Composition Of Fermentation Products Research Articles

Influence of microbial fermentation on the antioxidant activity of phenolic substances in Saccharomyces cerevisiae.

Using in vitro assay and eukaryotic cell model of Saccharomyces cerevisiae, we investigated the impact of microbial fermentation on the antioxidant activity of phenolic substances. Caffeic acid phenethyl ester (CAPE) and mangiferin were fermented by lactic acid bacteria (LAB), and the antioxidant activity of the fermented products was compared to that of the pure substances. This comparison was assessed using high-performance liquid chromatography (HPLC), in vitro by 2,2-Diphenyl-1-picrylhydrazyl (DPPH), and in vivo in yeast cells. The wild-type strain (BY4741) and its isogenic mutants in glutathione (Δgsh1), catalase (Δctt1), and superoxide dismutase (Δsod1) were treated with CAPE and mangiferin, fermented or not, and exposed to hydrogen peroxide (H2O2)-induced stress. The antioxidant activity was evaluated by cellular viability, intracellular oxidation, and lipid peroxidation. We expected that fermentation would change the antioxidant activity of phenolic substances. While HPLC analysis revealed changes in the composition of fermented products, significant alterations in antioxidant activity were only observed when using mutant strains. The fermentation of mangiferin increased dependency on GSH compared to the respective pure phenolic substance to resolve H2O2-induced stress. Additionally, CAPE appeared to act as a preconditioning agent, enhancing antioxidant responses, and promoting increased tolerance to H2O2 stress, and this mechanism was maintained after fermentation. This study highlights that fermentation impacts the enzymatic mechanism of oxidative stress resolution, even though differences could not be observed in in vitro assays or in the wild-type strain.

Effects of inoculation of Lactiplantibacillus plantarum and Lentilactobacillus buchneri on fermentation quality, aerobic stability, and microbial community dynamics of wilted Leymus chinensis silage.

Leymus chinensis is an important crop that can be fed to ruminants. The purpose of this study was to investigate the roles of Lactiplantibacillus plantarum and Lentilactobacillus buchneri in fermentation quality, aerobic stability, and dynamics of wilted L. chinensis silage microorganisms. Wilted L. chinensis silages were ensiled with/without L. plantarum and L. buchneri. After 14 and 56 days of ensiling, the silos were opened and subjected to a 7-day aerobic deterioration test. This study looked at the composition of fermentation products as well as the microbial communities in silage. Silage inoculated with L. plantarum and L. buchneri had an increased lactic acid content as well as lactic acid bacterial (LAB) quantity, but a decrease in pH and levels of butyric acid, 2,3-butanediol, and ethanol was observed during ensiling. Non-treated and L. plantarum-treated silages deteriorated in the 7-day spoilage test after opening day-14 silos, whereas L. buchneri-inoculated silage showed no signs of deterioration. Lactobacillus abundance increased in the 7-day spoilage test after opening day-56 silos, while undesirable microorganisms such as Acetobacter, Bacillus, and molds, namely, Aspergillus and Penicillium were inhibited within L. plantarum- and L. buchneri-inoculated silages. The composition of fermentation products was related to the bacterial community, particularly Lactobacillus, Enterococcus, and Acetobacter. To summarize, L. plantarum- and L. buchneri-inoculated silage enhanced fermentation quality during ensiling and inhibited aerobic spoilage in a 7-day spoilage test of 56 days ensiling within wilted L. chinensis silage.

