Starter cultures for semi hard cheese

Abstract

29 starter cultures for semi hard cheese are formed from natural isolates of lactic acid bacteria. They are isolated from traditionally home made cheese produced without the addition of starter cultures. Natural isolates had previously been characterized in detail which helped in construction of the starter cultures. 24 starter cultures belong to group of mesophilic starter cultures and 5 are thermophilic starter cultures. In all starter cultures dominant isolates were lactic acid bacteria of genera Lactobacillus {Lactobacillus Helveticas, Lactobacillus acidophilus, Lactobacillus plant arum and Lactobacillus rhamnosus). This is in contrast to the commercial mesophylic starter cultures for semi hard cheese which contain isolates of genera Lactococcus. Three starter cultures S12, S19 and S21 cause rapid acidification (S12 - 4 hours, pH 4,63, sourness 23°SH; S19 - 8 hours, pH 4,75, sourness 25°SH; S21 - 8 hours, pH 4.83, sourness 26°SH). Proteolityc activity showed that thermophilic starter culture completely hydrolysis total casein within 5 hours at 37°C. In contrast, mesophilic starter cultures expressed very low proteolytic activity towards total casein after 5 hours of incubation at temperature 30°C. .

Formirano je 29 starter kultura za polutvrdi sir od bakterija mlečne kiseline (BMK) izolovanih iz sireva proizvedenih u domaćinstvima na tradicionalan način bez upotrebe starter kultura. Svi prirodni izolati prethodno su u potpunosti biohemijski i genetički okarakterisani, što je pomoglo pri formiranju starter kultura. Formirane su 24 starter kulture mezofilnih vrsta BMK, dok u sastav 5 starter kultura ulaze termofilne vrste BMK. U svim starter kulturama dominiraju vrste roda Lactobacillus {Lactobacillus helveticus, Lactobacillus acidophillus, Lactobacillus plantarum, Lactobacillus paracasei i Lactobacillus rhamnosus). Za razliku od njih, komercijalne starter kulture namenjene proizvodnji polutvrdog sira uglavnom su sastavljene od mezofilnih vrsta roda Lactobacillus. Tri starter kulture S12, S19 i S21 postižu dobru aktivnost (S12 4 sata, pH 4,63, kiselost 23°SH ; S19 8 sati, pH 4,75, kiselost 25°SH ; S21 8 sati, pH 4,83, kiselost 26°SH). Ispitivanje proteolitičke aktivnosti pokazalo je da termofilne starter kulture u potpunosti hidrolizuju totalni kazein nakon 5 sati inkubacije na temperaturi od 37°C. Za razliku od njih, mezofilne starter kulture pokazale su veoma slabu proteolitičku aktivnost posle 5 sati inkubacije na temperaturi od 30°C. .