSTRACT

Okara is a promising by-product from soybean and a rich source of dietary fibre, chiefly insoluble (IDF). To increase its solubility and functionality, a treatment with high hydrostatic pressure (HHP) assisted by food grade enzymes -Ultraflo® L or Viscozyme® L- has been performed. To monitor the effectiveness, an analysis of dietary fibre, mainly the soluble fraction (SDF), was accomplished by the AOAC enzymatic-gravimetric method with dialysis followed by both, spectrophotometric methods and High Performance Liquid Chromatography with Evaporative Light Scattering Detector (HPLC-ELSD) analysis of the soluble fraction. A significant increase in SDF (≈1.5-times) to the expense of a decrease in IDF was shown and chromatograms revealed two peaks of 95 and 22 kDa. Thus, treated Okara possessed a more balanced and convenient ratio of soluble to insoluble dietary fibre, which could have health benefits as prebiotic. Inbuilt interferences of the official AOAC's method for dietary fibre were confirmed and the direct HPLC-ELSD approach was about twice more sensitive than spectrophotometric methods. Consequently, the direct HPLC-ELSD analysis of the supernatant is proposed as a cheaper, faster and reliable method. Combined HHP-treatments plus specific enzymes represent a promising alternative for the valorisation and preservation of agrofood by-products.

GRAPHICAL ABSTRACT

Plant Food Residues as a Source of Nutraceuticals and Functional Foods

This chapter describes the use of different plant and vegetable food residues as nutraceuticals and functional foods. Different nutraceuticals are mentioned and explained. Their uses are well addressed along with their disease management and their action as nutraceutical delivery vehicles.

Soy and Gut Microbiota: Interaction and Implication for Human Health

Soy (Glycine max) is a major commodity in the United States, and soy foods are gaining popularity due to their reported health-promoting effects. In the past two decades, soy and soy bioactive components have been studied for their health-promoting/disease-preventing activities and potential mechanisms of action. Recent studies have identified gut microbiota as an important component in the human body ecosystem and possibly a critical modulator of human health. Soy foods' interaction with the gut microbiota may critically influence many aspects of human development, physiology, immunity, and nutrition at different stages of life. This review summarizes current knowledge on the effects of soy foods and soy components on gut microbiota population and composition. It was found, although results vary in different studies, in general, both animal and human studies have shown that consumption of soy foods can increase the levels of bifidobacteria and lactobacilli and alter the ratio between Firmicutes and Bacteroidetes. These changes in microbiota are consistent with reported reductions in pathogenic bacteria populations in the gut, thereby lowering the risk of diseases and leading to beneficial effects on human health.

Soymilk residue (okara) as a natural immobilization carrier for Lactobacillus plantarum cells enhances soymilk fermentation, glucosidic isoflavone bioconversion, and cell survival under simulated gastric and intestinal conditions

Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. However, artificial immobilization carriers are expensive and pose a high safety risk. Okara, a food-grade byproduct from soymilk production, is rich in prebiotics. Lactobacilli could provide health enhancing effects to the host. This study aimed to evaluate the potential of okara as a natural immobilizer for L. plantarum 70810 cells. The study also aimed to evaluate the effects of okara-immobilized L. plantarum 70810 cells (IL) on soymilk fermentation, glucosidic isoflavone bioconversion, and cell resistance to simulated gastric and intestinal stresses. Scanning electron microscopy (SEM) was used to show cells adherence to the surface of okara. Lactic acid, acetic acid and isoflavone analyses in unfermented and fermented soymilk were performed by HPLC with UV detection. Viability and growth kinetics of immobilized and free L. plantarum 70810 cells (FL) were followed during soymilk fermentation. Moreover, changes in pH, titrable acidity and viscosity were measured by conventional methods. For in vitro testing of simulated gastrointestinal resistance, fermented soymilk was inoculated with FL or IL and an aliquot incubated into acidic MRS broth which was conveniently prepared to simulate gastric, pancreatic juices and bile salts. Survival to simulated gastric and intestinal stresses was evaluated by plate count of colony forming units on MRS agar. SEM revealed that the lactobacilli cells attached and bound to the surface of okara. Compared with FL, IL exhibited a significantly higher specific growth rate, shorter lag phase of growth, higher productions of lactic and acetic acids, a faster decrease in pH and increase in titrable acidity, and a higher soymilk viscosity. Similarly, IL in soymilk showed higher productions of daizein and genistein compared with the control. Compared with FL, IL showed reinforced resistance to simulatedgastric and intestinal stresses in vitro that included low pH, low pH plus pepsin, pancreatin, and bile salt. Our results indicate that okara is a new potential immobilization carrier to enhance the growth and glucosidic isoflavone bioconversion activities of L. plantarum in soymilk and improve cell survivability following simulated gastric and intestinal conditions.

