Effects of Lactobacillus combined with semidry flour milling on the quality and flavor of fermented rice noodles

Exploring Core fermentation microorganisms, flavor compounds, and metabolic pathways in fermented Rice and wheat foods

The unique flavors of fermented foods significantly influence consumer purchasing choices, prompting widespread scientific interest in the flavor development process. Fermented rice and wheat foods are known for their unique flavors and they occupy an important place in the global diet. Many of these are produced on an industrial scale using starter cultures, whereas others rely on spontaneous fermentation, homemade production, or traditional activities. Microorganisms are key in shaping the sensory properties of fermented products through different metabolic pathways, thus earning the title "the essence of fermentation." Therefore, this study systematically summarizes the key microbial communities and their interactions that contribute positively to iconic fermented rice and wheat foods, such as steamed bread, bread, Mifen, and rice wine. This study revealed the mechanism by which these core microbial communities affect flavor and revealed the strategies of core microorganisms and related enzymes to enhance flavor during fermentation.

Developing high resistant starch content rice noodles with superior quality: A method using modified rice flour and psyllium fiber

The effects of high-resistant starch (RS) content rice flour, psyllium husk powder (PHP), and psyllium powder (PP) on the edible quality and starch digestibility of rice noodles were investigated in this study. High-RS rice noodles showed lower digestibility but poor edible quality. With the addition of PHP and PP, high-RS rice noodles' cooking and texture quality were improved significantly, especially the breakage rates, cooking losses, and chewiness (P < 0.05). Compared to traditional white rice noodle's estimated glycemic index (eGI) of 86.69, the eGI values for 5PHP-RN and 5PHP-2PP-RN were significantly decreased to 66.74 and 65.77, achieving a medium GI status (P < 0.05). This resulted from the high amylose and lipid content in the modified rice flour and psyllium, leading to increase of starch crystallinity. Besides, based on the analysis of Pearson's correlation, it can be found that PHP rich in insoluble dietary fiber (IDF) could improve high-RS noodle cooking and texture quality better, while PP rich in soluble dietary fiber (SDF) can further reduce the RDS content and its starch digestibility. Therefore, utilizing modified rice flour with an appropriate addition of PHP and PP can be considered an effective strategy for producing superior-quality lower glycemic index rice noodles.

Intensification of rice flour gel structure by fermenting corresponding rice with Lactobacillus plantarum

In starch gel foods processing, lactic acid fermentation is an effective strategy to improve the quality of the gel. This study revealed the effects of Lactobacillus plantarum fermentation for rice on the textural and rheological properties of the corresponding gels. The hardness, adhesiveness and chewiness of the gel showed ascending trends with the forwarding of fermentation. The role of Lactobacillus plantarum on rheological properties of gel depended on fermentation time. As the time was within 3 days, the process reduced the viscoelastic of the gel, while as the time was for 5 days, the process enhanced the viscoelastic of the gel. During fermentation, amylose content increased from 21.56 ± 1.17% to 27.39 ± 0.63%, and crude protein content descended from 12.60 ± 0.44 g/100 g DW to 4.8 ± 0.49 g/100 g DW. Total organic acids were ascending in the whole process, and lactic acid (LA), acetic acid (AA) and citric acid (CA) made the dominant contribution. The enthalpy change (ΔH) of the rice flour fermented for 5 days was significantly (p < 0.05) increased to 9.90 ± 0.24 J/g, indicating the formation of more double helix structures. These organic acids may contribute to the formation of the pores on the surface of granules by hydrolyzing the components, which provides a channel for enzymes to enter the interior of granules. These results provide the basis for the development of fermented rice-based foods.

A review of the effects of fermentation on the structure, properties, and application of cereal starch in foods

Fermentation is one of the oldest food processing techniques known to humans and cereal fermentation is still widely used to create many types of foods and beverages. Starch is a major component of cereals and the changes in its structure and function during fermentation are of great importance for scientific research and industrial applications. This review summarizes the preparation of fermented cereals and the effects of fermentation on the structure, properties, and application of cereal starch in foods. The most important factors influencing cereal fermentation are pretreatment, starter culture, and fermentation conditions. Fermentation preferentially hydrolyzes the amorphous regions of starch and fermented starches have a coarser appearance and a smaller molecular weight. In addition, fermentation increases the starch gelatinization temperature and enthalpy and reduces the setback viscosity. This means that fermentation leads to a more stable and retrogradation-resistant structure, which could expand its application in products prone to staling during storage. Furthermore, fermented cereals have potential health benefits. This review may have important implications for the modulation of the quality and nutritional value of starch-based foods through fermentation.

