Enhancement of bioactive compounds in barley cultivars by solid substrate fermentation

Recent Developments in Polyphenol Applications on Human Health: A Review with Current Knowledge

Polyphenol has been used in treatment for some health disorders due to their diverse health promoting properties. These compounds can reduce the impacts of oxidation on the human body, prevent the organs and cell structure against deterioration and protect their functional integrity. The health promoting abilities are attributed to their high bioactivity imparting them high antioxidative, antihypertensive, immunomodulatory, antimicrobial, and antiviral activity, as well as anticancer properties. The application of polyphenols such as flavonoids, catechin, tannins, and phenolic acids in the food industry as bio-preservative substances for foods and beverages can exert a superb activity on the inhibition of oxidative stress via different types of mechanisms. In this review, the detailed classification of polyphenolic compunds and their important bioactivity with special focus on human health are addressed. Additionally, their ability to inhibit SARS-CoV-2 could be used as alternative therapy to treat COVID patients. Inclusions of polyphenolic compounds in various foods have demonstrated their ability to extend shelf life and they positive impacts on human health (antioxidative, antihypertensive, immunomodulatory, antimicrobial, anticancer). Additionally, their ability to inhibit the SARS-CoV-2 virus has been reported. Considering their natural occurrence and GRAS status they are highly recommended in food.

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.

Comparison of Liquid and Solid-State Fermentation Processes for the Production of Enzymes and Beta-Glucan from Hulled Barley

Solid-state fermentation using hulled barley was carried out to produce enzymes and β-glucan. The one-factor-at-a-time experiments were carried out to determine the optimal composition of the basal medium. The modified synthetic medium composition in liquid-state fermentation was determined to be 70 g/l hulled barley, 0 g/l rice bran, 5 g/l soytone, and 6 g/l ascorbic acid. Optimal pretreatment conditions of hulled barley by solid-state fermentation were evaluated in terms of maximum production of fungal biomass, amylase, protease, and β-glucan, which were 1.26 mg/g, 31310.34 U/g, 2614.95 U/g, and 14.6% (w/w), respectively, at 60 min of pretreatment condition. Thus, the solid-state fermentation process was found to enhance the overall fermentation yields of hulled barley to produce high amounts of enzymes and β-glucan.

Modern Methods of Pre-Treatment of Plant Material for the Extraction of Bioactive Compounds

In this review, recent advances in the methods of pre-treatment of plant material for the extraction of secondary metabolites with high biological activity are presented. The correct preparation of the material for extraction is as important as the selection of the extraction method. This step should prevent the degradation of bioactive compounds as well as the development of fungi and bacteria. Currently, the methods of preparation are expected to modify the particles of the plant material in such a way that will contribute to the release of bioactive compounds loosely bonded to cell wall polymers. This review presents a wide range of methods of preparing plant material, including drying, freeze-drying, convection drying, microwave vacuum drying, enzymatic processes, and fermentation. The influence of the particular methods on the structure of plant material particles, the level of preserved bioactive compounds, and the possibility of their release during the extraction were highlighted. The plant material pre-treatment techniques used were discussed with respect to the amount of compounds released during extraction as well their application in various industries interested in products with a high content of biologically active compounds, such as the pharmaceutical, cosmetics, and food industries.

Limosilactobacillus reuteri Fermented Brown Rice: A Product with Enhanced Bioactive Compounds and Antioxidant Potential

Oxidative stress has been postulated to play a role in several diseases, including cardiovascular diseases, diabetes, and stress-related disorders (anxiety/depression). Presently, natural plant-derived phytochemicals are an important tool in reducing metabolomic disorders or for avoiding the side effects of current medicinal therapies. Brown Rice (Oryza sativa L.) is an important part of Asian diets reported as a rich source of bioactive phytonutrients. In our present study, we have analyzed the effect of different lactic acid bacteria (LABs) fermentation on antioxidant properties and in the enhancement of bioactive constituents in Korean brown rice. Therefore, the antioxidant activities and phytochemical analysis were investigated for raw brown rice (BR) and different fermented brown rice (FBR). BR fermented with Limosilactobacillus reuteri, showed the highest antioxidant activities among all samples: DPPH (121.19 ± 1.0), ABTS (145.80 ± 0.99), and FRAP (171.89 ± 0.71) mg Trolox equiv./100 g, dry weight (DW). Total phenolic content (108.86 ± 0.63) mg GAE equiv./100 g, DW and total flavonoids content (86.79 ± 0.83) mg catechin equiv./100 g, DW was also observed highest in Limosilactobacillus reuteri FBR. Furthermore, phytochemical profiling using ultra-high-performance liquid tandem chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF/MS) and cell antioxidant assay (CAA) revealed L. reuteri FBR as a strong antioxidant with an abundance of bioactive compounds such as gamma-aminobutyric acid, coumarin, cinnamic acid, butanoic acid, ascorbic acid, nicotinic acid, and stearic acid. This study expanded current knowledge on the impact of fermentation leading to the enhancement of antioxidant capacity with an abundance of health-related bioactive compounds in BR. The results obtained may provide useful information on functional food production using fermented brown rice.

