Solid-state bioconversion of chickpea (Cicer arietinumL.) byRhizopus oligosporusto improve total phenolic content, antioxidant activity and hypoglycemic functionality

Protective Effects of Medicinal Plant-Based Foods against Diabetes: A Review on Pharmacology, Phytochemistry, and Molecular Mechanisms

Diabetes mellitus (DM) comprises a range of metabolic disorders characterized by high blood glucose levels caused by defects in insulin release, insulin action, or both. DM is a widespread condition that affects a substantial portion of the global population, causing high morbidity and mortality rates. The prevalence of this major public health crisis is predicted to increase in the forthcoming years. Although several drugs are available to manage DM, these are associated with adverse side effects, which limits their use. In underdeveloped countries, where such drugs are often costly and not widely available, many people continue to rely on alternative traditional medicine, including medicinal plants. The latter serves as a source of primary healthcare and plant-based foods in many low- and middle-income countries. Interestingly, many of the phytochemicals they contain have been demonstrated to possess antidiabetic activity such as lowering blood glucose levels, stimulating insulin secretion, and alleviating diabetic complications. Therefore, such plants may provide protective effects that could be used in the management of DM. The purpose of this article was to review the medicinal plant-based foods traditionally used for the management of DM, including their therapeutic effects, pharmacologically active phytoconstituents, and antidiabetic mode of action at the molecular level. It also presents future avenues for research in this field.

Effects of in vitro digestion on protein degradation, phenolic compound release, and bioactivity of black bean tempeh

The nutritional value and bioactivity of black beans are enhanced when fermented as tempeh, but their bioaccessibility and bioactivity after ingestion remain unclear. In this study, black bean tempeh and unfermented black beans were digested in vitro and changes in protein degradation, phenolic compound release, angiotensin I-converting enzyme (ACE)-inhibitory activity, and antioxidant activity between the two groups were compared. We observed that the soluble protein content of digested black bean tempeh was generally significantly higher than that of digested unfermented black beans at the same digestion stage (P < 0.05). The degree of protein hydrolysis and the content of <10 kDa peptides were also significantly higher in the digested black bean tempeh than in digested unfermented black beans (P < 0.05). SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high-performance liquid chromatography (RP-HPLC) analysis showed that most macromolecular proteins in tempeh had been degraded during fermentation and more of the small peptides were released from black bean tempeh during digestion, respectively. Compared to that of the unfermented black beans, the level of ACE inhibition of black bean tempeh was lower, but this significantly increased to 82.51% following digestion, closing the gap with unfermented black beans. In addition, the total respective levels of phenolics, flavonoids, and proanthocyanidins released from black bean tempeh were 1.21, 1.40, and 1.55 times those of unfermented black beans following in vitro digestion, respectively. Antioxidant activity was also significantly higher in digested black bean tempeh than in digested unfermented black beans and showed a positive correlation with phenolic compound contents (P < 0.05). The results of this study proved that, compared to unfermented black beans, black bean tempeh retained protein and phenolic compound bioaccessibility and antioxidant activity and showed an improved ACE-inhibitory activity even after consumption.

Antioxidant Activity, Probiotic Survivability, and Sensory Properties of a Phenolic-Rich Pulse Snack Bar Enriched with Lactiplantibacillus plantarum

Pulse-based snack bars incorporated with probiotics were developed to provide an overview for the preparation of simple functional food concerning the antioxidant load and iron status improvement. The study focused on the application of microencapsulated probiotics in dry matrices, such as chickpeas and green lentils, in snack bars. The study aims to analyse the products’ antioxidative activities, chemical and sensory properties, as well as the probiotic survivability in the dry matrices. The basic chemical composition showed that 100 g of product can fulfil up to 4.4% and 3.3% of the daily iron value from chickpeas and green lentils, respectively (assuming the iron bioavailability is 23%). Sensory evaluation and hedonic analysis of the fresh pulse snack bar showed that panelists preferred the chickpea snack bar over the green lentil snack bar. For storage analysis, snack bars were stored at 20 °C and were vacuum packaged in sealed low density polyethylene (LDPE) pouches with no light exposure for two months. Hedonic analysis during storage showed significant differences in the aroma of the snack bars (p < 0.05). Generally, the antioxidant activities decreased during the two months of storage. A strong correlation was observed between total phenolic content (TPC) and antioxidant activity assays: ORAC (Oxygen Radical Absorbance Capacity), DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt), PCL (Photochemiluminescence,). Moreover, after two months of storage, a 1-log decrease of probiotic viable cells was observed in both snack bars. To meet the dietary requirement of probiotics, it is suggested that people consume five portions and 9.4 portions of the chickpea and green lentil snack bars, respectively. The resulting products have promising properties with respect to probiotics and antioxidant potential in an unconventional way.

