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Summary: Brown rice‐based foods are thought to be effective in preventing obesity. In this study, the effect of whole‐grain flat rice noodles (WFRN) on lipid metabolism as well as their relationship with gut microbiota was investigated in mice fed a high‐fat diet (HFD). The results indicated that WFRN reduced the degree of obesity, the lipid levels in the liver and serum, and the risk of liver inflammation. Moreover, WFRN significantly increased the contents of total short‐chain fatty acids (SCFAs) (from 162.06 ± 29.79 to 272.97 ± 59.26 μg mL−1; P < 0.05) and reshaped the composition of gut microbiota in mice cecum. As the beneficial bacteria with boosted abundance, higher Coriobacteriaceae_UCG‐002 was negatively related to the lipid levels in the liver and serum, and positively correlated with the content of hexanoic acid. On the contrary, the lower abundance of harmful bacteria Staphylococcus was positively correlated to body fat and inversely related to isovaleric acid, and Helicobacter was positively associated with higher serum LDL‐C and lower hexanoic acid. This study suggested that WFRN played a positive role in ameliorating lipid accumulation and inflammation caused by obesity, and this effect was closely associated with the regulation of gut microbiota and SCFAs. [ABSTRACT FROM AUTHOR]

Summary: Brown rice noodles (RN) are typical whole‐grain products with health benefits. This study investigated the effects of rice bran fermented with Lactobacillus plantarum on palatability, volatile profiles, and antioxidant activity of brown RN. Three kinds of RN, including RN, brown RN (BRN), and bran fermented RN (BFRN), were involved in this study. The results indicated that bran fermentation reduced the cooking loss of BFRN and improved the elongation and the sensory attributes of brown RN. After fermentation, aldehydes were significantly decreased while alcohols increased, and more pleasant flavours were shown in BFRN. Fermentation increased the content of free phenolics and decreased the content of bound phenolics. Among the four major phenolics detected in this study, ferulic acid was the most abundant one in all three RN samples. The DPPH radical scavenging activity and the ferric reducing antioxidant power of free phenolics in BFRN increased significantly compared to BRN. This study proved that rice bran fermentation is an effective approach to improve palatability, enrich the flavour as well as enhance the antioxidant activity of brown RN, which may facilitate the development of processing technology for brown RN. [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]

Starch is the largest component in frequently consumed fresh rice noodles (FRN). The effects of morphology, relative crystallinity, molecular weight distribution and physicochemical (rheological, water hydration and gel texture) properties of starch from five rice cultivars with different amylose contents on the formation of FRN were investigated. FRN made from NR rice cultivar, used for commercial rice noodles making, showed excellent FRN texture. NR starch exhibited larger G′ and smaller tan δ values. The morphology of FRN from GM03 cultivar was closest to NR, but had higher hardness and lower springiness, resilience and cohesiveness. Its starch granules morphology was relatively small and round. The extracted starch from Zhongzao 35, Zao 87 and BX02 rice cultivars, with higher swelling power or lower proportions of amylose (FrI) and higher proportions of amylopectin (FrII), could not produce a dense and consistent FRN structure. It was observed that relative crystallinity of the starch samples had no influence on the formation of FRN. Nevertheless, the gel texture of starch played a role in the formation of FRN. The formation of FRN is the common effect of structure and physicochemical properties of rice starch. The finding of this research would be useful in understanding the role of starch in producing FRN of high quality. [Display omitted] • Both amylose and amylopectin affected the formation of the fresh rice noodles. • Larger storage modulus and smaller loss tangent led to more favorable noodle texture. • Higher swelling power of starch did not favor fresh rice noodles formation. • The texture of starch gels has a positive effect on the formation of noodle structure. [ABSTRACT FROM AUTHOR]

To investigate the effect of soy protein isolate on the quality of whole-grain flat rice noodles, the texture as well as the cooking properties and flavor of flat rice noodles, whole-grain flat rice noodles and whole-grain flat rice noodles with soy protein isolate were investigated. Among the three tested rice noodles, whole-grain flat rice noodles with soy protein isolate showed the highest cohesiveness, adhesiveness, resilience, and springiness. Compared to the flat rice noodles and whole-grain flat rice noodles, whole-grain flat rice noodles with soy protein isolate increased their moisture content and water absorption, whereas the opposite trend was observed for their cooking loss. The electronic nose analysis showed stronger response values at W5S, W1W, and W2W. Solid phase micro extraction and gas chromatography–mass spectrometry results showed that aldehydes are the main volatile compounds in whole-grain flat rice noodles and whole-grain flat rice noodles with soy protein isolate. Moreover, seven more volatile compounds were detected in whole-grain flat rice noodles with soy protein isolate compared to flat rice noodles and whole-grain flat rice noodles. The whole-grain flat noodles with the addition of SPI are more sensory acceptable. Thus, soy protein isolate, as a natural and safe additive, could be used to improve the quality and enrich the flavor of whole-grain flat rice noodles. [ABSTRACT FROM AUTHOR]

