Exploitation of Yeasts with Probiotic Traits for Kefir Production: Effectiveness of the Microbial Consortium

Abstract

Kefir is a fermented milk made by beneficial lactic acid bacteria and yeasts inoculated as grains or free cultures. In this work, five yeast strains with probiotic aptitudes belonging to Candida zeylanoides, Yarrowia lipolytica, Kluyveromyces lactis, and Debaryomyces hansenii species were assessed in a defined consortium, in co-culture with a commercial strain of Lactobacillus casei, in order to evaluate the yeasts’ fermentation performance during kefir production, using different milks. The concentration of each yeast was modulated to obtain a stable consortium that was not negatively affected by the bacteria. Furthermore, all yeasts remained viable for five weeks at 4 °C, reaching about 8.00 Log CFU in 150 mL of kefir, a volume corresponding to a pot of a commercial product. The yeasts consortium showed a suitable fermentation performance in all milks, conferring peculiar and distinctive analytical and aromatic properties to the kefirs, confirmed by a pleasant taste. Overall, the panel test revealed that the cow’s and sheep’s kefir were more appreciated than the others; this evaluation was supported by a distinctive fermentation by-products’ content that positively influences the final aroma, conferring to the kefir exalted taste and complexity. These results allow us to propose the yeasts consortium as a versatile and promising multistarter candidate able to affect industrial kefir with both recognizable organoleptic properties and probiotic aptitudes.

Lacticaseibacillus rhamnosus GG Survival and Quality Parameters in Kefir Produced from Kefir Grains and Natural Kefir Starter Culture

“…Due to the lack of reliable population of microorganisms in commercial kefir starter cultures, a remarkable diminution in sensory properties is usually observed. In fact, fermented dairy products develop their unique organoleptic and functional attributes as result from the metabolic activity of the multispecies microflora, where more than one type of interaction may occur concomitantly [ 12 ]. Kefir can also be manufactured from natural kefir starter culture, which is initially captured from kefir grains with the same microbial composition.…”

Application of Ultrafiltration To Produce Sheep’s and Goat’s Whey Based Synbiotic Kefir Products

“…In relation to sensory analysis, it has been reported that the ovine kefir is more appreciated than the goat kefir [31]. The sensory scores of our ovine and goat kefirs showed significant differences but some sensorial aspects of both kefirs can be improved.…”

“…Some authors developed synbiotic drinks from milk fermented by kefir grains and supplemented by inulin, quinoa flour, or with the addition of specific probiotic bacteria [20,29,30]. However, most available milk-based kefir products on the market are produced without kefir grains; they use commercial kefir cultures [31]. This study will also aim to develop new synbiotic kefir products based on sheep's and goat's UF concentrated CW, fermented by kefir grains or commercial kefir starter, with and without the addition of a commercial probiotic culture, and supplemented with inulin.…”

Engineering the synthesis of unsaturated fatty acids by introducing desaturase improved the stress tolerance of yeast

“…During the fermentation of foods and beverages, like wine, beer and cheese, aromatic chemicals are created in large part as a result of yeast growth. 1,2 Meanwhile, yeast is often used to build cell factories to produce various chemicals or nutrient substances. 3,4 Efficiencies of cell proliferation and product accumulation may be impacted by the stressful environments encountered by cells during fermentation.…”

“…During the fermentation of foods and beverages, like wine, beer and cheese, aromatic chemicals are created in large part as a result of yeast growth 1,2 . Meanwhile, yeast is often used to build cell factories to produce various chemicals or nutrient substances 3,4 .…”