Sahar Adnan Sheet( 1) and Waleed Ahmed Mahmood*(1)
(1). Faculty of Agriculture and Forestry, University of Mosul. Iraq.
(*Corresponding author: Dr. Waleed Ahmed Mahmood. E-Mail: waleedahmed53@yahoo.com).
Received: 04/01/2020 Accepted: 09/02/2020
Abstract
The study was carried out at Faculty of Agriculture and Forestry, Univ. of Mosul in 2018 and 2019. Lactic acid was produced from cheese whey of buffalo’s milk by free mixed cultures of Streptococcus thermophilus and Lactobacillus bulgaricus. Some factors affecting acid productivity were studied which included type and concentration of carbon and nitrogen sources, concentration of magnesium sulphate and manganese sulphate, inoculum concentration, pH and fermentation time. Results showed a significant increase in acid production upon using the mixed culture as compared to pure culture of each species. Yeast extract (12 gm/l) and lactose (15 gm/l) were found the best addition as a source of nitrogen and carbon for improving acid production, respectively. Addition of magnesium sulphate (0.35 gm/l) and manganese sulphate (0.05 gm/l) had significantly increased lactic acid production. Maximum lactic acid production was obtained upon the addition of the inoculum with a concentration of 10×107 cell/ml. Optimum initial pH of whey for acid production was 5.5 with non-significant differences within the range of 5-6.5. Incubation time of 48 hours was found suitable for acid production since the increment beyond this time was non-significant.
Key words: Lactic acid,Cheese whey, Streptococcus thermophilus, Lactobacillus bulgaricus.
Full Paper in Arabic: PDF