Structure, physicochemical properties and effects on nutrients digestion of modified soluble dietary fiber extracted from sweet potato residue

Modification of black soybean (Glycine max(L.)merr.) residue insoluble dietary fiber with ultrasonic, microwave, high temperature and high-pressure, and extrusion

Recent studies have emphasized the modification of Insoluble Dietary Fiber (IDF) to enhance its physicochemical properties and functional performance. This study systematically examined the effects of ultrasonic treatment, microwave irradiation, high-temperature and high-pressure processing, and screw extrusion on the physicochemical characteristics, in vitro antioxidant activity, and adsorption capacities of High-Purity Insoluble Dietary Fiber (HPIDF) derived from black bean residues. Although these physical modifications did not alter the functional group composition or crystalline structure of HPIDF, they significantly enhanced its porosity, water-holding capacity (WHC), oil-holding capacity (OHC), and adsorption capacities for glucose, cholesterol, bile salts, and metal ions. Notably, HPIDF treated under high-temperature and high-pressure conditions exhibited the highest adsorption capacities: 9.86 mmol/g for glucose, 8.69 mg/g (pH 2) and 9.69 mg/g (pH 7) for cholesterol, 0.183 g/g (pH 2) and 0.127 g/g (pH 7) for sodium cholate, and 0.699 mg/g (pH 2) and 0.774 mg/g (pH 7) for Cr2+.

Identification of single nucleotide polymorphisms and candidate genes associated with fiber content in sweetpotato (Ipomoea batatas (L.) Lam.) through a genome-wide association study

BACKGROUND

Sweetpotato (Ipomoea batatas (L.) Lam.) is an essential root crop with several nutritional benefits, including high dietary fiber content. While fiber contributes positively to human health by reducing the risk of metabolic and gastrointestinal diseases, excessive fiber accumulation can negatively impact texture and consumer preference. Despite its importance, the genetic mechanisms underlying fiber content in sweetpotato remain largely unexplored. Therefore, this study aimed to identify the genomic regions and candidate genes associated with fiber content through a genome-wide association study (GWAS).

RESULTS

Significant phenotypic variation in fiber content were observed among 140 sweetpotato genotypes. The GWAS analysis identified seven significant single nucleotide polymorphisms (SNPs), with Iba_chr07a_20294133 and Iba_chr12a_38616338 consistently detected across the FarmCPU and BLINK models. Notably, three SNPs (Iba_chr01a_17621178, Iba_chr10a_773882, and Iba_chr12a_38616338) showed significant phenotypic differentiation between homozygous alleles, making them promising candidates for marker development. Candidate gene analysis identified four genes with significantly upregulated expression in high-fiber genotypes: IbANT1 (adenine nucleotide transporter BT1), IbCYP86B1 (cytochrome P450 86B1), IbSCR3 (scarecrow-like protein 3), and IbFER (FERONIA receptor-like kinase). These genes are involved in suberin biosynthesis, cell wall remodeling, and metabolic regulation, suggesting their crucial roles in fiber accumulation.

CONCLUSION

This study provides novel insights into the genetic regulation of fiber content in sweetpotato. The identification of significant SNPs and candidate genes offers valuable resources for breeding programs targeting fiber optimization. Further validation is essential for the effective application of these SNPs and genes into marker-assisted selection strategies.

Physical modifications of dietary fibers from kiwifruit pomace: Physicochemical, structural and functional properties

The impacts of high pressure homogenization (HPH), high temperature cooking (HTC), ultrasonic treatment (UT) and electron beam irradiation (EBI) on the composition of monosaccharides, physicochemical characteristics as well as structural and functional properties of kiwifruit pomace dietary fibers (KPDFs) were evaluated. The results demonstrated that all the four modification technologies significantly enhanced the soluble dietary fiber (SDF) yield and improved functional properties, including water and oil retention capacities, nitrite ion binding capacity, glucose adsorption capacity, and cholesterol adsorption capacity. Notably, HTC exhibited superior water holding capacity (16.3 g/g), yet it was accompanied by an increase in particle size and a reduction in antioxidant activity. In contrast, HPH demonstrated superior efficacy in the modification of KPDFs, resulting in a significant increase in the SDF content by 2.08 times, exhibiting a microstructure with the smallest particle size and loose dispersion. Therefore, HPH technology was suggested as the best option for modified KPDFs.

