Impact of oat protein fortification on physicochemical stability and microbial viability in dairy-based kefir
Abstract
This study was designed to investigate the application of oat protein in kefir production and to characterize the resulting product as a dairy-based functional food. The functional characteristics of oat protein, including oil holding capacity, water holding capacity, protein solubility, foaming properties and emulsion characteristics were determined. The functional evaluation of oat protein revealed strong water and oil binding capacities, moderate foaming ability, and improved emulsification stability at higher concentrations, contributing to enhanced texture and stability of kefir. Kefir samples were produced by fortifying cow’s milk with oat protein at levels of 0.5%, 1%, and 2% (w/v) using kefir grains. Changes in the physicochemical and microbiological properties of kefir samples were monitored over the storage period. Oat protein fortification significantly affected pH, titratable acidity, serum separation, viscosity, total phenolic content and Lactococcus counts (p < 0.05). Increased oat protein concentration resulted in higher viscosity and reduced serum separation, with the lowest separation observed in kefir fortified with 2% oat protein. The addition of oat protein promoted the growth of Lactococcus spp., suggesting a potential prebiotic effect. These findings demonstrate that oat protein can be successfully incorporated into kefir as a plant-derived protein source, improving physicochemical stability, microbial viability, and overall quality attributes, thereby supporting the development of functional and nutritionally enriched fermented dairy products.
Keywords
Kefir, Oat protein, Protein fortification, Fermentation, Functional dairy product, Physicochemical properties
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