Eurotium cristatum produced β-hydroxy acid metabolite of monacolin K and improved bioactive compound contents as well as functional properties in fermented wheat bran

Cereal dietary fiber regulates the quality of whole grain products: Interaction between composition, modification and processing adaptability

The coarse texture and difficulty in processing dietary fiber (DF) in cereal bran have become limiting factors for the development of the whole cereal grain (WCG) food industry. To promote the development of the WCG industry, this review comprehensively summarizes the various forms and structures of cereal DF, including key features such as molecular weight, chain structure, and substitution groups. Different modification methods for changing the chemical structure of DF and their effects on the modification methods on physicochemical properties and biological activities of DF are discussed systematically. Furthermore, the review focusses on exploring the interactions between DF and dough components and discusses the effects on the gluten network structure, starch gelatinization and retrogradation, fermentation, glass transition, gelation, and rheological and crystalline characteristics of dough. Additionally, opportunities and challenges regarding the further development of DF for the four products are also reviewed. The objective of this review is to establish a comprehensive foundation for the precise modification of cereal DF, particularly focusing on its application in dough-related products, and to advance the development and production of WCG products.

Morphological variation and expressed sequence tags-simple sequence repeats-based genetic diversity of Aspergillus cristatus in Chinese dark tea

Introduction

Aspergillus cristatus is a homothallic fungus that is used in the natural fermentation process of Chinese Fuzhuan tea and has been linked to the production of bioactive components. However, not much is known about the variations present in the fungus. To understand the variation of the dominant microorganism, A. cristatus, within dark tea, the present study investigated the genetic and morphological diversity of 70 A. cristatus collected across six provinces of China.

Methods

Expressed sequence tags-simple sequence repeats (EST-SSR) loci for A. cristatus were identified and corresponding primers were developed. Subsequently, 15 specimens were selected for PCR amplification.

Results

The phylogenetic tree obtained revealed four distinct clusters with a genetic similarity coefficient of 0.983, corresponding to previously identified morphological groups. Five strains (A1, A11, B1, D1, and JH1805) with considerable differences in EST-SSR results were selected for further physiological variation investigation. Microstructural examinations revealed no apparent differentiation among the representative strains. However, colony morphology under a range of culture media varied substantially between strains, as did the extracellular enzymatic activity (cellulase, pectinase, protease, and polyphenol oxidase); the data indicate that there are differences in physiological metabolic capacity among A. cristatus strains.

Discussion

Notably, JH1805, B1, and A11 exhibited higher enzymatic activity, indicating their potential application in the production of genetically improved strains. The findings provide valuable insights into species identification, genetic diversity determination, and marker-assisted breeding strategies for A. cristatus.

Dynamic changes on sensory property, nutritional quality and metabolic profiles of green kernel black beans during Eurotium cristatum-based solid-state fermentation

Eurotium cristatum, a unique probiotic in Fu brick tea, is widely used in food processing to enhance added values. Here, green kernel black beans (GKBBs) were solid-fermented with E. cristatum and dynamic changes in flavour, chemical composition and metabolites during fermentation were investigated. As results, E. cristatum fermentation altered aroma profiles and sensory attributes of GKBBs, especially reduced sourness. After fermentation, total polyphenolic and flavonoid contents in GKBBs were elevated, while polysaccharides, soluble proteins and short-chain fatty acids contents were decreased. E. cristatum fermentation also induced biotransformation of glycosidic isoflavones into sapogenic isoflavones. During fermentation, dynamic changes in levels of 17 amino acids were observed, in which 3 branched-chain amino acids were increased. Non-targeted metabolomics identified 51 differential compounds and 10 related metabolic pathways involved in E. cristatum fermentation of GKBBs. This study lays foundation for the development of green kernel black bean-based functional food products with E. cristatum fermentation.

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.