Physicochemical, Functional, and In Vitro Fermentation Characteristics of Buckwheat Bran Dietary Fiber Modified by Enzymatic Extrusion

The effects of cellulase-xylanase synergistic treatment combined with twin-screw extrusion on the physicochemical, functional, and in vitro fermentation characteristics of buckwheat bran dietary fiber (BBDF) were investigated. Compared to single enzymatic hydrolysis, the synergetic modification was more effective in promoting the soluble DF (SDF) ratio (increased from 10.68% to 32.67%), functional properties, and prebiotic activities of BBDF and decreasing the insoluble DF (IDF) content. Under 0.6% (w/w) cellulase and xylanase with mild extrusion conditions (40-80 °C), the modified BBDF exhibited the highest capacities for glucose and cholesterol adsorption. FTIR and XRD experiments indicated that the enzymatic extrusion destroyed the intermolecular interactions of BBDF. Furthermore, enzymatically extruded BBDFs showed 2.2-fold higher short-chain fatty acid (SCFA) yields during in vitro fecal fermentation (total SCFAs: 87.8 mM vs. 40.0 mM in control), with butyrate production reaching 2.5 mM (+76.3%), among which the mildly extruded BBDFs exhibited superior prebiotic effects.

Influence and underlying mechanism of soluble dietary fiber derived from Ganoderma Lucidum-fermented sweet potato residue on the physicochemical-digestive characteristics of wheat starch

Chronic overconsumption of starchy foods has been associated with health risks including cardiovascular diseases and diabetes. Soluble dietary fiber (SDF) presents a promising solution for modifying starch-based food products. In this study, SDF extracted from sweet potato residue (SPR) before and after fermentation with Ganoderma lucidum was incorporated into wheat starch (WS) at varying proportions (0.2 %-0.8 %). Compared with unfermented SDF, the fermented SDF exhibited stronger intermolecular interactions and physical entanglement with WS. As the concentration of fermented SDF increased, the ratio of free water in the gel system increased, while the leaching of amylose (16.64 %-13.68 %), hardness (444-288 g) and chewiness (254.83-170.61) gradually decreased, resulting in the disruption of the WS network structure, increased crystallinity and thermal stability, and inhibition of starch retrogradation. Additionally, the content of resistant starch increased (44.87 %-51.15 %), and the starch digestibility rate decreased. This research furnishes a theoretical foundation for enhancing the resource utilization of SPR and developing functional starch-based foods with improved starch properties and low glycemic index.

Effects of enzymatic hydrolysis, ball milling, and extrusion on the physical and functional properties of dietary fibers from sweet potatoes

Sweet potato pulp is a by-product of sweet potato processing with a relatively high content of dietary fiber. However, due to its less-explored functional properties, its development and utilization rate are very low. In this paper, non-fiber components in raw sweet potato dietary fiber were first removed. Subsequently, cellulase treatment, ball milling and extrusion were employed to modify it respectively. The results showed that all properties were significantly improved after removing non-fiber components. On the basis of removing non-fiber components, three groups of samples with cellulase treatment, 0 min ball milling and extrusion at 140 °C could significantly improve the water holding capacity (WHC) and oil holding capacity (OHC) of the samples. The highest WHC could reach 7.21 g/g, 7.52 g/g, and 6.88 g/g respectively, while 5.20 g/g, 5.21 g/g, and 5.61 g/g for OHC. The sample with 0 min ball milling had the highest swelling power, up to 5.40 mL/g. Extrusion at 140 °C could increase the water solubility index, glucose adsorption capacity, and cholesterol adsorption capacity of the sample to the highest, reaching 40.33 %, 44.15 mmol/g, and 26.54 mg/g (pH 7). This study provides a theoretical and experimental basis for improving the processing and functional performance of crude sweet potato dietary fiber.

