Influence of microencapsulated probiotic strain Lactobacillus helveticus M92 and transglutaminase on the properties of set-style yoghurt

Cilj ovog diplomskog rada bio je istražiti utjecaj mikroinkapsuliranih stanica probiotičkog soja Lactobacillus helveticus M92 u kazeinu s TGazom i transglutaminaze na kvalitetu i senzorska svojstva čvrstog jogurta. Za proizvodnju jogurta je korišteno svježe homogenizirano mlijeko s 3,3 % mliječne masti kojemu je dodana mikroinkapsulirana kultura L. helveticus M92 i 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 mikroinkapsuliranom probiotičkom kulturom L. helveticus M92. Proizvedeni su i kontrolni uzorci bez dodatka mikroinkapsulirane probiotičke kulture i transglutaminaze. U radu je određivan fizikalno-kemijski sastav mlijeka i jogurta, broj živih stanica probiotičke kulture L. helveticus M92 kao i senzorska svojstva proizvedenog čvrstog jogurta. Utvrđeno je da trajanje fermentacije uzoraka probiotičkih jogurta proizvedenih s dodatkom mikroinkapsuliranih stanica probiotičkog soja L. helveticus M92 bilo kraće nego vrijeme fermentacije kontrolnih uzoraka jogurata. Rezultati senzorske analize su pokazali da su jogurti s dodatkom mikroinkapsuliranih probiotičkih stanica L. helveticus M92 i TGaze dobili bolje senzorske ocjene za svojstvo izgleda tijekom skladištenja, dok su uzorci jogurta bez dodatka TGaze dobili bolje senzorske ocjene za svojstva mirisa i okusa tijekom perioda skladištenja. Broj živih stanica probiotičke bakterije L. helveticus M92 u svim uzorcima čvrstog probiotičkog jogurta bio je veci od 106 CFU/g nakon 21 dan čuvanja pri 4 oC, što je u skladu sa zahtjevima koje moraju ispunjavati probiotički proizvodi.The aim of this graduate thesis was to investigate the influence of the transglutaminase-induced caseinate microencapsulated probiotic culture Lactobacillus helveticus M92 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 microencapsulated probiotic strain L.helveticus M92 and transglutaminase (TGase) activated during 1,5 h at 55 °C. Enzyme inactivation was completed by pasteurization of milk during 15 minutes at 85 °C. Milk was inoculated with the yoghurt starter culture (BT10X and 100F) and microencapsulated probiotic culture L. helveticus M92, after cooling to the temperature of 43 °C. The control was yoghurt performed with yoghurt starter culture (BT10X and 100F) and with the addition of free probiotic cells of L. helveticus M92 without TGase. Physico-chemical parameters of milk and set-style yoghurt, as well as viable cell counts of probiotic culture L. helveticus M92, and sensoric properties of produced set-style yoghurt were determined. The results have shown that the time of fermentation of the set-style functional yoghurts produced with the addition of microencapsulated L. helveticus M92 probiotic cells and with microencapsulated L. helveticus M92 probiotic cells where TGase was added, was shortened compared with control yoghurt. The results of sensoric analysis have shown that the yoghurt with added microencapsulated strain and TGase had better sensoric properties, while yoghurt with added microencapsulated strain without TGase, has shown better properties for odour and flavor, during the storage. The viable cell counts of probiotic strain L. helveticus M92 in all samples of produced yoghurt was maintained above 106 CFU/ml during the 21 day of storage at 4 oC, what is in accordance with the claims set up for probiotic products