Upgrading of valuable food component contents and anti-nutritional factors depletion by solid-state fermentation: A way to valorize wheat bran for nutrition

Effects of Lactiplantibacillus plantarum and Bacillus subtilis fermentation on the constituents of ground or extruded corn bran

The effects of two physical modifications of corn bran, namely, 1) grinding to < 500 μm and 2) extruding at two die temperature settings (high, 140 °C and low, 120 °C) were evaluated on growth performance of Lactiplantibacillus plantarum and Bacillus subtilis. The resulting constituent changes in dried fermented bran ingredients were also compared. Corn bran at 25 or 35 % moisture content were either ground or extruded prior to fermenting with L. plantarum or B. subtilis at 37 °C for 72 h at 200 rpm. Both the ground or extruded brans showed typical growth patterns for both probiotic bacteria studied. B. subtilis had the highest growth rate of 0.64 h-1 and lowest population doubling time of 1.09 h on corn bran (35 % moisture) extruded at 120 °C compared to no inoculation control. The major soluble sugars in corn bran were arabinose (0.011 to 1.68 g kg-1) and xylose (0.029 to 0.246 g kg-1) which decreased upon extrusion at higher temperature (HT: 140 °C). The total phenolic content range of 9-10 mg GAE g-1 for extruded and fermented brans was not significantly different from their respective controls. Phytic acid and trypsin inhibitors reduced by a maximum of 42 % and 34 %, respectively, when extruded and fermented with both microbes.

Recent advances of wheat bran arabinoxylan exploitation as the functional dough additive

Wheat bran is a significant byproduct of wheat flour milling and is enriched with dietary fiber. Arabinoxylan (AX), the major constituent of dietary fiber, plays a crucial role in the nutrition and processing of cereal food. This review comprehensively focuses on AX as a functional additive, specifically addressing its fractionation methods, structural characteristics, techno-functionality, and interactions with dough components. Structural features such as molecular weight (Mw), branching degree, and ferulic acid (FA) content significantly influence the functionality of AX, affecting gluten protein and starch characteristics during cereal food processing. Specifically, studies have shown that AX with optimum Mw and FA levels improved dough rheology and gas retention during bread-making. Furthermore, the solubility of AX varies across wheat bran fractions, with soluble AX fractions demonstrating notable dough-improving properties. By integrating structural complexity with functional properties, this review highlights the promising applications of wheat bran AX as a sustainable, functional dough additive.

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.

The Effects of Single- or Mixed-Strain Fermentation of Red Bean Sourdough, with or without Wheat Bran, on Bread Making Performance and Its Potential Health Benefits in Mice Model

The effects of single- (Lactobacillus fermentum) or mixed-strain (Lactobacillus fermentum, Kluyveromyces marxianus) fermentation of red bean with or without wheat bran on sourdough bread quality and nutritional aspects were investigated. The results showed that, compared to unfermented controls, the tannins, phytic acid, and trypsin inhibitor levels were significantly reduced, whereas the phytochemical (TPC, TFC, and gallic acid) and soluble dietary fiber were increased in sourdough. Meanwhile, more outstanding changes were obtained in sourdough following a mixed-strain than single-strain fermentation, which might be associated with its corresponding β-glucosidase, feruloyl esterase, and phytase activities. An increased specific volume, reduced crumb firmness, and greater sensory evaluation of bread was achieved after mixed-strain fermentation. Moreover, diets containing sourdough, especially those prepared with mixed-strain-fermented red bean with wheat bran, significantly decreased serum pro-inflammatory cytokines levels, and improved the lipid profile, HDL/LDL ratio, glucose tolerance, and insulin sensitivity of mice. Moreover, gut microbiota diversity increased towards beneficial genera (e.g., Bifidobacterium), accompanied with a greater increase in short-chain fatty acid production in mice fed on sourdough-based bread diets compared to their controls and white bread. In conclusion, mixed-strain fermentation's synergistic effect on high fiber-legume substrate improved the baking, sensory quality, and prebiotic effect of bread, leading to potential health benefits in mice.

