The role of bioconversion processes to enhance bioaccessibility of polyphenols in rice

Valorization of Date By-Products: Enhancement of Antioxidant and Antimicrobial Potentials through Fermentation

The by-products from three varieties of dates-Mozafati, Sayer, and Kabkab-were subjected to solid-state fermentation using Aspergillus niger alone or in co-culture with Lactiplantibacillus plantarum or Limosilactobacillus reuteri to enhance their phenolic and flavonoid content, along with antioxidant and antimicrobial activities. Solid-state fermentation, being environmentally friendly and cost-effective, is particularly suitable for agricultural residues. Significant increases (p < 0.05) in total polyphenol content (TPC), total flavonoid content (TFC), and antioxidant power were observed post-fermentation, especially under co-culture conditions. The highest TPC (12.98 ± 0.29 mg GA/g) and TFC (1.83 ± 0.07 mg QE/g) were recorded in the co-culture fermentation of by-products from the Mozafati and Sayer varieties, respectively. HPLC analysis revealed changes in polyphenol profiles post-fermentation, with reductions in gallic and ferulic acids and increases in caffeic acid, p-coumaric acid, rutin, quercetin, and kaempferol. FT-IR analysis confirmed significant alterations in polyphenolic functional groups. Enhanced antimicrobial activity was also observed, with inhibition zones ranging from 8.26 ± 0.06 mm for Kabkab to 17.73 ± 0.09 mm for Mozafati. These results suggest that co-culture solid-state fermentation is a promising strategy for valorizing date by-products, with potential applications in nutraceuticals and/or pharmaceutical products and as valuable additives in the food industry.

New horizon to the world of gut microbiome: seeds germination

The second brain of humans has been known as the microbiome. The microbiome is a dynamic network composed of commensal bacteria, archaea, viruses, and fungi colonized in the human gastrointestinal tract. They play a vital role in human health by metabolizing components, maturation of the immune system, and taking part in the treatment of various diseases. Two important factors that can affect the gut microbiome's composition and/or function are the food matrix and methods of food processing. Based on scientific research, the consumption of whole grains can make positive changes in the gut microbiota. Seeds contain different microbiota-accessible substrates that can resist digestion in the upper gastrointestinal tract. Seed germination is one of the simplest and newest food processing approaches to improve seeds' bioavailability and overall nutritional value. During germination, the dormant hydrolytic seed's enzymes have been activated and then metabolize the macromolecules. The quality and quantity of bioactive compounds like prebiotics, fiber, phenolic compounds (PC), total free amino acids, and γ-aminobutyric acid (GABA) can increase even up to 4-10 folds in some cases. These components stimulate the survival and growth of healthful bacteria like probiotics and boost their activity. This effect depends on several parameters, e.g., germination environmental conditions. This review aims to provide up-to-date and latest research about promoting bioactive components during seed germination and investigating their impacts on gut microbiota to understand the possible direct and indirect effects of seed germination on the microbiome and human health.

Impact of germination on the techno-functional properties, nutritional composition, and health-promoting compounds of brown rice and its products: A review

Rice is a popular grain and forms part of the daily diet of people throughout the world. However, the consumption of rice and its products is sometimes limited by its high glycemic index due to its high starch content, low protein content and quality, and low bioavailability of minerals due to the presence of anti-nutritional factors. This has partly stimulated research interest in recent times toward the use of bioprocessing techniques such as germination as cheap and natural means to improve the nutritional quality, digestibility, and health properties of cereals, including rice, to partially achieve nutrition and food security in the developing regions of the world. This review highlights the impact of germination on the nutritional quality, health-promoting properties, and techno-functional characteristics of germinated brown rice grains and their products. The review demonstrated that germinated rice grains and their products have improved nutritional quality and digestibility, modified functional properties, and showed antioxidant, anti-inflammatory, anti-diabetic, anti-obesity, anti-cancer, and anti-cardiovascular activities. Germination appears to be a suitable bioprocessing method to improve the nutritional quality and bioactive constituents and modify the techno-functional properties of rice grains for diverse food applications and improved global nutrition and food safety.

