Shelf life and quality of probiotic yogurt produced with Lactobacillus acidophilus and Gobdin

This study evaluated the effect of dry white mulberry and walnut paste (Gobdin, a traditional Turkish food) in probiotic yogurt on the survival of Lactobacillus acidophilus and yogurt properties. Six different yogurts were produced with 0%, 5% and 10% Gobdin using Lactobacillus bulgaricus+Streptococcus thermophilus and with 0%, 5% and 10% Gobdin using L.bulgaricus+S.thermophilus+L.acidophilus. The physical, chemical, microbiological and sensorial properties of the yogurts were evaluated based on storage at 4 +/- 1 degrees C. Probiotic shelf life and the most suitable combinations were determined. The highest L.acidophilus count (8.65 logcfug(-1)) was found in the 5% Gobdin-supplemented yogurt on the 7th day of storage, while the lowest count (8.11 log cfug(-1)) was found in the probiotic control yogurt on the 21st day. Although the L.acidophilus counts in the probiotic yogurts declined during storage, all values found throughout the 21-day storage period were >8 logcfug(-1). This is above the level necessary to provide the desired therapeutic effect in probiotic products (10(6)-10(7)cfug(-1)). The highest overall acceptability score was obtained on the first day from the yogurt with 5% Gobdin. However, all yogurt samples had general acceptability scores between 7 and 8 points from a 9-point maximum. Thus, this study determined that a new functional yogurt can be produced using L.acidophilus with 5% Gobdin.