Potato dietary fiber effectively inhibits structure damage and digestibility increase of potato starch gel due to freeze-thaw cycles

Repeated freeze-thaw (FT) cycles damage the quality of frozen starch-based foods and accelerate the digestion rate of starch. This study investigated how potato soluble dietary fiber (PSDF) affects the physicochemical characteristics and digestibility of potato starch (PS) after repeated FT cycles. Results indicated that repeated FT cycles of potato starch resulted in the enlargement of gel pores, an increase in hardness (from 322.5 g to 579.5 g), and a decrease in gel porosity, leading to reduced water-holding capacity (from 94.2 % to 85.4 %). However, the addition of PSDF stabilized the 3D structure of the PS/PSDF gel, with minimal fluctuations in hardness (413.0-447.5 g) and water-holding capacity (94.4-93.6 %). Meanwhile, PSDF enhanced intramolecular hydrogen bonding within starch molecules and promoted molecular interactions, increasing the PS/PSDF gel's helix structure; therefore, PSDF effectively addressed the increase in rapidly digestible starch caused by repeated FT cycles. Furthermore, PSDF might attach to the surface of starch particles, so limiting starch granule expansion and decreasing the peak viscosity increase caused by repeated FT cycles. The findings suggest that PSDF could be an effective component for improving the quality of potato starch-based frozen food.

Mechanisms of Degradation of Insoluble Dietary Fiber from Coconut Chips by Ultra-High Pressure

Coconut chips are a popular leisure food, but the residual crumbly feeling after chewing affects the eating experience. To address this problem, we investigated the mechanism of degradation of insoluble dietary fiber (IDF) from coconut chips by ultra-high pressure (UHP). The optimal conditions for UHP treatment were 100 MPa and 40 min. After UHP treatment, the hardness decreased by 60%, and the content of soluble dietary fiber (SDF) increased by 55%. So far, the meaning of SDF has not been defined. The microstructure of IDF was damaged and the surface was rough. There was no obvious change in the chemical structure. The position of the characteristic diffraction peaks was basically unchanged, but the crystallinity dropped by almost three times. The thermal stability decreased, and the composition of the monosaccharides changed. Together, UHP treatment can improve the problem of the residual crumbly feeling after chewing coconut chips and improve the quality of the product.

Ball Milling Improves Physicochemical, Functionality, and Emulsification Characteristics of Insoluble Dietary Fiber from Polygonatum sibiricum

The effects of ball milling on the physicochemical, functional, and emulsification characteristics of Polygonatum sibiricum insoluble dietary fiber (PIDF) were investigated. Through controlling milling time (4, 5, 6, 7, and 8 h), five PIDFs (PIDF-1, PIDF-2, PIDF-3, PIDF-4, and PIDF-5) were obtained. The results showed that ball milling effectively decreased the particle size and increased the zeta-potential of PIDF. Scanning electron microscope results revealed that PIDF-5 has a coarser microstructure. All PIDF samples had similar FTIR and XRD spectra. The functional properties of PIDF were all improved to varying degrees after ball milling. PIDF-3 had the highest water-holding capacity (5.12 g/g), oil-holding capacity (2.83 g/g), water-swelling capacity (3.83 mL/g), total phenol (8.12 mg/g), and total flavonoid (1.91 mg/g). PIDF-4 had the highest ion exchange capacity. Fat and glucose adsorption capacity were enhanced with ball milling time prolongation. PIDF-5 exhibited a contact angle of 88.7° and lower dynamic interfacial tension. Rheological results showed that PIDF-based emulsions had shear thinning and gel-like properties. PE-PIDF-5 emulsion had the smallest particle size and the highest zeta-potential value. PE-PIDF-5 was stable at pH 7 and high temperature. The findings of this study are of great significance to guide the utilization of the by-products of Polygonatum sibiricum.

