Jasmina Vitas

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.

Modeling and optimization of red currants vacuum drying process by response surface methodology (RSM).

Fresh red currants were dried by vacuum drying process under different drying conditions. Box-Behnken experimental design with response surface methodology was used for optimization of drying process in terms of physical (moisture content, water activity, total color change, firmness and rehydratation power) and chemical (total phenols, total flavonoids, monomeric anthocyanins and ascorbic acid content and antioxidant activity) properties of dried samples. Temperature (48-78 °C), pressure (30-330 mbar) and drying time (8-16 h) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where regression analysis and analysis of variance were used to determine model fitness and optimal drying conditions. The optimal conditions of simultaneously optimized responses were temperature of 70.2 °C, pressure of 39 mbar and drying time of 8 h. It could be concluded that vacuum drying provides samples with good physico-chemical properties, similar to lyophilized sample and better than conventionally dried sample.

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.

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.