Valorization of Wheat Bran by Three Fungi Solid-State Fermentation: Physicochemical Properties, Antioxidant Activity and Flavor Characteristics

New insights into adlay seed bran polysaccharides: Effects of enzyme-assisted Aspergillus niger solid-state fermentation on its structural features, simulated gastrointestinal digestion, and prebiotic activity

Adlay seed bran, typically discarded or used as animal feed, represents a significant resource waste. This study investigates the structural and physicochemical properties, in vitro digestive behavior, and fecal fermentation profiles of adlay seed bran polysaccharides (ASBPs) prepared using different methods. These methods include hot water extraction, Aspergillus niger solid-state fermentation (SSF), and enzyme-assisted SSF with β-glucosidase, cellulase, and xylanase, referred to as ASBP, ASBP-F, ASBP-GF, ASBP-CF, and ASBP-XF, respectively. Results showed that enzyme-assisted SSF with A. niger improved extraction efficiency and uniformity of ASBPs, increasing total neutral sugars, uronic acids, mannose, and galactose while reducing glucose content, molecular weight, and particle size. ASBP-CF had the best extraction rate, sugar content, lowest molecular weight, finest uniformity, and smallest particle size. In simulated digestion tests, all ASBP variants were stable in stomach and small intestine conditions but degradable by human fecal microbiota, showing varying fermentability levels. ASBPs increased Bacteroidetes populations, inhibited Proteobacteria growth, and enhanced short-chain fatty acid (SCFAs) production, with ASBP-CF showing the highest fermentability and prebiotic efficacy. ASBP-CF was particularly effective in promoting beneficial bacteria like Bacteroides and restraining harmful bacteria such as Escherichia_Shigella, producing more SCFAs during fermentation. These findings suggest that ASBP-CF has potential as a dietary supplement to improve gut health, presenting a high-value utilization strategy for adlay seed bran.

Correlation Analyses of Amylase and Protease Activities and Physicochemical Properties of Wheat Bran During Solid-State Fermentation

Solid-state fermentation (SSF) has emerged as an effective method for wheat bran valorization, providing advantages like cost reduction, decreased water usage, and enhanced product quality. In this study, wheat bran was fermented using Rhizopus oryzae to evaluate the extraction yield of soluble dietary fiber, the activities of protease and amylase, and the physicochemical characteristics of wheat bran during SSF. The findings demonstrated that the maximum yield of soluble dietary fiber was achieved after 120 h of fermentation at a moisture content of 55%. Simultaneously, protease activity peaked at 45% moisture content after 120 h, while amylase activity was maximized at 55% moisture content after 96 h. The microstructure result indicated that most of the starch granules degraded after 144 h of fermentation at a moisture content of 55%, exhibiting a smooth outer layer of wheat bran. Furthermore, fermented bran showed a significant rise in total phenols, peaking at 96 h at a moisture content of 55%. Flavonoid content also reached its maximum after 72 h of fermentation at 55% moisture content. The content of alkylresorcinols in fermented wheat bran changed slightly under different moisture content and fermentation time conditions, which was consistent with the change in pH value. The DPPH radical scavenging rate was optimal when the moisture content was 55% after 96 h. The ABTS radical scavenging rate, hydroxyl radical scavenging rate, and reducing ability were optimal at 55% moisture content after 120 h. These findings demonstrate that the optimal conditions for the SSF of wheat bran using Rhizopus oryzae involve maintaining the moisture at 55%, suggesting that this method is effective for enhancing the value of wheat bran.

Effects of airflow superfine pulverization on the structure, functional properties, and flavor quality of wheat bran

BACKGROUND

Wheat bran (WB) is a byproduct of refined wheat flour production with poor edible taste and low economic value. Herein, the WB was micronized via airflow superfine pulverization (ASP), and the effects of the ASP conditions on its particle size, nutritive compositions, whiteness, hydration characteristics, moisture distribution, microstructure, cation exchange capacity, volatile flavor components, and other characteristics were investigated.