Tempeh: A semicentennial review on its health benefits, fermentation, safety, processing, sustainability, and affordability

Tempeh is a fermented food made of mainly soybeans and is a nutritious, affordable, and sustainable functional source of protein. Globally, tempeh is a widely accepted fermented product. Although there is a growing body of literature on tempeh, most research has focused on unfermented soybeans, thus the impact of tempeh fermentation on biological properties of soybeans has been largely left scattered. The objective of this review is to summarize the literature of tempeh fermentation over the past 60 years. A search of articles on tempeh published from 1960 to 2020 was performed using the Cochrane Library, Web of Science, EBSCOhost FSTA database, and Google Scholar. References from identified articles were reviewed for additional sources. In total, 321 papers were selected for this review, of which 64 papers were related to the health benefits of tempeh. This review concluded that sufficient evidence exists in the literature supporting tempeh fermentation as a low-cost, health-promoting, and sustainable food processing technology to produce protein-rich foods using various beans, legumes, and grains. This comprehensive review suggests further studies are needed on tempeh fermentation and its impact on human health; research and standardization of nonsoy tempeh; assessment of food safety-improving modification in tempeh production system; and initiatives supporting the sourcing of local ingredients in tempeh production.

Evaluation of biochemical and antioxidant dynamics during the co-fermentation of dehusked barley with Rhizopus oryzae and Lactobacillus plantarum

Barley is an ancient and important functional crop. In this study, the biochemical and antioxidant dynamics of dehusked barley during co-fermentation with Lactobacillus plantarum and Rhizopus oryzae were investigated. Results showed that amino acid nitrogen, soluble protein, <10 kDa peptide, and free phenolic contents increased with fermentation time; whereas the lactic acid bacteria count, reducing sugar, and free flavonoid contents showed a tendency to increase first and then decrease. SDS-PAGE analysis indicated that bands at >25 and <18.4 kDa were shown with improved intensity with time, whereas bands at 18.4-25 kDa were disappeared. Additionally, fermentation time led to an increase in DPPH, hydroxyl, ABTS⁺ radical scavenging activity, and ferric reducing antioxidant power. Thus, this study demonstrated that co-fermentation with L. plantarum and R. oryzae could improve nutrition and potential bioactivity of barley, and use barley as a good solid-state food carrier for probiotics. PRACTICAL APPLICATIONS: Barley is rich in nutrition and has a huge production. However, due to its high-fiber and special protein composition, there is a certain palatability problem whether it is used to produce flour or other products. Therefore, most of the barley is destined to animal feed and malt, and only a small part is used directly for human consumption. Aiming at this problem, on the basis of the optimization of the fermentation process at early stage, our results further demonstrated co-fermentation with L. plantarum and R. oryzae could enhance the nutritional value and potential bioactivity of barley, thus providing a novel approach to develop functional barley food and improve the direct utilization rate of barley in food processing.

Is Chickpea a Potential Substitute for Soybean? Phenolic Bioactives and Potential Health Benefits

Legume seeds are rich sources of protein, fiber, and minerals. In addition, their phenolic compounds as secondary metabolites render health benefits beyond basic nutrition. Lowering apolipoprotein B secretion from HepG2 cells and decreasing the level of low-density lipoprotein (LDL)-cholesterol oxidation are mechanisms related to the prevention of cardiovascular diseases (CVD). Likewise, low-level chronic inflammation and related disorders of the immune system are clinical predictors of cardiovascular pathology. Furthermore, DNA-damage signaling and repair are crucial pathways to the etiology of human cancers. Along CVD and cancer, the prevalence of obesity and diabetes is constantly increasing. Screening the ability of polyphenols in inactivating digestive enzymes is a good option in pre-clinical studies. In addition, in vivo studies support the role of polyphenols in the prevention and/or management of diabetes and obesity. Soybean, a well-recognized source of phenolic isoflavones, exerts health benefits by decreasing oxidative stress and inflammation related to the above-mentioned chronic ailments. Similar to soybeans, chickpeas are good sources of nutrients and phenolic compounds, especially isoflavones. This review summarizes the potential of chickpea as a substitute for soybean in terms of health beneficial outcomes. Therefore, this contribution may guide the industry in manufacturing functional foods and/or ingredients by using an undervalued feedstock.

