Structure, properties and potential bioactivities of high-purity insoluble fibre from soybean dregs (Okara)

Investigating the physicochemical characteristics and importance of insoluble dietary fiber extracted from legumes: An in-depth study on its biological functions

Legumes are widely appreciated for their abundant reserves of insoluble dietary fiber, which are characterized by their high fiber content and diverse bioactive compounds. Insoluble dietary fiber in leguminous crops is primarily localized in the structural cell walls and outer integument and exhibits strong hydrophilic properties that enable water absorption and volumetric expansion, resulting in increased food bulk and viscosity. This contributes to enhanced satiety and accelerated gastrointestinal transit. The benefits of legume insoluble dietary fiber extend to its notable antioxidant, anti-inflammatory, and anti-cancer properties, as well as its ability to modulate the composition of the intestinal microbiota, promoting the growth of beneficial bacteria while suppressing the proliferation of harmful pathogens, thereby promoting optimal intestinal health. It is highly valued as a valuable thickening agent, stabilizer, and emulsifier, contributing to the texture and stability of a wide range of food products.

Modification, biological activity, applications, and future trends of citrus fiber as a functional component: A comprehensive review

Citrus fiber, a by-product of citrus processing that has significant nutritional and bioactive properties, has gained attention as a promising raw material with extensive developmental potential in the food, pharmaceutical, and feed industries. However, the lack of in-depth understanding regarding citrus fiber, including its structure, modification, mechanism of action, and potential applications is holding back its development and utilization in functional foods and drugs. This review explores the status of extraction methods and modifications applied to citrus fiber to augment its health benefits. With the aim of introducing readers to the potential health benefits of citrus fibers, we have placed special emphasis on their regulatory mechanisms in the context of various conditions, including type 2 diabetes mellitus, cardiovascular disease, obesity, and cancer. Furthermore, this review highlights the applications and prospects of citrus fiber, aiming to provide a theoretical basis for the utilization and exploration of this valuable resource.

Effect of structural characteristics on the physicochemical properties and functional activities of dietary fiber: A review of structure-activity relationship

Dietary fibers come from a wide range of sources and have a variety of preparation methods (including extraction and modification). The different structural characteristics of dietary fibers caused by source, extraction and modification methods directly affect their physicochemical properties and functional activities. The relationship between structure and physicochemical properties and functional activities is an indispensable basic theory for realizing the directional transformation of dietary fibers' structure and accurately regulating their specific properties and activities. In this paper, since a brief overview about the structural characteristics of dietary fiber, the effect of structural characteristics on a variety of physicochemical properties (hydration, electrical, thermal, rheological, emulsifying property, and oil holding capacity, cation exchange capacity) and functional activities (hypoglycemic, hypolipidemic, antioxidant, prebiotic and harmful substances-adsorption activity) of dietary fiber explored by researchers in last five years are emphatically reviewed. Moreover, the future perspectives of structure-activity relationship are discussed. This review aims to provide theoretical foundation for the targeted regulation of properties and activities of dietary fiber, so as to improve the quality of their applied products and physiological efficiency, and then to realize high value utilization of dietary fiber resources.

Modification of pea dietary fibre by superfine grinding assisted enzymatic modification: Structural, physicochemical, and functional properties

Using the optimal extraction conditions determined by response surface optimisation, the yield of soluble dietary fibre (SDF) modified by superfine grinding combined with enzymatic modification (SE-SDF) was significantly increased from 4.45 % ± 0.21 % (natural pea dietary fibre) to 16.24 % ± 0.09 %. To further analyse the modification mechanism, the effects of three modification methods-superfine grinding (S), enzymatic modification (E), and superfine grinding combined with enzymatic modification (SE)-on the structural, physicochemical, and functional properties of pea SDF were studied. Nuclear magnetic resonance spectroscopy results showed that all four SDFs had α- and β-glycosidic bonds. Fourier transform infrared spectroscopy and X-ray diffraction spectroscopy results showed that the crystal structure of SE-SDF was most severely damaged. The Congo red experimental results showed that none of the four SDFs had a triple-helical structure. Scanning electron microscopy showed that SE-SDF had a looser structure and an obvious honeycomb structure than other SDFs. Thermogravimetric analysis, particle size, and zeta potential results showed that SE-SDF had the highest thermal stability, smallest particle size, and excellent solution stability compared with the other samples. The hydration properties showed that SE-SDF had the best water solubility capacity and water-holding capacity. All three modification methods (S, E, and SE) enhanced the sodium cholate adsorption capacity, cholesterol adsorption capacity, cation exchange capacity, and nitrite ion adsorption capacity of pea SDF. Among them, the SE modification had the greatest effect. This study showed that superfine grinding combined with enzymatic modification can effectively improve the SDF content and the physicochemical and functional properties of pea dietary fibre, which gives pea dietary fibre great application potential in functional foods.

