Characterisation of flavour profiles and microbial communities of fermented peppers with different fermentation years by combining flavouromics and metagenomics

The changes in flavours, volatile aromas and microbial communities of fermented peppers with different fermentation years and their relationships were investigated in this study. Results indicated a gradual increase in organic acids during fermentation, whereas free amino acids and capsaicinoids reached stability after 1 year of fermentation. Overall, the analysis detected 340 volatile compounds in fermented peppers and regarded 69 of them as differential compounds. Peppers fermented for 2 (FY2) and 4 years (FY4) possessed a greater number of differential volatiles with large odour activity values, thus endowing them with more favourable flavours. Hence, metagenomic analysis compared their microbial communities and functional annotations. Results revealed that Lactiplantibacillus plantarum and Zygosaccharomyces rouxii were the dominant bacterium and fungus, and metabolism was the main Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway in FY2. Correlation analysis demonstrated that Hyphopichia, Kazachstania and Clavispora were highly positively correlated with 12 key aroma flavours.

Optimizing the Production of Probiotic Yogurt as a New Functional Food for Diabetics with Favorable Sensory Properties Using the Response Surface Methodology

This study aimed to optimize the processing of probiotic yogurt supplemented with cumin essential oil (CEO), vitamin C, D3 (Vit D), and reduction of fermentation time using response surface methodology as a new functional food for diabetics with desirable sensory properties. The central composite design (CCD) was used to analyze the effect of these independent variables on the growth of the Lactobacillus plantarum A7 (LA7), starter culture, and overall acceptability. Differences between treatments were analyzed. The data were evaluated by analysis of variance at the significance level of 0.05. The effective concentration of CEO and fermentation time had the significant effect on the Lactobacillus plantarum A7 (LA7) number. Variance analysis and three-dimensional graphs show that almost the only effective factor on the overall acceptability of probiotic yogurt containing essential oil and vitamin D3 was CEO. According to the obtained data from the analysis, the optimal amount of independent variables for probiotic yogurt formulation such as CEO, D3, and fermentation time was 0.02% (v/v), 400 IU, and 9 h, respectively. This functional product can be considered an efficient food to reduce or eliminate the complications of diabetes.

Nutrition profile and rumen fermentation of Tithonia diversifolia fermented with Lactobacillus bulgaricus at different times and doses

Objective

This study aims to investigate the nutritional composition and rumen fermentation attributes of the tithonia plant (Tithonia diversifolia) treated with Lactobacillus bulgaricus bacteria at different fermentation durations and doses.

Materials and Methods

In this research, an experimental approach employed a factorial pattern with two factors as treatments with three replications using a complete randomized design. The primary factor was the dose of L. bulgaricus inoculum, with concentrations at 2% and 3%. The secondary factor examined during the study revolved around the duration of fermentation, offering three time frames of 1 day, 3 days, and 5 days for analysis. The inoculum of L. bulgaricus contained 65 × 1015 CFU/ml.

Results

The use of L. bulgaricus bacteria on tithonia plants (T. diversifolia) with different inoculum doses and fermentation times demonstrated a highly significant effect and significant disparities (p < 0.05). In phytic acid content, nutrient content (crude protein (CP), crude fiber, crude fat, and dry matter (DM)), and in vitro digestibility, which includes DM, organic matter (OM), CP, volatile fatty acids (VFA), NH3, and gas production. However, it did not show any significant interaction between pH and OM content.

Conclusion

The optimal results of nutrient profiling and in vitro digestibility, including DM, OM, CP, rumen pH, VFA, NH3 (ammonia), and gas production, were observed when the tithonia plant (T. diversifolia) was fermented using L. bulgaricus with 3% inoculum doses and a fermentation time of 5 days.

Effect of fat concentration on protein digestibility of Chinese sausage

Chinese sausage is a popular traditional Chinese meat product, but its high-fat content makes consumers hesitant. The purpose of this study is to compare the nutritional differences of Chinese sausages with different fermentation times (0, 10, 20, 30 d) and fat content (the initial content was 11.59% and 20.14%) during digestion. The comparison of digestion degree, protein structure, and peptide composition between different sausages were studied through in vitro simulated digestion. Chinese sausages with high-fat content had higher α-helix, β-turn, and random coil, making them easier to digest. The fermentation process made this phenomenon more pronounced. The high-fat sausage fermented for 10 d showed the highest release of primary amino acids (about 9.5%), which was about 3.5% higher than the low-fat sausage under the same conditions. The results of peptidomics confirmed the relevant conclusions. After gastric digestion, the types of peptides in the digestive fluid of high-fat sausages were generally more than those in low-fat sausages, while after intestinal digestion, the opposite results were observed. The type of peptide reached its peak after fermentation for 20 d. These findings are of obvious significance for selecting the appropriate fermentation time and fat content of Chinese sausages.

Flavor characteristics of Shanlan rice wines fermented for different time based on HS-SPME-GC-MS-O, HS-GC-IMS, and electronic sensory analyses

Flavor characteristics of Shanlan rice wines with different fermentation time were analyzed. Results suggested that 3-methyl-1-butanol, phenylethyl alcohol, ethyl acetate, and diethyl succinate were the characteristic volatiles of Shanlan rice wine by using headspace solid-phase microextraction-gas chromatography-mass spectrometry-olfactometry. The most varieties (38) of volatiles appeared at a 3-year-fermentation time, contributing a unique and harmonious aroma to the Shanlan rice wine fermented for 3 years, but only 19 types were observed at 45-days and 1-year fermentation times. A similar trend was intuitively visible in the headspace-gas chromatography-ion mobility spectrometry analysis. The Shanlan rice wine fermented for 3 years had a similar taste profile to that fermented for 45 days, but with distinguishing contents of free amino acids (1352.80 mg/L and 2261.50 mg/L, respectively) and organic acids (9.58 g/L and 49.88 g/L, respectively). The Shanlan rice wine fermented for 1 year had a strong taste with more intensity of most taste attributes.

