beneficial effect of using starter cultures to inhibit outgrowth of spoilage organisms in kareish cheese during storage

ABSTRACT

The antagonistic effect of S. lactis [Lactococcus lactis subsp diacetylactis], S .thermophilus [S. salivarius subsp thermophilus] and L. bulgaricus [L. delbruckii subsp. bulgaricus] strains against E. coli, Ent. aerogenes, Ps. fluorescens and Sacch. cerevisiae was studied on a laboratory scale in skim milk or in contaminated and respectively uncontaminated kareish cheese In skim milk L. bulgaricus was the most effective culture in suppressing the growth of the spoilage microorganisms investigated, followed by S. lactis subsp diacetylactis, S.thermophilus and lastly S. lactis which showed the least suppressing effect. Ps. fluorescens and Ent. aerogenes were most sensitive to all tested starter cultures followed by E. coli and Sacch cerevisiae. In contaminated kareish cheese Sacch cerevisiae and S. lactis were not included due to minimal effect in skim milk experiments Ent, aero genes was generally the most sensitive spoilage organism followed by Ps. fluorescens while E. coli was the least affected by the starters investigated. L. bulgaricus was the most effective strain against Ent. aero genes followed by S. lactis subsp diacetylactis and S. thermophilus in a descending order. S, lactis subsp diacetylactis was the most effective strain against Ps. fluorescens and E. coli followed by L. bulgaricus and S. thermophilus in descending order. In uncontaminated kareish cheese the psychrotrophs were generally more sensitive to the various starters used than the coli forms L. bulgaricus and S. lactis subsp diacetylactis were most suppressive