The influence of sterilized goats and cow\u27s milk on yoghurt quality during storage

U ovom je radu proučen utjecaj steriliziranog kozjeg i kravljeg mlijeka te njihove mješavine (1:1) na kakvoću jogurta tijekom devet dana čuvanja pri temperaturi +8°C. Viskoznost jogurta od kravljeg mlijeka (A) tijekom svih devet dana čuvanja bila je uglavnom najmanja, dok je najveća bila uglavnom viskoznost jogurta od mješavine mlijeka (1:1) (AB). Pad pH vrijednosti bio je tijekom čuvanja jogurta od kozjeg mlijeka (B) brži nego kod jogurta od kravljeg mlijeka (A). Najviše mliječne kiseline sadržavao je jogurt od kravljeg mlijeka (A), a najmanje jogurt od kozjeg mlijeka (B) tijekom čitavog perioda čuvanja. Broj živih bakterija u svim uzorcima bio je najveći nakon 24 sata čuvanja jogurta (log Nmax = 9,839 - 9,668). Tijekom devet dana čuvanja omjer laktobacila i streptokoka se mijenjao u svim uzorcima. U uzorcima kravljeg (A) i miješanog (AB) jogurta streptokoki su brže odumirali od laktobacila. Jedino u uzorcima kozjeg jogurta (B) laktobacili su brže odumirali do šestog dana čuvanja te je omjer laktobacili: streptokoki trećeg i šestog dana čuvanja bio 1:1,63 i 1:1,60. Devetog dana čuvanja u svim je uzorcima jogurta bilo više laktobacila nego streptokoka. Senzorska ocjena jogurta nije pokazala značajnu razliku između uzoraka jogurta od kravljeg, kozjeg i mješavine mlijeka.In this work the influence of sterilized goat\u27s and cow\u27s milk and theirs mixture (1:1) on yoghurt quality during nine days of storage at +8 °C, were investigated. The viscosity of cow\u27s milk yoghurt was a lower during all nine days of storage, while the viscosity of yoghurt from mixed milk was greater. The decrease of pH value during goat\u27s yoghurt samples was faster as in cow\u27s yoghurt samples. The most lactic acid was in cow\u27s yoghurt, and the least in goat\u27s yoghurt during storage. Viable count was maximal after 24 hours of storage in all samples (logNmax = 9.839-9.668). During nine days of storage the ratio between lactobacilli and streptococci was changed in all yoghurt samples, respectively. In the samples cow\u27s and mixed yoghurt streptococii died faster than lactobacilii. Only in goat\u27s yoghurt lactobacillii died faster until sixth day of storage and share lactobacillii: streptococcii third and sixth day of storage was 1:1.63 and 1:1.60. Ninth day of storage in all samples were more lactobacilii than streptococii. The differences in sensory scores between yoghurt samples from cow\u27s, goat\u27s and mixed milks were not significant