RESULTS

Reducing the rotational speed of the ASP screw and increasing the number of pulverizations significantly decreased the median particle size Dx(50) of WB to a minimum of 12.97 ± 0.19 μm (P < 0.05), increased the soluble dietary fiber content from 55.05 ± 2.94 to 106.86 ± 1.60 mg g-1, and improved the whiteness and water solubility index. In addition, the water holding capacity and oil holding capacity were significantly reduced (P < 0.05), while the cation exchange and swelling capacities first increased and then decreased. Up to about 70% of water in WB exists as bound water. As the Dx(50) of WB decreased, the content of bound and immobile water increased, while the free water decreased from 14.37 ± 1.21% to 7.59 ± 1.03%. Furthermore, WB was micronized and the particles became smaller and more evenly distributed. Using gas chromatography-ion mobility spectrometry, a total of 37 volatile compounds in micronized WB (including 10 aldehydes, 9 esters, 7 alcohols, and several acids, furans, ethers, aldehydes, esters, and alcohols) were identified as the main volatile compounds of WB.

CONCLUSION

Collectively, ASP improved the physicochemical properties of WB. This study provides theoretical references for the use of ASP to improve the utilization and edibility of WB. © 2024 Society of Chemical Industry.

How lignocellulose degradation can promote the quality and function of dietary fiber from bamboo shoot residue by Inonotus obliquus fermentation

Lignocellulose constitutes the primary component of dietary fiber. We assessed how fermenting bamboo shoot residue with the medicinal white-rot fungus Inonotus obliquus affected the yield, composition, and functional attributes of dietary fiber by altering bamboo shoot residue lignocellulose's spatial structure and composition. I. obliquus secretes lignocellulolytic enzymes, which effectively enhance the degradation of holocellulose and lignin by 87.8% and 25.5%, respectively. Fermentation led to a more porous structure and reduced crystallinity. The yield of soluble dietary fiber increased from 5.1 g/100 g raw BSR to 7.1 g/100 g 9-day-fermented bamboo shoot residue. The total soluble sugar content of dietary fiber significantly increased from 9.2% to 13.8%, which improved the hydration, oil holding capacity, in vitro cholesterol, sodium cholate, and nitrite adsorption properties of dietary fiber from bamboo shoot residue. These findings confirm that I. obliquus biotransformation is promising for enhancing dietary fiber yield and quality.

Cereal dietary fiber regulates the quality of whole grain products: Interaction between composition, modification and processing adaptability

The coarse texture and difficulty in processing dietary fiber (DF) in cereal bran have become limiting factors for the development of the whole cereal grain (WCG) food industry. To promote the development of the WCG industry, this review comprehensively summarizes the various forms and structures of cereal DF, including key features such as molecular weight, chain structure, and substitution groups. Different modification methods for changing the chemical structure of DF and their effects on the modification methods on physicochemical properties and biological activities of DF are discussed systematically. Furthermore, the review focusses on exploring the interactions between DF and dough components and discusses the effects on the gluten network structure, starch gelatinization and retrogradation, fermentation, glass transition, gelation, and rheological and crystalline characteristics of dough. Additionally, opportunities and challenges regarding the further development of DF for the flour products are also reviewed. The objective of this review is to establish a comprehensive foundation for the precise modification of cereal DF, particularly focusing on its application in dough-related products, and to advance the development and production of WCG products.

Fermentation biotechnology applied to wheat bran for the degradation of cell wall fiber and its potential health benefits: A review

Consumption of wheat bran is associated with health benefits. However, the insoluble cell layer fiber and considerable levels of anti-nutritional factors limit bioavailability of wheat bran, which can be effectively improved through fermentation. To comprehensively elucidate the precise biotransformation and health benefits mechanisms underlying wheat bran fermentation. This review investigates current fermentation biotechnology for wheat bran, nutritional effects of fermented wheat bran, mechanisms by which fermented wheat bran induces health benefits, and the application of fermented wheat bran in food systems. The potential strategies to improve fermented wheat bran and existing limitations on its application are also covered. Current findings support that microorganisms produce enzymes that degrade the cell wall fiber of wheat bran during the fermentation, releasing nutrients and producing new active substances while degrading anti-nutrient factors in order to effectively improve nutrient bioavailability, enhance antioxidant activity, and regulate gut microbes for health effects. Fermentation has been an effective way to degrade cell wall fiber, thereby improving nutrition and quality of whole grain or bran-rich food products. Currently, there is a lack of standardization in fermentation and human intervention studies. In conclusion, understanding effects of fermentation on wheat bran should guide the development and application of bran-rich products.