Ultrasound as Green Technology for the Valorization of Pumpkin Leaves: Intensification of Protein Recovery

The recovery of valuable nutritional compounds, like proteins, from waste streams and by-products is a key strategy for enhancing production sustainability and opening up new market potential. This research aimed to use high-intensity ultrasound as an innovative technique to extract the soluble proteins from the pumpkin leaves. The impact of various sonication amplitudes and duration periods on protein yield, functional properties, antioxidant qualities, and structural characteristics, were studied. Utilization of ultrasound technology significantly increased the yield of pumpkin leaf protein by up to 40%-six times higher than maceration. The ultrasound extraction provided a RuBisCO-rich protein fraction with high radical scavenging and chelating activities, especially at 40% amplitude. Cavitation modified the tertiary and secondary structures of leaf proteins: the amount of α-helix changed based on amplitude (12.3-37.7%), the amount of random coil increased to 20.4%, and the amount of β-turn reduced from 31 to 18.6%. The alteration of the protein fluorescence spectrum (blue shift in spectrum) provides further evidence that ultrasound alters the proteins' molecular structure in comparation with maceration; the maximum tryptophan fluorescence intensity decreased from 22.000 to 17.096. The hydrophobicity values of 76.8-101.5 were substantially higher than the maceration value of 53.4, indicating that ultrasound improved the hydrophobicity of protein surfaces. Ultrasound resulted in a significant increase in solubility in an acidic environment with the increase in sonication amplitude. A 2.4-fold increase in solubility at pH 2 becomes apparent (20% amplitude; 43.1%) versus maceration (18.2%). The emulsifying ability decreases from 6.62 to 5.13 m2/g once the sonication amplitude increases by 20-70%. By combining the ultrasound periods and amplitudes, it is possible to create high-value protein leaf extracts with improved properties which can find real application as food additives and dietary supplements.

Exploring community succession and metabolic changes in corn gluten meal-bran mixed wastes during fermentation

Addressing the challenge of sustainable agricultural processing waste management is crucial. Protein sources are essential for livestock farming, and one viable solution is the microbial fermentation of agricultural by-products. In this study, the microorganisms utilized for fermentation were Pichia fermentans PFZS and Limmosilactobacillus fermentum LFZS. The results demonstrated that the fermented corn gluten meal-bran mixture (FCBM) effectively degraded high molecular weight proteins, resulting in increases of approximately 23.3%, 367.6%, and 159.3% in crude protein (CP), trichloroacetic acid-soluble protein (TCA-SP), and free amino acid (FAA), respectively. Additionally, there was a significant enhancement in the content of beneficial metabolites, including total phenols, carotenoids, and microorganisms. FCBM also effectively reduced anti-nutritional factors while boosting antioxidant and anti-inflammatory substances, such as dipeptides and tripeptides. The fermentation process was marked by an increase in beneficial endophytes, which was closely correlated with the enhancement of beneficial metabolites. Overall, FCBM provides a theoretical basis for substituting traditional protein resources in animal husbandry.

Solid-state fermentation using wheat bran to produce glucose syrup and functional cereal bars

Wheat bran is one of the most abundant by-products from grain milling, which can be used as substrate for solid-state fermentation (SSF) to obtain enzymes able to convert this agro-industrial waste into glucose syrup, which in turn can be applied for the production of different food products. The present study aimed to determine centesimal composition of wheat bran, obtain enzymatic extract that converts wheat bran into wheat glucose syrup (WGS), produce rice flakes cereal bars (RFCB), and evaluate their nutritional composition and the presence of functional compounds, as well as their antioxidant potential. Determination of centesimal composition of wheat bran demonstrated its nutritional potential. Enzymatic extract was obtained and it converted wheat bran into WGS, which were applied to rice flakes producing RFCB. These cereal bars proved to be a source of dietary fiber (1.8 g) and soluble protein (7.2 g) while RCFB produced with corn glucose syrup did not present these nutritional components. In addition, RFCB produced with WGS showed polyphenolic compounds, among them flavonoids, which exhibited antioxidant activity by DPPH and ABTS radical scavenging (47.46% and 711.89 μM Trolox Equivalent/g, respectively), and iron ion reduction (71.70 μM Trolox equivalent/g). Final product showed a decrease in caloric value and sodium content. Therefore, the present study showed that the bioprocess of SSF yields a nutritional, ecological, and functional food product, which might be of great interest for food industry, adding nutritional and functional value to a well-stablished product.

