Impact of Lactobacillus plantarum 423 fermentation on the antioxidant activity and flavor properties of rice bran and wheat bran

A further understanding of changes of wheat bran functionality induced by different types of probiotics fermentation: From molecules to regulation mechanism

Wheat bran (WB) was solid-state fermented by either Lacticaseibacillus rhamnosus (LGG), Levilactobacillus brevis (LB) or Lactiplantibacillus plantarum (LP), respectively, and then their corresponding physicochemical and metabolic characteristics were investigated. Current study revealed fermentation of either Lacticaseibacillus rhamnosus or Lactiplantibacillus plantarum quickly generated lactic acid, but not for Levilactobacillus brevis. Importantly, all LAB fermentation promoted total phenolic acids contents, fermentation of LB-WB led to the greatest total phenolic content, followed by LGG-WB, with the least for LP-WB. Moreover, LGG fermentation significantly increased levels of oleic acid, stearic acid and phosphoenolpyruvic acid on carbon metabolism and fatty acid biosynthesis, while LB fermentation mainly increased levels of L-phenylalanine, cholecalciferol, D-gluconic acid and D-glucarate with the influence on the entire metabolic pathway. In contrast, LP fermentation significantly decreased levels of alpha-ketoglutaric acid, cis-aconitic acid on the citrate cycle (TCA cycle). This study revealed their corresponding metabolic characteristics, which might highlight potentially individual nutritional aspects.

Enhanced resistance of Lactiplantibacillus plantarum by expression of albumin

BACKGROUND

Human serum albumin (HSA) is the most abundant protein in plasma, playing crucial roles in regulating osmotic pressure and maintaining protein homeostasis. It is widely applied in the clinical treatment of various diseases. HSA can be purified from plasma or produced using recombinant DNA technology. Due to the improved efficiency and reduced costs, a growing body of research has focused on enhancing albumin production through bacterial strain overexpression. However, there have been few studies on the effect of albumin on the characteristics of the overexpressing-strain itself, particularly stress resistance. In this study, we utilized Lactiplantibacillus plantarum (L. plantarum) AR113 as the expression host and successfully constructed the albumin overexpression strain AR113-pLLY01 through gene editing technology. The successful expression of albumin was achieved and subsequently compared with the wild-type strain AR113-pIB184.

RESULTS

The results demonstrated that the survival rate of AR113-pLLY01 was also significantly better than that of AR113-pIB184 after lyophilization. In addition, AR113-pLLY01 exhibited a significantly better protective effect than AR113-pIB184 at pH 3, indicating that albumin possesses a certain tolerance to acidic stress. At bile salt concentrations higher than 0.03%, both strains showed limited growth, but at a concentration of 0.02%, AR113-pLLY01 had a significant protective effect.

CONCLUSION

This study suggest that albumin can improve strain tolerance, which has significant implications for future applications. © 2024 Society of Chemical Industry.

Combined treatment of rice bran by solid-state fermentation and extrusion: Effect of processing sequence and microbial strains

Solid-state fermentation (SSF) and extrusion are effective methods to improve the nutritional and sensory quality of rice bran. The effect of the processing sequence of SSF and extrusion and microbial strains on the quality of rice bran was studied. The results showed that the first SSF followed by extrusion increased the contents of phenolic, flavonoid and γ-oryzanol, but the color changed to brown. The first extrusion followed by SSF caused damage to bioactive components and antioxidant activity, but significantly increased the content of arabinoxylans. The difference between the two processing sequences may be related to the process time and the effect of substrate on microbial induction. Aspergillus oryzae and Neurospora sitophila were suitable for increasing the bioactive components of rice bran, while Lactiplantibacillus plantarum was suitable for increasing water-extractable arabinoxylan content. Different processing sequences and microbial strains have their advantages, and these results can provide reference for rice bran processing.

The Impact of Fermentation on the Antioxidant Activity of Food Products

From ancient times to the present day, fermentation has been utilized not only for food preservation but also for enhancing the nutritional and functional properties of foods. This process is influenced by numerous factors, including the type of microorganisms used, substrate composition, pH, time, and temperature, all of which can significantly alter the characteristics of the final product. Depending on the parameters, fermentation enhances the bioactive content of the products and imparts the necessary properties, such as antioxidant characteristics, for the products to be considered functional. The enhancement of these properties, particularly antioxidant activity, enriches foods with bioactive compounds and functional attributes, contributing to improved health benefits. Through a review of recent research, this study elucidates how different fermentation processes can enhance the bioavailability and efficacy of antioxidants, thereby improving the nutritional and functional qualities of foods. This study investigated the multifaceted effects of fermentation on antioxidant properties by exploring various types and conditions of fermentation. It highlights specific examples from dairy products and other food categories as well as the valorization of food waste and byproducts. The findings underscore the potential of fermentation as a sustainable method to produce health-promoting foods with elevated antioxidant activities, offering new perspectives for food science and technology.

