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Abstract The volatile profiles of fresh rice noodles (FRN) fermented with pure and five commercial mixed cultures were studied by using solid phase micro extraction/ gas chromatography-mass spectrometry, electronic nose, and sensory evaluations. The main volatile compounds of FRN by pure culture included aldehydes represented by nonanal, octanal, and 2,4-Pentadienal, and alcohols represented by hexanol and 1-nonanol. Its aroma profiles showed remarkable changes during the storage time from 0 to 30 h, indicating the reduction in aldehydes and the increase in alcohols and isoamyl alcohol. Significant variations such as the types, relative amounts, and category distributions of volatile compounds were observed in FRN by five mixed cultures. The bacterial compositions of these mixed cultures were quite different, which might be responsible for the significant variations in volatile profiles. Principal component analysis on E -nose data demonstrated that FRN by Culture A, B, and C shared similar flavor, while FRN by Culture D and E possessed different aroma compared to the above three. FRN produced with pure fermentation showed the highest score in sensory evaluation, whereas FRN by mixed cultures indicated rice fragrance, light fragrance, peculiar smell, or foul smell. Graphical abstract Unlabelled Image Highlights • Aroma profiles of fresh rice noodles (FRN) fermented by various cultures were studied. • FRN volatile compounds included aldehydes, ketones, hydrocarbons alcohols, and acids. • Volatile profiles of FRN fermented by pure culture remarkably changed during storage. • FRN fermented by five mixed cultures showed obvious variations in volatile compounds. • FRN fermented with pure culture showed a superior flavor compared with mixed cultures. [ABSTRACT FROM AUTHOR]

