Evaluation of freeze-dried Tibetan kefir co-culture as a starter for production of Bod ljong cheese

Abstract

The physico-chemical profile, proteolysis, flavor, and microbiological changes were investigated, and a sensory evaluation was performed for Bod ljong cheese prepared using a freeze-dried Tibetan kefir co-culture during ripening. The proteolysis level was high, the pH 4.6-soluble nitrogen, 12% trichloroacetic acid-soluble nitrogen, water soluble nitrogen, and total free amino acid contents increased, and the protein content decreased during ripening. The effect of the starter culture on production of aroma-related compounds responsible for cheese flavor was also studied using solidphase microextraction GC-MS techniques. Alcohols and esters were the most abundant volatile compounds. Microbial counts during ripening increased steadily. Lactic acid bacteria, Lactobacillus and Lactococcus, were the dominant flora during ripening. Enterococci, Enterobacteriaceae, and Salmonella sp. bacterial counts were low or zero. The cheese was subjected to sensory evaluation by a panel and compared to commercial Bod ljong-type cheese.