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.

Antioxidative Potential and Ameliorative Effects of Rice Bran Fermented with Lactobacillus against High-Fat Diet-Induced Oxidative Stress in Mice

Rice bran is an important byproduct of the rice polishing process, rich in nutrients, but it is underutilized and often used as feed or discarded, resulting in a huge amount of waste. In this study, rice bran was fermented by Lactobacillus fermentum MF423 to obtain a product with high antioxidant activity. First, a reliable and efficient method for assessing the antioxidant capacity of the fermentation products was established using high-performance liquid chromatography (HPLC), which ensured the consistency of the batch fermentation. The fermented rice bran product (FLRB) exhibited significant antioxidant activity in cells, C. elegans, and hyperlipidemic mice. Transcriptome analysis of mouse livers showed that the expression of plin5 was upregulated in diabetic mice administered FLRB, thereby preventing the excessive production of free fatty acids (FFAs) and the subsequent generation of large amounts of reactive oxygen species (ROS). These studies lay the foundation for the application of rice bran fermentation products.

Co-culture fermentation by Saccharomycopsis fibuligera and lactic acid bacteria improves bioactivity and aroma profile of wheat bran and the bran-containing Chinese steamed bread

Co-culture fermentation with yeast and lactic acid bacteria (LAB) exhibits advantages in improving the bioactivity and flavor of wheat bran compared to single-culture fermentation, showing application potentials in bran-containing Chinese steamed bread (CSB). To explore the effects of combination of yeast and different LAB on the bioactivity and flavor of fermented wheat bran, this study analyzed the physicochemical properties, phytate degradation capacity, antioxidant activities, and aroma profile of wheat bran treated with co-culture fermentation by Saccharomycopsis fibuligera and eight different species of LAB. Further, the phenolic acid composition, antioxidant activities, texture properties, aroma profile, and sensory quality of CSB containing fermented wheat bran were evaluated. The results revealed that co-culture fermentation brought about three types of volatile characteristics for wheat bran, including ester-feature, alcohol and acid-feature, and phenol-feature, and the representative strain combinations for these characteristics were S. fibuligera with Limosilactobacillus fermentum, Pediococcus pentosaceus, and Latilactobacillus curvatus, respectively. Co-culture fermentation by S. fibuligera and L. fermentum for 36 h promoted acidification with a phytate degradation rate reaching 51.70 %, and improved the production of volatile ethyl esters with a relative content of 58.47 % in wheat bran. Wheat bran treated with co-culture fermentation by S. fibuligera and L. curvatus for 36 h had high relative content of 4-ethylguaiacol at 52.81 %, and exhibited strong antioxidant activities, with ABTS•+ and DPPH• scavenging rates at 65.87 % and 69.41 %, respectively, and ferric reducing antioxidant power (FRAP) at 37.91 μmol/g. In addition, CSB containing wheat bran treated with co-culture fermentation by S. fibuligera and L. fermentum showed a large specific volume, soft texture, and pleasant aroma, and received high sensory scores. CSB containing wheat bran treated with co-culture fermentation by S. fibuligera and L. curvatus, with high contents of 4-ethylguaiacol, 4-vinylguaiacol, ferulic acid, vanillin, syringaldehyde, and protocatechualdehyde, demonstrated strong antioxidant activities. This study is beneficial to the comprehensive utilization of wheat bran resources and provides novel insights into the enhancement of functions and quality for CSB.

Fermentation of Lactobacillus fermentum NB02 with feruloyl esterase production increases the phenolic compounds content and antioxidant properties of oat bran

In this study, strains producing feruloyl esterase were screened by Oxford Cup clear zones method and by evaluating the ability to decompose hydroxycinnamoyl esters. The strain was identified by 16S rDNA molecular biology. The contents of dietary fiber, reducing sugar, water-extractable arabinoxylans, phytic acid, total phenolics, total flavonoid, phenolic compounds composition, microstructure and antioxidant activity in bran before and after fermentation were studied. Eight strains producing feruloyl esterase were screened, among which strain P1 had the strongest ability to decompose hydroxycinnamoyl esters. The strain was identified and named L. fermentum NB02. Compared with unfermented bran, fermented bran exhibited higher contents of soluble dietary fiber, reducing sugar, water-extractable arabinoxylans, total phenolics, total flavonoid, and lower insoluble dietary fiber and phytic acid content. The dense surface structure of bran was destroyed, forming a porous structure. The release of phenolic compounds increased significantly. L. fermentum NB02 fermentation improved the antioxidant capacity of bran.

