Different Stages Of Fermentation Process Research Articles

In-depth exploration on the effects of organic nitrogen addition during different fermentation periods on the quality of cider

Nitrogen is an essential element for the growth and metabolism of Saccharomyces cerevisiae, and has a great impact on the quality of cider. In this study, the effects of organic nitrogen addition at different stages of fermentation process on the quality of cider were systematically explored. The main projects included the analysis of fermentation rate, yeast growth, organic acids, amino acids, and volatile aroma compounds. The results indicated that organic nitrogen addition speeded up fermentation rate and shortened fermentation time. The organic nitrogen addition before fermentation and at the early stationary phase altered the composition of organic acids in cider. Moreover, with the addition of organic nitrogen at three stages of fermentation (pre-fermentation, logarithmic and stable phases of yeast growth), the total concentrations of volatile aroma substances in ciders were 10.57 mg/L, 11.97 mg/L and 11.05 mg/L respectively, which were all significantly higher than that in control group (9.69 mg/L). A close relationship between free amino acids consumed during fermentation and volatile aroma compounds produced was revealed by partial least-squares regression analysis. Overall, this study provided a new strategy for cider quality improvement by evaluating the effects of organic nitrogen on the aroma composition of cider.

Isolation and selection of microorganisms in cocoa fermentation

The objectives of this study were to investigate the change of microorganisms involved in cocoa (Theobroma cacao) fermentation and then to isolate, characterize and select the important microorganisms in cocoa fermentation. The results showed that microbial quantities continuously changed during cocoa fermentation and the highest quantity of dominant microorganisms at different stages of fermentation process as 8.03 log cfu/g of yeast, 6.34 log cfu/g of mold, 7.77 log cfu/g of lactic acid bacteria, 7.87 log cfu/g of acetic acid bacteria, 7.25 log cfu/g of Bacillus, and 10.93 log cfu/g of the total aerobic bacteria. There were nine yeast isolates belonging 5 genera of Saccharomyces, Kluyveromyces, Brettanomyces, Candida and Cystofilobasidium; 9 mould isolates belonging to 2 genera of Rhizopus and Aspergillus; 11 acetic acid bacteria isolates belonging to Acetobacter; and 13 spore-forming bacterial isolates belonging to Bacillus isolates. Three isolates of yeast (CY-1a, CY-1b, CY-2a) belonging to Kluyveromyces possessed the high fermentative capacity and 4 Acetobacter isolates (CAAB-1d, CAAB-1a, CAAB-1e and CAAB-2d) produced high amounts of acetic acid.

Dynamic effects of fermentation on phytochemical composition and antioxidant properties of wampee (Clausena lansium (Lour.) Skeel) leaves.

Variations in the phytochemical composition and antioxidant properties were studied in the wine of wampee leaves obtained at different stages of fermentation process. The highest concentrations of total phenolic and flavonoid contents were attained at Day 12 and Day 21 of fermentation, respectively. In addition, five phytochemical compounds including vanillic acid, p‐coumaric acid, rutin, ferulic acid, and 7‐hydroxycoumarin were identified and quantified by HPLC in fermented wampee products. The strongest antioxidant activity in wine was monitored on Day 12. Furthermore, total antioxidant activity was significantly correlated with vanillic acid, p‐coumaric acid, ferulic acid, and 7‐hydroxycoumarin compared with rutin. The obtained results suggested that 12‐day fermentation could be an optimal process for excavation of applying wampee leaves into food and wine industries.

MICROBIOLOGICAL ANALYSIS OF SAUERKRAUT IN THE PROCESS OF ITS FERMENTATION ACCORDING TO THE TRADITIONAL AND MODERNIZED TECHNOLOGIES

Aim. The aim of this work is detection of the differences in the quantitative and qualitative content of the microorganisms involved in fermentation of traditional Ukrainian food – sauerkraut (cabbage) under various conditions of its production. Methods. Microbiological methods for the isolation (cultivation on selective chromogenic medium) and identification of isolated microorganisms: using the semi-automatic biochemical test systems and laser desorption technique (MALDI). Results. The changes in qualitative and quantitative composition of microorganisms in tested sauerkraut samples taken at different stages of fermentation process by the traditional local (original) recipe and produced by upgraded modern technology have been revealed. In particular, the strains of Lactobacillus delbrueckii were isolated from all tested samples of fermented product, while the strain of L. casei was isolated only from sauerkraut’ samples made according to the original recipe. In these same samples, as opposed to those that were manufactured by industrial technology, the number of isolated strains of enterococci was insignificant. Conclusion. The results obtained confirmed the significant differences in qualitative and quantitative content of isolated microorganisms isolated from tested sauerkraut samples depending of methodology of its fermentation. The important differences in the composition of microorganisms associations at the beginning and at the end of sauerkraut fermentation have also been detected and defined.