Whole-grain brown rice might regulate obesity, and the specific mechanism could be referenced through in vitro digestion and fermentation. This study aimed to investigate the gut bacteria-modifying of brown rice gel (BRG) which was prepared by backfilled rice slurry with rice bran. Due to the existence of rice bran, compared with rice gel, BRG could inhibit starch expansion, reduce viscosity and breakdown, increase short-term aging degree, and then reduce the glycemic index of in vitro digestion from 85.79 to 72.76. Gas chromatography-mass spectrometry showed that BRG promoted the production of short-chain fatty acids after 24 h of fermentation, and the contents of acetic acid, propionic acid, and butyric acid increased to 10.84 ± 0.16, 2.86 ± 0.05, 2.68 ± 0.13 μg/mL (p < 0.05), respectively. After fermentation for 0, 6, 12, and 24 h, 16S rRNA sequencing revealed that BRG could improve the uniformity of gut microbial community and reduce its diversity, but had little effect on the richness. Notably, BRG could regulate the relative abundance of gut bacteria. At the phylum level, the ratio of Firmicutes/Bacteroidetes (F/B) decreased, which might be associated with prevention of obesity. At the genus level, it increased the beneficial bacteria Bifidobacterium and reduced the pernicious bacteria Bilophila. The results will facilitate the application of whole-grain brown rice in gel-based functional foods. [Display omitted] • Brown rice gel (BRG) reduced the glycemic index compared with rice gel. • BRG promoted the SCFAs and decreased the pH. • BRG did not change the richness of gut microbiota. • BRG regulated the relative abundance of beneficial and pernicious gut bacteria. • BRG had a potential prebiotic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Whole grains provide a variety of nutrients and bioactive substances. • Extrusion modifies the physicochemical properties of whole grains. • Consuming extruded whole grain foods could reduce the risk of chronic diseases. Whole grains (WGs) contain a variety of bioactive components and have a proven role in the control of chronic diseases. Worldwide dietary guidelines recommend increasing the intake of WGs in the diet. Extrusion is a versatile and advanced technology that is often used to develop foods with high nutritional and sensory quality. This technology is widely used in the production of WG foods, and the extrusion process can leads to a series of changes in the properties and composition of WGs. In this review, we introduce the composition of WGs and describe how extrusion affects their physicochemical properties, including their chemical composition, expansion properties, pasting properties, hydration properties, texture, color, and microstructure. Extruded WG foods (EWGFs) can significantly inhibit chronic diseases such as diabetes and obesity, as well as reducing oxidation and inflammation due to the changes in the physicochemical properties of WGs during extrusion. Therefore, extrusion is an effective method to improve the functional properties of WG foods. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a novel plant-based yoghurt with high sensory acceptance and nutrition value. Soybean and quinoa were used as the substrates, and all formulations with different substrate ratios were inoculated with lactic acid bacteria (LAB). Fermentation modified the proximate composition, and a higher content of soybean accentuated the growth of LAB. Formulated yoghurts presented a weak post-acidification, and the viability of LAB was higher than 106−7 CFU/g during a 21 days storage. Quinoa addition significantly improved the water holding capacity (WHC) and decreased the yellowness, and an increase of lightness and a decrease of WHC occurred during the storage. Compared with the plain substrate yoghurt, mixed formulation had no significant impact on textual parameters, whereas increased the liking scores in sensory evaluation. Furthermore, fermentation improved the total phenolic content (TPC), which showed a dose-dependent relationship between soybean content. Results obtained from DPPH, ABTS, hydroxyl radical scavenging assay, FRAP assay, and α-amylase, α-glucosidase and pancreatic lipase inhibition assay showed that fermentation enhanced the antioxidant capacities and digestive enzyme inhibitory activities. TPC increase and phenolic biotransformation may explain the enhancement of the nutritive values. Based on the sensory and function evaluation, the ratio of quinoa against soybean at 8:2 and 2:8 presented the best formulations. [Display omitted] • Quinoa and soybean were used to prepare plant-based yoghurt. • Mixed formulation improved fermentation and storage properties of yoghurt. • Mixed substrates enhanced textual and rheological properties of yoghurt. • Fermentation enhanced the antioxidant and digestive properties. • The ratio of quinoa against soybean at 8:2 and 2:8 presented the best formulations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lactococcus and Leuconostoc were the core bacteria of fresh fermented rice noodle. • Aldehyde, ester, alcohol, ketone were the key volatiles of fresh fermented rice noodle. • 171 pair-wise correlations among 61 volatiles and 10 bacteria were found. To clarify the discrepancy in characteristic flavor and bacteria composition of 10 fresh fermented rice noodles from southern China, the volatile and bacteria composition were determined by headspace-gas chromatography ion mobility spectrometry and 16SrRNA sequencing methods. The potential relationship between volatile compounds and bacterial composition has also been further revealed using spearman's correlation analysis. The contents of proximate composition, cooking properties and texture properties of 10 fresh fermented rice noodles exhibited significant different among them (p ＜ 0.05). The flavor analysis showed that a total of 54 compounds were detected. 1-Octen-one, ethyl 3-methylbutanoate, 3-methylbutanal, n-nonanal, hexanal, amyl acetate, ethanol and 2-pentyl furan were the key volatiles among them. The bacterial analysis showed that Leuconostoc and Lactococcus were the core bacteria at the genu level of all samples. Amyl acetate, 2-butanone and methyl-2-methylpropanoate were positively related to Lactococcus while ethanol was negatively correlated with Lactococcus. And Leuconostoc was positively related to 3-methylbutanal and acetone, while was negatively correlated with hexanal. Results indicated that key volatiles and textural properties of different fresh fermented rice noodle samples were associated with bacterial composition. [ABSTRACT FROM AUTHOR]

