Modification of insoluble dietary fibres in soya bean okara and their physicochemical properties

Advancements in modifying insoluble dietary fiber: Exploring the microstructure, physicochemical properties, biological activity, and applications in food industry-A review

Recent research has primarily focused on strategies for modifying insoluble dietary fiber (IDF) to enhance its performance and functionality. IDF is obtained from various inexpensive sources and can be manipulated to alter its biological effects, making it possible to revolutionize food processing and nutrition. In this review, multiple IDF modification techniques are thoroughly examined and discussed, with particular emphasis on the resulting changes in the physicochemical properties, biological activities, and microstructure of the fiber. An extensive overview of the practical applications of modified IDF in food processing is provided. Our study aims to raise awareness about the vast possibilities presented by modified IDF and encourage further exploration and utilization of this field in the realm of food production.

Effects of Different Extraction Methods on the Structural and Functional Properties of Soluble Dietary Fibre from Sweet Potatoes

In this study, hot water treatment (WT), ultrasonic treatment (UT), ultrasonic-sodium hydroxide treatment (UST), ultrasonic-enzyme treatment (UET), and ultrasonic-microwave treatment (UMT) were used to treat sweet potatoes. The structural, physicochemical, and functional properties of the extracted soluble dietary fibres (SDFs) were named WT-SDF, UT-SDF, UST-SDF, UET-SDF, and UMT-SDF, respectively. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal properties, and Brunauer-Emmett-Teller (BET) analysis were employed. The structural results indicated that the UST-SDF exhibited the best thermal stability, highest crystallinity, and maximum specific surface area. Moreover, compared to hot water extraction, ultrasonic extraction, or ultrasonic extraction in combination with other methods, enhanced the physicochemical and functional properties of the SDF, including extraction yield, water-holding capacity (WHC), oil-holding capacity (OHC), glucose adsorption capacity (GAC), glucose dialysis retardation index (GDRI), sodium cholate adsorption capacity (SCAC), cholesterol adsorption capacity (CAC), nitrite ion adsorption capacity (NIAC), and antioxidant properties. Specifically, the UST-SDF and UMT-SDF showed better extraction yield, WHC, OHC, GAC, CAC, SCAC, and NIAC values than the other samples. In summary, these results indicate that UST and UMT could be applied as ideal extraction methods for sweet potato SDF and that UST-SDF and UMT-SDF show enormous potential for use in the functional food industry.

Characterization of the Structure and Physicochemical Properties of Soluble Dietary Fiber from Peanut Shells Prepared by Pulsed Electric Fields with Three-Phase Partitioning

This study evaluated the impact of pulsed electric fields (PEFs) combined with three-phase partitioning (TPP) extraction methods on the physicochemical properties, functional properties, and structural characterization of the soluble dietary fiber (SDF) derived from peanut shells (PS). The findings of this study indicated that the application of a PEF-TPP treatment leads to a notable improvement in both the extraction yield and purity of SDF. Consequently, the PEF-TPP treatment resulted in the formation of more intricate and permeable structures, a decrease in molecular weight, and an increase in thermal stability compared to SDFs without TPP treatment. An analysis revealed that the PEF-TPP method resulted in an increase in the levels of arabinose and galacturonic acid, leading to enhanced antioxidant capacities. Specifically, the IC50 values were lower in SDFs which underwent PEF-TPP (4.42 for DPPH and 5.07 mg/mL for ABTS) compared to those precipitated with 40% alcohol (5.54 mg/mL for DPPH, 5.56 mg/mL for ABTS) and PEF75 (6.60 mg/mL for DPPH, 7.61 mg/mL for ABTS), respectively. Notably, the SDFs which underwent PEF-TPP demonstrated the highest water- and oil-holding capacity, swelling capacity, emulsifying activity, emulsion stability, glucose adsorption, pancreatic lipase inhibition, cholesterol adsorption, nitric ion adsorption capacity, and the least gelation concentration. Based on the synthesis scores obtained through PCA (0.536 > -0.030 > -0.33), which indicated that SDFs which underwent PEF-TPP exhibited the highest level of quality, the findings indicate that PEF-TPP exhibits potential and promise as a method for preparing SDFs.