Effects of unaltered and bioconverted mulberry leaf extracts on cellular glucose uptake and antidiabetic action in animals

Background

Mulberry is a Korean medicinal herb that shows effective prevention and treatment of obesity and diabetes. Bioconversion is the process of producing active ingredients from natural products using microorganisms or enzymes.

Methods

In this study, we prepared bioconverted mulberry leaf extract (BMLE) with Viscozyme L, which we tested in insulin-sensitive cells (i.e., skeletal muscle cells and adipocytes) and insulin-secreting pancreatic β-cells, as well as obese diabetic mice induced by co-administration of streptozotocin (100 mg/kg, IP) and nicotinamide (240 mg/kg, IP) and feeding high-fat diet, as compared to unaltered mulberry leaf extract (MLE).

Results

BMLE increased the glucose uptake in C2C12 myotubes and 3 T3-L1 adipocytes and increased glucose-stimulated insulin secretion in HIT-T15 pancreatic β-cells. The fasting blood glucose levels in diabetic mice treated with BMLE or MLE (300 and 600 mg/kg, PO, 7 weeks) were significantly lower than those of the vehicle-treated group. At the same concentration, BMLE-treated mice showed better glucose tolerance than MLE-treated mice. Moreover, the blood concentration of glycated hemoglobin (HbA_1C) in mice treated with BMLE was lower than that in the MLE group at the same concentration. Plasma insulin levels in mice treated with BMLE or MLE tended to increase compared to the vehicle-treated group. Treatment with BMLE yielded significant improvements in insulin resistance and insulin sensitivity.

Conclusion

These results indicate that in the management of diabetic condition, BMLE is superior to unaltered MLE due to at least, in part, high concentrations of maker compounds (trans-caffeic acid and syringaldehyde) in BMLE.

Electronic supplementary material

The online version of this article (10.1186/s12906-019-2460-5) contains supplementary material, which is available to authorized users.

Increase of content and bioactivity of total phenolic compounds from spent coffee grounds through solid state fermentation by Bacillus clausii

Spent coffee grounds are waste material generated during coffee beverage preparation. This by-product disposal causes a negative environmental impact, in addition to the loss of a rich source of nutrients and bioactive compounds. A rotating central composition design was used to determine the optimal conditions for the bioactivity of phenolic compounds obtained after the solid state fermentation of spent coffee grounds by Bacillus clausii. To achieve this, temperature and fermentation time were varied according to the experimental design and the total phenolic and flavonoid content, antioxidant activity and antimicrobial activity were determined. Surface response methodology showed that optimum bioprocessing conditions were a temperature of 37 °C and a fermentation time of 39 h. Under these conditions, total phenolic and flavonoid contents increased by 36 and 13%, respectively, in fermented extracts as compared to non-fermented. In addition, the antioxidant activity was increased by 15% and higher antimicrobial activity was observed against Gram positive and negative bacteria. These data demonstrated that bioprocessing optimization of spent coffee grounds using the surface response methodology was an important tool to improve phenolic extraction, which could be used as an antioxidant and antimicrobial agents incorporated into different types of food products.

Bioprocessing of common beans in diets for tilapia: in vivo digestibility and antinutritional factors

BACKGROUND

Bioprocessing of ingredients by solid-state fermentation is a low-cost technique for preparing diets. It is performed by adding microorganisms such as Rhizopus oligosporus to bean grains, achieving minimal degradation of nutrients and a significant improvement in digestibility. In particular, fermentation induces favorable changes in beans by reducing enzyme inhibitors, such as phytates and tannins.

RESULTS

Fermentation significantly (P < 0.05) increased the protein content and digestibility of dry matter and protein compared with whole bean grains, and decreased the content of lipids, ash and phytic acid. Hardening did not have a significant (P > 0.05) effect on the chemical content of beans and digestibility of diets. The dehulled bean meal significantly (P < 0.05) increased protein and lipid content and digestibility of dry matter and protein of beans, and decreased fiber, ash and tannin content. The chemical content of beans and digestibility of ingredients compare favorably with those reported by other authors, indicating the benefits of fermentation and dehulling.