To identify the microorganisms that cause yellowing of high moisture rice-based food (HMRF) and select the targeted control methods is the key to delaying yellowing phenomenon during shelf-life. In this study, the yellowing fresh rice noodles was selected as the representative HMRF, and the traditional culture and sequencing technology were used to identify the dominant yellow-causing bacteria (YCB). Two thermophilic bacteria (Sphingomonas and Microbacterium) were identified, and the optimal growth temperature were 30 °C. Maintaining at 65 °C for 10 min completely inactivated Sphingomonas. The optimal sterilization combination was obtained through orthogonal experiments: treatment at 60 °C for 8 min, addition of 6% salt and 0.5% lactic acid, achieving 100% sterilization rate without affecting the quality of HMRF. The surface of HMRF inoculated with Sphingomonas was dull and appeared golden yellow compared to the control group. HMRF inoculated with Microbacterium were more reddish and yellowish in color, with a significant increase in pH but a decrease in hardness, increased the sulfur-containing volatile compounds in HMRF, as well as the bitterness and sweetness through electronic nose and electronic tongue analysis. This study isolated and identified YCB in HMRF, and optimized an effective control method, which provided a theoretical basis and an effective way to control the quality deterioration of HMRF. This is of great significance for improving the edible quality and sales safety of HMRF. • Isolation and identification of dominant yellow-causing bacteria from high moisture rice-based food. • Sphingomonas and Microbacterium were the dominant yellow-causing bacteria. • Optimization of targeted methods for controlling yellow-causing bacteria growth based on tolerance. • The impact of yellow-causing bacteria on the quality of high moisture rice-based food during storage. [ABSTRACT FROM AUTHOR]

Molecular structure of linear α-glucans (LAGs) and crystallization temperature have great effects on the thermostability and digestibility of recrystallized LAGs, but the recrystallization behaviors of LAGs in response to temperature remain unclear. Here LAGs with different lengths were prepared from amylopectin via chain elongation and debranching. Recrystallization of LAGs at 4 °C yielded B-type crystalline structure with relative crystallinity ranged from 23.7% to 46.1%. With a chain length of 40.2, an A-type allomorph was observed for a slow recrystallization at 50 °C. Differential scanning calorimetry suggested that A-type crystal had a higher thermostability than the B-type crystal, and increasing LAGs' chain length improved the dimension of double helices, whose assembly produced starch crystallites that enhanced the thermostability and decreased the in vitro digestibility of recrystallized LAGs. An improved thermostability of recrystallized LAGs preserved their ordered structures and kept the resistance to digestive enzymes, with a RS content up to 75.4%. • Linear α-glucans (LAGs) with different chain lengths were prepared. • A-type pattern was formed when short LAGs recrystallized at 50 °C. • Increasing LAGs' chain length enlarged the dimension of double helices. • Resistant starch of LAGs correlated positively with gelatinization temperatures. [ABSTRACT FROM AUTHOR]

Complex gels of fermented indica rice starch (FIRS) and soybean protein isolate (SPI) (0%–12%) were prepared to investigate the relationship between gel characteristics and digestive properties. During the co-gelatinization process, adding 9% SPI increased the resistant starch content from 19.83% to 30.43%, and the glycemic index decreased from 78.05 to 67.34, meaning that the glycemic index of the system changed from high to medium. Gel characteristics showed that 3% SPI enhanced the gel strength of FIRS, concurrently impeding water absorption capacity and reducing solubility. Moreover, adding SPI improved the gelatinization stability of FIRS (pasting temperature increased and breakdown decreased significantly, P < 0.05). Analysis of rheological properties revealed that hydrophobic, hydrogen bonding, and electrostatic interactions were at play between FIRS and SPI, with the hydrophobic interaction being the most prominent. Fractionation of SPI into its 11S and 7S globulin components and subsequent testing of FIRS–globulin mixtures demonstrated that 11S contributed to hydrophobic interactions and 7S contributed to hydrogen bonding, thus affecting viscoelasticity and starch order (short-range and long-range structures). Collectively, these findings suggest that SPI hinders the digestion of FIRS through hydrophobic interactions and the inhibition of gelatinization. [Display omitted] • SPI inhibited water swelling of FIRS and improved its gel stability. • SPI was bound to FIRS mainly through hydrophobic bonds. • SPI lowered the glycemic index of FIRS. • The 7S and 11S components of SPI were related to non-covalent interactions. • SPI inhibited FIRS digestion by affecting its gel structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • LAB co-fermentation effectively improved flavor characteristics of jujube juice. • Essential amino acids of jujube juice were enhanced by LAB co-fermentation. • LAB co-fermentation enriched carboxylic acids and their derivative metabolites. • Key aroma compounds (pentanal, nonanal, etc) were correlated with D -galacturonate. Lactic acid bacteria (LAB) fermentation can enhance the quality and flavor characteristics of fruit juice. Herein, the impact of individual Lactiplantibacillus plantarum subsp. plantarum (L. plantarum) or Streptococcus thermophilus (S. thermophilus) and co-fermentation of them on jujube juice was compared, and their quality characteristics, volatile and non-volatile compounds were investigated. The results showed that the co-fermentation of selected LAB strains effectively improved the quality of fermented jujube juice (FJJ) as expected, and the types and content of volatile organic compounds (VOCs) increased in FJJs. Among them, the co-fermented sample posed relatively high content of aroma-active compounds with OAV ≥1 (nonanal, decanal, etc), benzaldehyde and acids compared with others, contributing to a more attractive and pleasant flavor. Moreover, non-targeted metabolomic analysis identified 114 and 79 differential metabolites (DMs) between co-fermented and L. plantarum fermented or S. thermophilus fermented samples, respectively. Notably, carboxylic acids and their derivative metabolites as well as organic acids were the crucial components affecting the quality of FJJ. Furthermore, metabolic pathways of DMs of different samples were predominantly enriched in "biosynthesis" and "metabolism", such as aline, leucine, and isoleucine biosynthesis pathway. Therefore, co-fermentation could enrich the acids, essential amino acid, and VOCs, thereby improving its quality and flavor characteristics. The correlation analysis revealed that most of key VOCs were positively or negatively correlated with D -galacturonate, indicating the importance of D -galactose pathway. Thus, this study provided a theoretical foundation for enhancing the quality and flavor of jujube juice through LAB co-fermentation, offering valuable insights for improving the juice processing. [ABSTRACT FROM AUTHOR]

