Radomir V. Malbaša

A Review on Kombucha Tea—Microbiology, Composition, Fermentation, Beneficial Effects, Toxicity, and Tea Fungus

Fermentation of sugared tea with a symbiotic culture of acetic acid bacteria and yeast (tea fungus) yields kombucha tea which is consumed worldwide for its refreshing and beneficial properties on human health. Important progress has been made in the past decade concerning research findings on kombucha tea and reports claiming that drinking kombucha can prevent various types of cancer and cardiovascular diseases, promote liver functions, and stimulate the immune system. Considering the widespread reports on kombucha, we recognized the need to review and update the research conducted in relation to kombucha tea, its products and tea fungus. Existing reports have suggested that the protective effects of kombucha tea are as good as those of black tea, however, more studies on kombucha tea and its composition are needed before final conclusions can be made.

Optimization of frozen sour cherries vacuum drying process.

The objective of this research was to optimize the vacuum-drying of frozen sour cherries in order to preserve health-beneficial phytochemicals, as well as textural characteristics. Investigated range of temperature was 46-74°C and, of pressure, 17-583mbar, in a new design of vacuum-dryer equipment. The total solids, a(w) value, total phenolics, vitamin C, antioxidant activity, anthocyanin content, total colour change and firmness were used as quality indicators of dried sour cherry. Within the experimental range of studied variables, the optimum conditions of 54.03°C and 148.16mbar were established for vacuum drying of sour cherry. Separate validation experiments were conducted, under optimum conditions, to verify predictions and adequacy of the second-order polynomial models. Under these optimal conditions, the predicted amount of total phenolics was 744mg CAE/100 dw, vitamin C 1.44mg/100g per dry weight (g dw), anthocyanin content 125mg/100g dw, IC(50) 3.23mg/ml, total solids 70.72%, a(w) value 0.646, total colour change 52.61 and firmness 3395.4g. The investigated parameters had a significant effect on the quality of the dried sour cherries.

Effect of sucrose concentration on the products of Kombucha fermentation on molasses

Fermentation of 1.5g/l of Indian black tea, sweetened with adequate quantities of molasses (containing approx. 70g/l, 50g/l and 35g/l of sucrose), was conducted using domestic Kombucha. Inoculation was performed with 10% of fermentation broth from a previous process. The fermentation in cylindrical vessels containing 2l of liquid phase, was carried out at 22±1°C for 14 days, with periodical sampling, to measure pH, content of acids (total, acetic and l-lactic), content of remaining sucrose, and the yield of biomass at the end of fermentation. A product with 70g/l sucrose from molasses corresponds to an optimal concentration of carbon source, which provided metabolites with high pH, a low content of less desired acetic acid, a high content of highly desired l-lactic acid, an acceptable content of total acids and the highest possible level of utilisation of sucrose.

TLC ANALYSIS OF SOME PHENOLIC COMPOUNDS IN KOMBUCHA BEVERAGE

Black and green tea contains a wide range of natural phenolic compounds Flavanoids and their glycosides, catechins and the products of their condensation, and phenolic acids are the most important. Kombucha beverage is obtained by fermentation of tea fungus on black or green tea sweetened with sucrose. The aim of this paper was to investigate the composition of some phenolic compounds, catechin, epicatechin, quercetin, myricetin, gallic and tanic acid, and monitoring of their status during tea fungus fermentation. The method used for this study was thin layer chromatography with two different systems. The main phenolic compounds in the samples with green tea were catechin and epicatechin, and in the samples with black tea it was quercetin.

Reversed-phase thin-layer chromatography behavior of aldopentose derivatives

Quantitative structure-retention relationships (QSRR) have been used to study the chromatographic behavior of some aldopentose. The behavior of aldopentose derivatives was investigated by means of reversed-phase thin-layer chromatography (RP TLC) on silica gel impregnated with paraffin oil stationary phases. Binary mixtures of methanol-water, acetone- water and dioxane-water were used as mobile phases. Retention factors, RM 0, corresponding to zero percent organic modifier in the aqueous mobile phase was determined. Lipophilicity, C0, was calculated as the ratio of the intercept and slope values. There was satisfactory correlation between them and log P values calculated using different theoretical procedures. Some of these correlations offer very good predicting models, which are important for a better understanding of the relationships between chemical structure and retention. The study showed that the hydrophobic parameters RM 0 and C0 can be used as a measures of lipophilicity of investigated compounds.

Chemometric approach to texture profile analysis of kombucha fermented milk products

In the present work, relationships between the textural characteristics of fermented milk products obtained by kombucha inoculums with various teas were investigated by using chemometric analysis. The presented data which describe numerically the textural characteristics (firmness, consistency, cohesiveness and index of viscosity) were analysed. The quadratic correlation was determined between the textural characteristics of fermented milk products obtained at fermentation temperatures of 40 and 43 °C, using milk with 0.8, 1.6 and 2.8% milk fat and kombucha inoculums cultivated on the extracts of peppermint, stinging nettle, wild thyme and winter savory. Hierarchical cluster analysis (HCA) was performed to identify the similarities among the fermented products. The best mathematical models predicting the textural characteristics of investigated samples were developed. The results of this study indicate that textural characteristics of sample based on winter savory have a significant effect on textural characteristics of samples based on peppermint, stinging nettle and wild thyme, which can be very useful in the determination of products texture profile.

Effects of High Temperatures and Drought During Anthesis and Grain Filling Period on Wheat Processing Quality and Underlying Gluten Structural Changes

BACKGROUND Climate changes do not only affect wheat yield, but also its quality. Information on this topic gathered so far is somewhat contradictory and insufficient. Climate changes also affect wheat indirectly through their influence on the ecosystem, including insects and fungi that affect wheat technological quality. The aim of this study was to examine trends in structural and technological changes of wheat quality under conditions typical of climate changes. With this in mind, three groups of wheat varieties with the same Glu-score were examined in three production years, characterized by different production conditions. RESULTS A production season characterized by climate change conditions results in lower activity of amylolytic enzymes. What is more, it results in lower content of gluten, higher gluten index value, its decrease after 1 h to 37 °C, lower number of free SH groups and higher content of free amino groups, which result in lower alveograph W, lower farinograph WA and higher extensograph dough resistance. CONCLUSION Variability in wheat quality produced under different climatic conditions is mainly influenced by the production conditions, including their influence on ecosystem factors. The influence of wheat cultivar genetic predisposition is much less expressed. This indicates that differences among cultivars with different Glu-score might be diminished under the influence of altered production conditions, as a consequence of climate change.

Variation of bioactive compounds content in fermented cabbage: influence of fermentation temperature

The aim of this study was to analyze the effect of different fermentation temperature on bioactive compounds content of cabbage heads (Brassica oleracea var. capitata). Fermentation process was carried out at the temperature intervals 16-18 °C, 18-20 °C and 20-22 °C for 40 days. Dry weight, soluble dry weight, pH value, water activity, salt and sugar concentration, total acidity, penetration force, total color change, total phenolic compounds and organic acidswere investigated as the most important quality parameters. The highest content of total phenol compounds, as well as the highest contents of oxalic and acetic acidswas obtained in cabbage and brine sample fermented at 16-18 °C. The highest content of lactic acid in the cabbage sample fermented at 20-22 °C was obtained. In the case of brine samples, the highest contents of oxalic and lactic acids in samples fermented at 16-18 °C were observed, while the highest content of acetic acid in the sample fermented at 20-22 °C was obtained. Formic acid in cabbage and brine samples only in samples fermented at 20-22 °C was detected.