Using of dairy propionibacteria as bio-preservative in kareish cheese

Abstract

Moulds and yeasts are a major cause of fermented foods spoilage, such as kareish cheese with the low pH being selective for them and can produce off-flavors, sticky texture and cheese becomes softer. Seventy two samples of kareish cheese were collected, examined for incidence of moulds and yeasts. Positive samples were non-conforming, contained 4-5 log10 CFU g-1 moulds and yeasts. Ten species of moulds and nine species of yeasts were detected in collected samples. All propionibacteria strains showed antagonistic effect against moulds and yeasts isolates using agar well diffusion technique. Cheese made with Propionibacterium thoenii 119 and L. lactis subsp. lactis (LPT) contained the highest folate, vitamin B12, diacetyl and acetaldehyde followed by cheese made with Propionibacterium jensenii 118 and L. lactis subsp. lactis (LPJ) then made with Propionibacterium acidicpropionici 117 and L. lactis subsp. lactis (LPA). The LPT cheese achieved the greatest of yield and sensory evaluation. The populations of Aspergillus flavus and Candida albicans decreased by (1.41, 1.24 and 1.2) and (1.49, 1.28 and 1.1) log cycle in kareish cheese made with LPT, LPJ and LPA after 30 days, respectively. Experimental cheeses were higher adhesiveness, cohesiveness, gumminess, hardness and springiness than control and contained the lowest counts of moulds and yeasts.