In this study, Glutinous rice (GR), Japonica rice (JR), and Indica rice (IR), with amylose contents at 1.57 ± 0.18%, 15.88 ± 1.16%, and 26.14 ± 0.25%, respectively, were selected to reveal the role of amylose in the gel forming of rice flours. The strength and elasticity of the associated gels were found in an ascendant order with the increase in amylose content. For the retrograded gels (at 4 °C for 7 days), the peak temperature (Trp) was positively related to the amylose content. In general, Trp of IR increased to 63.21 ± 0.13 °C, and the relative crystallinities of IR were in the top ranking at 10.67 ± 0.16%, followed by those of JR and GR. The relative amounts of short-range ordered structures to amorphous regions in JR and IR were also higher than that of GR, and the number of compact network structure were positively related to the amylose content. These results indicated that amylose can enhance the strength and elasticity of gels by facilitating the formation of crystalline, short-range ordered, and compact network structures. These results can provide a reference for the development of rice products.

One of the major issues in the food sector is the lack of resource utilization and the contamination of the environment caused by by-products. This study aimed to investigate the effects of Ganoderma lucidum (GL) fermentation on the nutritional components, structural characterization, metabolites, and antioxidant activity of soybean residue (SR), sweet potato residue (SPR), and zanthoxylum pericarpium residue (ZPR). The results showed that the nutrient contents of SR, SPR and ZPR increased. The active substances, amino acids (umami, aromatic and basic), metabolites and antioxidant activity (DPPH, ABTS, FRAP) (SR and SPR increased by 11.43, 32.64, 40.19 μmol Trolox/100 g and 19.29, 17.7, 32.35 μmol Trolox/100 g, respectively) of SR and SPR were increased. However, the results of ZPR showed a decrease in the content of bioactive substances, amino acids, and antioxidant activity. The results show that using GL fermentation can provide novel ideas and theoretical basis for improving SR and SPR to obtain new raw materials for antioxidant products.

In this study, we investigated the effect of thermally assisted potassium carbonate treatment sweet potato residue (TAPC-SPR) and its addition (0%, 5%, 10% and 15%) on the texture, multi-scale structure (microstructure, crystalline structure, short-range ordered structure) and in vitro starch digestibility of the noodles. The results demonstrated that the ratio of total dietary fiber (TDF) (75.62%-87.25%) and pectin (19.36%-23.36%) were increased, and the particle size distribution (175.67 & mu;m-47.42 & mu;m) was decreased in TAPC-SPR than sweet potato residues (SPR). This study suggested that suitable TAPC-SPR (5% and 10%) contributed to improving the texture properties of noodles, containing hardness, springiness, chewiness and adhesiveness. Sensory evaluation showed that noodles with suitable TAPC-SPR (5% and 10%) had an overall sensory acceptability relative to control. In addition, the intermolecular hydrogen bond interaction, the structure order, V-type starch complex and dense structure were observed. These structural changes limit the interaction of amylase with starch, elevate the resistant starch (RS) content, and lower the predicted glycemic index (pGI).

The antioxidant activity of Auricularia polytricha is associated tightly with its polysaccharide concentration, molar mass and architecture. This study aims to explore the differences in structural and physicochemical traits and oxidation resistances between the polysaccharides from fruit body (ABPs) and mycelial (IAPs) of Auricularia polytricha. The results showed that ABPs and IAPs were constituted by glucose, glucuronic acid, galactose and mannose. However, the molecular weight distribution of IAPs (3.22 × 104 Da (52.73%) and 1.95 × 106 Da (24.71%)) was wider than that of ABPs (5.4 × 106 Da (95.77%)). The shear-thinning performance and viscoelastic behavior of both IAPs and ABPs are representative. IAPs are scattered in sheets, with folds and holes, and have a triple helix structure. ABPs are compact in structure and clear in texture. The main functional groups and thermal stability of both polysaccharides were similar. Concerning the in-vitro oxidation resistance, both of the studied polysaccharides exhibited the potent potential to scavenge hydroxyl radicals (IC50 = 3.37 ± 0.32 and 6.56 ± 0.54 mg/mL, respectively) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals (IC50 = 0.89 ± 0.22 and 1.48 ± 0.63 mg/mL, respectively), as well as the moderate reduction power. In addition, IAPs and ABPs were both completely undigested in simulated contexts of saliva, small intestine and stomach, and the two polysaccharide types maintained high DPPH and hydroxyl radical scavenging activities. DDPH scavenging rate during digestion was positively correlated with uronic acid content. To conclude, this study suggests the potential of IAPs as an equivalent alternative to ABPs.

