Abstract
Traditional buffalo curd is a rich source of wild-type lactic acid bacteria (LAB) having a broad range of probiotic characteristics. However, its application in the dairy industry is minimal. The current study aims to 1) determine probiotic properties (i.e., resistance to pH, bile, phenol, antibiotics, cell surface hydrophobicity, antibacterial activity, antifungal susceptibility, haemolytic and DNase activity) of Lactobacillus strains inhabiting back-slopped buffalo curd, 2) evaluate the characteristics of fermented milk produced using these isolated bacterial monocultures, by testing for the viability of LAB in fermented milk, changes in pH value, measurement of syneresis, texture profile analysis, high-performance liquid chromatography (HPLC), and Fourier-transform infrared spectroscopy (FTIR) analysis. Results indicated that, five bacterial strains belonging to L. delbrueckii subsp. indicus with substantial genotypic diversity within the strains, showed the best probiotic and milk fermentation properties. Furthermore, out of the isolates, L. delbrueckii subsp. indicus SUR_IN-55 showed a significantly (p < 0.05) higher survival rate at pH 3, 0.3% bile, 0.6% phenol, and high cell surface hydrophobicity. In addition, all five L. delbrueckii subsp. indicus strains demonstrated good antibacterial activity and antibiotic resistivity, with minimal differences across the strains. HPLC and FTIR analysis results showed 2.6% ± 0.02% of lactic acid production during the lactic acid fermentation of strain SUR_IN-55 with significantly (p < 0.05) lower syneresis, and higher viability with acceptable texture parameters compared to other monocultures. Overall findings verify that L. delbrueckii subsp. indicus strains SUR_IN-55, ANU_IN-91, and THS_IN-36 can be used as starter culture bacteria in the production of value-added fermented dairy products with probiotic characteristics.
Published Version
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