Eurotium Cristatum Fermented Okara as a Potential Food Ingredient to Combat Diabetes

Metabolomics analysis of okara probiotic beverages fermented with Lactobacillus gasseri and Limosilactobacillus fermentum by LC-QTOF-MS/MS

In this study, okara was fermented with probiotic strains Lactobacillus gasseri LAC 343 and Limosilactobacillus fermentum PCC, respectively. Significant increases in cell count (by 2.22 log CFU/mL for LAC and 0.82 log CFU/mL for PCC) and significant decreases in pH (by 1.31 for LAC and 1.03 for PCC) were found in fermented okara slurry. In addition, strain LAC tended to produce amino acids, while strain PCC depleted most amino acids. An untargeted metabolomic-based approach using liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was used to further understand the compositional changes and potential health benefits by identifying bioactive metabolites in fermented okara slurry. We successfully identified various beneficial bioactive compounds including γ-aminobutyric acid, indolelactic acid, d-phenyllactic acid, and p-hydroxyphenyllactic acid which had differences in fold-changes in okara slurry fermented with different strains. Our study indicated the feasibility of using probiotics to ferment okara for novel functional food development.

Valorization and food applications of okara (soybean residue): A concurrent review

Agriculture waste is rising continuously across the globe due to enormous industrial, food processing, and household activities. Proper valorization of this waste could be a promising source of various essential bioactive and functional ingredients. Okara is a major residue produced as result of soybean processing and has a rich nutritional profile. The nutritional profile of okara is affected by the processing conditions, variety, pre-treatment, post-production treatments, and processing techniques. Owing to the high fibers, lipids, proteins, and bioactive components, it is being used as an essential industrial ingredient in various food processing industries. The prebiotic potential and nutritional profile can be increased by various techniques, that is, enzymatic, chemical, biotransformation, high-pressure microfludization, and fermentation. The prebiotic potential of okara makes it suitable as a therapeutic agent to prevent a variety of metabolic disorders such as diabetes, obesity, hypercholesterolemia, and hyperlipidemia. The current review highlights the structural, nutritional, functional, therapeutic, and industrial applications of okara.

Linoleic acid enrichment of cheese by okara flour and Geotrichum candidum overexpressing Δ12 fatty acid desaturase

BACKGROUND

Mold-ripened cheeses have low levels of unsaturated fatty acids (UFAs). Geotrichum candidum is an adjunct culture for the development of Geotrichum-ripened cheese but has a low ability to produce high levels of UFAs. Δ12 fatty acid desaturase (FADS12) is a pivotal enzyme that converts oleic acid (OA) to linoleic acid (LA) and plays a vital role in UFA biosynthesis. By investigating FADS12 catalytic activity from various species with OA substrates, we found that FADS12 from Mucor circinelloides (McFADS12) had the highest catalytic activity for OA.

RESULTS

In the current study, a plasmid harboring McFADS12 was constructed and overexpressed in G. candidum. Our results showed that LA production increased to 31.1 ± 1.4% in engineered G. candidum - three times higher than that in wild-type G. candidum. To enhance LA production, an exogenous substrate (OA) was supplemented, and the yield of LA was increased to 154 ± 6 mg L^-1 in engineered G. candidum. Engineered G. candidum was used as an adjunct culture for Geotrichum-ripened cheese production. The LA level reached 74.3 ± 5.4 g kg^-1 cheese, whereas the level of saturated fatty acids (SFAs) decreased by 9.9 ± 0.5%. In addition, the soybean byproduct (okara) was introduced into the engineered G. candidum growth and the level of LA increased to 126 ± 4 g kg^-1 cheese and the percentage of UFAs:SFAs increased from 0.8:1 to 1.3:1.

CONCLUSION

This study offers a suitable technology for converting SFAs to UFAs in Geotrichum-ripened cheeses and provides a novel trend for converting soybean waste into a value-added product. © 2022 Society of Chemical Industry.