The physicochemical properties and starch fine structure change during paddy storage, which may be beneficial for the qualities of rice-based products such as fresh rice noodles (FRN). In this study, the textural properties of FRN prepared from polished rice of six indica paddy cultivars after different storage period at 36 ± 2 °C and 85% ± 5% relative humidity were investigated. The pasting properties, solubility (S), swelling power (SP) of rice flour and morphology of the starch granules, chain length distribution of amylopectin were analyzed to determine factors that impact the texture of FRN. The chewiness and springiness of FRN increased, and the adhesiveness decreased with increase in storage duration. The setback (SB) and pasting temperature (PT) increased while the S and SP decreased with extension of storage duration (0–90 days). Chain length distributions of amylopectin also changed. Pearson correlation analysis revealed that cool paste viscosity (CPV) of indica rice flour, short chain (DP 6–12) and long chain (DP 37–60) of amylopectin were the most correlated parameters with adhesiveness of FRN. Our results may provide insights for selecting raw materials for production of high-quality FRN. • Pasting properties, solubility and swelling power of rice changed with storage time. • Starch fine structure of different cultivars varied during storage. • Texture profiles of fresh rice noodles depend on storage time and rice varieties. • Cool peak viscosity of rice strongly corelated with adhesiveness of rice noodle. • Chain length of amylopectin strongly corelated with adhesiveness of rice noodle. [ABSTRACT FROM AUTHOR]

The study investigated the correlations between microbial compositions and volatile profiles of six mixed culture rice noodle fermentation liquid (RNFL) samples labelled by YI, XX, HL, XL, KJ, and JJ, respectively. Through 16S rRNA high-throughput sequencing technology (HTS), the main microbial genera identified in RNFL samples were Lactobacillus , Burkholderia , Gluconacetobacter , Lactococcus , and Leuconostoc (≥5% of operational taxonomic units). A total of one hundred and ten volatile compounds were detected by using SPME/GC-MS. E-nose data showed that HL, XX, and JJ shared similarities in flavor characteristics. Correlation analysis between bacterial genus and volatile compounds indicated that Lactobacillus and Gluconacetobacter were strongly correlated with most flavor compounds detected. Moreover, YI and XX had higher fragrance scores in sensory evaluation, indicating thicker fermented rice fragrance than other RNFL samples. • Microbial compositions of rice noodle fermentation liquid (RNFL) were analyzed. • Five bacterial species were identified as the main microbial genera in RNFL. • Correlation between microbial compositions and volatile profiles were investigated. • Lactobacillus and Gluconacetobacter were strongly associated with aroma profiles. [ABSTRACT FROM AUTHOR]

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]

This study isolated four strains of Bacillus from slimy fresh rice noodles (FRN) and preliminary identified them as B. cereus , B. amyloliquefaciens , B. altitudinis , and B. subtilis , respectively, using morphological, physiological, and genetic analyses. The spoilage potential of each of these strains was then evaluated in FRN. The results indicated that both B. amyloliquefaciens and B. subtilis can cause FRN to become sticky and smelly, accompanied by an increase of acidity and high amylase activity. B. cereus and B. altitudinis mainly caused odor deterioration of FRN. There were 29, 20, 25, 25, and 27 volatile organic compounds (VOCs) identified from control FRN and FRN samples inoculated with B. cereus , B. amyloliquefaciens , B. altitudinis , and B. subtilis , respectively. The compositions of VOCs in the samples inoculated with B. amyloliquefaciens and B. subtilis were similar; esters, volatile organic acids, and acetoin were the main volatile compounds in the FRN. For B. cereus and B. altitudinis , the main adverse flavor substances were acetic acid and ammonia. This study provides a theoretical basis for quality control in the production, storage, and sale of FRN. • Four Bacillus strains isolated and identified from slimy fresh rice noodles (FRN). • Four strains were preliminary identified as B. cereus , B. amyloliquefaciens , B. altitudinis , and B. subtilis. • B. amyloliquefaciens and B. subtilis can cause FRN to become sticky and smelly. • B. cereus and B. altitudinis mainly caused odor deterioration of FRN. [ABSTRACT FROM AUTHOR]