Abstract
This study aims to compare the characterization of three Lactobacillus strains (L. helveticus, L. acidophilus, and L. paracasei subsp. paracasei) in camel milk and bovine milk during fermentation. Our finding showed that the average total viable counts of all three Lactobacilli strains in both milk types reached more than 7.0 log CFU/mL after 16 h of fermentation and continued to increase significantly (p < 0.05) as fermentation increased, which is according to the FAO and WHO, higher than the minimum recommended daily probiotic dose to provide the potential health benefits. The total count of L. paracasei subsp. paracasei was greater in fermented camel and bovine milk (8.76 and 8.98 log CFU/mL, respectively) compared to L. helveticus, and L. acidophilus. The L. helveticus exhibited the highest significant (p < 0.05) acidifying ability for both camel and bovine milk; on the other hand, L. paracasei subsp. paracasei revealed the highest significant (p < 0.05) pH in both milk. The L. acidophilus strain exhibited significantly (p < 0.05) the highest levels of free amino acids groups (FAAGs) among other tested strains in camel milk. It is concluded that the growth, viability, and proteolytic activity of three Lactobacilli strains were found to be mainly dependent on incubation time, strain, and type of milk.