Ammonia Production Using Bacteria and Yeast toward a Sustainable Society

Ammonia is an important chemical that is widely used in fertilizer applications as well as in the steel, chemical, textile, and pharmaceutical industries, which has attracted attention as a potential fuel. Thus, approaches to achieve sustainable ammonia production have attracted considerable attention. In particular, biological approaches are important for achieving a sustainable society because they can produce ammonia under mild conditions with minimal environmental impact compared with chemical methods. For example, nitrogen fixation by nitrogenase in heterogeneous hosts and ammonia production from food waste using microorganisms have been developed. In addition, crop production using nitrogen-fixing bacteria has been considered as a potential approach to achieving a sustainable ammonia economy. This review describes previous research on biological ammonia production and provides insights into achieving a sustainable society.

Overexpression of llm1 Affects the Synthesis of Secondary Metabolites of Aspergillus cristatus

Putative methyltransferases are thought to be involved in the regulation of secondary metabolites in filamentous fungi. Here, we report the effects of overexpression of a predicted LaeA-like methyltransferase gene llm1 on the synthesis of secondary metabolites in Aspergillus cristatus. Our results revealed that overexpression of the gene llm1 in A. cristatus significantly hindered the production of conidia and enhanced sexual development, and reduced oxidative tolerance to hydrogen peroxide. Compared with the wild-type, the metabolic profile of the overexpression transformant was distinct, and the contents of multiple secondary metabolites were markedly increased, mainly including terpenoids and flavonoids, such as (S)-olEuropeic acid, gibberellin A62, gibberellin A95, ovalitenone, PD 98059, and 1-isomangostin. A total of 600 significantly differentially expressed genes (DEGs) were identified utilizing transcriptome sequencing, and the DEGs were predominantly enriched in transmembrane transport and secondary metabolism-related biological processes. In summary, the strategy of overexpressing global secondary metabolite regulators successfully activated the expression of secondary metabolite gene clusters, and the numerous secondary metabolites were greatly strengthened in A. cristatus. This study provides new insights into the in-depth exploitation and utilization of novel secondary metabolites of A. cristatus.

Utilization of fermented and enzymatically hydrolyzed soy press cake as ingredient for meat analogues

The aim of the present study was to improve the properties of soy press cake to be utilized as an ingredient of meat analogues. Soy press cakes were fermented with lactobacillus strains, and separately hydrolyzed by cellulase/xylanase mixture and α-amylase. Meat analogues were produced with 10% fermented or hydrolyzed soy press cakes. The effect of applied processes on protein oxidation, physical and functional properties of soy press cakes were analyzed, as well as sensory and textural properties of meat analogues. The results indicated that soy press cake was a suitable source of fibre and energy with low content of saturated fatty acids, and provided plant-based proteins and essential amino acids. The study demonstrated the potential of lactic acid fermentation, and enzymatic hydrolysis to improve water- and oil-holding capacity and reduce protein oxidation in soy press cakes. L. acidophilus 336 and cellulase/xylanase mixture were recommended for fermentation and hydrolysis of soy press cakes, respectively, regarding reduction of protein oxidation. Fermentation of soy press cakes with L. plantarum P1 improved the texture of meat analogues. Press cakes fermentation reduced bitterness, increased juiciness, and balanced the taste of meat analogues. Fermented soy press cake was recommended for the production of meat analogues.

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This research was the 1st application of fermented soy press cake in meat analogue.

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Fermentation and hydrolysis improved the functional properties of soy press cakes.

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Protein oxidation in soy press cakes was reduced after fermentation and hydrolysis.

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Fermented soy press cakes improved sensory quality of the meat analogues.

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L. plantarum P1 is recommended for the fermentation of soy press cakes.

Micronized Dietary Okara Fiber: Characterization, Antioxidant, Antihyperglycemic, Antihyperlipidemic, and Pancreato-Protective Effects in High Fat Diet/Streptozotocin-Induced Diabetes Mellitus

