Lyophilization of <i>Kurut</i> Produced by Adding Probiotic Cultures to Skim Milk and Buttermilk Mixtures: Determination of Physicochemical, Microbial and Aromatic Properties

ABSTRACT This study investigated the potential of buttermilk, a dairy by‐product, in the production of kurut , a high‐protein, shelf‐stable functional dairy product. Various formulations were prepared by replacing skim milk (SM) with buttermilk at proportions ranging from 25%–100%. Probiotic cultures were incorporated, and the mixtures were freeze‐dried. Samples were stored at +4°C for 90 days and analyzed every 30 days for microbial, chemical, and sensory attributes. The 100% SM sample exhibited the highest protein content (55.14%–57.94%), whereas BM100 (100% buttermilk) had the lowest (50.67%–53.75%). BM50 (50% buttermilk) maintained probiotic viability above the therapeutic threshold (10 6 –10 7 log cfu/g) until day 60. Sensory analysis identified BM25 (25% buttermilk) as the most preferred formulation (7.45), whereas the 100% SM sample received the lowest score (5.91). The volatile profile was dominated by organic acids, alongside aldehydes, ketones, alcohols, and esters, with buttermilk significantly increasing organic acid content. These findings underscore buttermilk's functional role in kurut production, demonstrating its ability to enhance sensory and probiotic properties while ensuring biological and chemical stability under optimal storage conditions.