The effect of homogenization pressure and stages on viability of probiotic bacteria and overall acceptability of low-fat probiotic yogurt

Nowadays, the usage of probiotic products especially yoghurt due to having wonderful and health properties has become popular in the world. In this study, the effect of homogenization pressures (100, 150 and 200 bar) and stages (1 and 2) on viability of probiotic bacteria and sensory properties was investigated. The milk used for producing youghurt samples was preheated at 60 ºC and homogenized at 100, 150 and 200 bar; then, heated at 85°C for 30 minutes. After cooling milk up to fermentation temperature (42ºC), it was inoculated with mixture starter culture ABY1 and incubated. During fermentation, pH dropped until it reached 4.5. After fermentation, prepared yoghurt samples were held in refrigerator. Viability of probiotic bacteria and overall acceptability was determined during a 21-days cold storage (4ºC). With increasing pressure and stages of homogenization during storage, viability of probiotic bacteria increased (p<0/05). Also, the overall acceptability of the samples improved with increasing the pressure and stages of homogenization (p<0/01).The result of this study showed that with changing homogenization conditions, the viability of probiotic bacteria could be increased.