Diabetes mellitus (DM) is a lifelong devastating and debilitating disease with serious chronic complications. Okara is a byproduct generated from soymilk or tofu production and it has been reported to have antioxidant and lipid-lowering effects. However, the antidiabetic effects and pancreatic β-cells' secretory functions of micronized okara fiber (MOF) have not been reported. Therefore, this study explored the antidiabetic effects and modulatory potentials of MOF on pancreatic β-cells' secretory functions in a high fat/high sugar/streptozotocin rat model of diabetes mellitus. Fiber-rich okara was prepared by removing fat and proteins from freshly obtained okara, followed by micronization. Fiber-rich okara was prepared, micronized, and characterized for hydrophobicity, thermal stability, structure-function relationship, and antioxidant potentials. We then established a rat model of DM and MOF and two doses (100 and 400 mg kg^-1) were administered to see its anti-DM effect. Four weeks of MOF supplementation significantly reduced blood glucose, increased serum insulin level, improved hepatorenal functions, glucose tolerance, and regenerated pancreatic β-cells in the treated DM rats. Furthermore, MOF significantly improved the pancreatic antioxidant defense system by significantly elevating glutathione peroxidase, catalase, and superoxide dismutase activities while depleting the malonaldehyde level in the pancreas of the treated diabetic rats. Our results indicated that MOF ameliorated DM by impeding hyperglycemia, hyperlipidemia, and oxidative stress and enhancing the secretory functions of the beta cells, suggesting that MOF might be used as a protective nutrient in DM.

Effects of an Iranian traditional fermented food consumption on blood glucose, blood pressure, and lipid profile in type 2 diabetes: a randomized controlled clinical trial

BACKGROUND

Ash-Kardeh is one of the few fermented foods without a dairy base in Iran, which is traditionally prepared from cereals and plants in the presence of microorganisms (mainly lactic acid bacteria).

PURPOSE

This study aimed to assess the effects of Ash-Kardeh consumption on blood glucose, lipid profile, and blood pressure in type 2 diabetic patients.

METHODS

Forty-six patients with type 2 diabetes were studied in this randomized controlled clinical trial. Subjects were randomly allocated into intervention (n = 23) and control (n = 23) groups. Individuals of both groups received the usual treatment of diabetic patients, while those in the intervention group, in addition to the usual treatment, received 250 g of Ash-Kardeh daily for 6 weeks. Fasting blood glucose, blood pressure, and lipid profiles were measured before and after the intervention.

RESULTS

Compared to the control group, Ash-Kardeh consumption led to a significant decrease in fasting blood glucose (P = 0.003), total cholesterol (P = 0.025), triglyceride (P = 0.003), systolic (P < 0.001), and diastolic blood pressure (P = 0.014) in the intervention group. Also, a significant increase in the concentrations of high-density lipoprotein cholesterol (P = 0.048) was observed after Ash-Kardeh consumption.

CONCLUSION

It seems that Ash-Kardeh consumption could improve high blood glucose, lipid profile, and hypertension in type 2 diabetic patients but does not affect low-density lipoprotein cholesterol concentrations. This study was registered on 2019-09-15 in the Iranian Registry of Clinical Trials ( www.irct.ir ) with the code number IRCT20170202032367N3.

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

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

Solid-State Fermented Okara with Aspergillus spp. Improves Lipid Metabolism and High-Fat Diet Induced Obesity

Okara is a major by-product of soymilk and tofu production. Despite retaining abundant nutrients after the process, okara is often under-utilized. In this study, solid-state fermentation (SSF) of okara was carried out using a koji starter (containing both Aspergillus oryzae and Aspergillus sojae) with the intention of releasing its untapped nutrients. Its effects on lipid metabolism in diet-induced obesity (DIO) were observed. The nutritional profile of fermented okara was elucidated using the following parameters: total phenolic content (TPC), pH, protein content, dietary fiber, amino acid content, and free sugar content. In vivo experiments were conducted using high-fat diets supplemented with unfermented okara and fermented okara over three weeks. Supplementation with fermented okara reduced body weight gain, adipose tissue weight, the serum triglyceride profile, and lipid accumulation in the liver, and altered the mRNA expression levels related to lipid metabolism; however, it did not affect pH and short-chain fatty acid (SCFA) production in this study. In conclusion, high-fat diets supplemented using okara fermented with Aspergillus spp. improved the lipid metabolism in mice, due to their high nutritional value, such as TPC, soy protein, and amino acids, and their synergistic effects without altering the gut microbiota.

Sustainable Biological Ammonia Production towards a Carbon-Free Society

A sustainable society was proposed more than 50 years ago. However, it is yet to be realised. For example, the production of ammonia, an important chemical widely used in the agriculture, steel, chemical, textile, and pharmaceutical industries, still depends on fossil fuels. Recently, biological approaches to achieve sustainable ammonia production have been gaining attention. Moreover, unlike chemical methods, biological approaches have a lesser environmental impact because ammonia can be produced under mild conditions of normal temperature and pressure. Therefore, in previous studies, nitrogen fixation by nitrogenase, including enzymatic ammonia production using food waste, has been attempted. Additionally, the production of crops using nitrogen-fixing bacteria has been implemented in the industry as one of the most promising approaches to achieving a sustainable ammonia economy. Thus, in this review, we described previous studies on biological ammonia production and showed the prospects for realising a sustainable society.