Effect of modified okara insoluble dietary fibre on the quality of yoghurt

The aim of this study was to investigate the potential of adding soya bean dregs insoluble dietary fibre (IDF) modified by jet cavitation combined with cellulase to yoghurt to improve its functional properties (Yoghurt was prepared by adding 10 μL of yoghurt fermenter to 100 mL of milk, fermented to pH 4.5 in a constant temperature incubator at 42 °C, and then stored in a refrigerator at 4 °C after adding IDF separately). The results showed that the modified IDF had a rough structure with high water-holding capacity and sodium cholate adsorption capacity. The addition of modified IDF improved the pH, hardness, and elasticity of the yoghurt. During the entire storage period, the titratable acidity and whey precipitation rate of the modified IDF yoghurt gradually increased, and antioxidant activity gradually decreased, and its titratable acidity, whey precipitation rate, and antioxidant activity had a significant advantage compared with those of the blank group yoghurt. In conclusion, the modified soya bean dregs IDF-added yoghurt prepared by jet cavitation combined with the cellulase method has the potential for sodium cholate adsorption capacity and antioxidant activity, which can confer unique functional properties and improve the pH, texture, and reduce whey precipitation of yoghurt. This study provides a scientific basis for the application of soya bean dregs IDF as a fibre fortifier in yoghurt production and suggests innovative ideas for the design of functional dairy products.

In vitro gastrointestinal digestion methods of carbohydrate-rich foods

The trend toward healthier food products has led to an increase in the research of in vitro gastrointestinal digestion methods. Among the most used models, static models are the simplest. Most static models have three stages: oral, gastric, and intestinal, simulating the enzymatic, electrolyte, pH, temperature, and bile salt conditions. The studies that have taken the most notice are those related to antioxidant activity, followed by those dealing with proteins and carbohydrates using most of them static in vitro digestion models. The number of these studies has increased over the years, passing from 45 to 415 in a 10-year period (2012-2023) and showing an interest in knowing the impact of food on human health. Nevertheless, published papers report different methodologies and analytical approaches. This review discusses the similarities and differences between the published static in vitro gastrointestinal digestion methods, with a focus on carbohydrates, finding that the most used protocol is Infogest, but with differences, mainly in the type of enzymes and their activity. Regarding in vitro gastrointestinal digestion of carbohydrates, many of the published studies are related to food and biomacromolecules, being the oral phase the most omitted, while the intestinal phase in the most diverse. Other methodologies to study the intestinal phase have been recommended, but the number of in vitro digestion studies using these methodologies (RSIE and BBMV) is still scarce but could represent a good alternative to analyze carbohydrates foods when combining with Infogest. More studies are required in this area.

Effect of insoluble dietary fiber on printing properties and molecular interactions of 3D-printed soy protein isolate-wheat gluten plant-based meats

Insoluble dietary fiber (IDF) has been characterized to prevent chronic diseases and improve gastrointestinal health, and it has been added to 3D printing plant-based meats (PM) to enhance texture and increase nutritional properties. Therefore, the aim of this study was to investigate the effects of IDF on 3D printing properties and molecular interactions of soy protein isolate (SPI) - wheat gluten (WG) PM. Without the participation of IDF, PM appeared to collapse. When the IDF concentration increased from 0 to 10 %, PM displayed good printing properties, water holding capacity, tensile strength, and elongation at break were increased. Tensile strength and elongation at break reached a maximum at 10 % IDF, and clearly similar results were found for texture attribute indices such as hardness, gumminess, chewiness, and cohesiveness after cooking. All printing inks exhibited shear-thinning behavior and solid-like viscoelasticity, but the structural recovery properties of 3D-printed PM deteriorated when the IDF content was over 10 %. Intermolecular forces indicated that the addition of IDF enhanced the disulfide bonds so that 10 % IDF presented better printing properties. These results indicated the potential for developing PM with dietary fiber functionality through 3D printing technology.

Effects of extraction methods on the structure and functional properties of soluble dietary fiber from blue honeysuckle (Lonicera caerulea L.) berry

The work within this study aimed to investigate and compare the effects of compound enzyme extraction (CE), ultrasonic chemical extraction (UC) and combined fermentation extraction (CF) on the physicochemical properties, microstructure, and functional properties of soluble dietary fiber (SDF) extracted from blue honeysuckle berries. The results showed that CE-SDF had higher crystallinity (32.41%). UC-SDF had the highest yield (13.32 ± 0.80 g/100 g). CF-SDF had the maximum inhibition of α-amylase (50.82 ± 0.76%) and α-glucosidase (54.87 ± 1.25%). The in vitro hypoglycemic activity of the three SDFs was observed in the order of CF > CE > UC. Meanwhile, the purity of SDF had a strong positive correlation with its antioxidant and in vitro hypoglycemic capacities. The crystallinity of SDF was found to be positively correlated with its molecular weight and thermal properties. Additionally, the sugar composition of SDF was found to be an important factor affecting its biological activity.