Effects of L.plantarum dy-1 fermentation time on the characteristic structure and antioxidant activity of barley β-glucan in vitro

This article explored the effect of Lactobacillus plantarum dy-1 (L. plantarum dy-1) fermentation on the basic physicochemical properties and associated in vitro antioxidant activity of barley β-glucan, including its molecular weight, monosaccharide composition, characteristic structure and rheology. Its DPPH, ABTS, hydroxyl radical scavenging capacity, and ferric reducing antioxidant potential (FRAP) were measured at different fermentation times. The results showed that the molecular weight of barley β-glucan was decreased from 1.052 × 10⁵ Da to 4.965 × 10⁴ Da within 0–24 h by L. plantarum dy-1 fermentation, but there was no effect on its characteristic structure. The water- and oil-holding properties of barley β-glucan were significantly enhanced with increased fermentation time, and the fluid viscous behavior of barley β-glucan was enhanced at 6% concentration, while elastic characteristics were weakened. The fermentation had no significant effect on the scavenging effect of DPPH and ABTS radicals of barley β-glucan, but the hydroxyl radical scavenging activity and total antioxidant capacity of FRAP were enhanced with increased fermentation time. Fermentation time may change the physicochemical properties and enhance antioxidant activity of barley β-glucan by reducing its molecular weight.

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Increase the study on the effect of lactic acid bacteria fermentation on the antioxidant activity of barley β-glucan.

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The water-retaining and oil-controlling properties of barley β-glucan increased significantly.

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Fermentation time may enhance physicochemical properties and antioxidant activity of barley β-glucan.

Production of bacterial cellulose tubes for biomedical applications: Analysis of the effect of fermentation time on selected properties

Biosynthesis of bacterial cellulose (BC) in cylindrical oxygen permeable molds allows the production of hollow tubular structures of increasing interest for biomedical applications (artificial blood vessels, ureters, urethra, trachea, esophagus, etc.). In the current contribution a simple set-up is used to obtain BC tubes of predefined dimensions; and the effects of fermentation time on the water holding capacity, nanofibrils network architecture, specific surface area, chemical purity, thermal stability, mechanical properties, and cell adhesion, proliferation and migration of BC tubes are systematically analysed for the first time. The results reported highlight the role of culture time on key properties of the BC tubes produced, with significant differences arising from the denser and more compact fibril arrangements generated at longer fermentation intervals.

Nutrient consumption patterns of Lactobacillus plantarum and their application in suancai

The purpose of the present study was to control the fermentation time and nitrite content of suancai prepared with Lactobacillus plantarum. According to analyses of the consumption amount and rate of nutrients, growth-stimulating nutrients, essential nutrients and nutrients accelerating the fermentation process of suancai, Asp, Thr, Glu, Cys, Tyr, Mg²⁺, Mn²⁺ and inosine were selected as additions to suancai prepared with L. plantarum. The fermentation time and nitrite content of suancai supplemented with nutrients and prepared with L. plantarum were shortened by 2 days and 5 days and reduced by approximately 0.1-fold and 0.7-fold, respectively, compared with unsupplemented suancai prepared with L. plantarum at 25 °C and 10 °C. The fermentation time and nitrite content of suancai supplemented with nutrients and prepared with L. plantarum were shortened by 6 days and 15 days and reduced by approximately 0.17-fold and 0.8-fold, respectively, compared with suancai undergoing spontaneous fermentation at 25 °C and 10 °C. Furthermore, no significant differences were observed in sensory properties in suancai. The results of this study indicated that certain nutrients accelerated the growth of L. plantarum and reduced the fermentation time and nitrite content of suancai prepared with L. plantarum. These findings help to establish a foundation for the practical use of nutrients to control the fermentation of suancai.

Changes in antioxidant activities and physicochemical properties of Kapi, a fermented shrimp paste, during fermentation

Changes in chemical composition, physical properties and antioxidant activities of Kapi were monitored during fermentation for 12 months. DPPH (2, 2-diphenyl-1-picryl hydrazyl), ABTS (2, 2 - azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging activity as well as ferric reducing antioxidant power (FRAP) gradually increased as the fermentation time increased, particularly during the first 8 months (P < 0.05). Thereafter, the decreases in DPPH and ABTS radical scavenging activities were observed (P < 0.05), whereas FRAP remained constant (P > 0.05). The continuous increases in ammonia nitrogen, formaldehyde nitrogen and amino nitrogen contents were noticeable within the first 8 months (P < 0.05), indicating the formation of peptides and free amino acids via the hydrolysis of protein by both microbial and indigenous proteases. Browning intensity most likely caused by the formation of Maillard reaction products (MRPs) were concomitantly observed throughout fermentation, as evidenced by the decreases in lightness (L*-value), but the increases in redness (a*-value) and yellowness (b*-value). Low level of thiobarbituric acid reactive substances in Kapi was found during 12 months. Antioxidant activities of Kapi were more likely governed by the low molecular weight peptides, amino acids as well as Maillard reaction products generated during fermentation.