Metabolomics as a Tool to Study Underused Soy Parts: In Search of Bioactive Compounds

The valorization of agri-food by-products is essential from both economic and sustainability perspectives. The large quantity of such materials causes problems for the environment; however, they can also generate new valuable ingredients and products which promote beneficial effects on human health. It is estimated that soybean production, the major oilseed crop worldwide, will leave about 597 million metric tons of branches, leaves, pods, and roots on the ground post-harvesting in 2020/21. An alternative for the use of soy-related by-products arises from the several bioactive compounds found in this plant. Metabolomics studies have already identified isoflavonoids, saponins, and organic and fatty acids, among other metabolites, in all soy organs. The present review aims to show the application of metabolomics for identifying high-added-value compounds in underused parts of the soy plant, listing the main bioactive metabolites identified up to now, as well as the factors affecting their production.

Prebiotic Impacts of Soybean Residue (Okara) on Eubiosis/Dysbiosis Condition of the Gut and the Possible Effects on Liver and Kidney Functions

Okara is a white-yellow fibrous residue consisting of the insoluble fraction of the soybean seeds remaining after extraction of the aqueous fraction during the production of tofu and soymilk, and is generally considered a waste product. It is packed with a significant number of proteins, isoflavones, soluble and insoluble fibers, soyasaponins, and other mineral elements, which are all attributed with health merits. With the increasing production of soy beverages, huge quantities of this by-product are produced annually, which poses significant disposal problems and financial issues for producers. Extensive studies have been done on the biological activities, nutritional values, and chemical composition of okara as well as its potential utilization. Owing to its peculiar rich fiber composition and low cost of production, okara might be potentially useful in the food industry as a functional ingredient or good raw material and could be used as a dietary supplement to prevent varied ailments such as prevention of diabetes, hyperlipidemia, obesity, as well as to stimulate the growth of intestinal microbes and production of microbe-derived metabolites (xenometabolites), since gut dysbiosis (imbalanced microbiota) has been implicated in the progression of several complex diseases. This review seeks to compile scientific research on the bioactive compounds in soybean residue (okara) and discuss the possible prebiotic impact of this fiber-rich residue as a functional diet on eubiosis/dysbiosis condition of the gut, as well as the consequential influence on liver and kidney functions, to facilitate a detailed knowledge base for further exploration, implementation, and development.

Inhibitory Effects of Eurotium cristatum on Growth and Aflatoxin B1 Biosynthesis in Aspergillus flavus

Probiotic strain Eurotium cristatum was isolated from Chinese Fuzhuan brick-tea and tested for its in vitro activity against aflatoxigenic Aspergillus flavus. Results indicated that E. cristatum can inhibit the radial growth of A. flavus. Furthermore, this inhibition might be caused by E. cristatum secondary metabolites. The ability of culture filtrate of strain E. cristatum against growth and aflatoxin B₁ production by toxigenic A. flavus was evaluated in vitro. Meanwhile, the influence of filtrate on spore morphology of A. flavus was analyzed by scanning electron microscopy (SEM). Results demonstrated that both radial growth of A. flavus and aflatoxin B₁ production were significantly weakened following increases in the E. cristatum culture filtrate concentration. In addition, SEM showed that the culture filtrate seriously damaged hyphae morphology. Gas chromatography mass spectrometry (GC/MS) analysis of the E. cristatum culture supernatant revealed the presence of multiple antifungal compounds. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis showed that the expression of aflatoxin biosynthesis-related genes (aflD, aflQ, and aflS) were down-regulated. Importantly, this latter occurrence resulted in a reduction of the AflS/AflR ratio. Interestingly, cell-free supernatants of E. cristatum facilitated the effective degradation of aflatoxin B₁. In addition, two degradation products of aflatoxin B₁ lacking the toxic and carcinogenic lactone ring were identified. A toxicity study on the HepG2 cells showed that the degradation compounds were less toxic when compared with AFB₁.