Study On Effect Of LGG On Quality And Storage Property Of Yogurt

Probiotic are used widely in dairy products in resent years, especially in yogurt. Post-acidification and off-flavor of yogurt are the mainly problem in application, and are more obvious in China, which has no complete cold chain. This experiment systematically studied on the nutrition characteristic and metabolism of LGG in yogurt, factors result in post-acidification and off-flavor, and put forward some methods to control it.LGG produced L-lactic acid and survivaled well in yogurt during the storage (20℃). Compared with control (yogurt without LGG), acidity of yogurt with LGG was higher (p<0.01), content of diacetyl, acetaldehyde and pyruvic acid were lower (p<0.05 or p<0.01), lactic and acetic acids were higher (p<0.01), orotic and citric acids were not changed, formic, propionic, butyric, uric and hippuric acids were not detected under the condition used.Post-acidification of yogurt with LGG was significant influenced by inoculation amount of LGG, storage temperature and the starter used.Inoculated LGG after heat treatment(55℃5min), compared with control (yogurt with LGG not heat treated), acidity was lower (p<0.01), content of diacetyl was lower (p<0.01), acetaldehyde was higher (p<0.01), lactic and acetic acids were lower (p<0.01), pyruvic, orotic and citric acids were not changed during the storage (20℃), the post-acidification and off-flavor of yogurt were improved effectively.Inoculated LGG after fermented delayed the post-acidification and off-flavor of yogurt about 6 days compared with control (yogurt inoculate LGG before fermented).