Supplementation with fruit and okara soybean by-products and amaranth flour increases the folate production by starter and probiotic cultures

The ability of two starter cultures (Streptococcus (S.) thermophilus ST-M6 and St. thermophilus TA-40) and eleven probiotic cultures (St. thermophilus TH-4, Lactobacillus (Lb.) acidophilus LA-5, Lb. fermentum PCC, Lb. reuteri RC-14, Lb. paracasei subsp. paracasei, Lb. casei 431, Lb. paracasei subsp. paracasei F19, Lb. rhamnosus GR-1, and Lb. rhamnosus LGG, Bifidobacterium (B.) animalis subsp. lactis BB-12, B. longum subsp. longum BB-46, and B. longum subsp. infantis BB-02) to produce folate in a modified MRS broth (mMRS) supplemented with different fruit (passion fruit, acerola, orange, and mango) and okara soybean by-products and amaranth flour was investigated. Initially, the folate content of each vegetable substrate was determined: passion fruit by-product showed the lowest folate content (8±2ng/mL) and okara the highest (457±22ng/mL). When the orange by-product and amaranth flour were added to mMRS, all strains were able to increase folate production after 24h of fermentation. B. longum subsp infantis BB-02 produced the highest concentrations (1223±116ng/mL) in amaranth flour. Okara was the substrate that had the lowest impact on the folate production by all strains evaluated. Lb. acidophilus LA-5 (297±36ng/mL) and B. animalis subsp. lactis BB-12 (237±23ng/mL) were also able to produce folate after growth in mMRS containing acerola and orange by-products, respectively. The results of this study demonstrate that folate production is not only strain-dependent but also influenced by the addition of different substrates in the growth media.

In vitro fermentability and prebiotic potential of soyabean Okara by human faecal microbiota

At present, there is a huge interest in finding new prebiotics from agrofood industrial waste, such as the soyabean by-product Okara, rich in insoluble dietary fibre. A previous treatment of Okara with high hydrostatic pressure assisted by the food-grade enzyme Ultraflo ® L achieved a 58·2 % increment in its soluble dietary fibre (SDF) contents. Therefore, potential prebiotic effect of both treated and native Okara was assayed using 48 h, pH-controlled, anaerobic batch cultures inoculated with human faecal slurries, which simulate the human gut. Changes in faecal microbiota were evaluated using 16S rRNA-based fluorescence in situ hybridisation, whereas release of SCFA and lactic acid was assessed by HPLC. Both Okara samples exhibited potential prebiotic effects but Okara treated to maximise its SDF content showed higher SCFA plus lactic acid, better growth promotion of beneficial bacteria, including bifidobacteria after 4 and 48 h and lactobacilli after 4 h of fermentation, and a greater inhibition of potentially harmful bacterial groups such as clostridia and Bacteroides. Differences found between fructo-oligosaccharides and Okara substrates could be attributed to the great complexity of Okara's cell wall, which would need longer times to be fermented than other easily digested molecules, thus allowing an extended potential prebiotic effect. These results support an in vitro potential prebiotic effect of Okara.

