The influence of the different initial probiotic bacteria concentration on sweet whey fermentation

Sirutka je nutritivno visokovrijedan sporedni proizvod sirarstva, nedovoljno iskorišten u ljudskoj prehrani. Ukoliko se fermentacija sirutke provodi probiotičkim bakterijama, dodatno se povećava njezina nutritivna i zdravstvena vrijednost. U radu je ispitivan utjecaj dodatka različitih količina inokuluma (2,5, 5 i 7,5 %) monokulture Lactobacillus acidophilus La-5 ili Bifidobacterium animalis subsp. lactis BB-12 na fermentaciju rekonstituirane slatke sirutke pri 37 °C. Tijekom fermentacije i 28 dana čuvanja fermentiranih uzoraka u hladnjaku praćeni su pH-vrijednost, titracijska kiselost i broj živih bakterija. Fermentacija sa 7,5 % inokuluma monokulture Lactobacillus acidophilus La-5 trajala je najkraće (oko 13,3 sati), dok je fermentacija sa 2,5 % inokuluma trajala najduže (oko 15,5 sati). Broj živih stanica Lactobacillus acidophilus La-5 u svim uzorcima sirutke tijekom fermentacije povećao se oko 1,3 log CFU/mL i na kraju fermentacije iznosio oko 8,5 log CFU/mL. Fermentacija sirutke sa 7,5 % dodanog inokuluma monokulture Bifidobacterium animalis subsp. lactis BB-12 nije bila kraća u odnosu na fermentaciju sirutke sa 2,5 % dodanog inokuluma. Broj živih stanica Bifidobacterium animalis subsp. lactis BB-12 tijekom fermentacije sirutke povećao se oko 0,9 log CFU/mL i na kraju fermentacije iznosio oko 8,7 log CFU/mL. Međutim, količina inokuluma nije utjecala na preživljavanje probiotičkih bakterija u fermentiranoj sirutki tijekom čuvanja bez obzira na uporabljenu monokulturu.Whey is nutritiously very high-quality secondary product from cheese making which is not used enough in human diet. When the fermentation is performed with probiotic bacteria it additionally increases its nutritional and health values. This research examines the influence of different amount of inoculum addition (2.5, 5 and 7.5 %) of monoculture Lactobacillus acidophilus La-5 or Bifidobacterium animalis subsp. lactis BB-12, on the course of fermentation of reconstitued sweet whey at 37 °C. During fermentation and 28 days of cool storage fermented whey pH value, titratable acidity and the viable cells count was monitored. Fermentation with 7.5 % inoculum of monoculture Lactobacillus acidophilus La-5 lasted the shortest (about 13.3 hours), while the fermentation with 2.5 % inoculum lasted the longest (about 15.5 hours). The viable cells count of Lactobacillus acidophilus La-5 cells in all whey samples has increased during fermentation for about 1.3 log CFU/mL and at the end of fermentation was about 8.5 log CFU/mL. Whey fermentation with 7.5 % added inoculum of monoculture Bifidobacterium animalis subsp. lactis BB-12 showed no difference in duration time in comparison to whey fermentation with 2.5 % inoculum addition. The viable cells count of Bifidobacterium animalis subsp. lactis BB-12 has increased during fermentation for about 0.9 log CFU/mL and at the end of fermentation was about 8.7 log CFU/mL. The amount of inoculum had no influence on survival of probiotic bacteria in fermented whey regardless of monoculture used