The aim of this work was to study the production of kefir-like beverage by fed-batch fermentation of red table grape juice at initial pHs of 3.99 (fermentation A) and 5.99 (fermentation B) with kefir grains during four repeated 24-h fed-batch subcultures. However, all kefir-like beverages (KLB) were characterized by low alcoholic grade (≤ 3.6%, v/v) and lactic and acetic acid concentrations. The beverages obtained from fermentation B had lower concentrations of sugars and higher microbial counts than the KLB obtained in fermentation A. In addition, the KLB from fermentation B were the most aromatic and had the highest contents in alcohols, esters, aldehydes and organic acids compared to the non-fermented juice and KLB from fermentation A. These results indicate the possibility of obtaining red table grapes KLB with their own distinctive aromatic characteristics and a high content in probiotic viable cells, contributing to the valorization of this fruit.

The present study has been one of the first attempts to thoroughly examine the effects of different kefir sources on fermentation characteristics, aerobic stability, and microbial communities of alfalfa silages. The effects of commercial kefir (CK) and homemade kefir culture (HK) applied with four different application doses (untreated control (CON), 5.0, 5.7, and 6.0 log cfu g-1) on wilted alfalfa and stored at an ambient temperature of 25-30 °C. After 45 days ensiling, fermentation characteristics and aerobic stability of silages were measured and bacterial diversity was investigated by 16S ribosomal RNA gene sequencing using GenomeLab™ GeXP platform. Both CK and HK accelerate more lactic acid production and reduced ammonia nitrogen concentration. Factor analysis of kefir sources suggest that the addition of kefir improves the aerobic stability of silages even the initial water soluble carbohydrate (WSC) content is inadequate via its antimicrobial effect on yeast and mould formation. Enterococcus faecium, Pediococcus pentosaceous, and Lactobacillus brevis were dominant bacterial species among the treated groups at silo opening while Lactobacillus plantarum and Lactobacillus brevis became dominant bacterial species after 7 days of aerobic exposure. In conclusion, application of kefir on alfalfa silages improves fermentation quality and aerobic stability even with low WSC content.

This is the first study that investigates the effect of kefir with an emphasis on the production of short-chain fatty acids (SCFA) during the fermentation process in food products. The products developed and characterized were an artisanal cream cheese without cream and with added cream and for the analysis of the fatty acid profile, both cream cheeses were compared with commercial cream cheese. The artisan cream cheese had a high amount of lactic acid bacteria characterizing the product formed by lactobacilli and a low concentration of lactose due to the fermentation process. Compared to commercial cream cheese, our products without and with added cream had a higher concentration of short-chain fatty acids (SCFA), especially butyric acid which is important for the health of the gastrointestinal tract and oleic fatty acid which has been associated with the prevention and control of some diseases. Overall, the artisan cream cheese cream with fermented cream with kefir grains is a functional product with an innovative character compared to current products on the market and was well accepted by the younger public. This new product comes as an option for those who need to change their eating habits and maintain a healthy lifestyle.

Comparative metatranscriptomics of bacterial and yeast communities of two milk kefir beverages (MKAA1 and MKAA2) obtained by fermentation with two different frozen stocks of the kefir grain CIDCA AGK1, and differing in rheological features and organic acid amounts production was carried out to figure out the relation between differences in physicochemical and rheological properties of kefir and the microbial active profile associated with each product. The dominance of lactic acid bacteria and yeast and a marginal amount of acetic acid bacteria marked the microbiome. The bacterial families Lactobacillaceae and Streptococcaceae account for almost all bacterial gene transcripts, with Lactobacillus helveticus, L. kefiranofaciens, L. gallinarum and Lactococcus lactis being most frequent in the microbiome of MKAA1 beverage, and L. kefiranofaciens, Lc. lactis and Leuconostoc mesenteroides being most prevalent in the MKAA2. Dipodascaceae and Saccharomycetaceae were the leading yeast families represented by Yarrowia lipolytica, Saccharomyces unisporus, and Kluyveromyces marxianus. The MKAA1 and MKAA2 shared >75% KEGG Ortologs (KO) in bacteria and yeast libraries. Considerable decreases in total expressed genes (KEGG Ortolog) assigned to Lactobacillus helveticus and L. gallinarum might be related to the variations in rheological features of the beverages, probably by compromising the interrelations with L. kefiranofaciens which might explain the variations in rheological features of the beverages.

Conclusions: It could be concluded that small/medium scale dairy plants can use UF equipment with the aim to valorize sheep´s and goat´s CW through the production of dairy formulations with added prebiotics and probiotics, while reducing the environmental impact of their activities.

