Characterization of kefir produced in household conditions: Physicochemical and nutritional profile, and storage stability

Kefir, a traditional fermented food, has numerous health benefits due to its unique chemical composition, which is reflected in its excellent nutritional value. Physicochemical and microbial composition of kefir obtained from fermented milk are influenced by the type of the milk, grain to milk ratio, time and temperature of fermentation, and storage conditions. It is crucial that kefir characteristics are maintained during storage since continuous metabolic activities of residual kefir microbiota may occur. This study aimed to examine the nutritional profile of kefir produced in traditional in use conditions by fermentation of ultra-high temperature pasteurized (UHT) semi-skimmed cow milk using argentinean kefir grains and compare the stability and nutritional compliance of freshly made and refrigerated kefir. Results indicate that kefir produced under home use conditions maintains the expected characteristics with respect to the physicochemical parameters and composition, both after fermentation and after refrigerated storage. This work further contributes to the characterization of this food product that is so widely consumed around the world by focusing on kefir that was produced in a typical household setting.Emília Alves and Epole Ntungwe acknowledge ALIES, Portugal for the grant PADDIC 2019–2020 and 2020–2021. The authors gratefully thank Professor Angela Leon, from the Centro de Investigacíon y Desarrollo en Criotecnologia de Alimentos (CIDCA), Universidad de La Plata, Argentina, for providing the CIDCA AGK1 kefir grains. The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/2020). L. Barros would like to thank the national funding by FCT, P.I., through the institutional scientific employment program-contract. To the project AllNat for the contract of C. Caleja (Project AllNat POCI-01-0145-FEDER-030463) and to the Project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural® for the contract of E. Pereira.