Improvement of technological methods of raw fodder grain preservation

Increasing the efficiency of the livestock industry is largely determined by the quality of the most valuable component of diets - forage grain. The properties of reliable preservation of its quality today possess the technology of preservation of raw fodder grain with chemical and biological preparations. Biopreparations with strains of lactic acid bacteria are the cheapest and most environmentally safe. Among chemical preparations powdered sulphur is cheap and environmentally safe one. The two-component mixture of L. casei + L. lactis had a certain advantage for preserving raw barley grain from three strains of homofermentative lactic acid bacteria: Lactobacillus species (L. species), Lactobacillus casei (L. casei) and Lactococus lactis (L. Lactis). The mixture of L. casei + L. lactis in a ratio of 1:1 and a dose of 1 l/40t was called Biosil NN. When processing grain with a moisture content of about 35 % using Biosil NN, it was optimally acidified with lactic acid, which is dominant in the composition of fermentation products, and had a high energy value. Careful grain ramming enhanced the preservation effect of Biosil NN. A similar effect on the preserved grain was provided by powdered sulphur at a dose of 1 kg/t. The most preserving effect of preparation was at an average degree of compaction of the flattened grain with a moisture content of about 25 %. According to the quality of fermentation of preserved grain the chemical preservative Promir had worse results than those stimulated with Biosil NN and powdered sulfur.

METHODS OF DETERMINATION OF PARAMETERS OF FERMENTED WHEY-MALTY MIXTURES

The article presents main methods of studying restored whey-malty mixtures after fermentation by lactose-fermenting yeast and saccharomyces for getting a beverage of the kvass type. The methods of accumulation of yeast cells Kluyveromyces lactis 469 and their percent with glycogen from the general concentration at fermentation of wort of the restored mixture at different ratios of dry malt and whey are offered and results are obtained. According to the obtained data, it was established, that yeast cells actively developed in the period from 4 to 16 fermentation hour at the ratio of malt and whey in the restored mixture as 1:1,5 and 1:2. The increment of cells with glycogen in mixtures with the ratio – malt:whey as 1,5:1 and 2:1 was intensive. Thus, at 36 hour of fermentation the amount of yeast was 67,2 and 68,9 % respectively from the total number of cells. The generative capacity of yeast allowed to specify the fermentation temperature of wort of restored mixtures, cultivated by different races. It was established, that for Kluyveromyces lactis 469 the maximal accumulation of yeast (67…69 mln cell/cm3 of wort) is observed at fermentation temperature – 30…32 °С, for Saccharomyces cerevisiae Р-87 and Saccharomyces cerevisiae M-5 – 30…34 °С. The gasochromatographic method allowed to identify side products of fermentation of fermented whey-malty wort by both lactose fermenting yeast and saccharomyces. The presented information is enough for the objective assessment of the qualitative composition of fermentation products as a result of the effect of different yeast races. The use of Saccharomyces cerevisiae Р-87 for fermentation of whey-malty wort positively influences metabolism of a producer, stimulating biosynthesis or transformation of aromatic substances of the nutritive medium. The obtained research results indicate objective possibilities for the effective functioning of the aforesaid yeast race for fermentation of restored whey-malty wort in production systems.

Changes in the bacterial community and composition of fermentation products during ensiling of wiltedItalian ryegrass and wilted guinea grass silages

To gain further insights into temperate and tropical grass ensiling, fermentation products and bacterial communities were examined at both the initial and late stages of ensiling of wilted Italian ryegrass and wilted guinea grass silages. 2,3-Butanediol and ethanol fermentation were observed in wilted Italian ryegrass silage. Enterobacteria such as Rahnella sp. and Enterobacter sp. may have been involved in fermentation; however, alcohol production was intensified after the silage enterobacterial community overwhelmed the pre-ensiled enterobacterial community. Pediococcus spp. appeared in silage stored for 4 months, when a significant increase in lactic acid content was seen compared with that at 2 months. Prolonged storage enhanced acetic acid fermentation in wilted guinea grass silage. The disappearance of Enterococcus sulfureus and appearance of Lactobacillus plantarum may have been associated with the increased acetic acid content. Although many species of enterobacteria were found in common between the pre-ensiled crop and silages of Italian ryegrass and guinea grass, marked differences were seen in the type of fermentation from the initial stages. These results indicate that the bacterial community of pre-ensiled crops may be immediately replaced by one that is adapted to ensiling environments, although metabolic changes may continue over the course of ensiling.