The potential of dietary fiber in building immunity against gastrointestinal and respiratory disorders

The numerous health benefits of dietary fibers (DFs) justify their inclusion in human diets and biomedical products. Given the short- and long-term human impacts of the COVID-19 virus on human health, the potential of DFs in building immunity against gastrointestinal and respiratory disorders is currently receiving high attention. This paper reviews the physicochemical properties of DFs, together with their immune functions and effects on the gastrointestinal tract and respiratory system mainly based on research in the last ten years. Possible modes of action of DFs in promoting health, especially building immunity, are explored. We seek to highlight the importance of understanding the exact physical and chemical characteristics and molecular behaviors of DFs in providing specific immune function. This review provides a perspective beyond the existing recognition of DFs' positive effects on human health, and offers a theoretical framework for the development of special DFs components and their application in functional foods and other therapeutic products against gastrointestinal and respiratory disorders. DFs enhance immunity from gastrointestinal and respiratory diseases to promote host health.

The Principle of Steam Explosion Technology and Its Application in Food Processing By-Products

Steam explosion technology is an emerging pretreatment method that has shown great promise for food processing due to its ability to efficiently destroy the natural barrier structure of materials. This narrative review summarizes the principle of steam explosion technology, its similarities and differences with traditional screw extrusion technology, and the factors that affect the technology. In addition, we reviewed the applications in food processing by-products in recent years. The results of the current study indicate that moderate steam explosion treatment can improve the quality and extraction rate of the target products. Finally, we provided an outlook on the development of steam explosion technology with a reference for a wider application of this technology in the food processing field.

Characterization and the cholesterol-lowering effect of dietary fiber from fermented black rice (Oryza sativa L.)

Black rice was fermented with Neurospora crassa, after which the dietary fiber (DF) extracted from it was characterized and evaluated for its cholesterol-lowering effect in mice. The findings demonstrated that fermentation increased the level of soluble DF from 17.27% ± 0.12 to 29.69% ± 0.26 and increased the adsorption capacity of DF for water, oil, cholesterol, glucose and sodium cholate. The fermented DF had a more loose and porous structure than that extracted from unfermented rice. Additionally, feeding with DF from the fermented black rice significantly reduced body weight, lowered total cholesterol levels and improved the lipid profile in mice gavaged with a high dose (5 g per kg bw) or a low dose (2.5 g per kg·bw). ELISA showed that the hepatic expression of typical proteins and enzymes that are involved in cholesterol metabolism was regulated by the fermented rice DF, leading to reduced cholesterol production and increased cholesterol clearance. The fermented DF also modified the gut microbiota composition (e.g. Firmicutes reduced and Akkermansia increased), which promoted the production of short-chain fatty acids. In conclusion, fermentation can modify the structure and function of DF in black rice and the fermented dietary fiber has excellent cholesterol lowering effects possibly by cholesterol adsorption, cholesterol metabolism modulation, and intestinal microflora regulation.

Optical sensor arrays for the detection and discrimination of natural products

Covering: up to the end of 2022Natural products (NPs) have found uses in medicine, food, cosmetics, materials science, environmental protection, and other fields related to our life. Their beneficial properties along with potential toxicities make the detection and discrimination of NPs crucial for their applications. Owing to the merits of low cost and simple operation, optical sensor arrays, including colorimetric and fluorometric sensor arrays, have been widely applied in the detection of small molecule NPs and discrimination of structurally similar small molecule NPs or complex mixtures of NPs. This review provides a brief introduction to the optical sensor array and focuses on its progress toward the detection and discrimination of NPs. We summarized the design principle of sensor arrays toward various NPs (i.e., saccharides and polyhydroxy compounds, organic acids, flavonoids, organic sulfur compounds, amines, amino acids, and saponins) based on their functional groups and characteristic chemical properties, along with representative examples. Moreover, the challenges and potential directions for further research of optical sensor arrays for NPs are proposed.

