PROTEOLYTIC BACTERIA STUDY IN PRODUCTION OF CHEESE BY FERMENTATION

Arry Miryanti (a) and I Nyoman Pugeg Aryanth (a,b)

a Industrial Technology Faculty, Catholic Parahyangan University Bandung, Indonesia
b School Of Life Sciences and Technology, Institut Teknologi Bandung, Indonesia

Abstract

The main target of this research is to obtain bacteria isolates from food and beverage products with good proteolytic characteristic in forming curd, and also to optimize the type and inoculum ratio, fermentation temperature, initial medium pH, inoculum concentration and milk composition. The first step was microorganism isolation from whey and traditional food than followed by isolates screening, identification of chosen isolate, activation of chosen isolate, growth characterization, and finally the optimization in three phases. First optimization was conducted by varying the inoculum ratio of Leuconostoc paramesenteroides and Lactobacillus delbrueckii. The 2nd optimization was conducted by varying initial medium pH and inoculum concentration. The 3rd optimization was conducted by varying the weight ratio (in gram) of skim milk and cow milk and control treatment without skim milk addition. From 13 isolates which were screened, two bacteria isolates have proteolytic property and produce good quantity of curd. These isolates are isolate-B (Leuconostoc paramesenteroides) and isolate-L (Lactobacillus delbrueckii). The age of Leuconostoc paramesenteroides culture which was used as inoculum was 4-6 hours with a maximum growth rate 0.4704 cell/hour and fastest generation time of 1.4734 hour. The age of Lactobacillus delbrueckii culture which was used as inoculum was 2-4 hours with a maximum growth rate 0.4820 cell/hour and fastest generation time of 1.4378 hour. The optimum condition was reached by using single inoculum from Lactobacillus delbrueckii, with fermentation temperature of 370C, inoculum concentration of 10%-v/v, initial medium pH of 6,8 and skim milk to cow milk ratio of (50:250)-w/w. The results on cheese production at these optimum conditions were as follows : yield of cheese 13.31%, water content 57.76%, protein 17.24%, fat 6.73%, the rating of colour 2.67 (rather white), texture 3.00 (rather soft), taste 4.60 (not acid) and flavour 3.07 (delicious enough).

Keywords : proteolytic, coagulation, skim milk, cow milk, cheese.

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 2nd International Conference on Mathematics and Natural Sciences (ICMNS), Bandung 2008