Influence of Working Conditions Upon Kombucha Conducted Fermentation of Black Tea

Local domestic Kombucha was used in fermentation of 1.5 g l−1 of black tea (Indian tea, ‘Vitamin’, Horgoš, Serbia and Montenegro), sweetened with 66.47 g l−1 of sucrose. Inoculation was performed by both 10% and 15% of fermentation broth from previous process. The fermentation was conducted alternatively, at 22°C and 30°C, for 10 days. The samples were analysed after 0, 3, 4, 5, 6, 7 and 10 days, so that their pH values, content of total acids, sucrose, glucose and fructose contents as well as quantity of ethanol were determined. At the same time, experiments were performed on tea inoculated with 10% of fermentation broth, at temperatures 22°C, 30°C and 35°C, for 21 days. The samples were taken after 0, 3, 7, 10, 14, 17 and 21 days and quantity of vitamin C was measured. Experimentally obtained results were analysed and the response functions of glucose, fructose, metabolites and biosynthesized vitamin C were defined. Process duration was found the most influencing on the composition of fermentation products, then temperature and inoculum concentration.

Effects of feed solutions on refuse hydrolysis and landfill leachate characteristics

Tap water, aerobically pre-treated leachate, and anaerobically pre-treated leachate, were each fed into the top of a series of three simulated landfills columns, filled with municipal solid waste collected in Shanghai, China. Changes in leachate, including pH, total organic carbon (TOC), and volatile fatty acids (VFAs), and the produced biogas were monitored over time. The tap-water-fed columns had a low hydrolysis rate that yielded an acidic environment (pH 4.8–5.4) in the leachate that inhibited methanogenesis reaction in the refuse. When aerobically pre-treated leachate was fed into the columns, the hydrolysis rate of total organic carbon fluctuated between 200 and 400 mg d −1 and methanogenesis in the refuse column was only partly activated. The hydrolysis rate of refuse fed with anaerobically pre-treated leachate was the highest among the three solutions. The high alkaline levels of the anaerobically pre-treated leachate and its methanogenic bacteria led to an early activation of methanogenesis in the refuse columns. The VFAs contributed approximately 40–60% of TOC in tap-water-fed columns, 60–80% of TOC in the columns fed aerobically pre-treated leachate, and up to 70–90% of TOC in columns fed with anaerobically pre-treated leachate. The feed solution had considerably affected leachate characteristics, and then the build-up of the methanogenesis in the refuse column and the composition of fermentation products in the leachate. The success of a bioreactor landfill depends on whether the recycled leachate could yield a favorable methanogenic environment in the top refuse layer, or whether an appropriate pre-treatment is adopted to modify the leachate characteristics.

Physico-mechanical Properties and Chemical Analysis of Raw and Brined Caperberries

Fruits of Capparis spinosa L. var. spinosa and Capparis ovata Desf. var. canescens (Coss.) Heywood 21·14 and 19·78 mm in diameter were collected and brined at 10% salt concentration for 30 days, respectively. The physical and chemical properties were determined in developing Capparis spinosa and C. ovata fruits from Mersin and Konya to investigate potential uses. The moisture, crude protein, crude ash, crude oil, crude fibre, crude energy, Na, P and K contents of raw and pickled fruits of C. spinosa were higher than those of C. ovata. The composition of fermented products were generally lower compared with the raw fruits. Fruits of C. spinosa were more suitable for pickling due to the high levels of several nutrients. In addition, physical properties such as length and width of fruits, projected area, rupture strength, terminal velocity, kernel density, bulk density, sphericity, geometric mean diameters and rupture strength were measured.

On the Metabolism of Organic Acids by Clostridium acetobutylicum

Pyridoxine analogues promoted the racemiase formation by Clostridium acetobutylicum. This effect was investigated employing culture media supplemented with these analogues. Pyridine, nicotinic acid and niacinamide, meanwhile, showed intensive inhibition on the formation of this enzyme. In these cases, scarcely any variation was detected in the growth of organism and the composition of fermentation products. In the crotonate-added culture, a considerable amount of latic acid accumulated and the formation of racemiase was accelerated remarkably.