Green biosynthesis of DHA-phospholipids in tailor-made supersaturated DHA aqueous solution and catalytic mechanism study

Docosahexaenoic acid-phospholipids (DHA-PLs) were prepared via lipase-mediated transesterification of DHA donor and phosphatidylcholine (PC) in a purely aqueous solution. Pre-existing carriers would play the role as "artificial interfaces" to adsorb water-insoluble PC and made them disperse in water. DHA donors were concentrated by a pH-responsive method and presented as supersaturated salt solutions. 153 triacylglycerol lipase structures were analyzed and screened in silico. Transesterification was carried out to further evaluate the six lipase candidates. Lipase B from Candida antarctica (CALB) was the best biocatalyst with 34.8% of DHA incorporation and 80.0% of PLs yields (involving 38.1% PC and 41.9% sn-1 lyso-PC). Toxic organic solvents were avoided. Six possible microunits of our aqueous system consisting of three PLs donors (PC, lyso-PC, sn-glycero-3-PC) and two DHA donors (DHA and DHA salts), were simulated by molecular dynamics (MD) to illustrate the enzymatic mechanism based on diffusional channels, competitive bindings, and enzymatic structures.

Modified dietary fiber from soybean dregs by fermentation alleviated constipation in mice

Soybean dregs are the main by-product obtained from the processing of soy products and are good sources of dietary fiber (DF). This study showed that the soluble DF content increased from 4.97% to 18.82%, while the insoluble DF content decreased from 59.37% to 44.89% after soybean dreg fermentation using Trichoderma spp., without any significant change in the total DF content (p > 0.05). Physicochemical property and electron microscopy analysis revealed that the rehydration ratio, dissolution rate, expansion force, and oil holding capacity of DF significantly increased (p < 0.05) with finer microstructure. Additionally, we found that fermented DF could further promote intestinal peristalsis in mice. Furthermore, fermented DF was more effective in balancing and adjusting intestinal flora in mice and promoting the production of short-chain fatty acids. Therefore, this study provides evidence indicating a correlation between the physicochemical properties and functional benefits of DF derived from soybean dregs.

Optimization of Ultrasound-Assisted Extraction of Dietary Fiber from Yellow Dragon Fruit Peels and Its Application in Low-Fat Alpaca-Based Sausages

The main objective of this study was to optimize the extraction of dietary fiber (insoluble dietary fiber and soluble dietary fiber) and degree of esterification from yellow dragon fruit peels using ultrasound-assisted extraction. Additionally, the study aimed to investigate the potential application of this fiber as a fat replacement in alpaca-based sausages. The optimization process for extracting dietary fiber and degree of esterification involved considering various factors, including the liquid-to-solid ratio, pause time, and total ultrasound application time. A Box-Behnken design consisting of 15 treatments was employed to determine the optimal levels for ultrasound-assisted extraction. The optimized conditions were found to be a liquid-to-solid ratio = 30 mL/g, pause time = 1 s, and total ultrasound application time = 60 min, which resulted in the highest values of insoluble dietary fiber (61.3%), soluble dietary fiber (10.8%), and the lowest value of degree of esterification (39.7%). The predicted values were validated against experimental data and showed no significant differences (p > 0.05). Furthermore, a completely randomized design was utilized to assess the effect of dietary fiber on replacing fat content during the production of alpaca-based sausages. The findings revealed that up to 78% of the fat content could be successfully replaced by soluble dietary fiber obtained from yellow dragon fruit peels when compared to high-fat sausages. Additionally, experimental sausages using soluble dietary fiber showed similar (p > 0.05) quality characteristics, such as hardness (24.2 N), chewiness (11.8 N), springiness (0.900), cohesiveness (0.543), redness (a* = 17.4), and chroma values (20.0), as low-fat commercial sausages.

Valorization of Fibrous Plant-Based Food Waste as Biosorbents for Remediation of Heavy Metals from Wastewater-A Review

Mobilization of heavy metals in the environment has been a matter of concern for several decades due to their toxicity for humans, environments, and other living organisms. In recent years, use of inexpensive and abundantly available biosorbents generated from fibrous plant-based food-waste materials to remove heavy metals has garnered considerable research attention. The aim of this review is to investigate the applicability of using fibrous plant-based food waste, which comprises different components such as pectin, hemicellulose, cellulose, and lignin, to remove heavy metals from wastewater. This contribution confirms that plant-fiber-based food waste has the potential to bind heavy metals from wastewater and aqueous solutions. The binding capacities of these biosorbents vary depending on the source, chemical structure, type of metal, modification technology applied, and process conditions used to improve functionalities. This review concludes with a discussion of arguments and prospects, as well as future research directions, to support valorization of fibrous plant-based food waste as an efficient and promising strategy for water purification.

