Influence of the probiotic strain Bifidobacterium animalis subsp. lactis B94, inulin and transglutaminase on the properties of set-style yoghurt

Cilj ovog diplomskog rada bio je istražiti utjecaj probiotičkog soja Bifidobacterium animalis subsp. lactis B94, inulina i transglutaminaze na kvalitetu i senzorska svojstva čvrstog jogurta. Za proizvodnju jogurta je korišteno svježe homogenizirano mlijeko s 3,3 % mliječne masti kojemu je dodan Bifidobacterium animalis subsp. lactis B94, inulin te enzim transglutaminaza aktiviran 1,5 h pri 55 °C. Inaktivacija enzima provedena je postupkom pasterizacije 15 min pri 85 °C. Nakon hlađenja na 43°C, mlijeko za proizvodnju čvrstog jogurta inokulirano je zamrznutom starter kulturom (BT10X i 100F) i probiotičkom kulturom Bifidobacterium animalis subsp. lactis B94. Proizvedeni su i kontrolni uzorci bez dodatka transglutaminaze, inulina i probiotičke kulture. U radu je određivan fizikalno-kemijski sastav mlijeka i jogurta, broj živih stanica probiotičke kulture Bifidobacterium animalis subsp. lactis B94 kao i senzorska svojstva proizvedenog čvrstog jogurta. Utvrđeno je da proizvedeni čvrsti jogurti s probiotičkom kulturom Bifidobacterium animalis subsp. lactis B94, inulinom i transglutaminazom imaju veću čvrstoću, pokazali su manju sinerezu te su dobili višu ocjenu senzorskih svojstava u odnosu na kontrolne jogurte. Broj živih stanica Bifidobacterium animalis subsp. lactis B94 nakon 28 dana čuvanja bio je viši u uzorcima jogurta koji su sadržavali inulin kao prebiotik. Fermentacija jogurta s inulinom i transglutaminazom traje kraće od fermentacije jogurta bez dodatka inulina i transglutaminaze.The aim of this graduate thesis was to investigate the influence of the probiotic strain Bifidobacterium animalis subsp. lactis B94, inulin and transglutaminase on the quality and sensoric properties of set-style yoghurt. Fresh homogenised milk with 3,3 % of milk fat was used for the yoghurt production, with addition of Bifidobacterium animalis subsp. lactis B94, inulin and transglutaminase activated during 1,5 h at 55 °C. Enzyme inactivation was completed by pasterization of milk during 15 minutes at 85 °C. Milk was inoculated with the yoghurt starter culture (BT10X and 100F) and probiotic culture Bifidobacterium animalis subsp. lactis B94, afer cooling to the temperature of 43 °C. Beside the experimental samples, control samples were also made, without addition of transglutaminase, inulin and probiotic culture. Physico-chemical parameters of milk and set-style yoghurt, as well as viable count of probiotic culture Bifidobacterium animalis subsp. lactis B94, and sensoric properties of produced set-style yoghurt have been determined. It has been shown that produced set-style yoghurts with probiotic culture Bifidobacterium animalis subsp. lactis B94, inulin and transglutaminase had higher firmness, less syneresis, and better sensoric properties than control yoghurts. The viable count of Bifidobacterium animalis subsp. lactis B94 was higher in the samples containing inulin as prebiotic during 28 days of storage. Fermentation of yoghurt samples containing inulin and transglutaminase lasted shorter than fermentation of samples without inulin and transglutaminase