Performance of Commercial Cultures in Fluid Milk Applications

• Published in: Journal of dairy science Vol. 79; no. 6; pp. 943 - 955
• Main Authors: Sanders, M.E., Walker, D.C., Walker, K.M., Aoyama, K., Klaenhammer, T.R.
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.06.1996; Am Dairy Sci Assoc; American Dairy Science Association
• Subjects: Animals; beta-Galactosidase - metabolism; bifidobacteria; Bifidobacterium - genetics; Bifidobacterium - physiology; Bile; Biological and medical sciences; Electrophoresis, Gel, Pulsed-Field; Food industries; Fundamental and applied biological sciences. Psychology; Genotype; Lactase; lactobacilli; Lactobacillus acidophilus - genetics; Lactobacillus acidophilus - physiology; Milk - microbiology; Milk and cheese industries. Ice creams; Oligonucleotide Probes; probiotics; Streptococcus - genetics; Streptococcus - physiology; Streptococcus thermophilus; PFGE; lactobacilli; bifidobacteria; Streptococcus thermophilus; probiotics; Probiotic; Bifidobacterium; Stability; Actinomycetaceae; Enzyme; Lactase; Lactobacillus acidophilus; Actinomycetales; Streptococcaceae; Sensitivity resistance; Enzymatic activity; Streptococcus salivarius subsp. thermophilus; Glycosidases; Formulation; Bacteria; Hydrolases; Lactobacillaceae; Micrococcales; Actinomycetes; O-Glycosidases; Speciation; Bile; Milk
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(96)76445-7

Six Lactobacillus acidophilus, 5 Bifidobacterium, and 6 Streptococcus thermophilus strains were studied for characteristics that are important to activity and stability in unfermented fluid milk products. Speciation, strain relatedness, frozen concentrate stability, bile sensitivity, and lactase activity were evaluated. The microbiological stability of a culture-containing fluid milk product was also determined. Two of the bifidobacteria cultures contained >1 strain. Some strains were shown to be closely related or identical by pulsed-field gel electrophoresis of fragmented chromosomal DNA. Selective media that distinguished among all 3 added genera were identified. All lactobacilli and most of the bifidobacteria were resistant to bile concentrations varying from 1 to 3%, and all streptococci were sensitive to bile. Lactase activities were highest for S. thermophilus strains, supporting use of this species in fluid milk and dairy products to aid in the digestion of lactose by consumers. The experimental product evaluated in this study contained 107 cfu/ml of both L. acidophilus and Bifidobacterium spp. and 5 × 107 cfu/ml of S. thermophilus. Lactic, but not psychrotrophic, populations were fairly stable during storage. The results suggest that milk formulated with high concentrations of three different genera of probiotic bacteria can be manufactured with commercial strains.