Fabrication and characterization of colorimetric indicator for Salmon freshness monitoring using agar/polyvinyl alcohol gel and anthocyanin from different plant sources

In order to investigate the sensitivity of anthocyanins from different plant origin as indicators for salmon freshness, nine plant anthocyanins were extracted and fabricated into colorimetric sensor arrays to detect NH₃, trimethylamine (TMA), dimethylamine (DMA) to indicate salmon freshness. Rosella anthocyanin had the highest sensitivity for amines, ammonia and salmon. HPLC-MSS analysis indicated that Delphinidin-3 glucoside accounted for 75.48 % of the Rosella anthocyanin. UV-visible spectral analysis showed that the maximum absorbance band of Roselle anthocyanins for acid and alkaline forms were located at 525 nm and 625 nm which showed a relatively broader spectrum than other anthocyanins. An indicator film was fabricated by combining Roselle anthocyanin with agar and polyvinyl alcohol (PVA), which showed visible changes from red to green when employed to monitor the freshness of salmon stored at 4 °C. The ΔE value of Roselle anthocyanin indicator film was changed from 5.94 to >10. The ΔE value also can predict the chemical quality indicators of salmon effectively, especially with characteristic volatile components, and the predictive correlation coefficient was above 0.98. Therefore, the proposed indicating film showed great potential monitoring salmon freshness.

Physicochemical Characteristics of Soluble Dietary Fiber Obtained from Grapefruit Peel Insoluble Dietary Fiber and Its Effects on Blueberry Jam

Appropriate modification methods can increase the proportion of soluble dietary fiber (SDF). In this study, grapefruit peel insoluble dietary fiber (GP-IDF) was modified with the combined microwave and enzymatic method to obtain SDF. With regard to structural characterization, SDF from grapefruit peel IDF (GP-IDF-SDF) presented as a flat sheet with cracks, composed of a typical cellulose type I crystal, and had good stability below 200 °C. Galacturonic acid, arabinose and glucuronic acid were the main monosaccharide compositions, indicating that pectin might have been the principal component. Moreover, GP-IDF-SDF was excellent in water retention capacity (13.43 ± 1.19 g/g), oil retention capacity (22.10 ± 0.85 g/g) and glucose adsorption capacity (14.49 ± 0.068 mg/g). Thereafter, the effects of GP-IDF-SDF and commercial pectin addition on the color, rheology, texture and sensory properties of blueberry jam were compared. The results showed that the color of jam with GP-IDF-SDF was lighter. The addition of GP-IDF-SDF had less effects on the viscosity and gel strength of jam, but it enhanced the stability of jam. According to sensory data, the color, texture and spreadability of jam with GP-IDF-SDF or pectin were improved and more acceptable. Overall, GP-IDF-SDF had functional characteristics and played a positive role in jam, and it is expected to be a candidate for the development of functional food ingredients.

Principle and Application of Steam Explosion Technology in Modification of Food Fiber

Steam explosion is a widely used hydrothermal pretreatment method, also known as autohydrolysis, which has become a popular pretreatment method due to its lower energy consumption and lower chemical usage. In this review, we summarized the technical principle of steam explosion, and its definition, modification and application in dietary fiber, which have been explored by researchers in recent years. The principle and application of steam explosion technology in the modification of food dietary fiber were analyzed. The change in dietary fiber structure; physical, chemical, and functional characteristics; the advantages and disadvantages of the method; and future development trends were discussed, with the aim to strengthen the economic value and utilization of plants with high dietary fiber content and their byproducts.

Wet Grinder-Treated Okara Improved Both Mechanical Properties and Intermolecular Forces of Soybean Protein Isolate Gels

The application of okara treated by a wet-type grinder (WG) is discussed in this paper. We examined the effect of WG-treated okara on the mechanical properties and intermolecular forces in soybean protein isolate (SPI) gels. SPI gels were prepared with varying amounts of WG-treated okara, and compression tests were performed. Protein solubility was also examined by homogenizing the gel in four different solutions (S1, 0.6 M sodium chloride (NaCl); S2, 0.6 M NaCl and 1.5 M urea; S3, 0.6 M NaCl and 8.0 M urea; and S4, 1.0 M sodium hydroxide). The gel with WG-treated okara had higher breaking stress but not breaking strain. In contrast, the protein solubility in S3 was lower than those of the gel without okara or with WG-untreated okara. A negative correlation (R2 = 0.86) was observed between breaking stress and protein solubility in S3. These results suggest that WG-treated okara enhanced the hydrophobic interactions of SPI gels because protein solubilization by S3 is caused by the differences in hydrophobic interactions.