Impact of Insoluble Dietary Fiber and CaCl2 on Structural Properties of Soybean Protein Isolate-Wheat Gluten Composite Gel

The effect and mechanism of soybean insoluble dietary fiber (SIDF) (0~4%) and CaCl₂ (0~0.005 M) on the properties of soybean protein isolate (SPI)-wheat gluten (WG) composite gel were studied. It was revealed that the addition of insoluble dietary fiber (1~2%) increased the strength and water-holding capacity (WHC) of the composite gel (p < 0.05) and enhanced the gel network structure compared with the control. WHC and LF-NMR showed that the water-binding ability of the gel system with only 2% SIDF was the strongest. The addition of excessive SIDF increased the distance between protein molecules, impeded the cross-linking of protein, and formed a three-dimensional network with low gel strength. The infrared spectrum and intermolecular force indicated that the interaction between SIDF and SPI were mainly physical, and the hydrophobic interaction and disulfide bond were the main forces in the gel system. The addition of CaCl₂ can increase the critical content of gel texture destruction caused by SIDF, and the gel strength attained its peak at 3% SIDF, indicating that appropriate CaCl₂ improved gel structure weakening caused by excessive SIDF. This study provides insights in enhancing the production of multi-component composite gel systems.

Optimization of Mixed Fermentation Conditions of Dietary Fiber from Soybean Residue and the Effect on Structure, Properties and Potential Biological Activity of Dietary Fiber from Soybean Residue

Soybean residue is a by-product of soybean product production that is wasted unreasonably at present. Accomplishing the efficient utilization of soybean residue can save resources. A composite microbial system was constructed using lactic acid bacteria (LAB) and Saccharomyces cerevisiae (SC), and modified soybean residue was prepared by solid fermentation. In order to explore the value of modified soybean residue as a food raw material, its physical and chemical properties, adsorption properties, and antioxidant properties were studied. The results showed that the soluble dietary fiber (SDF) yield of mixed fermentation (MF) increased significantly. Both groups of soybean residues had representative polysaccharide infrared absorption peaks, and MF showed a looser structure and lower crystallinity. In terms of the adsorption capacity index, MF also has a higher adsorption capacity for water molecules, oil molecules, and cholesterol molecules. In addition, the in vitro antioxidant capacity of MF was also significantly higher than that of unfermented soybean residue (UF). In conclusion, our study shows that mixed fermentation could increase SDF content and improve the functional properties of soybean residue. Modified soybean residue prepared by mixed fermentation is the ideal food raw material.

Effects of electron beam irradiation treatment on the structural and functional properties of okara insoluble dietary fiber

BACKGROUND

Insoluble dietary fiber (IDF) has beneficial physiological effects, such as the promoting of intestinal peristalsis, the improving of intestinal flora, and the absorbing of some harmful substances. Okara, a byproduct of soybean processing, is a potential source of IDF. But the larger particle size and poor water solubility of okara IDF have adverse effects on sensory properties and functional characteristics. Therefore, we used an emerging type of physical method is electron beam irradiation (EBI) to modify okara, and investigated that the effects of EBI doses on the structure and functional properties of okara IDF.

RESULTS

It was found that the electron beam treatment damaged the crystalline structure of IDF. Observation of the surface of EBI-treated IDF revealed a loose and porous morphology rather than the typical smooth structure. At a dose of 6 kGy, a smallest particle size and largest specific surface area of IDF was obtained, and these factors increased the apparent viscosity of an IDF dispersion. The water holding capacity, swelling capacity and the oil holding capacity upon irradiation at 6 kGy increased 74.13%, 84.76% and 41.62%, respectively. In addition, the capacity for adsorption of cholesterol, sodium cholate, glucose and nitrite ion were improved after electron beam treatment.

CONCLUSION

The modified okara IDF showed improved particle sizes and hydration properties, and these changes correlated with an improvement to the rough taste of IDF and improvements to the texture and storage period upon supplementation into food. © 2022 Society of Chemical Industry.

