Alginate-Based Encapsulation of Pistacia lentiscus (Mastic Gum) Extract and Its Application in Functional Kefir: Physicochemical, Antioxidant, and Textural Properties.

Bioactive compounds derived from natural sources are increasingly incorporated into functional dairy products; however, their limited stability during processing and storage may affect their functional performance. Encapsulation has been applied as a strategy to improve the stability and controlled delivery of sensitive bioactive compounds in food matrices. In this study, Pistacia lentiscus (mastic gum) extract was encapsulated using alginate and incorporated into kefir to evaluate the effects of free and encapsulated extract on physicochemical, antioxidant, and textural properties during refrigerated storage. The encapsulation efficiency of alginate beads was 78.15%, with a loading capacity of 15.30%. Kefir samples containing free or alginate-encapsulated mastic gum extract at two concentrations were evaluated during 14 days of refrigerated storage. Total phenolic content and antioxidant activity ranged from 802.50 to 865.00 mg GAE/L and from 5.87 to 14.08 mM TE, respectively, depending on formulation and storage period. Encapsulated formulations exhibited phenolic content comparable to those containing free extract. Water-holding capacity values ranged from 34.96% ± 0.20% to 47.10% ± 0.37%, while color and textural properties were influenced by formulation and storage time, with significant differences observed only in firmness among specific encapsulated formulations. These findings suggest that alginate encapsulation may contribute to the stabilization and controlled delivery of mastic gum bioactive compounds in kefir, supporting the development of fermented dairy products enriched with plant-derived functional ingredients.