Soluble dietary fibers from solid-state fermentation of wheat bran by the fungus Cordyceps cicadae and their effects on colitis mice

Ulcerative colitis is a chronic inflammatory disease with a complex pathogenesis for which there is no definitive therapeutic agent. Fermentation, as a green and efficient bioprocessing technique, has been shown to enhance the biological activity of food ingredients. Soluble dietary fiber isolated from plants is thought to have the potential to prevent and alleviate ulcerative colitis. This work was designed to study the differences in the chemical properties of the soluble dietary fiber from wheat bran fermented by Isaria cicadae Miq. (FSDF) and the unfermented soluble dietary fiber from wheat bran (UFSDF) and their effects on colitis mice. The results showed that FSDF and UFSDF differed in molecular weight, monosaccharide compositions, and surface morphology. In addition, supplementation with UFSDF and FSDF ameliorated the symptoms of DSS-induced colitis in mice by attenuating body weight loss, decreasing the disease activity index and splenic index, shortening the length of the colon, and attenuating colonic tissue damage. UFSDF and FSDF also increased the production of the anti-inflammatory cytokine IL-10 and inhibited the expression of IL-6, IL-1β, and TNF-α. The results of gut flora and short-chain fatty acid analyses showed that UFSDF and FSDF improved the diversity of gut microbiota, up-regulated the abundance of some beneficial bacteria such as Akkermansia and Muribaculaceae, increased the levels of acetic acid, propionic acid, and butyric acid, and restored dextran sodium sulfate (DSS)-induced dysbiosis of the intestinal flora in mice. These findings provide guidance for the development of FSDF and UFSDF as functional foods for the relief of ulcerative colitis.

Decolorization of Textile Azo Dye via Solid-State Fermented Wheat Bran by Lasiodiplodia sp. YZH1

Textile dyes are one of the major water pollutants released into water in various ways, posing serious hazards for both aquatic organisms and human beings. Bioremediation is a significantly promising technique for dye decolorization. In the present study, the fungal strain Lasiodiplodia sp. was isolated from the fruiting bodies of Schizophyllum for the first time. The isolated fungal strain was examined for laccase enzyme production under solid-state fermentation conditions with wheat bran (WB) using ABTS and 2,6-Dimethoxyphenol (DMP) as substrates, then the fermented wheat bran (FWB) was evaluated as a biosorbent for Congo red dye adsorption from aqueous solutions in comparison with unfermented wheat bran. A Box-Behnken design was used to optimize the dye removal by FWB and to analyze the interaction effects between three factors: fermentation duration, pH, and dye concentration. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were applied to study the changes in the physical and chemical characteristics of wheat bran before and after fermentation. An additional experiment was conducted to investigate the ability of the Lasiodiplodia sp. YZH1 to remove Congo red in the dye-containing liquid culture. The results showed that laccase was produced throughout the cultivation, reaching peak activities of ∼6.2 and 22.3 U/mL for ABTS and DMP, respectively, on the fourth day of cultivation. FWB removed 89.8% of the dye (100 mg L-1) from the aqueous solution after 12 h of contact, whereas WB removed only 77.5%. Based on the Box-Behnken design results, FWB achieved 93.08% dye removal percentage under the conditions of 6 days of fermentation, pH 8.5, and 150 mg L-1 of the dye concentration after 24 h. The fungal strain removed 95.3% of 150 mg L-1 of the dye concentration after 8 days of inoculation in the dye-containing liquid culture. These findings indicate that this strain is a worthy candidate for dye removal from environmental effluents.

The Flavor Profiles of Highland Barley Fermented with Different Mushroom Mycelium

Highland barley was fermented with Cordyceps militaris, Stropharia rugoso-annulata, Morchella esculenta, Schizophyllum commune and Tremella sanguinea. The flavor profiles were investigated by electronic nose (E-nose), headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and sensory evaluation by train panel. Fermentation with mushroom mycelium was able to change the aroma profile of highland barley. The original strong grassy taste was reduced due to a decrease in hexanal, decanal and 2-pentylfuran, and new aromatic flavors (floral, sweet and mushroom fragrance) were acquired after fermentation. The overall flavor of the fermented highland barley varied with mushroom strains. Schizophyllum commune gave a heavier sour taste to the fermented highland barley. However, fermentation with T. sanguinea increased the content of methyl 4-methoxybenzoate making the sample difficult to accepted. Fermentation with C. militaris, M. esculenta, and S. rugoso-annulata increased the volatile contents. The high levels of 1-octen-3-ol and esters gave a strong mushroom, oily and fruity flavor. Morchella esculenta showed the best performance and the highest acceptance in the fermented highland barley. Our results suggest that fermentation with mushroom mycelium can improve the flavor of highland barley, which provides an innovative utilization of highland barley.