Effects of rice bran rancidity on the release of phenolics and antioxidative properties of rice bran dietary fiber in vitro gastrointestinal digestion products

Rice bran (RB) as the raw material for rice bran dietary fiber (RBDF) extraction, is rapidly rancidified prior to stabilization. To enhance the RBDF utilization in food industry, effects of RB rancidity (RB was stored for 0, 1, 5, 7, and 10 d) on the bioaccessibility and bioavailability of RBDF-bound phenolics were investigated. With the increase in RB storage time, the RB rancidity degree significantly increased (the acid value of rice bran oil from 5.08 mg KOH/g to 60.59 mg KOH/g), and the endogenous phenolics content in RBDF also increased. Simultaneously, RB rancidity reduced the antioxidant activity of RBDF digestion products during the gastric digestion phase, while RB rancidity increased the antioxidant activity of RBDF digestion products during the intestinal digestion phase. In addition, in vitro gastrointestinal digestion stimulated the release of RBDF-bound phenolics. The released monomeric phenolics (especially ferulic acid and p-coumaric acid) were the major contributors to the increased antioxidant properties of RBDF digestion products. RBDF digestion products could inhibit H2O2-induced oxidative stress and apoptosis of HUVECs. In conclusion, the study found that RB rancidity could improve the antioxidant capacity of RBDF in the small intestine by promoting RB endogenous phenolics bound to RBDF release.

Evaluation of co-fermentation of L. plantarum and P. kluyveri of a plant-based fermented beverage: Physicochemical, functional, and sensory properties

In this study, Pichia kluyveri (P. kluyveri) and Lactobacillus plantarum (L. plantarum) were sequentially inoculated into a plant-based beverage consisting of bananas, broccoli, and wolfberries. The physicochemical characteristics, functional components, and taste of it at different stages were determined. After 8-d fermentation, the viable counts of P. kluyveri and L. plantarum were 6.50 log CFU/mL and 8.43 log CFU/mL, respectively. The ethanol was <0.5 % (v/v). Compared with control group, the superoxide dismutase (SOD) activity increased by 96.08 folds and total phenolics content increased by 1.09 folds. The contents of lactic acid, protocatechuic acid, and chlorogenic acid exhibited an upgrade trend, whereas the contents of caffeic acid and malic acid presented a downward tendency. Some organic acids had positive correlations with sensory quality, especially sourness. In addition, the γ-amino butyric acid (GABA) concentration and antioxidant activity were also improved during fermentation. Results showed the nutritional functional properties and sensory quality of this beverage could be improved through co-fermentation of P. kluyveri and L. plantarum.

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.

Effect of fermented heat-treated rice bran on performance and possible role of intestinal microbiota in laying hens

Rice bran is a high-quality and renewable livestock feed material rich in nutrients and bioactive substances. To investigate the effects of dietary supplementation with fermented heat-treated rice bran on the performance, apparent digestibility of nutrients, cecal microbiota and metabolites in laying hens, a total of 128 18-week-old Hy-Line brown layers were randomly assigned to four treatment groups: 2.5% HRB (basal diet contained 2.5% heat-treated rice bran), 5.0% HRB (5.0% heat-treated rice bran), 2.5% FHRB (2.5% fermented heat-treated rice bran), 5.0% FHRB (5.0% fermented heat-treated rice bran). Results showed that FHRB supplementation significantly increased the average daily feed intake (ADFI) during 25-28 weeks, and improved apparent digestibility of dry matter (DM), crude protein (CP), ether extract (EE) and crude fiber (CF) in laying hens. Moreover, feeding 5.0% of HRB and FHRB resulted higher egg production (EP) and average egg weight (AEW) during the feeding period, and decreased the feed conversion ratio (FCR) during 21 to 28 weeks. The alpha and beta diversity indices indicated that FHRB altered the cecal microbiota. In particular, dietary supplementation with FHRB significantly increased the relative abundances of Lachnospira and Clostridium. Compared with the 2.5% level of supplementation, supplementing 5.0% HRB and 5.0% FHRB increased the relative abundances of Firmicutes, Ruminococcus and Peptococcus, and lowered the relative abundance of Actinobacteria. Furthermore, dietary FHRB supplementation significantly increased the concentration of short-chain fatty acids in cecum and changed the overall metabolome. The results of correlation analysis showed a close interaction between cecal microbiota, metabolites and apparent digestibility of nutrients. Taken together, we revealed that FHRB supplementation can induce characteristic structural and metabolic changes in the cecal microbiome, which could potentially promote nutrient digestion and absorption, and improve the production performance of laying hens.

