Unveiling the potential of oleaster (Elaeagnus angustifolia L.) in coconut milk kefir fermentation: volatile compounds, physicochemical and sensory characterization

Abstract

Fermented beverages are recognized for their health benefits. Versatile kefir can be produced from non-dairy sources and making it suitable for plant-based diets. This study aimed to evaluate the potential of oleaster seed waste in the non-dairy coconut milk fermentation, and to investigate physicochemical characteristics, lactic acid, CO₂, ethanol and vitamin B₁₂ levels and identify volatiles of coconut milk kefir. Findings indicated that both whole oleaster- and oleaster seed powder-fermented kefirs exhibited elevated density, brix values, and viscosity compared to the plain control, while maintaining similar pH levels. Fermentation with oleaster seed powder notably improved beverage yield and induced the highest color change. The highest concentrations of lactic acid and CO₂ were observed in the whole oleaster-fermented samples. The oleaster seed powder-fermented kefir displayed the lowest ethanol content and contained detectable levels of vitamin B₁₂ (0.130 ± 0.0400 µg cyanocobalamin/100 g); however, this was lower than the control, and vitamin B₁₂ was not quantifiable in the whole oleaster-fermented samples. Samples fermented with oleaster seed powder showed the greatest diversity of volatile compounds (30 out of 31). From a sensory perspective, kefir produced with whole oleaster was most favorably received by the panellists.