Functional improvement of synbiotic yogurt enriched with Lacticaseibacillus rhamnosus and aloe vera gel using the response surface method

The response surface technique was applied to produce synbiotic yogurt containing Lacticaseibacillus rhamnosus and aloe vera gel (AVG) with high functionality (antioxidant and antimicrobial characters), superior physicochemical properties, and desirable sensory attributes. The experiments were planned around a central composite design (CCD) with two independent variables: AVG concentration (0-5%, w/w) and storage time (1-28 days). The AVG concentration and storage time significantly improved the viability of L. rhamnosus up to 7.9 cfu/g during the shelf life which is a practical limit for a probiotic. It enhanced the yogurt's antioxidant and antipathogenic activity, proteolytic content, water-holding capacity, and sensory aspects. High concentrations of AVG reduced the yogurt's desirable textural aspects (hardness and gumminess) except for firmness and adhesiveness and to some degree the sensory properties as well. The results showed that adding 5% AVG to probiotic yogurt produced a functional food with 68% desirability that retained its beneficial properties for at least 14 days under refrigerated storage.