Aspergillus oryzae Fermented Rice Bran: A Byproduct with Enhanced Bioactive Compounds and Antioxidant Potential

Rice bran (RB) is a byproduct of the rice industry (milling). For the fermentation process and to add value to it, RB was sprayed with fungal spores (Aspergillus oryzae MTCC 3107). The impact of fermentation duration on antioxidant properties was studied. Total phenolic content (TPC) determined using the Folin–Ciocalteu method, increased during fermentation until the 4th day. The antioxidant activity analyzed using the 2,2 Diphenyl–1′ picrylhydrazyl (DPPH) assay, total antioxidant activity (TAC), 2,2′-azinobis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) assay, reducing power assay (RPA) and hydroxyl free radical scavenging activity (HFRSA) for fermented rice bran (FRB) were determined and compared to unfermented rice bran (URB). TAC, DPPH, ABTS⁺ and RPA of FRB increased till 4th day of fermentation, and then decreased. The specific bioactive constituents in extracts (Ethanol 50%) from FRB and URB were identified using high performance liquid chromatography (HPLC). HPLC confirmed a significant (p < 0.05) increase in gallic acid and ascorbic acid. On the 4th day of fermentation, the concentrations of gallic acid and ascorbic acid were 23.3 and 12.7 µg/g, respectively. The outcome of present investigation confirms that antioxidant potential and TPC of rice bran may be augmented using SSF.

Solid state fermentation of fenugreek (Trigonella foenum-graecum): implications on bioactive compounds, mineral content and in vitro bioavailability

In the present study, solid-state fermentation (SSF) of four fenugreek cultivars viz. HM-57, AFG-2, RMT-1 and RMT-303 were carried out using Aspergillus awamori and its effect on antioxidant properties, phenolic content and bioactive compounds were studied. Macro (Ca, K, and Na) as well as micro (Fe, Zn, and Cu) elements and in vitro bioavailability of the unfermented fenugreek (UFF) and Aspergillus-fermented fenugreek (AFF) samples were assessed with standard methods. On 5th day, total phenolic and condensed tannin contents showed significant (p ≤ 0.05) increase for all cultivars. Further, HPLC analysis confirmed formation of some new bioactive (vanillin, benzoic acid and catechin) compounds. Similarly, extracts from all AFF also showed an increase in the antioxidant potential such as inhibition of DPPH, hydroxyl free radical scavenging, reducing power, and total antioxidant capacity up to 5th day of SSF. Mineral in AFF were found with enhanced values when compared with respective UFF. In vitro bioavailability of Fe, Zn and Ca was also improved during SSF. Results from the present study may be helpful to food industry in developing new health foods and may provide a rational for development of functional ingredient in preparation of novel nutraceuticals.

Quantification of phenolic acids and antioxidant potential of wheat rusks as influenced by partial replacement with barley flour

This study was investigated to evaluate the phenolic acid composition, antioxidant potential and acceptance of rusk prepared by the progressive replacement of wheat flour with barley flour. The wheat-barley blends rusks were also evaluated for their pasting and sensorial properties. The pasting characteristics of wheat flour was influenced by barley flour incorporation with a increase in peak and final viscosity values with increasing amount of barley flour. The results revealed that incorporation of barley flour into wheat flour improved the nutritional and bioactive compounds profile. The free radical scavenging activities towards DPPH and ABTS⁺ was found to be higher for wheat-barley blends rusk in comparison with wheat rusk. As evident from total phenolic content, total flavonoids contents and antioxidant activities, barley flour was found to be rich in bioactive compounds in comparison with wheat flour. Supplementation of rusks with 30% barley flour were suggested to be nutritionally superior with an acceptable sensory score and is a successful approach to enrich rusks with nutrients.

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.

Fermented pearl millet (Pennisetum glaucum) with in vitro DNA damage protection activity, bioactive compounds and antioxidant potential

In the present study, pearl millet cultivar PUSA-415 was fermented by solid state fermentation (SSF) process using Aspergillus sojae (MTCC-8779) as starter culture. The fermentation was carried out for the period of ten days. The effect of SSF on phenolic content, condensed tannin content, antioxidant potential and DNA damage protection of pearl millet during different fermentation period was determined. Results showed that SSF and thermal processing significantly affect the bioactive profile and antioxidant potential of bio-transformed pearl millet. Extracts prepared from 6th days fermented pearl millet flour exhibited the highest TPC, antioxidant potential and DNA damage protection activity. Qualitative and quantitative analysis of bioactive compounds were done by HPLC. During SSF, production of enzymes (α-amylase, β-glucosidase and xylanase) as well as specific bioactive compounds (ascorbic acid, gallic acid and p-Coumaric acid) was significantly increased. Thus, bio-transformed Aspergillus sojae fermented pearl millet could be used in preparation of functional foods and novel nutraceuticals in health promotions. Chapatti was formulated from unfermented as well as fermented flour and the effect of thermal processing on bioactive compounds and antioxidant potential was studied. Thermal processing resulted in decrease in TPC of both, AFM and UFM by 4.75-16.27% and increase in CTC by 38.52-67.41%.