Solid-State Fermented Plant Foods as New Protein Sources

The current animal-based production of protein-rich foods is unsustainable, especially in light of continued population growth. New alternative proteinaceous foods are therefore required. Solid-state fermented plant foods from Africa and Asia include several mold- and Bacillus-fermented foods such as tempeh, sufu, and natto. These fermentations improve the protein digestibility of the plant food materials while also creating unique textures, flavors, and taste sensations. Understanding the nature of these transformations is of crucial interest to inspire the development of new plant-protein foods. In this review, we describe the conversions taking place in the plant food matrix as a result of these solid-state fermentations. We also summarize how these (nonlactic) plant food fermentations can lead to desirable flavor properties, such as kokumi and umami sensations, and improve the protein quality by removing antinutritional factors and producing additional essential amino acids in these foods.

Functional and Nutritional Characteristics of Natural or Modified Wheat Bran Non-Starch Polysaccharides: A Literature Review

Wheat bran (WB) consists mainly of different histological cell layers (pericarp, testa, hyaline layer and aleurone). WB contains large quantities of non-starch polysaccharides (NSP), including arabinoxylans (AX) and β-glucans. These dietary fibres have long been studied for their health effects on management and prevention of cardiovascular diseases, cholesterol, obesity, type-2 diabetes, and cancer. NSP benefits depend on their dose and molecular characteristics, including concentration, viscosity, molecular weight, and linked-polyphenols bioavailability. Given the positive health effects of WB, its incorporation in different food products is steadily increasing. However, the rheological, organoleptic and other problems associated with WB integration are numerous. Biological, physical, chemical and combined methods have been developed to optimise and modify NSP molecular characteristics. Most of these techniques aimed to potentially improve food processing, nutritional and health benefits. In this review, the physicochemical, molecular and functional properties of modified and unmodified WB are highlighted and explored. Up-to-date research findings from the clinical trials on mechanisms that WB have and their effects on health markers are critically reviewed. The review points out the lack of research using WB or purified WB fibre components in randomized, controlled clinical trials.

Modified cereal bran (MCB) from finger millet, kodo millet, and rice bran prevents high-fat diet-induced metabolic derangements

Cereal bran consumption improves gastrointestinal and metabolic health. Unprocessed cereal brans have a limited shelf-life and contain anti-nutrient phytochemicals. In the present study, lipids and antinutrients (flavonoids, tannin, and polyphenol) were removed from finger millet, kodo millet and rice bran using chemo-enzymatic processing. The thus-obtained modified cereal brans (MCBs) were evaluated for their potential in preventing high fat diet (HFD)-induced obesity. C57BL/6 mice were fed a HFD or a HFD supplemented with 10% w/w modified finger millet bran (mFMB), modified kodo millet bran (mKMB), modified rice bran (mRB), or a combination of the modified brans (1 : 1 : 1) for twelve weeks. The MCBs reduced HFD-induced body weight gain, improved glucose homeostasis, decreased the Firmicutes/Bacteroidetes ratio, and increased the short chain fatty acid (SCFA) levels in the cecum. Liver dyslipidemia, oxidative stress, inflammation, visceral white adipose tissue (vWAT) hypertrophy, and lipolysis were also prevented by the MCBs. Among the individual MCBs, mRB showed a greater effect in preventing HFD-induced increase in the inflammatory cytokines (IL-6, TNF-α, and LPS) than mFMB and mKMB. mFMB and mKMB supplementation more significantly restored the relative abundance of Akkermansia muciniphila and butyrate-producing genera such as Lachnospiraceae, Eubacterium, and Ruminococcus than mRB. Ex vivo gut permeability assay, immunohistochemistry of tight junction proteins, and gene expression analysis in the colon revealed that the combination of three brans was better in preventing HFD-induced leaky gut in comparison to the individual brans. Hierarchical clustering analysis showed that the combination group was clustered closest to the NPD group, suggesting an additive effect. Our study implies that a combination of mFMB, mKMB, and mRB could be used as a nutraceutical or functional food ingredient for preventing HFD-induced gut derangements and associated metabolic complications.