Withanolides from Physalis angulata var. villosa and the Relative Configurational Revision of Some Known Analogs

Physalis angulata var. villosa is a plant possessing abundant withanolides, but in-depth research is lacking. In our ongoing study of P. angulata var. villosa, 15 previously undescribed withanolides (1-15), along with 21 known analogs (16-36), were isolated from the whole plant. The structures of the withanolides (1-15) were elucidated based on analysis of their 1D and 2D NMR, HRESIMS, and ECD data. Additionally, the application of γ-gauche effects with the help of ROESY correlations led to the formulation of empirical rules for withanolides with 14-OH/15-OAc to rapidly determine the 14-OH orientations, making it possible to propose configurational revisions of 19 previously reported analogs (1'-19'). Withanolides 1, 4-6, and 10 showed potent cytotoxic activities against three human cancer cell lines (HCT-116, MDA-MB-231, and A549).

Secondary Metabolites from the Genus Eurotium and Their Biological Activities

Eurotium is the teleomorph genus associated with the section Aspergillus. Eurotium comprises approximately 20 species, which are widely distributed in nature and human environments. Eurotium is usually the key microorganism for the fermentation of traditional food, such as Fuzhuan brick tea, Liupao tea, Meju, and Karebushi; thus, Eurotium is an important fungus in the food industry. Eurotium has been extensively studied because it contains a series of interesting, structurally diverse, and biologically important secondary metabolites, including anthraquinones, benzaldehyde derivatives, and indol diketopiperazine alkaloids. These secondary metabolites have shown multiple biological activities, including antioxidative, antimicrobial, cytotoxic, antitumor, insecticidal, antimalarial, and anti-inflammatory activities. This study presents an up-to-date review of the phytochemistry and biological activities of all Eurotium species. This review will provide recent advances on the secondary metabolites and their bioactivities in the genus Eurotium for the first time and serve as a database for future research and drug development from the genus Eurotium.

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.

Comparative Study of Raw and Fermented Oat Bran: Nutritional Composition with Special Reference to Their Structural and Antioxidant Profile

Oat bran has gained significant attention among cereal brans owing to its comparatively higher presence of dietary fibers and phytochemicals. The objective of the current research is to personify the nutritional and functional aspects of oat bran after yeast-induced (Saccharomyces cerevisiae) fermentation. For this purpose, a comparative study of raw and fermented oat bran was conducted to investigate the nutritional profile, antioxidant activity and functional characteristics of oat bran. Furthermore, pre- and post-structural variations on fermented bran were determined through scanning electron microscopy (SEM). The results show that crude fat, protein and total dietary fiber (soluble and insoluble) contents were significantly improved after fermentation. Moreover, the post-fermentation value of soluble dietary fiber was increased from 5.01 ± 0.21 to 7.2 ± 0.1%. Antioxidant activity, DPPH-RSA and ferric reducing antioxidant power values of bran samples were also enhanced through fermentation and the anti-nutritional factor, i.e., phytate, was significantly reduced from 1113.3 ± 8.5 to 283.4 ± 3.5 mg/100 g in bran samples after fermentation. Furthermore, the surface morphology of fermented oat bran shows scattering and pores, while raw oat bran shows visible aggregation in SEM micrographs. Water-holding capacity was also enhanced up to 2.11 (5.68%) after fermentation. In conclusion, the post-fermentation results revealed that yeast-induced fermentation enhanced the physicochemical, structural and antioxidant characteristics of oat bran.

Recent Developments in Fermented Cereals on Nutritional Constituents and Potential Health Benefits

Fermentation is one of the most economical and safe methods to improve the nutritional value, sensory quality and functional characteristics of raw materials, and it is also an important method for cereal processing. This paper reviews the effects of microbial fermentation on cereals, focusing on their nutritional value and health benefits, including the effects of fermentation on the protein, starch, phenolic compounds contents, and other nutrient components of cereals. The bioactive compounds produced by fermented cereals have positive effects on health regulation. Finally, the future market development of fermented cereal products is summarized and prospected.