Impact of Lactobacillus apis on the antioxidant activity, phytic acid degradation, nutraceutical value and flavor properties of fermented wheat bran, compared to Saccharomyces cerevisiae and Lactobacillus plantarum

This study aimed to use a novel Lactobacillus strain (L. apis) isolated from the bee gut to develop a wheat bran (WB) deep-processing technology. Compared to the most popular strains (S. cerevisiae and L. plantarum), we found that L. apis had a greater ability to enhance the fermented WB antioxidant activity through hydroxyl radical scavenging, metal chelating ability, reducing power, and ferric reducing antioxidant power. While L. apis and L. plantarum had similar effects on DPPH^• and ABTS^•+ scavenging activities. This improvement in antioxidant activity has been associated with some metabolic compounds, such as sinapic acid, hydroferulic acid, pyruvic acid, neocostose, oxalic acid, salicylic acid, and schaftoside. Furthermore, L. apis degraded 48.33% of the phytic acid in WB, higher than S. cerevisiae (26.73%) and L. plantarum (35.89%). All strains improved the volatile profile of WB, and the fermented WB by each strain displayed a unique volatile composition. L. apis increased the level of conditional amino acids and branched-chain amino acids significantly. S. cerevisiae increased γ-aminobutyric acid the most, from 230.8 mg/L in unfermented samples to 609.8 mg/L in the fermented WB. While L. apis and L. plantarum also increased the level of γ-aminobutyric acid to 384.5 mg/L and 295.04 mg/L, respectively. Finally, we found that L. apis remarkably increased the content of organic acids and water-soluble vitamins in wheat bran.

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.

Non-Dairy Fermented Beverages Produced with Functional Lactic Acid Bacteria

At present, there is an increasing interest in beverages of non-dairy origin, as alternatives to those based on milk, but having similar health-promoting properties. Fermentation with specific bacteria or consortia may enhance the functionality of these products. In our study, selected lactic acid bacteria, that have been previously shown to possess functional properties (antimicrobial activity, probiotic potential), were used for the fermentation of wheat bran combined with root vegetables. Strains were investigated for their safety, while the obtained beverages were characterized in terms of microbial content, physical, chemical, nutritional, and functional properties. None of the strains harbors virulence genes, but all of them possess genes for survival at low pH, starch metabolism, and vitamin biosynthesis. Three strains (Lactiplantibacillus plantarum BR9, L. plantarum P35, and Lactobacillus acidophilus IBB801) and two substrates (5% wheat bran with 10% red beetroot/carrots) were selected based on a preliminary assessment of the beverage's sensory acceptability. These strains showed good growth and stability over time in the stored beverages. No enterobacteria were detected at the end of fermentations, while the final pH was, in most cases, below 3.5. Free phenolics, flavonoids, and DPPH scavenging effect increased during fermentation in all drinks, reaching 24h values that were much higher than in the unfermented substrates. Most of the obtained drinks were able to prevent the growth of certain pathogens, including Listeria monocytogenes ATCC 19111, Salmonella enterica ATCC 14028, Staphylococcus aureus ATCC 25923, and Escherichia coli ATCC 25922. The obtained beverages would combine the nutritiveness of the raw ingredients with the beneficial effect of fermentation (increasing shelf life, health-promoting effect, pleasant flavor, etc.). They would also fill a gap in the non-dairy probiotics sector, which is constantly increasing due to the increasing number of vegan people or people that cannot consume dairy products.

Prebiotic, Antipathogenic Bacteria and Hypocholesterolemia Properties of Fermented Rice Bran Extracts Derived from Black Rice and Germinated Brown Rice

Rice bran is a rich source of health-promoting nutrition and bioactive compounds; nevertheless, the properties of rice brans depend on cultivars, ages, and preparation methods, drawing the potential of raw materials for health benefits. Therefore, this research aimed to investigate the health-promoting properties of fermented rice bran extracts from cultivar black rice (H7F) and germinated brown rice (G13F), focusing on their prebiotic, antipathogenic bacteria activity and safety demonstrated in vitro and in vivo study models, respectively. Here, the screening of metabolites' change after rice bran fermentation by ATR-FTIR spectra revealed specific peaks corresponding to the composited components of protein, carbohydrate, and lipid. Then, in the in vitro study, the prebiotic capability of H7F and G13F extracts was demonstrated by a growth-promoting effect on Lactobacillus delbrueckii subsp. lactis under specific acidic conditions. Furthermore, antipathogenic bacterial activity against Escherichia coli and Staphylococcus aureus was presented at 25 mg/mL of MIC values and 50 mg/mL of MBC of both fermented rice bran extracts, eliminating the bacteria by interfering with the biofilm formation. For safety, an acute and chronic toxicity study using Wistar rats was conducted, in which changes in the body and organ weights, histopathology of organs, blood chemistry, and hematological parameters were observed after H7F and G13F treatment. Desirably, they showed no toxicity, with a significant reduction in blood cholesterol levels in the chronic treatment of H7F and G13F. Conclusively, the overall results evidenced the health benefits of H7F and G13F related to their prebiotic and antipathogenic bacteria properties and hypocholesterolemia potential with a high level of safety. Therefore, the fermented rice bran extracts were demonstrated as potential materials for the further development of functional ingredients and health products.