Modification of Artichoke Dietary Fiber by Superfine Grinding and High-Pressure Homogenization and Its Protection against Cadmium Poisoning in Rats

This study was carried out to investigate the effects of superfine grinding (SP) and high-pressure homogenization (HPH) on the structural and physicochemical properties of artichoke dietary fiber (ADF), as well as the protective effects against cadmium poisoning in rats. The structural characteristics and physicochemical properties of ADF, HPH-ADF (ADF treated by HPH) and CM-ADF (ADF treated by SP and HPH) were determined, and cadmium chloride (CdCl2) was induced by exposing rats for 7 weeks. The amounts of creatinine and urea; the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum; the quantity of red blood cells, hemoglobin, white blood cells and neutrophil proportion in blood samples; and the activity of glutathione peroxidase (GSH-Px) in liver tissue were analyzed. Hematoxylin-eosin (HE) staining was performed to analyze the tissue structure and pathology of the liver and testis. The results showed that ADF subjected to HPH and SP-HPH exhibited increased content of soluble dietary fiber (SDF) (p < 0.05). HPH and SP-HPH treatments increased oil-holding capacity (OHC), total negative charge (TNC) and heavy metal adsorption capacity (p < 0.05). The CdCl2 intervention led to a significant increase in AST, ALT, creatinine, urea, neutrophil proportion and white blood cell count, as well as a significant decrease in GSH-Px activity, red blood cell count and hemoglobin (HGB) (p < 0.05). In rats fed with ADF, HPH-ADF and CM-ADF significantly reduced creatinine, urea amounts, ALT, AST activity in serum, leukocyte count and the neutrophil ratio in blood and increased GSH-Px activity in the liver, in addition to increasing the erythrocyte count and hemoglobin count in blood (p < 0.05). H&E staining results showed that steatosis in the liver was significantly reduced, whereas testicular tissue edema was improved. These results indicate that ADF exhibited positive activity against cadmium poisoning in rats and that CM-ADF had a better protective effect than ADF and HPH-ADF. ADF has specific potential to be used in health foods or therapeutic drugs, providing a reference for the development and utilization of artichoke waste.

Efficiency Assessment of Bacterial Cellulose on Lowering Lipid Levels In Vitro and Improving Lipid Metabolism In Vivo

Bacterial cellulose (BC) is well known as a high-performance dietary fiber. This study investigates the adsorption capacity of BC for cholesterol, sodium cholate, unsaturated oil, and heavy metal ions in vitro. Further, a hyperlipidemia mouse model was constructed to investigate the effects of BC on lipid metabolism, antioxidant levels, and intestinal microflora. The results showed that the maximum adsorption capacities of BC for cholesterol, sodium cholate, Pb²⁺ and Cr⁶⁺ were 11.910, 16.149, 238.337, 1.525 and 1.809 mg/g, respectively. Additionally, BC reduced the blood lipid levels, regulated the peroxide levels, and ameliorated the liver injury in hyperlipidemia mice. Analysis of the intestinal flora revealed that BC improved the bacterial community of intestinal microflora in hyperlipidemia mice. It was found that the abundance of Bacteroidetes was increased, while the abundance of Firmicutes and Proteobacteria was decreased at the phylum level. In addition, increased abundance of Lactobacillus and decreased abundance of Lachnospiraceae and Prevotellaceae were obtained at the genus level. These changes were supposed to be beneficial to the activities of intestinal microflora. To conclude, the findings prove the role of BC in improving lipid metabolism in hyperlipidemia mice and provide a theoretical basis for the utilization of BC in functional food.

