Impact of Different Lactobacillus spp. and Apple Fiber Supplementation on the Technological and Biofunctional Properties of Fermented Goat Milk Beverages

Fermented goat milk beverages have emerged as promising functional dairy matrices due to their high nutritional value, probiotic content, and associated health-promoting potential. Growing demand for fiber-enriched probiotic dairy products has stimulated efforts to improve technological stability, biofunctional performance, and sensory quality. However, limitations related to fermentation efficiency, product structure, sensory acceptance, and probiotic survival during storage remain critical challenges. Consequently, the incorporation of functional ingredients such as dietary fiber in combination with selected probiotic bacteria represents an approach to overcome these constraints and optimize product quality. This study evaluated the effects of three Lactobacillus spp. (L. acidophilus, L. casei, and L. helveticus); 1% apple fiber (AF) supplementation; and 21-day storage on the technological, functional, microbiological, and sensory properties of fermented goat milk beverages. L. casei significantly reduced fermentation time by 305 min compared with L. acidophilus and by 62.65 min compared with L. helveticus, while producing beverages with the highest water-holding capacity (WHC; 46.20%), consistency index (1.11 Pa.sⁿ), and probiotic viability (8.99 log cfu/mL). AF supplementation improved technological and functional attributes by increasing WHC by 3.72%, total phenolic content by 0.56%, and antioxidant activity (DPPH 4.9%, ABTS 1.14 μmol Trolox/g fresh weight), while reducing syneresis by 3.47% and suppressing goaty flavor intensity. Sensory evaluation showed that AF addition decreased fermented flavor intensity but added fruity notes, resulting in a sensory trade-off, whereas L. casei beverages achieved the highest overall acceptability. Correlation analysis showed that flavor was the strongest predictor of product acceptance (r = 0.901, p < 0.01). Principal component analysis (PCA) revealed clear clustering based on both culture type and AF supplementation. Overall, the combined application of L. casei and AF provides an effective technological and biofunctional strategy for the development of structurally stable, nutritionally enhanced, and consumer-oriented fermented goat milk beverages, highlighting its relevance for next-generation functional dairy product innovation.