Evaluation the antibacterial effect of hydroalcoholic coffee extract on L. monocytogenes isolated from milk and milk products

Document Type : Research article


Department of Food Hygiene, Faculty of Veterinary Medicine, South Valley University, Qena 83523, Egypt


A total of 450 samples of raw milk, pasteurized milk, flavored milk, dominate cheese, kareish cheese, small scale ice cream, large scale ice cream, small scale yoghurt and large scale yogurt. Samples were inspected for incidence of Listeria spp. and genetic detection of 16S rRNA gene by PCR. Listeria spp. isolated from 27 (6%) out of total samples examined. Listeria spp. recovered from tested market raw milk, kareish cheese, small scale ice cream and domiati cheese samples with 20, 16, 14% and 4%, respectively. However, Listeria spp. was absent in other analyzed samples. The most prevalent species was L. monocytogenes 10 (2.22%), followed by L. grayii 9 (2%), L. welshimeri 4 (0.89%) and L. innocua 3 (0.67%) with overall 5.7% verified by PCR. Eight out of 10 L. monocytogenes isolates confirmed by 16S rRNA gene that implies risk of food-borne listeriosis among dairy product consumers. Furthermore, a unique approach used for assessment antibacterial activity of different concentrations of gentamicin and hydroalcoholic coffee extract (H. A. coffee extract) against isolated L. monocytogenes strain in vitro using a microplate in ELISA reader is provided in current work. The potent antimicrobial activity of gentamicin and H. A. coffee extract obtained at 30 µg/ml against isolated L. monocytogenes strain. At which not exhibit listeria growth up to 98.3 % and 96.1 %, respectively. H. A. coffee extract was screened using gas chromatography-mass spectrometry (GC-Mass). This analysis showed that antibacterial impact of H. A. coffee extract against L. monocytogenes is attributed to caffein and eugenol.


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