Abstract: The effects of ionic strength on heat-induced aggregation of soy protein and phase separation of different soy protein aggregates with dextran were investigated. The increase of ionic strength accelerated protein aggregation as shown by an increase in turbidity, aggregate fraction and particle size of salt-induced aggregates (SA). Adding salt (NaCl) to the aggregates formed at the ionic strength of zero (non-salt aggregates, non-SA), the increase of aggregate size was also found. Zeta potential results evidenced the charge screening effects of NaCl. The results of phase diagrams indicated that the compatibility of mixtures at higher ionic strength was lower than those at lower ionic strength, and SA was more incompatible with dextran than non-SA. The effects of the increase of aggregate size on the phase separation outweighed the ionic strength, which indicated that the depletion interaction also played an important role in the phase separation of soy protein aggregates and dextran. CLSM (Confocal Laser Scanning Microscopy) and rheological observations provided additional information of the microstructures of the mixtures. [Copyright &y& Elsevier]

Retrogradation of fresh rice noodles (FRNs) is detrimental to the customers' acceptance of these rice products. In this study, combined experimental analysis and molecular dynamics simulation were used to explore the mechanism underlying soybean protein isolate (SPI, 0–12%) inhibiting the retrogradation of FRNs. The FRNs showed fast retrogradation and hardening at the 1st day, whereas the aging rate was slowed down in the presence of SPI during the 5-day storage. This was due to that SPI increased the water-holding capacity and buffered the acidity of the system. Differential scanning calorimetry showed that SPI prevented the formation of ordered starch structures during retrogradation. From the results of molecular dynamics simulation, it was found that 7S of SPI could reduce the deformation degree of starch to a lower extent than 11S in the gelatinization process at 95 °C. However, 11S elicited stronger non-covalent interactions with starch than 7S during retrogradation at 4 °C, thus stabilizing starch structures and inhibiting retrogradation of FRNs. Our study illustrated a facile approach to inhibit the retrogradation of FRNs, which would properly broaden the application scenarios of traditional products with enhanced shelf life and taste attributes. [Display omitted] • SPI inhibited the retrogradation of fresh rice noodles. • MD simulated starch-protein behavior at 95 °C and 4 °C. • SPI slowed down starch gelatinization, heating disorder and cooling ordering. • 7 S could better inhibit the starch deformation under 95 °C simulation. • 11 S was more stable at 4 °C because of strong non-covalent bonds with starch. [ABSTRACT FROM AUTHOR]