Effects of soluble dietary fiber from pomegranate peel on the physicochemical properties and in-vitro digestibility of sweet potato starch

The effects of soluble dietary fiber (SDF) from pomegranate peel obtained through enzyme (E-SDF) and alkali (A-SDF) extractions on the structural, physicochemical properties, and in vitro digestibility of sweet potato starch (SPS) were investigated. The expansion degree of SPS granules, pasting viscosity, gel strength and hardness were decreased after adding E-SDF. The setback was accelerated in the presence of A-SDF but E-SDF delayed this effect during the cooling of the starch paste. However, the addition of A-SDF significantly reduced the breakdown of SPS and improved the freeze-thaw stability of starch gels, even at low concentrations (0.1 %), while E-SDF showed the opposite result. The structural characterization of SDF-SPS mixtures showed that A-SDF can help SPS form an enhanced microstructure compared with E-SDF, while polar groups such as hydroxyl group in E-SDF may bind to leached amylose through hydrogen bonding, leading to a decrease in SPS viscoelasticity. In addition, the results of in vitro digestion analysis indicated that A-SDF and E-SDF could decreased the digestibility of SPS and increased the content of resistant starch, especially when 0.5 % E-SDF was added. This study provides a new perspective on the application of SDF from pomegranate peel in improving starch-based foods processing and nutritional characteristics.

Impact of Simulated Human Gastrointestinal Digestion on the Functional Properties of Dietary Fibres Obtained from Broccoli Leaves, Grape Stems, Pomegranate and Tomato Peels

This study aimed to analyse the impact of a simulated human digestion process on the composition and functional properties of dietary fibres derived from pomegranate-peel, tomato-peel, broccoli-stem and grape-stem by-products. For this purpose, a computer-controlled simulated digestion system consisting of three bioreactors (simulating the stomach, small intestine and colon) was utilised. Non-extractable phenols associated with dietary fibre and their influence on antioxidant capacity and antiproliferative activity were investigated throughout the simulated digestive phases. Additionally, the modifications in oligosaccharide composition, the microbiological population and short-chain fatty acids produced within the digestion media were examined. The type and composition of each dietary fibre significantly influenced its functional properties and behaviour during intestinal transit. Notably, the dietary fibre from the pomegranate peel retained its high phenol content throughout colon digestion, potentially enhancing intestinal health due to its strong antioxidant activity. Similarly, the dietary fibre from broccoli stems and pomegranate peel demonstrated anti-proliferative effects in both the small and the large intestines, prompting significant modifications in colonic microbiology. Moreover, these fibre types promoted the growth of bifidobacteria over lactic acid bacteria. Thus, these results suggest that the dietary fibre from pomegranate peel seems to be a promising functional food ingredient for improving human health.

Extraction of Heracleum dissectum soluble dietary fiber by different methods: Structure and antioxidant properties

Heracleum dissectum is rich in nutrients, but there is little research on its soluble dietary fiber (SDF). In this study, SDF from H. dissectum was extracted by enzyme extraction (E-SDF), enzyme chemical extraction (EC-SDF), and fermentation extraction (F-SDF). The composition, molecular weight (Mw), structural characterization, and antioxidant activity of SDF extracted by the three methods were compared. This study showed that different extraction methods lead to differences in their structure. The Mw results showed that F-SDF had the largest Mw, the structure of SDF could be destroyed by enzymatic hydrolysis, and large molecules could be converted into small molecules. The monosaccharide composition analysis showed that the main sugars of E-SDF, EC-SDF, and F-SDF were galacturonic acid and galactose, and the main components of the three SDF samples were hemicellulose hydrolyzed pectin and soluble polysaccharide. Notably, E-SDF had the greatest antioxidant effect at the same concentration. In summary, different extraction methods can affect the structure and antioxidant capacity of H. dissectum SDF, among which E-SDF has potential as a functional food ingredient.