Further Interpretation of the Volatile, Microbial Community and Edible Quality of Fresh Fermented Rice Noodles with Different Selected Strains

Understanding bacteria and yeasts can reduce unpredictable changes in fresh fermented rice noodles (FFRN). The effects of selected strains (Limosilactobacillus fermentum, Lactoplantibacillus plantarum, Lactococcus lactis and Saccharomyces cerevisiae) on the edible quality, microbial community, and volatile component of FFRN were studied. The results indicated that the fermentation time could be shortened to 12 h when Limosilactobacillus fermentum, Lactoplantibacillus plantarum, and Lactococcus lactis were added, whereas it still required approximately 42 h after adding Saccharomyces cerevisiae. Only a steady bacterial composition was provided by adding Limosilactobacillus fermentum, Lactoplantibacillus plantarum, and Lactococcus lactis, and only a steady fungal composition was provided by adding Saccharomyces cerevisiae. Therefore, these microbial results indicated that the selected single strains cannot improve the safety of FFRN. However, the cooking loss was decreased from 3.11 ± 0.11 to 2.66 ± 0.13 and the hardness of FFRN was increased from 1186 ± 178 to 1980 ± 207 when it was fermented with single strains. Finally, a total of 42 volatile components were determined by Gas chromatography-ion Mobility Spectrometry and 8 aldehydes, 2 ketones, and 1 alcohol were added during the entire fermentation process. The main volatile components were different during fermentation depending on the added strain, and there was the greatest variety of volatiles in the group with added Saccharomyces cerevisiae.

Microbial Diversity and Flavor Regularity of Soy Milk Fermented Using Kombucha

Plant-based milk is considered a healthy and environmentally sustainable option. However, due to the low protein content of most plant-based milk and the difficulty of gaining flavor acceptance by consumers, its production scale is usually limited. Soy milk is a kind of food with comprehensive nutrition and high protein content. In addition, kombucha is naturally fermented by acetic acid bacteria (AAB), yeast, lactic acid bacteria (LAB), and other microorganisms, and the microorganisms in its system can improve the flavor characteristics of food. In the present study, LAB (commercially purchased) and kombucha were used as fermenting agents for soybean, which was used as a raw material to produce soy milk. A variety of characterization methods were used to study the relationship between the microbial composition and flavor regularity of soy milk produced with different proportions of fermenting agents and different fermentation times. In soy milk produced at 32 °C with a mass ratio of LAB to kombucha of 1:1 and a fermentation time of 42 h, the concentrations of LAB, yeast, and acetic acid bacteria in the milk were optimal at 7.48, 6.68, and 6.83 log CFU/mL, respectively. In fermented soy milk produced with kombucha and LAB, the dominant bacterial genera were Lactobacillus (41.58%) and Acetobacter (42.39%), while the dominant fungal genera were Zygosaccharomyces (38.89%) and Saccharomyces (35.86%). After 42 h, the content of hexanol in the fermentation system of kombucha and LAB decreased from 30.16% to 8.74%, while flavor substances such as 2,5-dimethylbenzaldehyde and linalool were produced. Soy milk fermented with kombucha offers the opportunity to explore the mechanisms associated with flavor formation in multi-strain co-fermentation systems and to develop commercial plant-based fermentation products.

Understanding the texture and digestibility attributes of rice noodles supplemented with common vetch starch

The effects of common vetch starch (CVS) substitution on rice noodle quality were investigated, aiming to improve their texture and reduce starch digestibility. The CVS had larger granule sizes, higher amylose content and more long branch chains compared with rice starch (RS). When the CVS substitution level was 20 %, the rice noodles had the best texture quality, as the mixtures with more total starch and amylose could form denser gel structures. Moreover, the starch chains were easier to rearrange to form double helix ordered structures, resulting in a slower digestion rate. With the further increase of CVS, the noodle structure weakened and the starch digestion rate increased. This was due to the formation of looser gel structures and less ordered structures as RS granules could be easily separated into different parts by large amount of CVS with larger granule sizes, and RS with more short chains tended to be cross-linked with RS during retrogradation. With increasing CVS substitution level, the estimated glycemic index (eGI) of rice noodles decreased and then tended to be stable. Therefore, appropriate CVS substitution could improve the texture quality of rice noodles and reduce the eGI value, and the best substitution level was 20 %.

Effects of Lactobacillus plantarum and Saccharomyces cerevisiae co-fermentation on the structure and flavor of wheat noodles

BACKGROUND

Although traditional fermented noodles possess high eating quality, it is difficult to realize large-scale industrialization as a result of the complexity of spontaneous fermentation. In present study, commercial Lactobacillus plantarum and Saccharomyces cerevisiae were applied in the preparation of fermented noodles.