Neuroprotective effects of hydroponic ginseng fermented by Lactococcus lactis KC24 in oxidatively stressed SH-SY5Y cells

BACKGROUND

Panax ginseng Meyer, a traditional herb in Asia, contains bioactive compounds such as polyphenolic compounds, flavonoids, and ginsenosides. Furthermore, fermentation with probiotics can promote the biofunctional activities of ginseng. This study's object was to investigate the neuroprotective effect of hydroponic ginseng against hydrogen peroxide (H₂ O₂ )-induced cytotoxicity and its effect on the fermentation time.

RESULTS

Nonfermented hydroponic ginseng (HNF) was fermented with Lactococcus lactis KC24 at 37 °C for 12 h (H12F) or 24 h (H24F). As fermentation progressed, the content of ginsenosides Rd and F2 increased slightly. The viability of cells pretreated with H₂ O₂ -exposed nonfermented soil-cultivated ginseng (SNF), HNF, H12F, and H24F gradually improved. In addition, a similar cytotoxicity trend was observed for the level of lactate dehydrogenase released. Fermentation with L. lactis KC24 also enhanced the protective effect of HNF in all assays related to the neuroprotective pathway. In other words, superoxide dismutase and catalase messenger RNA (mRNA) expression levels were upregulated in H24F-treated cells. Similarly, H24F also upregulated the mRNA and protein expression of brain-derived neurotrophic factor to the highest observed concentration. Moreover, the Bax/Bcl-2 ratio was the lowest after H24F pretreatment in H₂ O₂ -induced SH-SY5Y cells. Attenuating the cytotoxicity in H₂ O₂ -induced SH-SY5Y cells, H24F markedly reduced caspase-3 and -9 mRNA expression and caspase-3 activity.

CONCLUSION

These results suggest that HNF exhibited higher neuroprotection than SNF, which was enhanced after fermentation. This study demonstrates that H12F and H24F can be potential ingredients for developing healthy functional foods and pharmaceutical materials. © 2023 Society of Chemical Industry.

Bacterial cellulose: Strategies for its production in the context of bioeconomy

Bacterial cellulose has advantages over plant-derived cellulose, which make its use for industrial applications easier and more profitable. Its intrinsic properties have been stimulating the global biopolymer market, with strong growth expectations in the coming years. Several bacterial species are capable of producing bacterial cellulose under different culture conditions; in this context, strategies aimed at metabolic engineering and several possibilities of carbon sources have provided opportunities for the bacterial cellulose's biotechnological exploration. In this article, an overview of biosynthesis pathways in different carbon sources for the main producing microorganisms, metabolic flux under different growth conditions, and their influence on the structural and functional characteristics of bacterial cellulose is provided. In addition, the main industrial applications and ways to reduce costs and optimize its production using alternative sources are discussed, contributing to new insights on the exploitation of this biomaterial in the context of the bioeconomy.

Polyphenol Release from Wheat Bran Using Ethanol-Based Organosolv Treatment and Acid/Alkaline Catalysis: Process Modeling Based on Severity and Response Surface Optimization

Wheat bran (WB) is globally a major food industry waste, with a high prospect as a bioresource in the production of precious polyphenolic phytochemicals. In this framework, the current investigation had as objectives (i) to use ethanol organosolv treatment and study the effect of acid and alkali catalysts on releasing bound polyphenols, (ii) establish linear and quadratic models of polyphenol recovery based on severity and response surface, and (iii) examine the polyphenolic composition of the extracts generated. Using sulfuric acid and sodium hydroxide as the acid and the alkali catalyst, respectively, it was found that the correlation of combined severity factor with total polyphenol yield was significant in the acid catalysis, but a highly significant correlation in the alkali-catalyzed process was established with modified severity factor, which takes into consideration catalyst concentration, instead of pH. Optimization of the process with response surface confirmed that polyphenol release from WB was linked to treatment time, but also catalyst concentration. Under optimized conditions, the acid- and alkali-catalyzed processes afforded total polyphenol yields of 10.93 ± 0.62 and 19.76 ± 0.76 mg ferulic acid equivalents g^-1 dry mass, respectively. Examination of the polyphenolic composition revealed that the alkali-catalyzed process had a striking effect on releasing ferulic acid, but the acid catalysis was insufficient in this regard. The outcome concerning the antioxidant properties was contradictory with respect to the antiradical activity and ferric-reducing power of the extracts, a fact most probably attributed to extract constituents other than ferulic acid. The process modeling proposed herein may be valuable in assessing both process effectiveness and severity, with a perspective of establishing WB treatments that would provide maximum polyphenol recovery with minimum harshness and cost.

