GROWTH AND ENCAPSULATION OF LACTIC ACID BACTERIA IN DAIRY BY-PRODUCTS

Lactic acid bacteria (LAB) are employed as fermentation agents or probiotic cultures in a variety of products. In the fabrication of cheese, the main by-products released in the industry are cheese whey (CW) and second cheese whey (SCW). Because of their contents, they can be exploited for biotechnological purposes. In this perspective, the aim of this study was to evaluate the ability of endogenous Lactobacillus paracasei ATR6 to grow in CW and SCW, and to directly submit the cultivated media to the spray-drying (SD), using these materials as encapsulating agents. Growth at 37 ºC was evaluated in flasks (with and without agitation of 250 rpm) and in bioreactor (37 ºC, 150 rpm). SD was done in a laboratory-scale equipment, with inlet and outlet temperatures of 90 ºC and 75 ºC, respectively, and air flow rate of 1.10 m3/min. Results from growth experiments show that both CW and SCW are suited media for L. paracasei ATR6, since the bacterium increased its population in approximately 4 log cycles in both, similar (p ≤ 0.05) to the values obtained for control medium (skimmed milk). The survival rates after SD were similar for CW and SCW (> 78%), as well as the yields (> 47%) for this process. Regarding size and moisture of the microcapsules, SCW enabled the formation of particles in the range of 15.21 ± 7.24 μm, with 13.52% moisture, while CW values were of 5.31 ± 1.27 μm and 8.60% for these characteristics, respectively. SCW powder showed a significant (p ≤ 0.05) change in a* and b* color parameters after 15 days of storage. With these results, we conclude that CW and SCW are suited culture media for the growth of L. paracasei ATR6, however, the former enabled the formation of more stable capsules.