Bacterial Diversity, Organic Acid, and Flavor Analysis of Dacha and Ercha Fermented Grains of Fen Flavor Baijiu

Fen flavor Baijiu needs two rounds of fermentation, which will obtain Dacha after initial fermentation and Ercha after secondary fermentation. The quality of Baijiu is closely related to the microbes within fermented grains. However, the bacterial diversity in Dacha and Ercha fermented grains of Fen flavor Baijiu has not been reported. In the present study, the structure and diversity of bacteria communities within fermented grains of Fen flavor Baijiu were analyzed and evaluated using MiSeq platform’s HTS with a sequencing target of the V3-V4 region of the 16S rRNA gene. Through the analysis of physical and chemical indexes and electronic senses, the relationship between bacterial flora, organic acid, taste, and aroma in fermented grains was clarified. The results indicated that Lactobacillus was the main bacteria in Dacha, and the mean relative content was 97.53%. The bacteria within Ercha samples were Pseudomonas and Bacillus, mean relative content was 37.16 and 28.02%, respectively. The diversity of bacterial communities in Ercha samples was significantly greater than that in Dacha samples. The correlation between Lactobacillus and organic acids, especially lactic acid, led to the difference between Dacha and Ercha organic acids, which also made the pH value of Dacha lower and the sour taste significantly higher than Ercha. Lactobacillus was significantly positively correlated with a variety of aromas, which made Dacha the response value of aromas higher. In addition, Bacillus had a significant positive correlation with bitterness and aromatic compounds, which led to a higher response value of bitterness in Ercha and made it present an aromatic aroma. This study provides an in-depth analysis of the difference between different stages of Fen flavor Baijiu, and theoretical support for the standard production and improvement in quality of Fen flavor Baijiu in the future.

Comparative flavor analysis of four kinds of sweet fermented grains by sensory analysis combined with GC-MS

Four types of cereals (glutinous rice, purple rice, red rice, yellow millet) were selected to produce sweet fermented grains. Flavor profiles of sweet fermented grains are comparatively studied to distinguish various flavor types by using GC-MS, electronic nose (E-nose), and sensory analysis, and the amino acid composition and physicochemical properties of sweet fermented grains were analyzed. The results showed that the volatile compounds of sweet fermented grains were significantly different. Esters and alcohols were the major volatile compounds in sweet fermented grains. The electronic nose, electronic tongue and sensory analysis jointly verified that the volatile components of sweet fermented grains had differences between them. The sweet fermented grains could be classified based on differences in volatile compounds. In the amino acids analysis, Glu, Pro, Asp and Leu were the most abundant. The difference in physicochemical properties is more helpful to distinguish different types of sweet fermented grains. Correlation analysis between antioxidant active substances and color value showed a positive correlation between with a* value, and a negative correlation with L*, b* value. Our results suggested that there were differences in the flavor characteristics of sweet fermented grains fermented from different types of cereals. The results of the study will provide valuable information for the selection of raw materials for sweet fermented grains.

Detection of viable and total fungal community in zaopei of Chinese strong-flavor baijiu using PMA combined with qPCR and HTS based on ITS2 region

Background Chinese strong-flavor baijiu (CSFB), one of the three major baijiu types, is the most popular baijiu type among consumers in China. A variety of microbes are involved in metabolizing raw materials to produce ethanol and flavor substances during fermentation, which fundamentally determined the quality of baijiu. It is of great importance to study microbial community of fermented grains (zaopei) during baijiu brewing process for improving its quality. In this study, we firstly used propidium monoazide (PMA) to treat zaopei samples from 5-year pit and 20-year pit for removing the interference of non-viable fungi, and analyzed the diversity of total fungi and viable fungi by quantitative PCR (qPCR) and high-throughput sequencing (HTS) based on ITS2 gene. Results The results showed that total fungi and viable fungi displayed no significant differences at OTU, phylum, or genus levels during fermentation within two kinds of pits. A total of 6 phyla, 19 classes, and 118 genera in fungi were found based on OTUs annotation in zaopei samples from 5-year pit and 20-year pit. Besides, non-viable fungi had little effect on the fungal community diversity during the fermentation cycle. It was found that the most dominant viable fungi belonged to Saccharomyces, Kazachstania, Naumovozyma, and Trichosporon, and Naumovozyma was firstly detected in zaopei samples of CSFB. Moreover, based on the variation of flavor substances in zaopei samples, the quality of CSFB produced from older pit was better than that produced from younger pit. Conclusion The non-viable fungi had little effect on the fungal diversity, structure, and relative abundance in zaopei samples of CSFB, and Naumovozyma was firstly detected in zaopei samples of CSFB. Our findings can be applied as guidance for improving the quality and stability of CSFB.

108 Evaluation of Graded Levels of Grain Distillers Dried Yeast (GDDY) on Apparent Nutrient Digestibility and Stool Quality in Healthy Adult Dogs