Effect of alkaline hydrogen peroxide assisted with two modification methods on the physicochemical, structural and functional properties of bagasse insoluble dietary fiber

Bagasse is one of major by-product of sugar mills, but its utilization is limited by the high concentration of lignin. In this study, the optimal alkaline hydrogen peroxide (AHP) treatment conditions were determined by the response surface optimization method. The results showed that the lignin removal rate was 62.23% and the solid recovery rate was 53.76% when bagasse was prepared under optimal conditions (1.2% H₂O₂, 0.9% NaOH, and 46°C for 12.3 h), while higher purity of bagasse insoluble dietary fiber (BIDF) was obtained. To further investigate the modification effect, AHP assisted with high-temperature-pressure cooking (A-H) and enzymatic hydrolysis (A-E) were used to modify bagasse, respectively. The results showed that the water holding capacity (WHC), oil holding capacity (OHC), bile salt adsorption capacity (BSAC), and nitrite ion adsorption capacity (NIAC) were significantly improved after A-H treatment. With the A-E treatment, cation exchange capacity (CEC) and BSAC were significantly increased, while WHC, OHC, and glucose adsorption capacity (GAC) were decreased. Especially, the highest WHC, OHC, BSAC and NIAC were gained by A-H treatment compared to the A-E treatment. These changes in the physicochemical and functional properties of bagasse fiber were in agreement with the microscopic surface wrinkles and pore structure, crystallinity and functional groups. In summary, the A-H modification can effectively improve the functional properties of bagasse fiber, which potentially can be applied further in the food industry.

Complexation of multiple mineral elements by fermentation and its application in laying hens

To overcome the problems with current mineral supplements for laying hens including low absorption, mineral antagonism, and high cost, we developed mineral element fermentation complexes (MEFC) by synergistically fermenting bean dregs and soybean meal with strains and proteases and complexing with mineral elements. The fermentation complexation process was optimized based on the small peptide and organic acid contents and the complexation rate of mineral elements after fermentation. The optimal conditions were as follows: the total inoculum size was 5% (v/w), 15% (w/w) wheat flour middling was added to the medium, and mineral elements (with 4% CaCO3) were added after the completion of aerobic fermentation, fermentation at 34°C and 11 days of fermentation. Under these conditions, the complexation rates of Ca, Fe, Cu, Mn, and Zn were 90.62, 97.24, 73.33, 94.64, and 95.93%, respectively. The small peptide, free amino acid, and organic acid contents were 41.62%, 48.09 and 183.53 mg/g, respectively. After 60 days of fermentation, 82.11% of the Fe in the MEFC was ferrous ions, indicating that fermentation had a good antioxidant effect on ferrous ion, and the antioxidant protection period was at least 60 days. Fourier transform infrared spectroscopy showed that the mineral ions were complexed with amino and carboxyl groups. The added mineral elements promoted microbial growth, protein degradation, and organic acid secretion and significantly improved fermentation efficiency. Animal experiments showed that MEFC had positive effects on several parameters, including production performance (average daily feed intake, P < 0.05; egg production rate, P < 0.05; and average egg weight, P < 0.05), mineral absorption, intestinal morphology (villus height to crypt depth ratio in the jejunum and ileum, P < 0.05), and blood routine and biochemical indexes (red blood cells, P < 0.05; hemoglobin, P < 0.05). This study provides theoretical support for the development of mineral complexes for laying hens via fermentation.

Crosstalk between traditional Chinese medicine-derived polysaccharides and the gut microbiota: A new perspective to understand traditional Chinese medicine

Polysaccharide is a kind of macromolecule polymer composed of monosaccharides connected by glycosidic bonds. Traditional Chinese medicine (TCM), composed of various bioactive ingredients, is usually rich in polysaccharides. In recent years, extensive research on TCM polysaccharides has demonstrated their pharmacological effects. Polysaccharides can hardly be catabolized by enzymes encoded by the human genome but can be degraded to absorbable metabolites by bacteria inhabiting the colon. Hence, the gut microbiota plays a vital role in degrading TCM polysaccharides into short-chain fatty acids (SCFAs) which exert physiological functions locally and systemically. Besides, TCM polysaccharides can also modulate the composition and activities of the gut microbiota by promoting the growth of beneficial bacteria and inhibiting the colonization of pathogenic bacteria, ultimately restoring gut homeostasis and improving human health. In this review, we discuss the extraction and pharmacological effects of TCM polysaccharides, various functions of the gut microbiota, and the interactions between TCM polysaccharides and the gut microbiota, illuminating the mechanisms of TCM polysaccharides modulating host physiology via the gut microbiota. To firmly establish the clinical efficacy of TCM polysaccharides, further high-quality studies especially clinical trials are needed. Generally, discussion on the interplay between TCM polysaccharides and the gut microbiota is expected to elucidate their application prospects and inspire new thoughts in the development of TCM.

