Improvement of Yoghurt Quality with Probiotic Culture and Sous Vide Processing Technique: A Physicochemical, Textural, and Microbiological Approach

This research assessed the impact of probiotic culture incorporation and the sous vide manufacturing method on the physicochemical, textural, colorimetric, and microbiological characteristics of yoghurts during the storage duration. The trials used conventional and sous vide manufacturing techniques using probiotic and classical starting cultures, and the products were analyzed throughout the storage period. The findings indicate that the use of probiotic cultures significantly enhances organic acid synthesis. This rise resulted in a lower pH (≈4.54) and increased titratable acidity (≈1.60%). Furthermore, it has been shown that the total organic acid concentration, mostly lactic acid, rose (≈24,045 mg/kg), while concurrently, the yeast-mold load decreased (≈2.69 log CFU/g). Throughout the storage duration, a reduction in pH and an elevation in acidity and microbial activity were seen in all samples (p < 0.05). The sous vide manufacturing method, due to regulated heat processing and a sealed system design, has decreased syneresis (≈5.65%) and an enhanced dry matter content (≈13.09%). This circumstance has resulted in the development of a more uniform gel structure, thereby enhancing the textural attributes. Color investigations indicated that the integration of probiotics and sous vide decreased the ΔE values, and in samples with ΔE < 3, the color change was imperceptible to the human eye. In conclusion, the simultaneous application of probiotic culture addition and the sous vide production technique has exhibited a synergistic effect on acidity development, microbial stability, textural properties, and color stability, indicating its efficacy in producing higher-quality functional yoghurt.