Developing Soybean Protein Gel-Based Foods from Okara Using the Wet-Type Grinder Method

Okara, a by-product of tofu or soymilk, is rich in dietary fibers (DFs) that are mostly insoluble. A wet-type grinder (WG) system was used to produce nanocellulose (NC). We hypothesized that the WG system would increase the dispersion performance and viscosity of okara. These properties of WG-treated okara improve the gel-forming ability of soybean proteins. Here, the suspensions of 2 wt% okara were treated with WG for different passages (1, 3, and 5 times). The particle size distribution (PSD) and viscosity of WG-treated okara decreased and increased, respectively, with different passages. The five-time WG-treated okara homogeneously dispersed in water after 24 h, whereas untreated okara did not. The breaking stress, strain, and water holding capacity of soybean protein isolate (SPI) gels increased upon the addition of WG-treated okara. This effect increased as the number of WG treatments increased. The breaking stress and strain of SPI gels to which different concentrations of the five-time WG-treated okara were added also increased with increasing concentrations of WG-treated okara. These results suggest that NC technology can improve the physicochemical properties of okara and are useful in the development of protein gel-based foods.

Chemical Modification of Biomass Okara Using Poly(acrylic acid) through Free Radical Graft Polymerization

Okara (Ok) or soybean residue is produced as a byproduct from the soybean milk and soybean curd industries world wide, most of which is disposed or burned as waste. It is important to explore the possibilities to convert okara to useful materials, because okara is a naturally renewable bioresource. Here, we report the chemical modification of okara by grafting poly(acrylic acid) (PAA) onto the backbones of okara in water medium and the characterization of the Ok-PAA graft copolymers. It was found that the received okara mainly contained insoluble contents in water. The insoluble okara component Ok(Ins) was suspended in water and activated with ammonium persulfate as an initiator, followed by grafting PAA through a free radical polymerization. After the graft polymerization, the product (Ok-PAA) was separated into precipitate and supernatant, which were dried to give Ok-PAA(pre) and Ok-PAA(sup), respectively. It was found that PAA was grafted on Ok backbones and co-precipitated with the insoluble Ok. In addition, Ok-PAA(sup) was found to be translucent as a result of the grafting of PAA. Further, the successful grafting of PAA onto okara backbones was proven by Fourier transform infrared, thermogravimetric analysis, and microscopic measurements. Ok-PAA(sup) dispersed in water formed nanoparticles with an average diameter of 420 nm, while Ok-PAA(pre) was clustered coarse particles in water. The rheological data including the storage modulus, loss modulus, and viscosity indicated that the Ok-PAA product was a viscoelastic gel-like material with potential for agricultural and environmental applications.

Physicochemical quality and sensory acceptance of toasts with partial replacement of wheat flour by maize biomass flour

The aim of this study was to assess physicochemical and sensory viability of toasts developed from the partial replacement of wheat flour (WF) by maize biomass flour (MBF). Different levels of MBF (0, 5, 10, 15 and 20 g 100 g^-1) were used. Data obtained were evaluated by univariate and multivariate analyses. The level of replacement of WF by MBF influenced all physicochemical properties of the toast. Moisture (5.67-7.12 g 100 g^-1), hardness (56.67-131.66 N), chroma of crust and crumb (29.86-30.27 and 19.76-25.83, respectively), and hue angle of crust and crumb (60.32°-64.79° and 81.41°-82.06°, respectively) were increased; and area (2286.4-1658.1 mm²), specific volume (3.47-1.83 mL g^-1) and luminosity of crust and crumb (62.39-59.67 and 65.49-62.54, respectively) were decreased as the level of substitution of WF by MBF increased. The toasts did not present microbiological risk. The formulations with higher sensory acceptance were 5 and 15 g 100 g^-1 of MBF, being considered rich in proteins (16.25 and 15.43 g 100 g^-1, respectively) and rich in dietary fibers (12.10 and 16.02 g 100 g^-1, respectively), therefore with high nutritional and functional values. The production of toasts with partial replacement of WF by MBF is feasible in relation to physicochemical and sensory characteristics, which it may stimulate exploitation of this by-product and sustainable production of baked goods.