Screen of high efficiency cellulose degrading strains and effects on tea residues dietary fiber modification: Structural properties and adsorption capacities

In our study, two high efficiency cellulose degrading strains were screened, isolated and identified as Cochliobolus kusanoi and Aspergillus puulaauensis by 18S rDNA gene sequencing. In addition, the composite microbial system was constructed to develop the synergistic effect among different strains. Under the optimum conditions, the yield of soluble dietary fiber from tea residues by mixed fermentation method (MF-SDF) dramatically increased compared to single strain fermentation. The structural analysis demonstrated that all samples possessed the representative infrared absorption peaks of polysaccharides, whereas MF-SDF revealed more loose structure, lower crystallinity and smaller molecular size. For the adsorption capacities indexes, MF-SDF also owned the highest adsorbing capacity for the water molecule, oil molecule, cholesterol molecule and nitrite ion. Overall, our data showed that mixed fermentation method could be better choices to improve the functional properties of dietary fiber, and screening of cellulose degrading strains could provide new thinkings for the study of dietary fiber modification and realize high-quality utilization of crop residues.

Structural and Potential Functional Properties of Alkali-Extracted Dietary Fiber From Antrodia camphorata

Antrodia camphorata is rich in a variety of bioactive ingredients; however, the utilization efficiency of the residue of A. camphorata is low, resulting in serious waste. It is necessary to deeply study the functional components of A. camphorata residues to achieve high-value utilization. In this study, the components, structural characteristics, and functional properties of alkali-extracted dietary fiber extracted from residues of A. camphorata (basswood and dish cultured fruiting body, respectively) were investigated. There were similar components and structural characteristics of ACA-DK (extract from basswood cultured) and ACA-DF (extract from dish cultured). The two alkali-extracted dietary fiber were composed of mainly cellulose and xylan. However, ACA-DK has better adsorption capacities than ACA-DF on lipophilic substances such as oil (12.09 g/g), cholesterol (20.99 mg/g), and bile salts (69.68 mg/g). In vitro immunomodulatory assays stated that ACA-DK had a good effect on promoting the proliferation of RAW 264.7 cells and can activate cell phagocytosis, NO synthesis, and other immune capabilities. The edible fungus A. camphorata is a good source of functional dietary fiber. The alkali-extracted dietary fiber of A. camphorata might be used as a functional ingredient in the medicine and food industry.

Effect of γ-irradiation on structure, physicochemical property and bioactivity of soluble dietary fiber in navel orange peel

•

γ-Irradiation was effective to modify soluble dietary fiber of navel orange peel (OSDF).

•

γ-Irradiation could modify the chemical structure of OSDF.

•

γ-Irradiation could improve the bioactivities of OSDF.

•

The molecular weight profile of OSDF was modified by γ-irradiation.

Soluble dietary fibers are widely used in functional food. In this work, the effects of γ-irradiation on molecular weight, structure, physicochemical properties and bioactivities of soluble dietary fiber in navel orange peel (OSDF) were investigated. Γ-irradiation enhanced the extraction yield of OSDF. The molar ratio of glucose and galacturonic acid was increased. The molecular weight profile of OSDF was modified. Γ-irradiation (3–6 kGy) improved the water holding capacity, water swelling capacity, oil holding capacity, cation-exchange capacity, nitrite adsorption capacity and total antioxidant capacity of OSDF. Glucose adsorption capacity and bifidobacterium proliferation capacity of OSDF were improved in a dose-dependent behaviour. Moreover, γ-irradiation promoted the cracking of microstructure. FT-IR spectra showed that more carboxyl groups were newly formed by γ-irradiation. These findings indicated that γ-irradiation treatment was an efficient technique for improving physicochemical properties and health benefits.

Preparation of soybean dreg fiber solid emulsifier and its effect on the stability of Pickering emulsion

High purity insoluble dietary fiber (HPIDF) was extracted from Okara by compound enzyme method, and solid emulsifiers with different particle sizes were prepared by wet grinding. Its composition, structure and physicochemical properties were studied, and the influence mechanism of solid emulsifiers with different particle sizes on emulsifying properties and interface stability of Pickering emulsion was systematically studied. The results showed that the particle size of HPIDF decreased significantly, the ζ-potential, contact Angle and swelling capacity of HPIDF ncrease significantly (p < 0.05). HPIDF forms an adsorption layer at the oil-water interface, and some of them are connected to form a bridge network structure, which plays a role of steric hindrance. And the emulsion has excellent stability under different environmental factors. HPIDF are suitable raw materials as natural food-grade solid emulsifiers. It is cost-effective and eco-friendly to realize the high-value utilization of Okara resources, reduce resource waste, and extend the industrial chain.