Novel processing strategies to enhance the bioaccessibility and bioavailability of functional components in wheat bran

Dietary fiber, polysaccharides and phenols are the representative functional components in wheat bran, which have important nutritional properties and pharmacological effects. However, the most functional components in wheat bran exist in bound form with low bioaccessibility. This paper reviews these functional components, analyzes modification methods, and focuses on novel solid-state fermentation (SSF) strategies in the release of functional components. Mining efficient microbial resources from traditional fermented foods, exploring the law of material exchange between cell populations, and building a stable self-regulation co-culture system are expected to strengthen the SSF process. In addition, emerging biotechnology such as synthetic biology and genome editing are used to transform the mixed fermentation system. Furthermore, combined with the emerging physical-field pretreatment coupled with SSF strategies applied to the modification of wheat bran, which provides a theoretical basis for the high-value utilization of wheat bran and the development of related functional foods and drugs.

The Mechanisms of the Potential Probiotic Lactiplantibacillus plantarum against Cardiovascular Disease and the Recent Developments in its Fermented Foods

Cardiovascular disease (CVD) has become the leading cause of death worldwide. Many recent studies have pointed out that Lactiplantibacillus plantarum (Lb. plantarum) has great potential in reducing the risk of CVD. Lb. plantarum is a kind of lactic acid bacteria (LAB) widely distributed in fermented food and the human intestinal tract, some strains of which have important effects on human health and the potential to be developed into probiotics. In this review, we summarize the mechanism of potential probiotic strains of Lb. plantarum against CVD. It could regulate the body’s metabolism at the molecular, cellular, and population levels, thereby lowering blood glucose and blood lipids, regulating blood pressure, and ultimately reducing the incidence of CVD. Furthermore, since Lb. plantarum is widely utilized in food industry, we highlight some of the most important new developments in fermented food for combating CVD; providing an insight into these fermented foods can assist scientists in improving the quality of these foods as well as alleviating patients’ CVD symptoms. We hope that in the future functional foods fermented by Lb. plantarum can be developed and incorporated into the daily diet to assist medication in alleviating CVD to some extent, and maintaining good health.

Impact of a novel probiotic Lactobacillus strain isolated from the bee gut on GABA content, antioxidant activity, and potential cytotoxic activity against HT-29 cell line of rice bran

Rice bran was fermented with Lactobacillus apis, isolated from the bee gut as a novel probiotic strain, and Saccharomyces cerevisiae to investigate the relationship between its metabolites and antioxidant activity, nutraceutical value, and cytotoxic activity against the HT-29 cell line. The findings showed that L. apis improved the antioxidant activity (DPPH of 37.73%) and antioxidant capacity (ABTS of 37.62 mg Trolox/g,), as well as, hydroxyl radical-scavenging activity (91.55%) of rice bran compared to S. cerevisiae. The metabolic analysis of volatile compounds revealed an increase of alcohols and lactones in the samples fermented with S. cerevisiae. While the samples fermented with L. apis displayed an increase of ketones, esters, and thiazoles. On the other hand, L. apis and S. cerevisiae exhibited a significant ability to increase γ-aminobutyric acid during different fermentation times. Compared with non-fermented samples (18.54%), L. apis increased the cytotoxic activity of rice bran against the HT-29 cell line to 34.17%, and S. cerevisiae to 31.34%. These results suggest that the fermentation of rice bran with S. cerevisiae and L. apis provides a promising strategy to improve the antioxidant activity and nutraceuticals of rice bran, and a potential source for plant-based pharmaceutical products.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-022-05512-2.

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.

Fermentability of Maitake polysaccharides processed by various hydrothermal conditions and fermented with probiotic (Lactobacillus)

Maitake polysaccharides, after hydrothermal processing, were fermented with Lactobacillus acidophilus CCFM202 (L.A.) and Lactobacillus plantarum CCFM6392 (L.P.). The degradation of molecular weight of polysaccharides by hydrothermal processing under acidic conditions was obviously enhanced, which turned part of the water-insoluble-polysaccharides (WIP) into water-soluble-polysaccharides (WSPs). The pH value of water-soluble-polysaccharides (WSPs) and water-insoluble-polysaccharides (WIPs) were intensely dropped (4- 5) after 24 h fermentation. The optical density (O.D.) was increased (1.4- 2.3) due to bacterial growth, and short-chain fatty acids also followed this trend. LA-WSP predominantly produced acetic acid, 3- 4 folds to lactic acid, while LP-WIP groups produced dominant butyric acid (15- 17 folds). Hydrothermal processing induced the growth of L.A. and L.P., where the highest abundance was 2.5 × 10⁴. From the Venn diagram, WSP-1 produced the most elevated metabolites (874). Therefore, experimental results show a significant impact on making WSPs fragments, whereas temperature and pH influence the WSPs degradation, withstand to higher fermentation efficacy.