CONCLUSION

We concluded that bean meal obtained from fermentation or dehulling represents a low-cost alternative for diets for tilapia. © 2017 Society of Chemical Industry.

The solid-state fermentation of Artemisia capillaris leaves with Ganoderma lucidum enhances the anti-inflammatory effects in a model of atopic dermatitis

Artemisia capillaris, which belongs to the Asteraceae family and the genus Artemisia, has been reported to exert inhibitory effects on diabetes, cancer and inflammation. In this study, in order to enhance the bioactivity potential of the leaves of Artemisia by Ganoderma lucidum mycelium, we prepared aqueous samples of Artemisia capillaris (Ac) leaves, Ganoderma lucidum (Gl) and aqueous fractions produced by the solid fermentation of Ganoderma lucidum on Artemisia capillaris leaves (afAc/Gl). Thereafter, we evaluated whether these samples have potential to attenuate inflammation-related symptoms in an amimal model of 2,4-dinitrofluorobenzene (DNFB)-induced atopic dermatitis. We found that afAc/Gl exhibited enhanced anti-inflamamatory activity following the solid fermentation process when compared with Ac or Gl on ear thickness, ear epidermal thickness and eosinophil infiltration in the skin tissues. The expression of nitric oxide (NO) synthases (NOSs) was measured by immunohistochemical staining. The results revealed that afAc/Gl decreased endothelial NOS and inducible NOS expression compared with the DNFB group, while neuronal NOS expression was not altered. By comparing NO production, we found that as opposed to Ac, afAc/Gl has potential to inhibit atopic dermatitis-related symptoms during the inflammatory event. As regards matrix metalloproteinase (MMP) expression patterns, afAc/Gl exerted potent inhibitory activity on the mRNA expression of MMP-2, -7, -9, -12, -14 and -19. Taken together, these results suggest that the solid state fermentation of Ac by Gl is an effective strategy to obtaining useful ingredients which are converted into valuable compounds during an atopic inflammatory insult.

Modulation of coffee aroma via the fermentation of green coffee beans with Rhizopus oligosporus: I. Green coffee

Modulation of coffee aroma via the biotransformation/fermentation of different coffee matrices during post-harvest remains sparingly explored despite some studies showing their positive impacts on coffee aroma. Therefore, this is an unprecedented study aimed at modulating coffee aroma via the fermentation of green coffee beans with a food-grade fungus Rhizopus oligosporus. The objective of part I of this two-part study was to characterize the volatile and non-volatile profiles of green coffee beans after fermentation. Proteolysis during fermentation resulted in 1.5-fold increase in the concentrations of proline and aspartic acid which exhibited high Maillard reactivity. Extensive degradation of ferulic and caffeic acids led to 2-fold increase in the total concentrations of volatile phenolic derivatives. 36% of the total volatiles detected in fermented green coffee beans were generated during fermentation. Hence, the work presented demonstrated that R. oligosporus fermentation of green coffee beans could induce modification of the aroma precursors of green coffees.

Enhanced total phenolic and isoflavone aglycone content, antioxidant activity and DNA damage protection of soybeans processed by solid state fermentation with Rhizopus oligosporus RT-3

In this study,Rhizopus oligosporusRT-3, which was first isolated in our group, was used for solid state fermentation of soybeans (R. oligosporus-fermented soybeans, RFS) in a short time (22 h).

Enhancement of nutritional properties, and antioxidant and antihypertensive potential of black common bean seeds by optimizing the solid state bioconversion process

The aim of this work was to obtain a functional flour with enhanced nutritional properties, and antioxidant and antihypertensive potential from black bean seeds by optimizing the solid state bioconversion (SSB) process using a Rhizopus oligoporus strain. Response surface methodology was applied as optimization technique. A central composite experimental design with two factors [fermentation temperature (FT) = 30-40 °C/fermentation time (Ft) = 6-108 h] and five levels was used (13 treatments). The bioprocessed cotyledons from each treatment were dried, milled, and blended with its previously dried-milled seed coats. The best combination FT/Ft of SSB to obtain the functional flour was 38 °C/100 h. SSB increased the calculated protein efficiency ratio (from 1.59 to 2.40), antioxidant activity (from 13 948 to 22 733 µmol ET/100 g, dw), total phenolic compounds (TPC) (from 190 to 432 mg EGA/100 g, dw) and antihypertensive potential (IC(50) from 95.57 to 0.0321 µg/mL). SSB is an effective strategy to improve the TPC of common beans for enhanced functionality.