Effects of γ-Irradiation on Structure and Functional Properties of Pea Fiber

In this study, pea residue reserve insoluble diet fiber (hereinafter referred to as pea fiber) was used as a raw material. The effects of γ-irradiation doses (0, 0.5, 1, 2, 3, and 5 kGy) on the structural properties (main composition, particle size and specific surface area, scanning electron microscope (SEM) microstructure, Fourier transform infrared spectroscopy, and X-ray diffraction) and functional properties (oil-holding capacity, swelling and water-holding capacity, and adsorption properties) of pea fiber were explored. The results show that, when the γ-irradiation dose was 2 kGy, compared with the untreated sample, the contents of cellulose, hemicellulose and lignin in pea fiber decreased by 1.34 ± 0.42%, 2.56 ± 0.03% and 2.02 ± 0.05%, respectively, and the volume particle size of pea fiber decreased by 17.43 ± 2.35 μm. The specific surface area increased by 23.70 ± 2.24 m²/kg and the crystallinity decreased by 7.65%. Pore and irregular particles appeared on the microstructure surface of the pea fiber treated with γ-irradiation. The results of the infrared spectrum showed that the hemicellulose and lignin in pea fiber were destroyed by γ-irradiation. These results indicate that γ-irradiation can significantly affect the structural properties of pea fiber. When the γ-irradiation dose was 2 kGy, the highest oil-holding capacity, swelling capacity and water-holding capacity of pea fiber were 8.12 ± 0.12 g/g, 19.75 ± 0.37 mL/g and 8.35 ± 0.18 g/g, respectively, and the adsorption capacities of sodium nitre, cholesterol and glucose were also the strongest. These results indicate that the functional properties of pea fiber are improved by γ-irradiation. In this study, γ-irradiation technology was used as pretreatment to provide a theoretical basis for the application of pea fiber in food processing.

Structural Characteristics of Insoluble Dietary Fiber from Okara with Different Particle Sizes and Their Prebiotic Effects in Rats Fed High-Fat Diet

Dietary fiber, which is utilized to make functional meals, is an important component for promoting human health and managing calorie consumption. In this study, three different particle sizes of OIDF (Okara insoluble dietary fiber) were characterized. Their lipid-lowering effects and the impacts on gut microbiota were determined by OIDF intervention in high-fat diet rats. Scanning electron microscopy (SEM) results showed that the three particle sizes of OIDF have different morphologies. Fourier transform infrared spectroscopy (FT-IR) results showed that the three sources of IDF samples have similar active groups, but the thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and X-ray diffraction (XRD) showed that three different particle sizes of OIDF have different retention and crystallinity. Among the three OIDFs, OIDF-10 exhibited the stronger WSC, OHC, CAC, and SCAC. The results after the feeding showed that the OIDF of three particle sizes could improve the elevation of blood lipids and the disturbance of gut microbiota caused by the high-fat diet. Therefore, this study demonstrated the functional significance of the three particle sizes of OIDF and provided a reference for its application in functional food processing, aiming at maintaining healthy blood lipid and intestinal flora levels.

The Protein Composition Changed the Quality Characteristics of Plant-Based Meat Analogues Produced by a Single-Screw Extruder: Four Main Soybean Varieties in China as Representatives

Plant-based meat analogues (PBMs) are increasingly interesting to customers because of their meat-like quality and contribution to a healthy diet. The single-screw extruder is an important method for processing PBMs, and the characteristics of the product are directly affected by the composition of the raw materials; however, little research focuses on this issue. To explore the effect of protein composition on the quality characteristics of PBMs produced by a single-screw extruder, four soybean varieties used in China (Heihe 43 (HH 43), Jiyu 86 (JY 86), Suinong 52 (SN 52), and Shengfeng 5 (SF 5)) were selected. The 11S/7S ratios for these varieties ranged from 1.0: 1 to 2.5: 1 in order to produce PBMs with different protein compositions. The structure, processing, nutrition, and flavor characteristics were explored to analyze their differences. The results showed that protein composition affected the structure of PBMs, but the correlation was not significant. Meanwhile, a lower 11S/7S ratio (HH 43) did not prove to be a favorable characteristic for the processing of PBMs. From the perspective of nutrition and flavor, it seems acceptable to use a moderate 11S/7S ratio (JY 86 and SN 43) to produce PBMs. This study proved that the protein composition of raw materials affects the characteristics of PBM products produced by a single-screw extruder. To produce PBMs of higher quality, soybeans with a markedly different 11S/7S ratio should not be selected.