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.

Reclaiming Agriceuticals from Sweetpotato (Ipomoea batatas [L.] Lam.) By-Products

Sweetpotato (SP, Ipomoea batatas [L.] Lam.) is a globally significant food crop known for its high nutritional and functional values. Although the contents and compositions of bioactive constituents vary among SP varieties, sweetpotato by-products (SPBs), including aerial parts, storage root peels, and wastes generated from starch processing, are considered as excellent sources of polyphenols (e.g., chlorogenic acid, caffeoylquinic acid, and dicaffeoylquinic acid), lutein, functional carbohydrates (e.g., pectin, polysaccharides, and resin glycosides) or proteins (e.g., polyphenol oxidase, β-amylase, and sporamins). This review summarises the health benefits of these ingredients specifically derived from SPBs in vitro and/or in vivo, such as anti-obesity, anti-cancer, antioxidant, cardioprotective, and anti-diabetic, evidencing their potential to regenerate value-added bio-products in the fields of food and nutraceutical. Accordingly, conventional and novel technologies have been developed and sometimes combined for the pretreatment and extraction processes aimed at optimising the recovery efficiency of bioactive ingredients from SPBs while ensuring sustainability. However, so far, advanced extraction technologies have not been extensively applied for recovering bioactive compounds from SPBs except for SP leaves. Furthermore, the incorporation of reclaimed bioactive ingredients from SPBs into foods or other healthcare products remains limited. This review also briefly discusses current challenges faced by the SPB recycling industry while suggesting that more efforts should be made to facilitate the transition from scientific advances to commercialisation for reutilising and valorising SPBs.

Characterization and Function Analysis of Soluble Dietary Fiber Obtained from Radish Pomace by Different Extraction Methods

Soluble dietary fiber (SDF) benefits human health, and different extraction methods might modify the structure and functions of the SDFs. Radish is rich in dietary fiber. To assess the impact of various extraction techniques on the properties and functions of radish SDF, the SDFs were obtained from white radish pomace using alkaline, ultrasonic-assisted, and fermentation-assisted extraction methods. Analysis was conducted on the structure, physicochemical characteristics, thermal properties, and functional attributes of the SDFs. The study revealed that various extraction techniques can impact the monosaccharides composition and functionality of the SDFs. Compared with the other two extraction methods, the surface structures of SDFs obtained by fermentation-assisted extraction were looser and more porous, and the SDF had better water solubility and water/oil holding capacity. The adsorption capacities of glucose and cholesterol of the SDFs obtained from fermentation-assisted extraction were also improved. Wickerhamomyces anomalus YFJ252 seems the most appropriate strain to ferment white radish pomace to acquire SDF; the water holding, oil holding, glucose absorption capacity, and cholesterol absorption capacity at pH 2 and pH 7 have a 3.06, 1.65, 3.19, 1.27, and 1.83 fold increase than the SDF extracted through alkaline extraction method.

Dietary fiber modification: structure, physicochemical properties, bioactivities, and application-a review

There is increasing attention on the modification of dietary fiber (DF), since its effective improvement on properties and functions of DF. Modification of DF can change their structure and functions to enhance their bioactivities, and endow them with huge application potential in the field of food and nutrition. Here, we classified and explained the different modification methods of DF, especially dietary polysaccharides. Different modification methods exert variable effects on the chemical structure of DF such as molecular weight, monosaccharide composition, functional groups, chain structure, and conformation. Moreover, we have discussed the change in physicochemical properties and biological activities of DF, resulting from alterations in the chemical structure of DF, along with a few applications of modified DF. Finally, we have summarized the modified effects of DF. This review will provide a foundation for further studies on DF modification and promote the future application of DF in food products.