Dynamics of microbial communities, flavor, and physicochemical properties of pickled chayote during an industrial-scale natural fermentation: Correlation between microorganisms and metabolites

Pickled chayote is a Chinese fermented vegetable with unique flavors and is favored by local consumers. However, little is known about its quality changes and microbial community succession during fermentation and the relationship between microbes and quality. In the work, the physicochemical quality attributes (pH, acidity, nitrite, texture, and color) and flavor properties (sugars, organic acids, free amino acid [FAA], and volatiles) were investigated. The results revealed that organic acids, FAAs, and key volatiles (esters, terpenes, alcohols, and phenols) significantly increased during fermentation. Lactobacillus was the dominant bacterial genus with Lactobacillus alimentarius being the prevalent species; Kazachstania and Pichia were dominant fungal genera with Kazachstania humilis and Pichia membranifaciens being the prevalent species. The microbial metabolic network found that bacteria (L. alimentarius, L. futsaii, and L. paralimentarius) and fungi (K. humilis and P. membranifaciens) played significant roles in the physicochemical changes and flavor production of pickled chayote.

Study on the Enhancement of Antioxidant Properties of Rice Bran Using Mixed-Bacteria Solid-State Fermentation

Rice bran is usually mixed into animal feeds or discarded directly because of its harsh taste and undesirable flavor. Its bioavailability and exploitation are limited. In order to enhance the antioxidant properties of rice bran, the solid-state fermentation of rice bran with mixed bacteria was adopted in addition to the optimization of the fermentation technology. The bioactive constituents of water-soluble extracts and the in vivo antioxidant activity were compared before and after fermentation. The results revealed that the DPPH free radical scavenging rate of the water-soluble rice bran extracts under optimized fermentation technology conditions reached 86.38%, which was a 54.06% increase compared to that of raw materials. The mixed-bacteria solid-state fermentation increased the levels of bioactive constituents, including the polyphenols, flavonoid, protein, uronic acid, mannose, catechinic acid, caffeic acid, and ferulic acid contents. In a zebrafish model, the water-soluble fermented rice bran extracts (FRBE) displayed superior protective effects against 2,2′-azobis (2-methylpropionamidine) dihydrochloride (AAPH)-induced reactive oxygen species (ROS) production, lipid peroxidation, and cell death, and FRBE significantly improved SOD and CAT activity against the induced AAPH. Taken together, mixed-bacteria solid-state fermentation could change the bioactive constituents and enhance the antioxidant activity of water-soluble extracts from rice bran.

Production of flavor compounds from rice bran by yeasts metabolisms of Kluyveromyces marxianus and Debaryomyces hansenii

The aim of this study was to evaluate the biosynthesis of flavor compounds from rice bran by fermentation facilitated by Kluyveromyces marxianus and Debaryomyces hansenii. The growth of both yeasts was assessed by specific growth rates and doubling time. The biosynthesis of flavor compounds was evaluated by gas chromatography-olfactometry (GC-O), gas chromatography-mass spectrometry (GC-MS), and Spectrum™ sensory analysis. The specific growth rate (µ) and doubling time (t_d) of K. marxianus was calculated as 0.16/h and 4.21h, respectively, whereas that of D. hansenii was determined as 0.13/h and 5.33h, respectively. K. marxianus and D. hansenii produced significant levels of higher alcohols and acetate esters from rice bran. Results showed that K. marxianus can produce 827.27 µg/kg of isoamyl alcohol, 169.77 µg/kg of phenyl ethyl alcohol, and 216.08 µg/kg of phenyl ethyl acetate after 24-h batch fermentation. A significant amount of isovaleric acid was also synthesized by K. marxianus (4013 µg/kg) after the batch fermentation of 96 h. 415.64 µg/kg of isoamyl alcohol and 135.77 µg/kg of phenyl ethyl acetate was determined in rice bran fermented by D. hansenii after 24-h fermentation. Fermented cereals and rose were the characteristic flavor descriptors of the fermented rice bran samples. Rose flavor in fermented rice bran samples was found to be associated with phenyl ethyl alcohol, phenyl ethyl acetate, isoamyl acetate, and guaiacol. Thus, the findings of this study demonstrate that the valorization of rice bran can be achieved with the production of natural flavor compounds by yeast metabolism.