Influence of Lactobacillus (LAB) Fermentation on the Enhancement of Branched Chain Amino Acids and Antioxidant Properties in Bran among Wheat By-Products

The main objective of this study was to enhance the nutritional properties, including branched chain amino acids (BCAAs), through the solid-state fermentation (SSF) of wheat bran (WB) using lactic acid bacteria (LAB). The physicochemical properties, amino acid profiles, bioactive components, and antioxidant properties of raw and sterilized WB were compared with those of WB fermented with five different LAB strains. The highest level of BCAAs, isoleucine (Ile; 2.557 ± 0.05 mg/100 g), leucine (Leu; 7.703 ± 0.40 mg/100 g), and valine (Val; 7.207 ± 0.37 mg/100 g), was displayed in the WB fermented with Lactobacillus acidophilus (L.A WB). In addition, L.A WB showed the highest amount of total phenolic and flavonoid contents (2.80 mg GAE/g and 1.01 mg CE/g, respectively), and the highest Trolox equivalent antioxidant capacity (9.88 mM TE/g). Statistical analysis clearly revealed that L.A WB presented the highest abundance of branched chain amino acids as well as bioactive components. Overall, this study distinctly implemented the possibility of fermented WB with enhanced BCAAs for application in future functional food through experimental and statistical observations.

Production of lactic acid from pasta wastes using a biorefinery approach

A total of 398 kt of pasta waste (PW), generated during the production process of pasta, were produced in 2021. Due to its chemical composition and practically zero cost, PW has already been studied as a raw material for the production of lactic acid (LA) through fermentations. The main objective of this article was to improve the economic viability of the process by replacing commercial enzymes, necessary for starch hydrolysis in PW, with raw enzymes also produced from wastes. Enzyme synthesis was achieved through solid-state fermentation (SsF) of wheat bran by Aspergillus awamori or Aspergillus oryzae at various moisture contents. The maximum amylase activity (52 U/g dry solid) was achieved after 2 days of fermentation with A. awamori at 60% of moisture content. After that, the enzymes were used to hydrolyse PW, reaching 76 g/L of total sugars, 65 g/L of glucose and a yield of 0.72 g_glu/g_ds with the enzymes produced by A. awamori. Subsequently, the hydrolysate was fermented into LA using Bacillus coagulans A559, yielding 52 g/L and 49 g/L with and without yeast extract, respectively. Remarkably, compared to the process with commercial enzymes, a higher LA yield was reached when enzymes produced by SsF were added (0.80 g_LA/g_glu). Furthermore, the productivities between the two processes were similar (around 3.9 g/L/h) which highlights that yeast extract is not necessary when using enzymes produced by SsF.

Integrated Technology for Cereal Bran Valorization: Perspectives for a Sustainable Industrial Approach

Current research focuses on improving the bioaccessibility of functional components bound to cereal bran cell walls. The main bioactive components in cereal bran that have major biological activities include phenolic acids, biopeptides, dietary fiber, and novel carbohydrates. Because of the bound form in which these bioactive compounds exist in the bran matrix, their bioaccessibility is limited. This paper aims to comprehensively analyze the functionality of an integrated technology comprising pretreatment techniques applied to bran substrate followed by fermentation bioprocesses to improve the bioaccessibility and bioavailability of the functional components. The integrated technology of specific physical, chemical, and biological pretreatments coupled with fermentation strategies applied to cereal bran previously-pretreated substrate provide a theoretical basis for the high-value utilization of cereal bran and the development of related functional foods and drugs.