Characteristics and properties of a polysaccharide isolated from Wolfiporia cocos as potential dietary supplement for IBS

Introduction

As low FODMAP (Fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet therapy is recommended for most of Irritable Bowel Syndrome (IBS) patients, the consequent insufficient of dietary fibers (DFs) intake exert an adverse impact on intestinal health. It is necessary to find suitable DFs for IBS patients.

Methods

This study extracted a water-insoluble polysaccharide from Wolfiporia cocos (WIP) by alkali-extraction and acid-precipitation method. Its molecular weight was detected by high performance gel permeation chromatography (HPGPC) analysis. The structure of WIP was analyzed by Fourier transform infrared (FT-IR) spectrum, Nuclear Magnetic Resonance (NMR) spectra and X-ray diffraction (XRD). The properties related to stability, digestion, viscosity, osmotic activity, adsorption and fermentation were investigated, aimed to explore the feasibility of WIP as a new DF supplement for patients with IBS. In addition, 16S rRNA sequencing analysis was conducted to explore its effects on IBS-related gut microbiota.

Results and Discussion

The results showed that WIP had a single homogeneous composition and the molecular weight was 8.1 × 103 Da. WIP was indicated as a kind of pyranose form with β anomeric configuration and the main chain of WIP was 1,3-β-glucan with amorphous structure. In addition to good thermal stability, WIP also has low bioavailability and can reach the colon mostly without being digested. Moreover, the low viscosity and osmotic activity, the high water- swelling and water/oil-holding capacity, fructose adsorption capacity and poor fermentation performance of WIP demonstrated that it is suitable for IBS patients. It is worth noting that WIP regulates IBS associated gut microbiota effectively, such as the abundance of Lachnospiraceae and Prevotella. These findings provide a theoretical basis for the development of WIP as a dietary supplement for IBS patients with low FODMAP diet therapy.

GRAPHICAL ABSTRACT

Investigation of Structural Characteristics and Solubility Mechanism of Edible Bird Nest: A Mucin Glycoprotein

In this study, the possible solubility properties and water-holding capacity mechanism of edible bird nest (EBN) were investigated through a structural analysis of soluble and insoluble fractions. The protein solubility and the water-holding swelling multiple increased from 2.55% to 31.52% and 3.83 to 14.00, respectively, with the heat temperature increase from 40 °C to 100 °C. It was observed that the solubility of high-Mw protein increased through heat treatment; meanwhile, part of the low-Mw fragments was estimated to aggregate to high-Mw protein with the hydrophobic interactions and disulfide bonds. The increased crystallinity of the insoluble fraction from 39.50% to 47.81% also contributed to the higher solubility and stronger water-holding capacity. Furthermore, the hydrophobic interactions, hydrogen bonds, and disulfide bonds in EBN were analyzed and the results showed that hydrogen bonds with burial polar group made a favorable contribution to the protein solubility. Therefore, the crystallization area degradation under high temperature with hydrogen bonds and disulfide bonds may be the main reasons underlying the solubility properties and water-holding capacity of EBN.

Use of maltodextrin, sweet potato flour, pectin and gelatin as wall material for microencapsulating Lactiplantibacillus plantarum by spray drying: Thermal resistance, in vitro release behavior, storage stability and physicochemical properties

Different plant products and co-products have been studied as wall materials for the microencapsulation of probiotics due to the need for new lost-cost, abundant, and natural materials. In this study, microparticles were developed by spray drying using different combinations of conventional materials such as maltodextrin, pectin, gelatin, and agar-agar with unconventional materials such as sweet potato flour to microencapsulate Lactiplantibacillus plantarum. The microparticles obtained were evaluated for encapsulation efficiency, thermal resistance, and rupture test. The most resistant microparticles were characterized and evaluated for probiotic viability during storage and survival to in vitro gastrointestinal conditions. Microparticles A (10 % maltodextrin, 5 % sweet potato flour, and 1 % pectin) and B (10 % maltodextrin, 4 % sweet potato flour, and 2 % gelatin) showed high thermal resistance (>59 %) and survival in acidic conditions (>80 %). L. plantarum in microparticles A and B remained viable with counts > 6 log CFU.g^-1 for 45 days at 8 °C and -18 °C and resisted in vitro gastrointestinal conditions after processing with counts of 8.38 and 9.10 log CFU.g^-1, respectively. Therefore, the selected microparticles have great potential for application in different products in the food industry, as they promote the protection and distribution of probiotic microorganisms.