Antioxidant-polyphenols of saw palmetto seeds: statistical optimized production and improved functional properties under solid-state fermentation by Trichoderma reesei

Saw palmetto seeds (SPS) contain essential phenolic compounds that provide antioxidant, antimicrobial, anti-inflammatory, and anti-diabetic benefits when added to food. Maximized/improved production of these valuable phenolic compounds is the main purpose of this study. Solid-state fermentation (SSF) is a promising processing technique that positively alters the levels of health-promoting compounds in plants and plant residues. Here, a central composite design matrix (16 runs) and response surface methodology were experimentally applied to investigate the best SSF conditions and their interactions for maximum production of phenolic compounds from SPS. A good correlation between actual and expected results was observed with higher multiple coefficients (R2 ~ 0.93–0.97) and strongly significant P values (< 0.0001) proving the accuracy of the statistical model/design. Under optimized SSF conditions, temperature 30 °C, moisture 10%, pH 7.0, and fermentation time 6 days, the total phenolic content and total antioxidant activity of SPS were maximized by 11-fold and 46–49 folds, respectively. According to HPLC analysis, the contents of all identifying polyphenols were 3.3–30.0 times greater in fermented SPS extract (FSPS) than in the unfermented SPS extract (UFSPS). The FSPS extract also contained four new/additional polyphenols (vanillic, p-coumaric, cinnamic, and quercetin). FSPS extract demonstrated much greater antibacterial and antifungal activities than UFSPS extract against various human pathogenic bacteria and fungi. Consequently, the FSPS-phenolic compounds can be exploited as a food supplement and an antimicrobial remedy.

Diabetes and seeds: New horizon to promote human nutrition and anti-diabetics compounds in grains by germination

Type 2 diabetes (T2D) is a complex and heterogeneous chronic metabolic disorder disease that is associated with high blood sugar. Because of the side effects of synthetic drugs on T2D patients and their economic burden, interest in plant-derived functional foods like grains with biological activities has developed. Based on scientific reports, whole grains are rich sources of energy, nutrients, and bioactive compounds and are assumed to have beneficial health effects on glucose enzymes regulation or hyperglycemia. Nowadays, different methods have been applied to enhance whole seed healthful properties and anti-diabetic compounds, and germination is one of them. Germination (sprouting) is a cost-effective method for boosting the activity of endogenous seed enzymes and modifying the structure of macromolecules. Some of these macromolecules like bioactive peptides, polyphenols, dietary fiber, and vitamins are related to diabetes management. Determining the best germination condition can help to promote these anti-diabetics properties of compounds. This study presents relevant information about diabetes, the effect of seed germination on releasing bioactive compounds, and optimizing environmental germination conditions to improve the anti-diabetic compounds in seeds for reaching functional food.

Mixed solid-state fermentation for releasing bound polyphenols from insoluble dietary fiber in carrots via Trichoderma viride and Aspergillus niger

This study aimed to explore the release mechanism of bound polyphenols (BP) from the insoluble dietary fiber (IDF) in carrots via mixed solid-state fermentation (MSF) using Trichoderma viride and Aspergillus niger. The results indicated that BP released by MSF (80.8759 mg GAE per 10 g DW) was significantly higher than that by alkaline hydrolysis. In addition, 17 polyphenols were detected and their biotransformation pathways were proposed. Quantitative analysis showed that MSF released numerous p-coumaric and organic acids, which led to both an enhancement in α-amylase inhibitory activity and elevated antioxidant enzyme activity in Caenorhabditis elegans (C. elegans). Furthermore, the dynamic changes in the carbohydrate-hydrolyzing enzymes and the structural characteristics indicated that the destruction of hemicellulose, the deposition of lignin and the secretion of xylanase were vital for the release of BP. Overall, this study demonstrated that MSF is beneficial for the release of BP from IDF, which could provide new insight into the utilization of agricultural byproducts in a more natural and economical way.