Yeast and distillers’ grains from ethanol products have been included in pet food for many years. However, their combination has not been evaluated in pet food. Grain distillers dried yeast (GDDY) is a combination of fermented grains which is rich in yeast. The objectives of this study were to determine the effects of increasing levels of GDDY on apparent total tract digestibility (ATTD) and stool quality in adult dogs. Four extruded diets were fed to twelve adult Beagle dogs in a replicated 4 x 4 Latin Square design. The control diet contained 15% soybean meal (15S) and GDDY was exchanged for soybean meal at either 5%, 10%, or 15% (5G, 10G, 15G). Dogs were fed each dietary treatment for 9-d adaption followed by 5-d total fecal collection. Feces were scored on a 1–5 scale, with 1 representing liquid diarrhea. Titanium dioxide was added to all diets (0.4%) as a marker to estimate digestibility. Data were analyzed using a mixed model in SAS (version 9.4, SAS Institute, Inc., Cary, NC) with treatment as a fixed effect and dog and period as random effects. No differences (P > 0.05) were observed in wet fecal output or fecal pH (average; 112.74g/d and 5.77). Fecal DM and defecations per day were greater (P < 0.05) at elevated levels of GDDY. Stool scores were higher (P < 0.05) when dogs consumed diets containing GDDY versus 15S (average; 3.85 vs 3.67). Organic matter ATTD was the greatest (P < 0.05) for dogs fed 15S compared to GDDY treatments (average; 87.64% vs 86.67%). Dogs fed 10G had the lowest (P < 0.05) ATTD for crude protein compared to all others (average; 87.92% vs 88.78%). These results suggest that levels of GDDY between 5 and 15% are comparable to soybean meal when fed to adult dogs.

Physical and Sensory Properties of Bread Made with Wheat and Fermented Finger Millet (Eleusine coracana L.) Flours

Aim: The study was conducted to determine the effect of fermented finger millet flour supplementation in wheat on the physical and sensory properties of bread. Methodology: Finger millet grains were cleaned, washed and fermented in deionized water for 72 h at room temperature (27±2oC), with sampling at every 24 h interval. Fermented grains were washed, drained, dried (65oC, 4 h), milled and sieved (<250 µm) to produce Fermented Finger Millet Flour (FFMF). Composite flour was formulated by supplementing wheat flour with Fermented Finger Millet Flour (FFMF) at 0, 5, 10, 15 and 20 % (w/w), and used to produce bread samples. Physical (Oven spring, loaf weight, loaf volume and specific volume) and sensory (crust colour, crumb colour, aroma, texture, taste, mouth feel and overall acceptability) properties of the bread samples were determined. Results: Physical properties showed less oven spring, loaf volume and specific loaf volume and increased loaf weight with increased FFMF replacement. The sensory analysis showed significant differences (p<0.05) between 100% wheat bread and FFMF supplemented samples in all the determined sensory properties. It was concluded that fermentation period of 24-48 h, and substitution of 5-10% FFMF into wheat gave the bread samples with the best overall acceptability.

Liquor Flavour Is Associated With the Physicochemical Property and Microbial Diversity of Fermented Grains in Waxy and Non-waxy Sorghum (Sorghum bicolor) During Fermentation

The fermentation process of Chinese Xifeng liquor involves numerous microbes. However, the sources of microbes in fermented grain and the link between liquor flavour and physicochemical properties and microbial diversity during fermentation still remain unknown. Herein, two waxy (JiNiang 2 [JN-2] and JinNuo 3 [JN-3]) and four non-waxy (JiZa 127 [JZ-127], JinZa 34 [JZ-34], LiaoZa 19 [LZ-19], and JiaXian [JX]) sorghum varieties were selected for the comprehensive analysis of the relationship between liquor flavour and the physicochemical properties and microbial diversity of fermented grains. Results showed that ethyl acetate was the main flavour component of JZ-127, JZ-34, and JX, whereas ethyl lactate was mainly detected in JN-2, JN-3, and LZ-19. Ethyl lactate accounted for half of the ethyl acetate content, and JX exhibited a higher liquor yield than the other sorghum varieties. The fermented grains of waxy sorghum presented higher temperature and reducing sugar contents but lower moisture and starch contents than their non-waxy counterparts during fermentation. We selected JN-3 and JX sorghum varieties to further investigate the microbial changes in the fermented grains. The bacterial diversity gradually reduced, whereas the fungal diversity showed nearly no change in either JN-3 or JX. Lactobacillus was the most abundant bacterial genus, and its level rapidly increased during fermentation. The abundance of Lactobacillus accounted for the total proportion of bacteria in JX, and it was higher than that in JN-3. Saccharomyces was the most abundant fungal genus in JX, but its abundance accounted for a small proportion of fungi in JN-3. Four esters and five alcohols were significantly positively related to Proteobacteria, Bacteroidetes, and Actinobacteria; Alphaproteobacteria, Actinobacteria, and Bacteroidia; Bacillales, Bacteroidales, and Rhodospirillales; and Acetobacter, Pediococcus, and Prevotella_7. This positive relation is in contrast with that observed for Firmicutes, Bacilli, Lactobacillales, and Lactobacillus. Meanwhile, Aspergillus was the only fungal microorganism that showed a significantly negative relation with such compounds (except for butanol and isopentanol). These findings will help in understanding the fermentation mechanism and flavour formation of fermented Xifeng liquor.

Strain diversity of plant-associated Lactiplantibacillus plantarum

The intraspecific phenotypic and genetic diversity of Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) was examined for five strains isolated from fermented olives and eight strains from cactus fruit, fermented tomatoes, teff injera, wheat boza, and wheat sourdough starter sources. Carbohydrate utilization and stress tolerance characteristics showed that the olive isolates grew more robustly in galactose and raffinose, showed higher tolerance to 12% v/v EtOH, and exhibited a greater capacity to inhibit an olive spoilage strain of Saccharomyces cerevisiae than L. plantarum from the other plant sources. Certain traits were variable between fermented olive isolates such as the capacity for biofilm formation and survival at pH 2 or 50 °C. By comparison, all L. plantarum from fruit sources grew better at a pH of 3.5 than the strains from fermented grains. Multi-locus sequence typing and genome sequencing indicated that strains from the same source type tended to be genetically related. Comparative genomics was unable to resolve strain differences, with the exception of the most phenotypically impaired and robust isolates. The findings show that L. plantarum is adapted for growth on specific plants or plant food types, but that intraspecific variation may be important for ecological fitness of L. plantarum within individual habitats.