Effect of differential heat treatments on antibacterial activity of fermented goat milk

Abstract

The present study was conducted to evaluate the effect of three different temperatures on the antibacterial potential of fermented goat milk.Goat milk is one of the naturalfoods to complete perfection.Bioactive peptides, the specific protein fragments that have a positive impact on body functions, can be produced during milk fermentation. Thanks to the starter cultures’ proteolytic activity.Fresh pooled goat milk sample collected was divided into four lots. One set was used for raw milk analysis and the remaining three were subjected to heat treatment at three different timetemperature combinations namely;72°C for 15 sec, 85°C for 10 min, and 121° C for 15 min. These samples were cooled immediately to 42ºC, inoculated with 0.04 % DVS yogurt culture,incubated at 42º C for 4 hrs, and then stored at 5±2°C for 21 days for storage studies. The analysis was carried out at 7-day intervals. An agar well diffusion assay was performed to assess the inhibitory activity ofWater-soluble peptide extracts (WSPE) of these samples against Bacillus cereus ATCC 10876, Escherichia coli NCIM 2685, Salmonella enterica ATCC 6017, and Staphylococcus aureus ATCC 25923. The milk that was heated to 85°C for 10 min before fermentation showed the highest antibacterial activity against E.coli during the 7th and 14th day of storage, withthe zone of inhibition measuredat 17±0.433mm and 21±0.55mm respectively.Thus, it can be concluded that milk heated at 85°C for 10 min had better antibacterial activity than the other two treatments.

Keywords

• goat milk
• heat treatment
• antibacterial
• bioactive peptides