Comparison of structural, functional and in vitro digestion properties of bread incorporated with grapefruit peel soluble dietary fibers prepared by three microwave-assisted modifications

In our previous study, three kinds of grapefruit peel soluble dietary fibers (SDFs) were prepared by microwave-assisted modifications, including microwave-sodium hydroxide treatment SDF (MST-SDF), microwave-enzymatic treatment SDF (MET-SDF) and microwave-ultrasonic treatment SDF (MUT-SDF). The present study aimed to investigate the structural, functional and in vitro digestion properties of three kinds of bread incorporated with SDFs, named MST-SDF bread (SB), MET-SDF bread (EB), and MUT-SDF bread (UB). Scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and texture profile analysis were used to determine the structural properties. In comparison with the SB and EB, the UB showed an ideal hardness and internal structure, and also significant improvement of the thermal stability. Meanwhile, the UB exhibited the highest overall acceptability in the sensory evaluation. In addition, the water holding capacity (WHC), cholesterol adsorption capacity (CAC) and nitrite ion adsorption capacity (NIAC) of UB were superior to those of the other two samples. Moreover, the in vitro digestive glucose release rates of breads were all significantly reduced by the addition of SDFs, especially that of UB. In summary, the present study showed that UB presented the best performance in terms of structural, functional and in vitro digestion properties, implying that MUT-SDF could be utilized in bread with high quality and low glucose release rate, and developed as a potential ingredient of functional food.

Improved effects of okara atomized by a water jet system on α-amylase inhibition and butyrate production by Roseburia intestinalis

Improving the physicochemical properties of okara for various applications in foods is of great importance. Here, okara and microcrystalline cellulose (MCC) were atomized using a water jet (WJ) system. The WJ-treated okara and MCC dispersed homogeneously in water, and their median sizes in particle size distribution were 6.6 μm and 9.5 μm, respectively. The dispersions of WJ-treated okara and MCC showed high apparent viscosity and shear thinning behavior. Moreover, the inhibition of α-amylase activities by WJ-treated okara was more effective than that by untreated MCC and cellulose. Furthermore, the production of short-chain fatty acids by 32 dominant species of human gut microbes was determined. An increase in butyrate production by Roseburia intestinalis was observed in the presence of WJ-treated okara, but not in untreated okara or WJ-treated MCC. These results demonstrate that WJ system can be used on okara to increase inhibited α-amylase activities and butyrate production by gut microbiota.

Influence of okara with varying particle sizes on the gelling, rheological, and microstructural properties of glucono-δ-lactone-induced tofu

Influence of lyophilized okara with varying particle sizes (250-380, 150-180, 120-150, and < 75 μm) on the quality of glucono-δ-lactone-induced tofu was investigated. Adding okara significantly (p < 0.05) improved the yield, water-holding capacity, cooking loss, and nutritional value of the conventional tofu. The gel strength and sensory score of the okara-added tofu (OAT) increased with the decreasing of the particle size of okara, and these quality attributes of the OAT were better than those of the conventional tofu, except for the OAT with 250-380 μm okara. The microstructural profile of the OAT with reduced okara particle size was similar to that of the conventional tofu. Theoretically, the addition of okara mainly impacted the interactions among denatured proteins via disulfide bonding and hydrophobic interactions and the sizes of insoluble solid and oil droplet in soymilk, thereby affecting the formation of the gel network and finally the edible quality of tofu. In conclusion, the addition of okara with appropriate particle sizes can remarkably improve the processing quality and nutritional value of tofu, which is beneficial to the reasonable exploration of okara for the producers of soybean products.

Gut microbiota and short chain fatty acid composition as affected by legume type and processing methods as assessed by simulated in vitro digestion assays

This study's objective was to investigate how legume type and processing method affected digestibility, and subsequent gut microbiota and short chain fatty acid (SCFA) formation. After autoclaving and germinating-cooking, pinto bean and soybean were subjected to in vitro digestion. The digestion residues were fractionated into soluble and insoluble fiber, and fermented by microbiota from pig feces. Results showed the in vitro digestibility was affected significantly by processing method and legume type. Autoclaving resulted in higher digestibility. The in-vitro digested bean residues caused a rapid pH decrease in the first 12 h during the fermentation with pig feces, and a significant increse in the formation of SCFAs. A positive modulation of the gut microbiota by the in-vitro digested bean residues was observed. Prevotella copri and Bacteroides vulgatus exhibited the highest relative abundance in the treatments with germinated bean's soluble residues. Phascolarctobacterium succinatutens was increased by the insoluble residues.