RESULTS

The changes in the structural characteristics and aroma components of noodles after fermentation were investigated via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), low-field magenetic resonance imaging, electronic nose, and simultaneous distillation and extraction/gas chromatography-mass spectrometry (GC-MS) analysis. SEM images revealed that co-fermentation of the L. plantarum and S. cerevisiae for 10-40 min enhanced the continuity of the gluten network and promoted the formation of pores. FTIR spectra analysis showed that the co-fermentation increased significantly (P < 0.05) the proportion of α-helices of noodles gluten protein, enhancing the orderliness of the molecular structure of protein. After fermentation for 10-40 min, the signal density of hydrogen protons increased from the surface to the core, indicating that the water in the noodles migrated inward during a short fermentation process. The results of multivariate statistical analysis demonstrated that the main aroma differences between unfermented and fermented noodles were mainly in hydrocarbons, aromatic compounds and inorganic sulfides. GC-MS analysis indicated that the main volatile compounds detected were 2, 4-di-tert-butylphenol, bis (2-ethylhexyl) adipate, butyl acetate, dibutyl phthalate, dioctyl terephthalate, bis (2-ethylhexyl) phthalate, pentanol and 2-pentylfuran, etc. CONCLUSION: Co-fermentation with L. plantarum and S. cerevisiae improved the structure of gluten network and imparted more desirable volatile components to wheat noodles. © 2022 Society of Chemical Industry.

Properties of Rice-Based Beverages Fermented with Lactic Acid Bacteria and Propionibacterium

In recent times, consumers have shown increasing interest in plant substitutes for fermented dairy products. This study aimed to investigate the properties of yogurt-type rice-based beverages fermented with lactic acid bacteria and Propionibacterium. The changes in pH, viable population of bacteria, physical properties, and carbohydrate content of these beverages were tested. Fermentation using only Propionibacterium was insufficient to obtain a product with an acidity level similar to that of milk-based yogurt (pH < 4.5). After fermentation, the tested beverages had a high number of Lactobacillus sp. (7.42−8.23 log10 CFU/mL), Streptococcus thermophilus (8.01−8.65 log10 CFU/mL), and Bifidobacterium animalis subsp. lactis (8.28−8.50 log10 CFU/mL). The hardness (2.90−10.40 N) and adhesiveness (13.79−42.16 mJ) of the samples after 14 days of storage at 6 °C varied depending on the starter culture used. The syneresis of all samples ranged between 29% and 31%, which was lower or close to that of milk-based yogurts. The content of individual sugars in the samples also varied depending on the starter culture used for fermentation. The results suggest that the combination of lactic and propionic fermentation helps in the production of rice-based yogurt-type milk substitutes.

Effects of various preservation treatments on diversity and abundance of microbial community in rice product (MiBa) during storage

To determine the most effective preservation method for MiBa (a traditional Chinese rice product), MiBa treated with 75% alcohol, 75% alcohol + inhibitor, ozone treatment; untreated (control); and raw rice were subjected to 16S rRNA gene and ITS three-generation sequencing by High-throughput Sequencing Technology. According to the results the preservation effects of different treatment methods ranked as follows: ozone treatment >75% alcohol treatment >75% alcohol+inhibitor > control. Bacterial composition analysis showed that the bacterial community on the surface of MiBa treated with ozone was dominated by genera Leuconostoc and Serratia. The fungal community consisted mainly of Aspergillus and Alternaria. In summary, ozone treatment proved to be the most effective in inhibiting microbial contamination during the storage of MiBa, effectively extending its shelf life.

Volatile compounds, bacteria compositions and physicochemical properties of 10 fresh fermented rice noodles from southern China

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.

Effect of Soy Protein Isolate on Textural Properties, Cooking Properties and Flavor of Whole-Grain Flat Rice Noodles

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.

Effects of damaged starch on glutinous rice flour properties and sweet dumpling qualities

This study focused on exploring the effects of damaged starch on glutinous rice flour properties and sweet dumpling qualities. Glutinous rice flours with different damaged starch contents (2-8%) and the same particle size were prepared through sifting and blending of semidry-milled and dry-milled rice flour. The increase of damaged starch content led to an increase in elastic modulus (G'), viscous modulus (G″) and agglomeration of starch granules, and a decrease in peak viscosity, breakdown value and enthalpy change (ΔH). Among all the samples, the rice flour batters with damaged starch content 3% and 4% were more stable and structured, and rice flours with damaged starch content 2% and 3% showed better pasting properties. As for the sweet dumpling qualities, compact structure, weak water mobility, less water loss, slight cracking and desirable cooking and texture properties were observed in the sweet dumplings made from rice flour with damaged starch content of less than 5%. All the results demonstrated that glutinous rice flour with damaged starch content of less than 5% had good flour properties and was suitable for the production of sweet dumplings.