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.

The effect of ball milling on the structure, physicochemical and functional properties of insoluble dietary fiber from three grain bran

The effects of ball milling processing on the structure, physicochemical, and functional properties of insoluble dietary fiber (IDF) in bran from prosomillet, wheat and rice were investigated. Meanwhile, the effect of IDF on glucose tolerance and blood lipid levels in mice was evaluated as well. With findings, for all three grains, the particle sizes of IDF were significantly reduced after ball milling treatment (p < 0.05). Scanning electron microscopy revealed fragmented fiber with numerous pores and cracks. The reactive groups of three IDF samples were found to be similar by fourier transform infrared spectroscopy. And consistent with X-ray diffraction and thermal analysis, for all three grains, ball milling reduced the crystallinity of IDF and helped to increase the release of free phenol by 23.4 %, 8.9 %, and 12.2 %, respectively. Furthermore, the water holding capacity, glucose delay capacity, glucose, sodium cholate, and cholesterol adsorption capacity, and in vitro digestibility of starch and fat were all improved to varying degrees. Animal experiments showed that ball milling treatment effectively slowed the postprandial rise in blood sugar (especially IDF of rice bran) and blood lipids (especially IDF of prosomillet bran). As a result, ball milling treatment is a potential method for dietary fiber modification in the food industry.

Discovery of novel secretome CAZymes from Penicillium sclerotigenum by bioinformatics and explorative proteomics analyses during sweet potato pectin digestion

Novel selective enzymatic refining of sweet potato processing residues requires judicious enzyme selection and enzyme discovery. We prepared a pectinaceous cell wall polysaccharide fraction from sweet potato using an enzymatic a treatment to preserve the natural linkages and substitutions. Polysaccharide composition and linkage analysis data confirmed the pectinaceous polysaccharide fraction to be a rhamnogalacturonan I-rich fraction with a high content of arabinogalactan Type I. We hypothesized that the post-harvest tuber pathogenic fungus Penicillium sclerotigenum would harbor novel enzymes targeting selective sweet potato pectin modification. As part of the study, we also report the first genome sequence of P. sclerotigenum. We incubated the sweet potato pectinaceous fraction with P. sclerotigenum. Using proteomics accompanied by CUPP-bioinformatics analysis, we observed induced expression of 23 pectin-associated degradative enzymes. We also identified six abundantly secreted, induced proteins that do not correspond to known CAZymes, but which we suggest as novel enzymes involved in pectin degradation. For validation, the predicted CUPP grouping of putative CAZymes and the exo-proteome data obtained for P. sclerotigenum during growth on sweet potato pectin were compared with proteomics and transcriptomics data reported previously for pectin-associated CAZymes from Aspergillus niger strain NRRL3. The data infer that P. sclerotigenum has the capacity to express several novel enzymes that may provide novel opportunities for sweet potato pectin modification and valorization of sweet potato starch processing residues. In addition, the methodological approach employed represents an integrative systematic strategy for enzyme discovery.