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.

A colorimetric sensor array based on natural pigments for the discrimination of saccharides

A colorimetric sensor array based on natural pigments was developed to discriminate between various saccharides. Anthocyanins, pH-sensitive natural pigments, were extracted from fruits and flowers and used as components of the sensor array. Variation in pH, due to the reaction between saccharides and boronic acids, caused obvious colour changes in the natural pigments. Only by observing the difference map with the naked eye could 11 common saccharides be divided into independent individuals. In conjunction with pattern recognition, the sensor array clearly differentiated between sugar and sugar alcohol with highly accuracy and allowed rapid quantification of different concentrations of maltitol and fructose. This sensor array for saccharides is expected to become a promising alternative tool for food monitoring. The link between anthocyanin and saccharide detection opened a new guiding direction for the application of anthocyanins in foods.

Alkaline hydrogen peroxide improves physical, chemical, and techno-functional properties of okara

The objective was to evaluate the effect of modifying okara with alkaline hydrogen peroxide at different H2O2 concentrations and treatment temperatures on its soluble fiber content, water absorption and holding capacity, swelling capacity, and protein solubility in water. Multi-response optimization and characterization of physical, chemical, and techno-functional properties of unmodified and modified okara under optimal condition were performed. Treatment under optimal condition (2% H2O2 and 42 °C for 5 h) resulted in a 601% increase in soluble fiber content, a 26% increase in water absorption and holding capacity and swelling capacity, and a 609% increase in soluble protein. Scanning electron micrographs revealed that modified okara particles had a more fragmented structure and a rougher surface than control. Alkaline hydrogen peroxide treatment altered the color, chemical composition, and techno-functional properties of okara. The modification method has potential to add value to okara and contribute to the use of agro-industrial residues.

Comparative study of chemical treatments in combination with extrusion for the partial conversion of wheat and sorghum insoluble fiber into soluble

Dietary fiber has gained greater attention owing to their positive and potential health perspectives. Cereals are the most important and enriched source of dietary fiber with more insoluble dietary fiber than soluble. For dietary fiber modification, chemical treatment with various techniques is considered as significant approach owing to its safety point of view and involves less damage to the molecular structure of the dietary fiber through chemical reagents and content of soluble dietary fiber is increased more efficiently. The current study was aimed to nutritionally characterize the cereal grains and to partially convert insoluble dietary fiber into soluble dietary fiber through chemical treatments in combination with extrusion. For the purpose, two varieties of each cereal were characterized for their chemical composition, mineral profile, and dietary fiber content according to the respective methods. Then, dietary fiber ratio in cereals was modified through chemical treatments, that is, acid, alkaline, and consecutive acid-alkaline followed by extrusion. Results regarding dietary fiber content of cereal grains exhibited that wheat (12.03-12.20 g/100 g) contained higher total dietary fiber followed by sorghum (6.70-6.90 g/100 g). Additionally, modification of SDF (1.97%) and IDF (11.48%) ratio in wheat and SDF (1.19%) and IDF (24.25%) ratio in sorghum through extrusion processing was nonsignificant while acid-alkaline treatment showed highly significant results, that is, 768.2% increase in SDF and 56.5% decrease in IDF in wheat and 952.38% increase in SDF and 71.17% decrease in IDF in sorghum. Among chemical treatments, higher result was given by acid-alkaline method and the lower outputs were observed in case of extrusion in both cereals. Conclusively, soluble dietary fiber was significantly increased through chemical treatments alone or in combination with twin-screw extrusion.