Potential fat-lowering and prebiotic effects of enzymatically treated okara in high-cholesterol-fed Wistar rats

This study evaluates the effect of the lipid profile on serum, liver and faeces, and the potential prebiotic effect of diets supplemented with enzymatically treated okara (okara(ET)) in high-cholesterol fed Wistar rats. Triglyceride levels were significantly reduced in the serum (p < 0.01) and liver (p < 0.01) of okara(ET) treated rats. Total lipids, triglycerides and bile acids were significantly higher (p < 0.001) in the faeces of rats fed the okara(ET) diet. The pH of faecal contents from treated okara(ET) rats was lower (p < 0.001), probably due to the significantly higher (p < 0.001) production of short-chain fatty acids (SCFA). Okara(ET), therefore, reduced triglycerides in serum and liver, and increased the excretion of total lipids, triglycerides and bile acids, improving the lipid profile in rats fed with high-cholesterol diets. Okara(ET) fibre can improve intestinal transit by increasing faecal bulk. The decreased pH and increased SCFA production indicated that okara(ET) fibre fermentation occurred, suggesting a potential prebiotic effect.

Okara, a soybean by-product, prevents high fat diet-induced obesity and improves serum lipid profiles in C57BL/6J mice

This study aimed to validate the anti-obesity effect of okara, a soyfood byproduct, in diet induced obese mice. Thirty two C57BL/6J male 4 week old mice were divided into four dietary groups (n=8) fed either normal diet (ND), high fat diet (HD), HD with 10% okara (OL), or HD with 20% okara (OH) for 12 weeks. Body weight gain and epididymal fat weight of OL and OH group were significantly lower than HD group. Similarly, the serum and hepatic lipid profiles in OH were significantly lower than HD group. The fecal triacylglycerol and TC levels in OL and OH increased compared to HD. Also, the expression of PPAR-α was higher in OH than HD group; PPAR-γ and FAS levels were lower in OH compared to HD. In this study, okara consumption appears to protect mice against diet induced obesity (DIO) and metabolic dysregulation related to obesity.

Production and evaluation of breakfast cereals from blends of acha and fermented soybean paste (okara)

Breakfast cereals was formulated from blends of acha and fermented okara (soybean residue). Acha grains were cleaned, winnowed, washed, dried (at 50 °C for 4 h) and milled into flour. Okara was processed from soybean seed through the stepwise procedure of cleaning, soaking, washing, milling and sieving. The residue was divided into five portions, fermented differently for 0, 12, 24, 36, and 48 h and then dried at 50 °C for 6 h. Acha flour (UFAC) was milled and blended at 50, 60, 70, 80, 90, 100 % ratio with milled okara flour. Functional properties (bulk density, water absorption capacity, swelling capacity, wettability, viscosity and particle size distribution, microbial load, and proximate composition were carried out on the individual flour samples. The blended flours were conditioned, partially heat treated (for 10 min), aged (4 °C for 6 h), cut, toasted (120 °C for 1 h), cooled and packaged. The different toasted breakfast cereals, TBFC, were subjected to sensory evaluation, proximate composition, micronutrient composition (vitamin A, B1, B2, B3, calcium, iron, phosphorus, and zinc) and microbial analyses (mould count and total viable count). The proximate composition of the unfermented okara (UFOK) and fermented okara (FEOK 1, 2, 3, and 4 fermented at 12, 24, 36, 48 h respectively) flour samples showed that fermentation increased moisture from 4.71 ± 0.06 to 6.11 ± 0.05, crude fibre from 36.62 ± 0.01 to 46.18 ± 0.55, and carbohydrate from 2.50 ± 0.18 to 2.71 ± 0.34 contents. There was a decrease in the fat content from 16.29 ± 0.04 to 13.27 ± 0.22, ash from 1.41 ± 0.17 to 6.36 ± 0.17 and crude protein from 30.32 ± 0.21 to 33.53 ± 0.11 contents. From the sensory evaluation, the result showed that 70:30 acha-unfermented okara TBFC, FEOK 1D 60:40 acha-12 h FEOK TBFC, 70:30 acha-24 h FEOK TBFC, 50:50 acha-36 h FEOK TBFC, and 70:30 acha-48 h FEOK TBFC had the best overall acceptability for the different fermentation times. The functional properties, proximate and sensory evaluation were the basis for selection of the best products which were UFAC (control), UFOK C (70:30 acha UFOK TBFC) and FEOK 4C (70:30 acha 48 h FEOK TBFC) which were further subjected to proximate, micronutrient, and microbial analyses. There was an increase in the protein, fat, ash, crude fibre content whereas the moisture and carbohydrate contents decreased. A considerable decrease was found in vitamin A and B1 contents of the products, whereas vitamin B2 and B3 increased. Also the mineral contents of all the products were improved as indicated in the increase in ash content.