This work aimed to carry out a bioremediation study to evaluate the resistance of Penicillium sp. isolated from kefir grains for the treatment of copper. The fungal culture medium was prepared using a 2% malt-agar medium at pH 7.0 in which Penicillium sp. was inoculated. Penicillium sp. growing in a liquid medium showed a decrease in biomass in presence of Cu(NO3)2 (800 mg.L-1), suggesting that the metal impacts the growth rate of the fungus. Moreover, the combined factors of pH and the presence of the inorganic contaminant impacted the radial growth of the fungus, causing inhibition of 73% at pH 4.0, 75% at pH 7.0, and 77% at pH 9.0 in liquid medium compared to control. However, images obtained with scanning electron microscopy showed the integrity of the fungus cell, even at high doses of copper in the medium. Therefore, it can be concluded that Penicillium sp. isolated from kefir grain can bioremediate the environment and that the harmful effects of heavy metals can be minimized as a result biosorption. Although the growth of Penicillium sp. is inhibited, such retardation requires high doses of copper nitrate, thus ensuring the use of this microorganism for protection against the harmful effects of non-essential copper in the environment.

Nowadays, probiotics has been proposed for substituting antibiotics in animal feed, since the European Union (EU) banned the latter compounds in 2006 to avoid their serious side effects on human health. Therefore, this work aimed to produce a probiotic product by fed-fermentation of whey with kefir grains for use in animal feed. The whey was fermented with a combination of kefir grains AGK1 and the free biomass present in whole milk fermented milk used to activate these kefir grains. The probiotic culture obtained was characterized with high levels of biomass, total viability and antibacterial activity. Some probiotic properties of the probiotic culture were investigated in vitro, including its survival at low pH values, under simulated gastrointestinal conditions, after freezing in skim milk at − 20 ºC, and in the commercial feed during storage at room temperature. The viable cells of lactic and acetic acid bacteria and yeasts exhibited higher tolerance to acidic pH and simulated gastrointestinal conditions when the cells were protected with skim milk and piglet feed, compared with washed cells. The results indicated the feasibility of producing a probiotic product at a low cost with a potential application in animal feed.

Wild artisanal cultures, such as SCOBY-based membranes (Symbiotic Culture of Bacteria and Yeasts) and water kefir grains (WKG), are complex consortia of microorganisms comprising yeasts, lactic and acetic acid bacteria, with a large strains’ diversity and abundance. The fermented products (FPs) obtained by the microbiome’s contribution can be included into functional products due to their metabiotics (pre-, pro-, post-, and paraprobiotics) as a result of the complex and synergistic association as well as due to the metabolic functionality. In this study, both consortia of SCOBY and WKG were involved in the co-fermentation of a new formulated substrate, that was further analysed aiming at increasing of the postbiotic composition of the FPs. Plackett-Burman (PB) and Response Surface Methodology (RSM) techniques were used for the experimental designs to select and optimize the most important parameters that influence the freeze-dried starter cultures of SCOBY and WKG activity as a multiple inoculum. The tea concentration (1-3%), sugar concentration (5-10%), raisins concentration (3-6%), SCOBY lyophilized culture concentration (0.2-0.5%), WKG lyophilized culture concentration (0.2-0.5%), and fermentation time (5-7 days), were considered the independent variables for mathematical analysis and fermentation conditions’ optimization. The pH, total acidity (TA), antioxidant activity (DPPH), and antimicrobial activity against Escherichia coli ATCC 25922, Bacillus subtilis MIUG B1, Staphylococcus aureus ATCC 25923, and Aspergillus niger MIUG M5 were evaluated as responses. The rich postbiotic bioactive composition of the FP obtained in optimized biotechnological conditions highlighted the usefulness of the artisanal co-cultures, through their symbiotic metabolic interactions for the improvement of bioactive potential.

Nowadays, there has been a significant rise in the consumption of kefir, a functional beverage touted for its perceived health benefits. To offer a high-quality beverage to consumers, it is imper-ative to scrutinize and fine-tune the fermentation process. This study seeks to investigate the im-pact of fermentation time and the number of subcultures on the physicochemical, microbiological, and volatile composition, as well as the visual appearance of kefir beverages obtained from four consecutive 24- or 48-h batch subcultures. All fermented beverages exhibited low lactose, ethanol and acids levels, with counts of viable probiotic lactic acid bacteria and yeast exceeding 106 colony forming units/mL. The four kefir beverages from the 48-h batch subcultures notably showed the lowest total concentrations of volatile compounds likely due to overfermentation and overacidifi-cation of the beverages. This caused separation of the whey and curd, along with the formation of large gas bubbles, negatively affecting the visual appearance of the products. These findings em-phasize the importance of fine-tuning the fermentation process to ensure the production of high-quality kefir beverages that align with consumer preferences. The four beverages from the 24-h batch subcultures exhibited high microbiological and physicochemical stability during stor-age at 4 °C for 28 days.