Pathogenic bacteria inhibition by fermented yak`s milk

U radu je istražen inhibitorni učin fermentiranog jakovog mlijeka, s dodatkom prebiotika konjaca, prema patogenim bakterijama Bacillus cereus, Enterococcus faecalis, Escherichia coli, Listeria monocytogenes, Pseudomonas fluorescens, Salmonella enteritidis, Staphylococcus aureus i Yersinia enterocolitica. Za inokulaciju mlijeka korištena je monokultura Bifidobacterium longum Bb-46. Za pripremu probiotičkih napitaka korišteno je kratkotrajno sterilizirano (UHT), homogenizirano i djelomično obrano jakovo mlijeko s 3,1 % mliječne masti. U mlijeko je dodavan prebiotik u udjelima od 0 %, 0,5 %, 1 % i 1,5 %. Fermentacija je vodena na 37 °C u trajanju od 24 sata, a odredivana je promjena aktivne i potencijalne kiselosti, kao i promjena broja probiotičkih bakterija. Mjerenja su se provodila u nultom, šestom, 12. , 18. , i 24. satu fermentacije, te tijekom četvrtog, osmog i 12. dana čuvanja. Probiotički napitci od jakovog mlijeka s dodatkom prebiotika konjaca pokazali su inhibitorni učin na sve patogene bakterije. Inhibitorni učin se razlikovao ovisno o dodanoj koncentraciji konjaca (0 %, 0,5 %, 1 %, 1,5 %), te o periodu fermentacije i skladištenja jakovog mlijeka.This work explores the inhibitory effect of jak fermented milk with prebiotic konjac toward pathogenic bacteria Bacillus cereus, Enterococcus faecalis, Escherichia coli, Listeria monocytogenes, Pseudomonas fluorescens, Salmonella enteritidis, Staphylococcus aureus and Yersinia enterocolitica. For inoculation of milk monoculture of Bifidobacterium longum Bb-46 was used. For the preparation of probiotic a short-sterilized (UHT), homogenized and partially skimmed jak milk with 3.1% milk fat was used. Prebiotic was added in milk in the amount of 0%, 0.5%, 1% and 1.5%, respectively. During 24 hours of fermentation at 37 °C, active and potential acidity and changes of probiotic cell numbers were measured. Changes were measured at 0, 6th, 12th, 18th and 24th hour of fermentation, and at fourth, eight and 12th days of storage. Jak milk fermented by B. longum Bb-46 with prebiotic konjac showed inhibitory effect on all pathogenic bacteria. The inhibitory effect is different depending on the amount of added konjac (0%, 0.5%, 1%, 1.5%) and the period of fermentation and storage of jak milk