The growth and antimicrobial activity of Lactobacillus acidophilus in probiotic fermented cheese whey beverages

The research aims were to study the growth of Lactobacillus acidophilus and its antimicrobial activity in fermented cheese whey beverages added with combination of skim milk and sucrose at various concentrations incubated at various fermentation times. Cheese whey was added with skim milk and sucrose at a ratio of 3:9, 6:6, 9:3 (%) and fermented for 18, 24, 30, 36 hours on 37°C by Lactobacillus acidophilus. Antimicrobial activity was measured using turbidimetric assay method. Fermented beverage was added into culture media of Staphylococcus aureus. The growth of indicator culture was monitored by measuring absorbance every 3 hours at 600 nm. The result showed that the total viable Lactobacillus acidophilus in the fermented cheese whey beverages range between 9,8832 - 11,6959 log cycle (7,7x 10⁹ - 4,9. x 10¹¹ cfu/mL) and there were inhibition against indicator bacteria (Staphylococcus aureus) indicated by the decrease of absorbance ratio of fermented beverages compared with the control media. Fermentation time of 24 hours and ratio of skim milk and sucrose 6:6 was the best treatment based on microbiological and physical-chemical parameter.