Determining Antibacterial Effect of Yellow Onion (Allium Cepa) Peel Extract on Some Pathogen Inoculated in Raw, UHT and Pasteurized Milks

Abstract

In this research, yellow onion peel extract (YOPE) was tested against some pathogens inoculated into pasteurized, UHT and raw milks. Milk samples were added with YOPE at 10% (v/v) and were left at 4 ºC for 5 days. The pH and colour of milk samples were determined at 1, 3 and 5th day of storage. Moreover, the milk samples were inoculated by 0.0, 5.0 and 7.0 log cfu/mL of Escherichia coli ATCC 25922 and by 0.0, 5.0 and 7.0 log cfu/mL of S. aureus ATCC 25923. All the above samples were then added with YOPE at a rate of 0.0 or 5.0% (v/v). YOPE had the greatest inhibitory effect on E. coli inoculated pasteurized milk at a concentration of 7.00±0.24 log cfu/mL, whereas the lowest inhibitory effect was shown on the raw milk inoculated with 7.00±0.87 log cfu/mL S. aureus and 5.00±0.21 log cfu/mL E. coli.