Mineral elements, lipoxygenase activity, and antioxidant capacity of okara as a byproduct in hydrothermal processing of soy milk

Minerals and antioxidative capacity of raw okara that was obtained as a byproduct from six soybean varieties during hydrothermal cooking (HTC) of soy milk were assessed. Lipoxygenase (Lox), an enzyme deteriorating the sensory characteristics of okara, was also investigated. All genotypes had very similar concentrations of Lox (4.32-5.62%). Compared to raw soybeans, the applied HTC significantly reduced Lox content in okara (0.54-0.19%) and lowered its activity to 0.004-0.007 μmol g(-1) min (-1). Correlation between the content of Lox in soybeans and that in okara (r = 0.21;p < 0.05) was not registered. This indicates that the content of this enzyme in okara depended much more on the technological process than on soybean genotype. Very strong correlation (r = 0.99; p < 0.05) between okara Lox content and its activity was found. The most abundant minerals in raw okara were potassium (1.04-1.21 g/100g), phosphorus (0.45-0.50 g/100 g), calcium (0.26-0.39 g/100 g), and iron (5.45-10.95 mg/100 g). A very high antioxidant capacity (19.06-29.36 mmol Trolox kg(-1)) contributes to the nutritional value of raw okara.

Nutritional recovery with okara diet prevented hypercholesterolemia, hepatic steatosis and glucose intolerance

We assessed the biological value of an okara diet and its effects on the hormonal and metabolic profile of rats submitted to protein restriction during intra-uterine life and lactation and recovered after weaning. Male rats from mothers fed either 17% or 6% protein during pregnancy and lactation were maintained on 17% casein (CC, LC), 17% okara (CO, LO) or 6% casein (LL) diets over 60 d. The nutritional quality of the okara protein was similar to that of casein. The okara diet was effective in the nutritional recovery of rats in growing that were malnourished in early life. Furthermore, the okara diet reversed the hypercholesterolemia and the hepatic steatosis observed in the malnutrition and prevented glucose intolerance in an animal model prone to diabetes mellitus.

Interactions between prebiotics, probiotics, polyunsaturated fatty acids and polyphenols: diet or supplementation for metabolic syndrome prevention?

The metabolic syndrome can be prevented by the Mediterranean diet, characterized by fiber, omega-3 polyunsaturated fatty acids and polyphenols. However, the composition of the Mediterranean diet, which can be viewed as a natural multiple supplement, is poorly controlled, and its beneficial effects poorly predictable. The metabolic syndrome is associated with intestinal dysbiosis and the gut microbioma seems to be the main target and player in the interactions occurring between probiotics, prebiotics, omega 3 polyunsaturated fatty acids, and polyphenols. From the reviewed evidence, it is reasonable to manage growth and metabolism of gut microflora with specific prebiotics and polyphenols. Even though the healthy properties of functional foods and nutraceuticals still need to be fully elucidated, available data suggest that well-designed supplements, containing the better ratio of omega-3 polyunsaturated fatty acids and antioxidants, specific probiotic strains, and selected polyphenols and prebiotics, could be useful in metabolic syndrome prevention and treatment.