The Impacts of Lactiplantibacillus plantarum on the Functional Properties of Fermented Foods: A Review of Current Knowledge

One of the most varied species of lactic acid bacteria is Lactiplantibacillus plantarum (Lb. plantarum), formerly known as Lactobacillus plantarum. It is one of the most common species of bacteria found in foods, probiotics, dairy products, and beverages. Studies related to genomic mapping and gene locations of Lb. plantarum have shown the novel findings of its new strains along with their non-pathogenic or non-antibiotic resistance genes. Safe strains obtained with new technologies are a pioneer in the development of new probiotics and starter cultures for the food industry. However, the safety of Lb. plantarum strains and their bacteriocins should also be confirmed with in vivo studies before being employed as food additives. Many of the Lb. plantarum strains and their bacteriocins are generally safe in terms of antibiotic resistance genes. Thus, they provide a great opportunity for improving the nutritional composition, shelf life, antioxidant activity, flavour properties and antimicrobial activities in the food industry. Moreover, since some Lb. plantarum strains have the ability to reduce undesirable compounds such as aflatoxins, they have potential use in maintaining food safety and preventing food spoilage. This review emphasizes the impacts of Lb. plantarum strains on fermented foods, along with novel approaches to their genomic mapping and safety aspects.

Comparative Effects of L. plantarum CGMCC 1258 and L. reuteri LR1 on Growth Performance, Antioxidant Function, and Intestinal Immunity in Weaned Pigs

Lactobacillus plantarum CGMCC 1258 and Lactobacillus reuteri LR1 are two important strains of probiotics. However, their different advantages in the probiotic effect of weaned pigs are still poorly understood. Therefore, the study was to investigate the comparative effects of dietary supplementation of L. plantarum CGMCC 1258 and L. reuteri LR1 on growth performance, antioxidant function, and intestinal immunity in weaned pigs. Ninety barrows [initial body weight (BW) = 6.10 ± 0.1 kg] 21 days old were randomly divided into 3 treatments with 5 replicates, each replicate containing 6 pigs. Pigs in control (CON) were fed a basal diet, and the basal diets supplemented with 5 × 10¹⁰ CFU/kg L. plantarum CGMCC 1258 (LP) or L. reuteri LR1 (LR) for 42 days, respectively. The results showed that LP increased (p < 0.05) serum superoxide dismutase (SOD), and decreased (p < 0.05) serum malondialdehyde (MDA) and the expression and secretion of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) in intestinal mucosa, but has no significant effect on growth performance and diarrheal incidence. However, LR increased (p < 0.05) final BW and average daily gain (ADG), reduced (p < 0.05) 29–42-day diarrheal incidence, decreased (p < 0.05) the expression and secretion of IL-1β, IL-6, TNF-α, and IFN-γ, and increased (p < 0.05) the expression of transforming growth factor-β (TGF-β) in intestinal mucosa. In addition, the serum glutathione peroxidase (GSH-PX), mRNA relative expression of Na+-K+-2Cl– co-transporter 1 (NKCC1) and cystic fibrosis transmembrane conductance regulator (CFTR) and the content of toll-like relative (TLR2) and TLR4 in the jejunum, and secretory immunoglobulin (sIgA) content of ileal mucosa were higher (p < 0.05) than LP. Collectively, dietary L. plantarum CGMCC 1258 improved intestinal morphology, intestinal permeability, intestinal immunity, and antioxidant function in weaned pigs. Dietary L. reuteri LR1 showed better growth performance, a lower incidence of diarrhea, better intestinal morphology, and a higher extent of immune activation in weaned pigs.

Enhanced exopolysaccharide yield and antioxidant activities of Schizophyllum commune fermented products by the addition of Radix Puerariae

To increase the production of exopolysaccharides (EPS) and expand the application of Schizophyllum commune (S. commune) fermentation liquid, the traditional Chinese medicine Radix Puerariae (RP) with outstanding biological activity was selected as a culture additive to improve the EPS yield and enhance the antioxidant activity of fermented products from S. commune. The effects of three independent factors: A: initial pH (5.0-6.0), B: concentration of RP (10-14 g L-1), and C: inoculum size (8-12%, v/v) on the EPS yield were evaluated. The results of response surface methodology (RSM) showed that the optimal fermentation conditions were: A: 5.40, B: 12.80 g L-1, and C: 10.0%. The optimal yield of EPS was 8.41 ± 0.12 mg mL-1, which showed an insignificant (p > 0.05) difference with the predicted value (8.45 mg mL-1). The fermented supernatants cultured from RP-supplemented medium (SC-RP) or regular medium (SC) were collected for further study. FT-IR analysis of EPS-1 (purified from SC) and EPS-2 (purified from SC-RP) showed that their structures were consistent, indicating that the addition of RP did not affect the structure of schizophyllan (SPG). In addition, compared with SC, the in vitro antioxidant activities of SC-RP were significantly improved with ORAC values and FRAP values increasing by 11.56-fold and 14.69-fold, respectively. There was a significant correlation among the phenolic compounds, flavonoids, and antioxidant activity of SC-RP in this study. Besides, SC-RP was detected to contain more than 25 bioactive ingredients compared with that of SC, which may play a key role in its antioxidant activities. Thus, these results indicated that RP enhanced the yield of SPG and improved the antioxidant activity of the fermented products by S. commune. Accordingly, the fermentation liquid of S. commune with the addition of RP may have potential application in food, cosmetics, and pharmaceutical industries.

