Quality Properties of Innovative Goat Milk Kefir Enriched with Date Paste (Phoenix dactylifera L.) and Whey Derived from Goat Cheese Production

The aim of this work was to evaluate the impact of fortifying goat milk kefir with high-value ingredients (3% and 6% date paste, and 25% and 50% goat milk substitution with date-cheese whey), derived from the valorization of date coproducts, on its nutritional (proximate composition and mineral profile), technological (pH, acidity, viscosity, color, sugar and organic acid content), microbiological and sensory properties. Both ingredients enhanced the growth and stability of the kefir starter culture, thereby improving the probiotic potential of date-added kefir and also its nutritious quality (lower fat content and higher protein content). The mineral profile of kefir was improved only when the date paste was added. Date paste could be used as an ingredient in fortified kefir (up to 6%) without altering its flow properties because it was perfectly integrated within the milk matrix. The use of date-cheese whey as a goat milk substitution (>25%) decreased the typical kefir viscosity, inducing an excessive phase separation negatively valued by consumers. Consumers preferred the kefir with 6% date paste mainly due to its higher scores for aroma, flavor, sweetness and acidity.