The differences in structural and physicochemical traits and oxidation resistances between the fruit body (ABPs) and mycelial polysaccharides (IAPS) of Auricularia polytricha were explored in this study. ABPs and IAPs were constituted by glucose, glucuronic acid, galactose and mannose. The molecular weight distribution of IAPs was wider than that of ABPs. IAPs are scattered in sheets, with folds and holes, and have a triple helix structure. ABPs are compact in structure and clear in texture. The main functional groups and thermal stability of both polysaccharides were similar. Both of the studied polysaccharides exhibited potent hydroxyl radical eliminating potential and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical eliminating potential. In addition, decomposition of IAPs and ABPs was impossible in simulated contexts of saliva, small intestine and stomach, and the two polysaccharide types maintained high DPPH and hydroxyl radical scavenging activities. DDPH scavenging rate during digestion was positively correlated with uronic acid content.

SummaryIn this study, the ultrafine grinding (UG) and high pressure homogenization (HPH) treated slurry on the particle size and rheological property of slurry, texture, in vitro starch digestibility, and multiscale structure of steamed rice bread (SRB) were investigated. Then, it was found that the average particle size of slurry treated by UG and HPH reduced from 84.6 to 38.6 μm and 22.6 μm, respectively. The rheological properties results demonstrated that G′ resulted in higher values than G″, and that the values of G′, G″ and tan δ of slurry decreased obviously after UG and HPH treatment. Obviously, the hardness and viscidity of SRB made by UG and HPH were lower, while the elasticity and specific volume were higher. The determination of in vitro starch digestibility revealed that UG treated on slurry accelerated the starch hydrolysis rate of SRB, resulting in an increase in the pGI from 76.17 to 79.36, while HPH treatment reduced the pGI from 76.17 to 73.49. Furthermore, XRD and FTIR demonstrated that both UG and HPH increased the intermolecular hydrogen bonds, and both treatments also assisted in starch arrangement for increasing the ordered crystallization of starch, which may contribute to the increasing amylose content.

Summary This research aims to monitor the modori of fermented fish sausage and determine the effect of endogenous cathepsins. Proteolysis, structure and physico‐chemical properties of carp sausage were determined using texture profile, rheological, SEM, FTIR and SDS‐PAGE, respectively. In the forming stage of gels, the rapid reduction in pH dropped below 5.16 within 36 h of fermentation. Meanwhile, the hardness (g), elasticity, Chewiness (mJ) and gumminess increased. The results of elasticity modulus (G′) exhibited strong correlation with TPA. Gels presented a three‐dimensional network structure at 36 h. In the degradation stage of gels, the increase of TVB‐N, TCA‐soluble peptides and FAAs indicated that muscle proteins were strongly degraded. SDS‐PAGE demonstrated that the degradation of insoluble protein was coincided with the modori of gels. During fermentation, cathepsin B (CPB) and cathepsin L (CPL) exhibited high activity, while cathepsin D (CPD) revealed low activity. β‐ sheet and α‐ helix increased to 1.07 and 1.05 times of the initial value ( P > 0.05), while random coil and β‐turn dropped to 10.27% and 21.98%, respectively. PCA suggested that acids played a major role in the formation of gels and that CPB and CPL were closely related to the modori of gels. Moreover, this study provided theoretical guidance for controlling the formation and inhibiting the modori of fish sausage gel.

To explore the effect of commercial Saccharomyces cerevisiae on the quality of traditional "Wanergao" for reasonable consuming guidance, the dominant microbes, physicochemical property, free amino acid content, texture, and sensory properties during fermentation of "Wanergao" were illustrated in this paper. Compared with the samples in the control group, "Wanergao" samples in the two groups that were subjected to S. cerevisiae inoculation had weaker acidity (the pH values dropped from 4.39 ± 0.08 to 4.36 ± 0.07 and 4.36 ± 0.07 within 2 h during fermentation), higher fermenting rate (volume increased from 100 ± 1.31 to 305 ± 4.61 and 316 ± 4.93 mL separately within 3 h), and the dominant lactic acid bacteria and yeast being leukonid and S. cerevisiae. More amylose, ethanol, and free amino acid were detected in "Wanergao" produced with S. cerevisiae inoculation compared with "Wanergao" produced by sourdough. The two kinds of "Wanergao" presented various hardness (2318 ± 112, 2279 ± 103), springiness (0.76 ± 0.03, 0.71 ± 0.03), chewiness (1.43 ± 0.05, 1.41 ± 0.06), and cohesiveness (0.68 ± 0.03, 0.62 ± 0.03) after fermentation. The result of sensory analysis revealed that "Wanergao" in the S. cerevisiae group had higher elasticity, aroma, and restoring force. The experiment demonstrated that "Wanergao" produced by using S. cerevisiae is a kind of fermented rice product with rich fragrance, high amount of nutrients, and strong elasticity.