Bound Polyphenols from Insoluble Dietary Fiber of Defatted Rice Bran by Solid-State Fermentation with Trichoderma viride: Profile, Activity, and Release Mechanism

This study is aimed at exploring the release of bound polyphenols (BP) from insoluble dietary fiber (IDF) and its mechanism by solid-state fermentation (SSF) via Trichoderma viride. The results indicated that BP released by SSF (5.55 mg GAE/g DW) was significantly higher than by alkaline hydrolysis. In addition, 39 polyphenols and catabolites were detected, and the related biotransformation pathways were speculated. Quantitative analysis showed that SSF released more ferulic acid, p-coumaric acid, and organic acids, which led to advances in antioxidant, α-amylase, and α-glucosidase inhibitory activities. Furthermore, structural characteristics (scanning electron microscopy, X-ray diffraction, thermos gravimetric analysis, and Fourier transform infrared spectroscopy) and dynamic changes of carbohydrate-hydrolyzing enzymes indicated that the destruction of hemicellulose and the secretion of xylanase were vital for releasing BP. Overall, this study demonstrated that SSF was beneficial to release BP from IDF, which could provide insight into utilizing agricultural byproducts in a more natural and economical way.

Untargeted Metabolomics of Korean Fermented Brown Rice Using UHPLC Q-TOF MS/MS Reveal an Abundance of Potential Dietary Antioxidative and Stress-Reducing Compounds

Free radical-induced oxidative stress is the root cause of many diseases, such as diabetes, stress and cardiovascular diseases. The objective of this research was to screen GABA levels, antioxidant activities and bioactive compounds in brown rice. In this study, we first fermented brown rice with different lactic acid bacteria (LABs), and the best LAB was selected based on the levels of GABA in the fermentate. Lactobacillus reuterii generated the highest levels of GABA after fermentation. To ascertain whether germination can improve the GABA levels of brown rice, we compared the levels of GABA in raw brown rice (Raw), germinated brown rice (Germ), fermented brown rice (Ferm) and fermented-germinated brown rice (G+F) to identify the best approach. Then, antioxidant activities were investigated for Raw BR, Germ BR, Ferm BR and G+F BR. Antioxidant activity was calculated using a 2,2-diphenyl-1-picryl hydrazile radical assay, 2,2-azino-bis-(3-ethylene benzothiozoline-6-sulfonic acid) radical assay and ferric-reducing antioxidant power. In Ferm BR, DPPH (114.40 ± 0.66), ABTS (130.52 ± 0.97) and FRAP (111.16 ± 1.83) mg Trolox equivalent 100 g, dry weight (DW), were observed as the highest among all samples. Total phenolic content (97.13 ± 0.59) and total flavonoids contents (79.62 ± 1.33) mg GAE/100 g and catechin equivalent/100 g, DW, were also found to be highest in fermented BR. Furthermore, an untargeted metabolomics approach using ultra-high-performance liquid tandem chromatography quadrupole time of flight mass spectrometry revealed the abundance of bioactive compounds in fermented BR, such as GABA, tryptophan, coumaric acid, L-ascorbic acid, linoleic acid, β-carotenol, eugenol, 6-gingerol, etc., as well as bioactive peptides which could contribute to the health-promoting properties of L. reuterii fermented brown rice.

Pulses' germination and fermentation: Two bioprocessing against hypertension by releasing ACE inhibitory peptides

Angiotensin-Converting Enzyme (ACE) is one of the main blood pressure regulators in the renin-angiotensin system leading to hypertension. Hypertension is known as the modern world disease which increases the risk of serious human health problems. Synthetic drugs and some natural compounds could treat this disease by binding to ACE and reducing its activity. Pulses, one of the legumes group, that are the rich in protein sources in the human diet, have several bioactive compounds with ACE inhibitory (ACE I) properties. However, several processes need to break down proteins and improve ACE I activity in foods. Germination and fermentation, known by bioprocessing, could make releasing bioactive peptides and polyphenols and exhibit ACE I and either other health properties such as antimicrobial, antioxidant, anti-diabetic and anticancer activities. Various factors such as kind of selective culture, temperature, time and humidity affect these processes. This review summarizes relevant studies about the effect of pulses' germination and fermentation to produce ACE I activity compounds and also explains about main parameters affecting the health properties of these two bioprocessing to treat hypertension that could lead to the development of their application in pharmaceuticals instead of synthetic drugs.