The influence of whey protein concentrate on growth and survival of bacteria culture ABT 5 in whey

Sirutka je nutritivno visoko vrijedan napitak koji je nedovoljno iskorišten u prehrani ljudi. Fermentacijom sirutke može se dobiti senzorski prihvatljiviji proizvod, a kad se fermentacija provodi s probiotičkim bakterijama dodatno se povećava njegova nutritivna i zdravstvena vrijednost. Sirutka je fermentirana bakterijskom kulturom ABT 5. Istraživan je rast i aktivnost sojeva Lactobacillus acidophilus, Bifidobacterium sp. i Streptococcus thermophilus u kontrolnoj i koncentratom proteina sirutke (1,5% i 3%) obogaćenoj slatkoj rekonstituiranoj sirutki te njihovo preživljavanje tijekom 28 dana hladnog čuvanja (4 °C) fermentirane sirutke. Fermentacija se odvijala na 37°C. Tijekom fermentacije i čuvanja praćena je pH-vrijednost, titracijska kiselost i broj živih stanica bakterija. Fermentacija je jednako dugo trajala bez obzira na količinu dodanog koncentrata proteina sirutke (KPS) i u oba slučaja (1,5% i 3% dodanog KPS-a) trajala u prosjeku 6,67 sati. Fermentacija bez dodatka KPS-a trajala je najkraće (u prosjeku 6,33 sati). Broj živih bakterijskih stanica Lactobacillus acidophilus se tijekom fermentacije, za sve uzorke, povećao za oko 1,14 log10CFU/mL, Bifidobacterium sp. za oko 0,60 log10CFU/mL i Streptococcus thermophilus za oko 2,18 log10CFU/ml. Koncentrat proteina sirutke podjednako je stimulirao rast probiotičkih bakterija, a nije stimulirao rast Streptococcus thermophilus u sirutki tijekom hladnog čuvanja uzoraka. Sirutka obogaćena KPS-om imala je nešto veću titracijsku kiselost tijekom fermentacije i čuvanja u odnosu na sirutku bez dodatka KPS-a.Whey is nutritive valuable product but poorly used in human diet. By whey fermentation with lactic acid bacteria acceptable product is produced and if whey is fermented with probiotic bacteria it has increased nutritive and health value. Whey was fermented with ABT 5 culture. The population growth of Lactobacillus acidophilus, Bifidobacterium sp. and Streptococcus thermophilus in plain and whey protein concentrate (1,5% and 3%) supplemented whey and their survival during 28 days of fermented whey cold storage (4°) was evaluated. The fermentation was followed at 37°C. Changes of pH-values, titratable acidity and viable cells count were measured during fermentation and storage. Concentration of added whey protein concentrate (WPC) did not influence the fermentation time and it lasted in average about 6,67 hours. The fermentation time was the shortest in case when no WPC was added (in average 6,33 hours). Viable cells count of Lactobacillus acidophilus during fermentation increased for about 1,14 log10CFU/mL, and in case Bifidobacterium sp. for 0,60 log10CFU/mL and Streptococcus thermophilus for about 2,18 log10CFU/ml. Addition of whey protein concentrate did not influence the survival of bacteria culture ABT 5 in whey during 28 days of cold storage (4°C). Whey enriched with WPC had slightly higher titratable acidity during fermentation and storage compared to whey without WPC addition