Starch structure and digestibility strongly depends on food composition during rice bread processing. This study investigates the effect of okara (0%, 7%, 14%, 21%) on the texture, in vitro starch digestibility, and multiscale structure (i.e. granule, crystallites, and short-range order) of steamed rice bread (SRB). Texture profile analysis results demonstrated that okara increased the elasticity and viscidity and reduced the hardness, cohesiveness, and chewiness of SRB. The addition of okara increased amylose content, slowly digestible starch (SDS), and resistant starch (RS) of SRB significantly, thereby reducing the predicted glycemic index (pGI) from 79.14 to 74.17–68.91. Meanwhile, SEM results showed that addition of 7% okara promoted the formation of the porous space starch–gel network structure in the SRB while 21% okara produced rougher surfaces and increased bread matrix density. XRD and FTIR revealed that suitable amounts of okara (<14%) assisted in starch arrangement while others (21%) reduced the ordered crystallization of starch. Results showed that the enhanced intermolecular hydrogen bonding between okara and water enhanced the viscosity and gas retention of SRB, thereby enabling the starch to retain more gas and form a loose starch gel structure spatial network. Furthermore, the addition of okara changed the multiscale structural and amylose contents when the SDS and RS contents are high and the pGI is low. As a result, the action sites of amylase can be shielded effectively to restrict the interaction of amylase with starch. Thus, this research suggests a potential approach in which rice complexed with okara can modify the texture and starch digestibility of SRB.

Abstract The objective of this study was to explore the effect of red kojis on essential indices of Wanergao. The results showed that red koji‐inoculated Wanergao showed higher pH values (4.38 ± 0.06 and 4.39 ± 0.06) and lower TA values (1.61 ± 0.05 and 1.63 ± 0.05) compared to the control group. LAB and yeast in the starter culture group gradually increased to 7.57 ± 0.12, 7.64 ± 0.15 log cfu.g−1 and 8.59 ± 0.21, 8.64 ± 0.23 log cfu.g−1, respectively. During fermentation, the dominant microorganism was Lactobacillus plantarum and Saccharomyces cerevisiae. Compared to the Wanergao made using traditional backslopping, the red koji‐inoculated Wanergao contained more amylases, EAA and DAA contents compared to the control sample. The red kojis and control samples presented different hardness, chewiness, and cohesiveness, as well as similar values in springiness, gumminess, and adhesiveness. Sensory analysis also showed higher chewiness aroma and resilience of Wanergao in the starter culture group than in the control group.

This study aims to investigate the technological properties of yeast strains isolated from traditional low-salt fermented Suan yu fish as starter culture. A step-by-step approach was used to determine the technological properties of the isolated yeast strains. The enzymatic activity (catalase, urease, beta-glucosidase, protease, and lipase) under adverse conditions (pH, salt, and temperature) were evaluated. Principal component analysis was used to assess data. Twenty-five strains with desirable technological properties were selected for evaluation of probiotic traits (tolerance at pH 2.5 and 0.3% bile salts, antimicrobial activity, hydrophobic properties, and biofilm production). These isolates were identified by sequencing the D1/D2 region of 26S rDNA. Finally, seven isolates with desirable probiotic traits were analyzed for their ability to survive through gastric transit using a gastrointestinal simulation model. An In vitro test showed that isolates 3, 12, 19, 24, and 43 exhibited high survival levels (60%-70%), similar to those of the indicator strain (Saccharomyces cerevisiae). The results suggest that five isolates (S. cerevisiae strains 3, 12, 19, 24, and 43) showed desirable technological properties and probiotic traits and therefore can be used as functional starter cultures to produce fermented fish products. Practical applications Researchers have investigated the activity of LAB as functional and probiotic microorganisms; however, information on the probiotic potential of yeasts remains limited. Yeasts are microorganisms that present and induce biochemical changes in several fermented meat and fish products. In the present study, the technological and probiotic properties of 52 isolates from Suan yu were investigated to identify potential probiotic strains for starter cultures. Our results suggest that five isolated S. cerevisiae strains showed desirable technological properties and probiotic traits and therefore can be used as functional starter cultures to produce fermented fish products, and other fermented foods. Functional yeast isolates are used to effectively improve the quality of fermented fish products for consumer acceptance. This study has focused on the possibility to produce a functional Suan yu using a potential probiotic S. cerevisiae as starter culture to enhance health benefits.