Solid-State Fermentation of Sorghum by Aspergillus oryzae and Aspergillus niger: Effects on Tannin Content, Phenolic Profile, and Antioxidant Activity

Sorghum contains antioxidants such as tannins. However, these are considered antinutritional factors since they are responsible for the low digestibility of proteins and carbohydrates. Nevertheless, these can be extracted by solid-state fermentation (SSF). Therefore, this study aimed to evaluate the effects of SSF from Aspergillus oryzae and Aspergillus niger Aa210 on the tannin contents, phenolic profiles determined by HPLC-MS, and antioxidant activities (ABTS, DPPH, and FRAP) of two genotypes of sorghum. The results showed that with SSF by A. niger Aa210, a higher tannin content was obtained, with yields of 70-84% in hydrolyzable tannins (HT) and 33-49% in condensed tannins (CT), while with SSF by A. oryzae the content of HT decreased by 2-3% and that of CT decreased by 6-23%. The extracts fermented by A. niger at 72 and 84 h exhibited a higher antioxidant activity. In the extracts, 21 polyphenols were identified, such as procyanidins, (+)-catechin, (-)-epicatechin, scutellarein, arbutin, and eriodictyol, among others. Therefore, SSF by A. niger was an efficient process for the release of phenolic compounds that can be used as antioxidants in different food products. It is also possible to improve the bioavailability of nutrients in sorghum through SSF. However, more studies are required.

Recent Developments in Fermented Cereals on Nutritional Constituents and Potential Health Benefits

Fermentation is one of the most economical and safe methods to improve the nutritional value, sensory quality and functional characteristics of raw materials, and it is also an important method for cereal processing. This paper reviews the effects of microbial fermentation on cereals, focusing on their nutritional value and health benefits, including the effects of fermentation on the protein, starch, phenolic compounds contents, and other nutrient components of cereals. The bioactive compounds produced by fermented cereals have positive effects on health regulation. Finally, the future market development of fermented cereal products is summarized and prospected.

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

Three medicinal fungi were used to carry out solid-state fermentation (SSF) of wheat bran. The results showed that the use of these fungi for SSF significantly improved wheat bran’s nutritional properties including the extraction yield of soluble dietary fiber (SDF), total phenolic content (TPC), total flavonoid content (TFC), physical properties containing swelling capacity (SC) and oil absorption capacity (OAC), as well as antioxidant activities. Electronic nose and GC–MS analyses showed that fermented wheat bran had different volatiles profiles compared to unfermented wheat bran. The results suggest that SSF by medicinal fungi is a promising way for the high-value utilization of wheat bran.

Sustainable Applications for the Valorization of Cereal Processing By-Products

This review article revises the sustainable practices and applications to valorize valuable components recovered from cereal processing by-products. After introducing cereal processing by-products, their healthy compounds, and corresponding functional properties, the article explores reutilization opportunities of by-products emphasizing specific sources (e.g., oat and wheat bran, distillers' dried grains, etc.) and the biorefinery approach. Proteins and soluble dietary fibers such as arabinoxylans are of particular interest due to their content in the cereal processing by-products and their easy extraction based on conventional technologies such as enzyme-assisted extraction and membrane filtration. Non-thermal technologies have also been suggested to improve sustainability recovery approaches. Finally, the article discusses the different applications for the recovered high-added value compounds that span across biotechnology, foods, and bakery products.

Wheat Bran Modifications for Enhanced Nutrition and Functionality in Selected Food Products

The established use of wheat bran (WB) as a food ingredient is related to the nutritional components locked in its dietary fibre. Concurrently, the technological impairment it poses has impeded its use in product formulations. For over two decades, several modifications have been investigated to combat this problem. Ninety-three (93) studies (review and original research) published in English between January 1997 and April 2021 reporting WB modifications for improved nutritional, structural, and functional properties and prospective utilisation in food formulations were included in this paper. The modification methods include mechanical (milling), bioprocessing (enzymatic hydrolysis and fermentation with yeasts and bacteria), and thermal (dry heat, extrusion, autoclaving), treatments. This review condenses the current knowledge on the single and combined impact of various WB pre-treatments on its antioxidant profile, fibre solubilisation, hydration properties, microstructure, chemical properties, and technological properties. The use of modified WB in gluten-free, baked, and other food products was reviewed and possible gaps for future research are proposed. The application of modified WB will have broader application prospects in food formulations.