• Enzyme hydrolysis and water-washing give high cellulose, hemicellulose, and lignin. • Cellulase modification decreased cellulose and increased lignin content of rice bran dietary fiber. • Changes of fiber properties after cellulase modification attributed to increased porosity. • Changes of fiber properties after cellulase modification attributed to reduced crystallinity. • Changes of fiber properties after cellulase modification attributed to changes of chemical composition. Rice bran dietary fiber (ERBDF) subjected to pre-water-washing and complex enzyme treatment using heat-stable α-amylase, alcalase, and glucoamylase had significantly higher (p < 0.05) proportions of cellulose, hemicellulose, lignin, and lower proportions of lipid, protein, and starch than rice bran dietary fiber subjected to complex enzyme treatment without pre-water-washing. Cellulase modification of ERBDF significantly decreased (p < 0.05) cellulose, hemicellulose, starch, and protein contents while the relative lignin content increased. Cellulase modification significantly improved (p < 0.05) water-holding capacity, oil-holding capacity, swelling capacity, cholesterol absorption capacity, and glucose adsorption capacity, while decreasing the emulsifying capacity and glucose dialysis retardation index. The changes of physicochemical and functional properties of fiber samples after cellulase modification were attributed to the increased porosity of the fiber surface, greater exposure of binding sites caused by reduced crystallinity, and changes to the chemical composition. [ABSTRACT FROM AUTHOR]

• Activities of PMRGGGGYHY's active sites are affected by intramolecular interaction. • Designed peptides by QM and MM calculations possess stronger antioxidant activity. • Structure, HOMO and interaction with radical affect antioxidant activity. The sequence and structure of antioxidant peptides play fundamental roles in their antioxidant functions. However, the structural mechanism of antioxidant peptides is still unclear. In this study, we used quantum calculations to reveal the antioxidant mechanism of the peptide PMRGGGGYHY. PMRGGGGYHY has multiple antioxidant active sites, and two tyrosine residues were determined to be the major active sites. Based on the structure-activity relationships of PMRGGGGYHY, the antioxidant activity of the modified peptide significantly improved by 4.8-fold to 9.73 ± 0.61 μmol TE/μmol. In addition, the removal of glycine residues from PMRGGGGYHY would increase the energy of the HOMOs and simplify the hydrogen bonding network, causing a significant increase in antioxidant activity. The intracellular ROS scavenging ability gradually decreased with decreasing glycine content. This same peptide has very different effects in vitro versus as a cellular antioxidant. This paper provides new insights into the structural mechanism and rational design/modification of novel antioxidant peptides. [ABSTRACT FROM AUTHOR]

• Rice bran (RB) and wheat bran (WB) were fermented with Lactobacillus plantarum 423. • RB and WB fermented with L. plantarum 423 had enhanced odor intensity. • RB and WB fermentation broths had perfect hydroxyl radical scavenging activity. • The antioxidant fractions from WB fermentation broth showed strong ROS-scavenging activity. • The dominant antioxidant components in RB and WB fermentation broths were acids and ketones. Rice bran (RB) and wheat bran (WB) fermented with L. plantarum 423 had enhanced odor intensity, especially for sulfides and aromatics. The hydroxyl radical-scavenging activity (73.28 ± 3.18%) and oxygen radical-scavenging activity (2.12 ± 0.08 mmol·TE/g) of RB fermentation broth were better than those of WB fermentation broth. Even at 2 μg/ml, the purified antioxidant fractions from the WB fermentation broth showed strong intracellular ROS-scavenging activity in human umbilical vein endothelial cells (HUVECs), and the purified antioxidant fractions (200 μg/ml) from the RB fermentation broth had a good antiaging effect. The dominant antioxidant components in the RB and WB fermentation broths were acids (70.21%) and ketones (10.64%), these components jointly give the RB and WB fermentation broths a variety of antioxidant properties. These results are beneficial for developing RB and WB deep-processing technology and laid the foundation for the preparation of antioxidant fractions with L. plantarum 423. [ABSTRACT FROM AUTHOR]