Valorisation of Dairy Wastes Through Kefir Grain Production

The main aim of this work was to investigate on kefir grains (KGs) increase using different dairy by-products. To this purpose, whey and deproteinized whey from cow, goat and sheep milk were compared to the pasteurized milk of the corresponding animal species. Each substrate was inoculated with 3% (w/v) of KGs cultivated in ultra-high temperature cow milk and evalu- ated for pH decrease, total titratable acidity increase and development of lactic acid bacteria (LAB) and yeasts released in the matrices after 24 h incubation at three different temperatures (20, 25 and 30 °C). The genotypic characterization of the dominating microbial populations resulted in the identification of two LAB belonging to the species Lactococcus lactis and Leuconostoc mesenteroides and one yeast strain within the species Kluyveromyces marxianus. Among whey based fermenta- tion media deproteinized sheep whey allowed the highest KGs increase (almost 50%). Results of the present investigations reveal the potential of the dairy wastes for KGs production at industrial level.