Incorporation of soybean by-product okara and inulin in a probiotic soy yoghurt: texture profile and sensory acceptance

BACKGROUND

This study evaluated the effect of inulin and okara flour on textural and sensory properties of probiotic soy yoghurt (SY) throughout 28 days of storage at 4 °C. Employing a 2(2) design, four formulations of SY produced from soymilk and fermented with an ABT-4 culture (Lactobacillus acidophilus La-5, Bifidobacterium animalis Bb-12 and Streptococcus thermophilus) were studied: SY-C (control); SY-I (with inulin); SY-O (with okara); SY-IO (with inulin + okara).

RESULTS

The addition of okara and the refrigerated storage led to significant differences in the instrumental texture parameters of SY (P < 0.05). Inulin and okara did not affect SY sensory acceptability (P > 0.05), but there was a tendency for higher scores in the presence of inulin. On the other hand, the storage period, particularly at 21 days, was unfavourable regarding the acceptance of the different SY.

CONCLUSION

The results showed that the addition of okara flour and the storage were significant factors to increase firmness of the soy yoghurts. SY acceptability was not affected by the incorporation of inulin or okara. These results suggest that okara, discarded as industrial waste, may be used in probiotic soy yoghurt, helping to increase the nutritional and functional properties without altering its acceptability.

Soy fiber improves weight loss and lipid profile in overweight and obese adults: a randomized controlled trial

SCOPE

Studies have suggested that food rich in dietary fiber may facilitate body weight loss, lower total and LDL-cholesterol levels, and reduce body fat. This study examined the effects of soy fiber (SF) on body weight, body composition, and blood lipids in overweight and obese participants.

METHODS AND RESULTS

Thirty-nine overweight and obese college adults (19-39 years of age) were randomly assigned to consume control biscuits or biscuits supplemented with SF for their breakfast for 12 wk (approximately 100 g/day). There were significant differences in changes on body weight, BMI, and LDL-cholesterol (LDL-C) between the two groups after 12-wk intervention (p < 0.05). The changes of body weight, BMI, waist circumference, diastolic blood pressure, serum levels of total cholesterol, LDL-C, and glucose, body fat, and trunk fat of participants in SF group were observed significantly after 12 wk.

CONCLUSION

SF had favorable effects on body weight, BMI, and fasting LDL-C levels in overweight and obese adults. These effects may be beneficial in antiobesity and the improvement of hyperlipidemia and hypertension (ClinicalTrials.gov registration number-NCT01802840).

Bioactive proteins and energy value of okara as a byproduct in hydrothermal processing of soy milk

The nutritional properties of raw okara obtained as a byproduct from six soybean varieties during hydrothermal cooking (HTC) of soy milk were assessed. The composition and residual activity (rTIA) of trypsin inhibitors (TIs), contents of lectin, proteins, fats, and carbohydrates, and energy values (EV) were correlated with the respective physicochemical properties of soybean and okara. Kunitz (KTI) and Bowman-Birk (BBI) TIs both comprised okara rTIA. TIs content was higher in okara (5.19-14.40%) than in soybean (3.10-12.17%), which additionally enriched okara by cysteine. Contents of KTI (r = 1.00;p < 0.05) and BBI (r = 0.89;p < 0.05) as well as BBI monomeric (r = 0.89;p < 0.05) and polymeric forms (r = 0.95;p < 0.05) in okara and in soybean were strongly correlated. Low urease index activity indicated that okara was heated adequately to inactivate antinutritional factors. The proximate composition of raw okara, advantageous rTIA, and a very low EV (2.74-3.78 kJ/g) qualify this byproduct for potential application in food preparation as a functional ingredient in dietary products.