Insoluble Dietary Fibers From By-Products of Edible Fungi Industry: Basic Structure, Physicochemical Properties, and Their Effects on Energy Intake

With the rapid development of the edible fungi industry in the world, especially in China, the resource utilization of edible fungi by-products has become an urgent problem for the industry's sustainable development. The waste residue of edible fungi after polysaccharide extraction by water accounts for a large proportion, which contains a large amount of water-insoluble dietary fiber (IDF). At present, the extracted residue is generally treated as fertilizer or solid waste, which not only pollutes the environment, but wastes resources too. In order to develop these by-products, expand their potential utilization in the food industry, the structure characterization, physicochemical properties, and the influence of IDF on dietary energy intake were studied. The IDF from the residues of polysaccharides extracted from four edible fungi was extracted using the Association of Official Analytical Chemists (AOAC) method. The results showed that IDF in the four kinds of edible fungi residues was similar in composition but different in texture. Cellulose and hemicellulose are the main IDF extracted from four kinds of edible fungi. Among them, Hericium erinaceus is the softest without obvious granular texture, following Lentinus edodes, while Ganoderma lucidum and Grifola frondosa have a relatively hard texture. The yield of four kinds of IDF from high to low came from Ganoderma lucidum, Hericium erinaceus, Lentinus edodes, and Grifola frondosa. Fourier transform IR (FTIR) and X-ray diffraction (XRD) spectra showed that the four IDFs had similar functional groups and all of them contained a large amount of cellulose. Physical and chemical analysis showed that all the four IDFs had certain water holding capacity, water binding capacity, and oil holding capacity. In-vitro digestion experiments showed that the four IDFs could inhibit the digestion of starch and fat to a certain extent. By-products of edible fungi are an ideal material for the recovery of IDFs, which have the potential to be processed into functional food materials due to their physicochemical properties and physiological functions.

Soy Protein Isolate/Sodium Alginate Microparticles under Different pH Conditions: Formation Mechanism and Physicochemical Properties

The effects of sodium alginate (SA) and pH value on the formation, structural properties, microscopic morphology, and physicochemical properties of soybean protein isolate (SPI)/SA microparticles were investigated. The results of ζ-potential and free sulfhydryl (SH) content showed electrostatic interactions between SPI and SA, which promoted the conversion of free SH into disulfide bonds within the protein. The surface hydrophobicity, fluorescence spectra, and Fourier transform infrared spectroscopy data suggested that the secondary structure and microenvironment of the internal hydrophobic groups of the protein in the SPI/SA microparticles were changed. Compared with SPI microparticles, the surface of SPI/SA microparticles was smoother, the degree of collapse was reduced, and the thermal stability was improved. In addition, under the condition of pH 9.0, the average particle size of SPI/SA microparticles was only 15.92 ± 0.66 μm, and the distribution was uniform. Rheological tests indicated that SA significantly increased the apparent viscosity of SPI/SA microparticles at pH 9.0. The maximum protein solubility (67.32%), foaming ability (91.53 ± 1.12%), and emulsion activity (200.29 ± 3.38 m²/g) of SPI/SA microparticles occurred at pH 9.0. The application of SPI/SA microparticles as ingredients in high-protein foods is expected to be of great significance in the food industry.

Comparison the Structural, Physicochemical, and Prebiotic Properties of Litchi Pomace Dietary Fibers before and after Modification

Litchi pomace, a by-product of litchi processing, is rich in dietary fiber. Soluble and insoluble dietary fibers were extracted from litchi pomace, and insoluble dietary fiber was modified by ultrasonic enzymatic treatment to obtain modified soluble and insoluble dietary fibers. The structural, physicochemical, and functional properties of the dietary fiber samples were evaluated and compared. It was found that all dietary fiber samples displayed typical polysaccharide absorption spectra, with arabinose being the most abundant monosaccharide component. Soluble dietary fibers from litchi pomace were morphologically fragmented and relatively smooth, with relatively high swelling capacity, whereas the insoluble dietary fibers possessed wrinkles and porous structures on the surface, as well as higher water holding capacity. Additionally, soluble dietary fiber content of litchi pomace was successfully increased by 6.32 ± 0.14% after ultrasonic enzymatic modification, and its arabinose content and apparent viscosity were also significantly increased. Further, the soluble dietary fibers exhibited superior radical scavenging ability and significantly stimulated the growth of probiotic bacterial species. Taken together, this study suggested that dietary fiber from litchi pomace could be a promising ingredient for functional foods industry.

Dry heat treatment induced the gelatinization, rheology and gel properties changes of chestnut starch

The effects of continuous dry heat treatment (CT) and repeated dry heat treatment (RT) on gel and structural properties of chestnut starch (CS) were investigated. CT and RT both reduced the swelling degree of starch and showed significant variations in pasting viscosity, viscoelasticity, gel strength and hardness varying from high to low after dry heat treatment, and CT was lower than that of RT. Neither dry heat treatment nor gelatinization produced new functional groups, and both reduced short-range ordered degree. There were significant decrease in spin-spin relaxation time (T₂) with dry heat treatment (CT and RT), which made the starch in the samples closely combine with water. These results are helpful to better understand the changes of physicochemical properties of starch gel products during dry heat treatment and provide some theoretical references for the application of CS in food industry.

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.