Tailoring the Optimized Fermentation Conditions of SCOBY-Based Membranes and Milk Kefir Grains to Promote Various Functional Properties

Abstract

Kombucha culture (named SCOBY-Symbiotic Culture of Bacteria and Yeasts) and milk kefir grains represent multiple consortia of wild microorganisms that include lactic acid bacteria, acetic acid bacteria and yeasts with valuable functional properties. Their fermentative potential provides a wide range of derivate metabiotics (prebiotics, probiotics, postbiotics and paraprobiotics) with valuable in vitro and in vivo benefits. This study targeted the evaluation of the functionality of a co-culture of SCOBY-based membranes and milk kefir grains, used as freeze-dried starter cultures, for the fermentation of a newly formulated medium based on black tea infusion, supplemented with bovine colostrum and sugar, in order to produce bioactive compounds with functional properties. The design and optimization of the biotechnological process were achieved by using the Plackett–Burman experimental design (six factorial points, three center points) and the response surface methodology and central composite design (three factorial points, six axial points and two center points in axial) tools. The statistical analysis and the mathematical modelling of the responses such as the pH, titratable acidity, antioxidant activity and antimicrobial activity (against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Aspergillus niger) were investigated. Further, the composition of organic acids, polyphenols and flavonoids of the fermented product obtained under the optimized fermentation conditions was also analyzed. The fermentation of the medium containing 6.27% (w/v) bovine colostrum powder, 1.64% (w/v) black tea, 7.5% (w/w) sugar, pH 6.7, with an inoculum based of 0.36% (w/v) milk kefir grains powder and 0.5% (w/v) SCOBY-based membrane (both as freeze-dried culture), at 30 °C, for 5 days, in an aerobic stationary system, revealed an antifungal activity between 80 and 100% against Aspergillus niger, an antibacterial activity of 8–22 mm against Escherichia coli and Bacillus spp. And a titratable acidity of 445 °Th. The chemical composition of the obtained product had a positive impact on the functional properties of the fermented products in terms of the antimicrobial and antioxidant properties.

Kombucha and Water Kefir Grains Microbiomes’ Symbiotic Contribution to Postbiotics Enhancement

“…Previously, in an FP obtained by co-fermentation with milk kefir grains and SCOBY, some organic acids such as lactic acid, acetic acid, citric acid, isovaleric acid, and butyric acid, which presented the following concentrations, respectively, of 24.39 mg/mL, 25.21 mg/mL, 5.77 mg/mL, 4.36 mg/mL, and 67.33 mg/mL, were synthesised by the artisanal cultures [ 12 ]. Therefore, the lactic and citric acids were not identified in the optimised fermented product’s composition obtained by fermentation of the formulated medium with a multiple starter culture, based on WKG and SCOBY microbiota; the result can be attributed to the synergistic functionality of the consortia in tested conditions, in correlation with the chemical composition of the fermentation substrate.…”

“…The mixture was incubated for 10 days at room temperature (22 ± 2 °C). Then, 20% ( w / w ) sterile inulin powder was added to 100 g of biofilm that was previously divided in small pieces, the mixture being homogenised and freeze-dried [ 12 ]. The resulting biofilm was finally mortared and stored at 4 °C.…”

Establishment of a rapid counting method for lactic acid bacteria and yeast in dairy products

“…During the fermentation process, yeast provides a variety of nutritive elements, such as amino acids, vitamins and pyruvate, to lactic acid bacteria (Fleet 2008). At the same time, the metabolites from lactic acid bacteria provide an energy source for yeast (Pihurov et al 2022). Previous studies have shown that these microbes can not only play an important role in the sensory quality development of dairy products (Perin et al 2017;Moubasher et al 2018;Sahina et al 2022), but also can inhibit the growth of certain bacteria or fungi through the metabolites produced during the fermentation process, thereby contributing to the microbial stability of the final product (Perin et al 2015;Colombo et al 2020;Merchán et al 2022).…”

“…At the same time, the metabolites from lactic acid bacteria provide an energy source for yeast (Pihurov et al . 2022). Previous studies have shown that these microbes can not only play an important role in the sensory quality development of dairy products (Perin et al .…”

New Developments in Nutraceuticals and Functional Food Products: Microorganisms as Alternative Sources of Nutritive and Beneficial Components

“…The last two articles of this series used statistical analysis and mathematical modeling to optimize the fermentation process to obtain new products with improved functional properties. In this frame, Pihurov et al [ 7 ] tested the functionality of a co-culture of SCOBY-based membranes (Kombucha culture known as SCOBY-Symbiotic Culture of Bacteria and Yeasts) and milk kefir grains to produce functional bioactive compounds by fermenting a newly formulated black tea infusion medium supplemented with bovine colostrum and sugar. The chemical composition of the fermented product obtained under the optimized fermentation conditions positively impacted its functional properties in terms of antimicrobial and antioxidant properties.…”