Structural and Physicochemical Characteristics of Rice Bran Dietary Fiber by Cellulase and High-Pressure Homogenization

The present paper aims to study the effect of cellulase hydrolysis and high-pressure homogenization on the structural and physicochemical properties of rice bran dietary fiber (RB-DF). Scanning electron microscopy showed that cellulase treatment led to the formation of a porous structure on RB-DF surface. High-pressure homogenization affected the laminated microstructure of RB-DF, leading to the formation of an irregular and loose surface structure. X-ray diffraction demonstrated that joint processing destroyed the amorphous hemicellulose and cellulose regions, and changed the crystallinity of RB-DF, albeit with a minor impact on the crystalline region of cellulose. Fourier transform infrared spectroscopy indicated that combined processing promoted dissociation of some glycosidic bonds in fiber structure, exposing the hydroxyl groups in cellulose, thus improving their ability to bind water molecules. Thermogravimetric analysis showed a significant decrease in the thermal decomposition temperature of RB-DF (p <0.05) as well as a decrease in thermal stability after combined processing. Cellulase hydrolysis and high-pressure homogenization treatment did not improve their oil holding capacity, but significantly increased water holding capacity, swelling capability, and cation exchange capacity of RB-DF. Thus, enzymatic hydrolysis and high-pressure homogenization treatment can change the structure of RB-DF, exposing a large number of hydrophilic groups and enhancing hydration, obtaining uniform RB-DF particle.

Modified insoluble dietary fibers in okara affect body composition, serum metabolic properties, and fatty acid profiles in mice fed high-fat diets: an NMR investigation

The potential health benefit of dietary fiber has attracted considerable attention in recent decades. In this study, the effects of modified dietary fibers (MDF) derived from okara on body composition, fat distribution, serum metabolomic parameters, and fatty acid profiles in mice fed high-fat diets (HFD) were evaluated by nuclear magnetic resonance (NMR)-based metabolic approach. HFD-induced C57BL mice were fed with a diet containing 100 g/kg MDF for 12 weeks. Compared with control mice, MDF-fed mice exhibited less fat and lower body weights, altered serum metabolomic profiles, and distinct fatty acid profiles. The levels of choline, phosphatidylcholine, glycerophosphorylcholine, glucose, lysine, scyllo-inositol, and glutamate for MDF group were higher than those for both CONT and HFD groups. A remarkable reduction of total cholesterol, total triglycerides, ω-6 fatty acids, alanine, citrate, creatine, or succinate was also observable for MDF group compared with HFD group. These findings demonstrated that the intake of MDF derived from okara clearly ameliorated some of the HFD-induced adverse metabolic effects and prevented adipose tissue accumulation.

Influence of the Addition of Potato, Okara, and Konjac Flours on Antioxidant Activity, Digestibility, and Quality of Dumpling Wrappers

To improve the antioxidant activity (AA), digestibility, and quality of fiber-rich dumpling wrappers, potato, okara, and konjac flours were added to wheat flour. The contents of these additional ingredients in the dumpling wrapper were optimized using the response surface methodology and the synthetic evaluation method. The dietary fiber content (DFC) and AA of blend flours and the optimized cooking time (OCT), cooking loss (CL), hardness, chewiness, firmness, color, and sensory evaluation (SE) of dumpling wrappers were evaluated as response quality parameters. The optimized flour was identified containing 17.5 g of potato flour, 8.5 g of okara flour, and 1.2 g of konjac flour per 100 g of blend flour, which resulted in a higher synthetic evaluation index value (0.71 compared with 0.68 for wheat flour). The qualities of the optimized flour dumpling wrappers were compared with those of wheat flour dumpling wrappers to verify the practicality of the optimized flour. The results showed that the optimized flour showed better comprehensive qualities, especially regarding DFC (9.59%, fourfold higher than that of wheat flour) and AA. Furthermore, the predicted glycemic index (GI) of the optimized flour (74.93%) was lower than that of the wheat flour (81.47%). Overall, the addition of potato, okara, and konjac flours can significantly (P<0.05) improve DFC, AA, and digestibility of wheat flour. The optimized flour not only maintains excellent dumpling wrapper quality but also increases the utilization of potato and okara flours, which has great potential for industrial applications.