The effect of microencapsulated probiotic supplementation on viability levels and certain quality parameters of functional whey cheese during storage

This study aimed to enhance the functional properties of whey cheese (Lor), obtained from serum proteins through thermal denaturation of whey, by supplementing it with probiotics. For this purpose, two probiotic strains, Lb acidophilus ATCC 4356 and B. bifidum, were microencapsulated using the coacervation method. To promote the growth of the probiotics and protect them from external factors, two different prebiotic substances, fructooligosaccharides (FOS) and inulin, were added to the encapsulation matrix. The viability and gastrointestinal stability of free and microencapsulated probiotics, added to the whey cheese at two different stages, before and after whey drainage, were investigated. On days 1, 7, 15, 21, and 30 of storage, general composition, biochemical, and microbiological analyses of the cheeses were conducted, while volatile compound analyses were performed on days 1, 15, and 30. In addition, the size and morphological characteristics of the obtained capsules were examined using scanning electron microscopy (SEM). The study demonstrated, through SEM imaging, that probiotics were successfully encapsulated and retained within the capsules for both probiotic strains and coating formulations. Encapsulated bacteria exhibited significantly (p < 0.05) higher viability under simulated gastric (pH 1.5) and bile (2%) conditions compared to free bacteria. While a reduction of approximately 4 logarithmic units was observed in free bacteria, the decrease in encapsulated probiotics was limited to around 2 logarithmic units. Although probiotic viability was higher in samples supplemented with microencapsulated probiotics, it was generally preserved, or even increased, in all cheese samples throughout the storage period, with viable cell counts exceeding 8 logarithmic units at the end of storage. It is noteworthy that yeast and mold counts showed a significant decrease throughout the storage period (p < 0.05). The values for dry matter, protein, and fat content in the whey cheese samples remained largely unchanged during the storage period. However, factors such as the form and timing of capsule addition had a significant effect statistically on these parameters (p < 0.05). Overall, a decrease in pH values and a corresponding increase in titratable acidity were observed as storage progressed. In line with lipolysis, the concentration of free fatty acids increased in all cheese samples over the storage period. Proteolysis values also increased with extended storage time; however, no significant difference was observed between cheeses supplemented with free or encapsulated probiotics. Electrophoretic analysis revealed no formation of advanced degradation products throughout storage, and as expected from the production process of whey cheese, serum protein bands corresponding to β-lactoglobulin and α-lactalbumin remained predominant. Volatile compound analysis identified the presence of esters, alcohols, aldehydes, alkanes, ketones, terpenes, and volatile acids in the samples, with their concentrations generally increasing over time. Based on all the findings of the study, it can be concluded that producing whey cheese with enhanced functional properties may serve as a suitable carrier for maintaining the viability of probiotic bacteria. Moreover, probiotic viability was better preserved in samples supplemented with microencapsulated probiotics. The encapsulation process improved the gastrointestinal stability of the probiotic strains, indicating that the expected health benefits of a probiotic product can be achieved. Sensory evaluations also revealed that such a product was not perceived differently from traditional whey cheese, suggesting that there would be no obstacle to its commercialization.