Nitrogen Removal from the Simulated Wastewater of Ionic Rare Earth Mining Using a Biological Aerated Filter: Influence of Medium and Carbon Source

In engineering application, a two-stage biological aerated filter (BAF) has been deployed to achieve the steady nitrogen removal of the wastewater from the mining area of ionic rare earth with a low carbon to nitrogen (C/N) ratio. However, the cost-efficiency of the medium and carbon source casts a shadow over further development. In this study, the influences of four media (i.e., volcanic, zeolite, quartz, and ceramisite) and three soluble carbon sources (i.e., acetate, glucose, and methanol) on the N removal were systematically compared. Applying volcanic and quartz showed a favorable start-up performance due to the biophilic surface and dense packing, respectively. However, regardless of medium type, with [NH4+-N]0 = 50 and [NO3−-N]0 = 30 mg/L, the C/N ratio of 3 was required to meet the discharge standards of NH4+-N, TN, and COD, and acetate was confirmed applicable for all the selected medium-packed BAFs. Introduction of sweet potato residues as the solid carbon source decreased the amount of added acetate by more than 13%. The 16S rRNA high-throughput gene sequencing revealed that Sphingomonas and Nitrospira were abundant in the aerobic stages of the volcanic and zeolite-packed BAFs, respectively. Such a community integrated with the extensively distributed Thauera, Clostridium_sensu_stricto, and Proteiniclasticum in the anoxic stage accounted for the efficient N removal. Thus, deploying volcanic as the medium and acetate as the soluble carbon source was proposed. These findings will provide valuable references for the selection of medium and carbon source and, consequently, further optimize the operational performance.

Physicochemical structure and functional properties of soluble dietary fibers obtained by different modification methods from Mesona chinensis Benth. residue

Alkaline hydrogen peroxide (AHP), high-temperature cooking combined with ultrasonic (HTCU) and high-temperature cooking combined with complex enzyme hydrolysis (HTCE) were used to modify soluble dietary fiber (SDF) in Mesona chinensis Benth. residue (MCBR), then the structural and in vitro functional properties of A-SDF, HU-SDF and HE-SDF were investigated. Results showed that the three treatments significantly increased the yield of SDF. Scanning electron microscopy, FT-IR, monosaccharide composition, X-ray diffraction, molecular weight distribution and thermal stability analysis were employed to determine the structural changes. Compared with the control SDF (CK-SDF), HE-SDF and HU-SDF had looser and more porous microstructure, as well as lower crystallinity. In contrast to HE-SDF and HU-SDF, A-SDF exhibited a dense wavy microstructure, and elevated crystallinity and thermal stability. In addition, the monosaccharide composition and molecular weight of HU-SDF, HE-SDF and A-SDF were significantly altered as compared to CK-SDF. Moreover, the functional properties of HE-SDF and HU-SDF, including water holding capacity (WHC), oil holding capacity (OHC), glucose adsorption capacity (GAC), α-amylase activity inhibition ratio (α-AAIR), cholesterol adsorption capacity (CAC) and nitrite ion adsorption capacity (NIAC), were significantly higher than those of CK-SDF. However, the dense structure and high crystallinity of A-SDF resulted in a significantly lower GAC and NIAC than that of CK-SDF, with only WHC and α-AAIR being improved. Overall, this study showed that HTCU and HTCE could be used as ideal modification methods for MCBR SDF, HE-SDF and HU-SDF have potential as functional additives in food.

Influence of modification methods on physicochemical and structural properties of soluble dietary fiber from corn bran

Soluble dietary fiber (SDF), which is a component of dietary fibers exhibit many physiological functions, biological activity, and good gel forming ability. In this study, extraction of SDF from corn bran was evaluated using twin-screw extrusion and ultrasonic treatment and the combinations of the respective methods with dual enzyme hydrolysis. The monosaccharide compositions, molecular weight, physicochemical properties, and structural and functional characteristics were determined. The results showed that ultrasonic and twin-extrusion treatments significantly increased the SDF content from 2.42 to 4.58 and 6.54%, respectively. Dual enzyme hydrolysis further increased the SDF content. Modification treatment changed the monosaccharide composition, improved physicochemical and functional properties, such as water and oil holding capacity, nitrite adsorption, and antioxidative ability. In conclusion, physical modification combined with enzyme treatment distinctly improved the extraction yield, physicochemical and functional properties of SDF. Therefore, the modified SDF is suitable as a functional food additive.