Antidiabetic Function of Lactobacillus fermentum MF423-Fermented Rice Bran and Its Effect on Gut Microbiota Structure in Type 2 Diabetic Mice

Rice bran is an industrial byproduct that exerts several bioactivities despite its limited bioavailability. In this study, rice bran fermented with Lactobacillus fermentum MF423 (FLRB) had enhanced antidiabetic effects both in vitro and in vivo. FLRB could increase glucose consumption and decrease lipid accumulation in insulin resistant HepG2 cells. Eight weeks of FLRB treatment significantly reduced the levels of blood glucose and lipids and elevated antioxidant activity in type 2 diabetic mellitus (T2DM) mice. H&E staining revealed alleviation of overt lesions in the livers of FLRB-treated mice. Moreover, high-throughput sequencing showed notable variation in the composition of gut microbiota in FLRB-treated mice, especially for short-chain fatty acids (SCFAs)-producing bacteria such as Dubosiella and Lactobacillus. In conclusion, our results suggested that rice bran fermentation products can modulate the intestinal microbiota and improve T2DM-related biochemical abnormalities, so they can be applied as potential probiotics or dietary supplements.

A centrifugation-based clearing method allows high-throughput acidification and growth-rate measurements in milk

The turbidity of milk prohibits the use of optical density measurements for strain characterizations. This often limits research to laboratory media. Here, we cleared milk through centrifugation to remove insoluble milk solids. This resulted in a clear liquid phase, termed milk serum, in which optical density measurements can be used to track microbial growth until a pH of 5.2 is reached. At pH 5.2 coagulation of the soluble protein occurs, making the medium opaque again. We found that behavior in milk serum was predictive of that in milk for 39 Lactococcus lactis (R² = 0.81) and to a lesser extent for 42 Lactiplantibacillus plantarum (formerly Lactobacillus plantarum; R² = 0.49) strains. Hence, milk serum can be used as an optically clear alternative to milk for comparison of microbial growth and metabolic characteristics. Characterization of the growth rate, specific acidification rate for optical density at a wavelength of 600 nm, and the amount of acid produced per unit of biomass for all these strains in milk serum, showed that almost all strains could grow in milk, with higher specific acidification and growth rates of Lc. lactis strains compared with Lb. plantarum strains. Nondairy Lc. lactis isolates had a lower growth and specific acidification rate than dairy isolates. The amount of acid produced per unit biomass was relatively high and similar for Lc. lactis dairy and nondairy isolates, as opposed to Lb. plantarum isolates. Lactococcus lactis ssp. lactis showed slightly lower growth and acidification rates when compared with ssp. cremoris. For Lc. lactis strains a doubling of the specific acidification rate occurred with a doubling of the maximum growth rate. This relation was not found for Lb. plantarum strains, where the acidification rate remained relatively constant across 39 strains with growth rates ranging from 0.2 h^-1 to 0.3 h^-1. We conclude that milk serum is a valuable alternative to milk for high-throughput strain characterization during milk fermentation.

Rice Bran Fermentation Using Lactiplantibacillus plantarum EM as a Starter and the Potential of the Fermented Rice Bran as a Functional Food

Rice bran was fermented using a functional starter culture of Lactiplantibacillus plantarum EM, which exhibited high cholesterol removal and strong antimicrobial activity. Highest viable cell counts (9.78 log CFU/mL) and strong antimicrobial activity were obtained by fermenting 20% rice bran supplemented with 1% glucose and 3% corn steep liquor (pH 6.0) at 30 °C for 48 h. The fermented rice bran slurry was hot air-dried (55 °C, 16 h) and ground (HFRB). HFRB obtained showed effective cholesterol removal (45-68%) and antimicrobial activities (100-400 AU/mL) against foodborne pathogenic bacteria and food spoilage fungi. Phytate levels were significantly reduced during fermentation by 53% due to the phytase activity of L. plantarum EM, indicating HFRB does not present nutrient deficiency issues. In addition, fermentation significantly improved overall organoleptic quality. Our results indicate that HFRB is a promising functional food candidate. Furthermore, HFRB appears to satisfy consumer demands for a health-promoting food and environmental and legal requirements concerning the re-utilization of biological byproducts.