ارتقا خصوصیات فیزیکوشیمیایی پروبیوتیک لاکتوباسیلوس رامنوسوس به‌وسیله ریز‌پوشانی اکستروژن دولایه با آلژینات سدیم و صمغ زودو

In food products packed in hot filling mode, the use of probiotic bacteria is very limited due to thermal sensitivity. The microencapsulation of probiotic bacteria is suggested as a suitable method for reducing thermal damage. Dual layer extrusion using high molecular weight hydrocolloids, such as zedo gum, can prevent thermal damage. In this research, microencapsulation by two layers extrusion method was performed on Lactobacillus rhamnosus. The first layer was sodium alginate and the second was zedo gum at 0.2, 0.4, 0.6, 0.8%., was used. Microencapsulation was followed by light microscopy, texture and color analysis. Thermal stability, acid and salt stability, acid production tests and the growth of microencapsulated bacteria during storage conditions in MRS medium were investigated. The results showed that 0.8% zedo gum used as the second layer could significantly change the outer layer diameter. However, the increase of zedo concentration did not increase the hardness component. Only at 0.2% zedo gum had a significant difference with the rest (p<0.05). At 0.6% and 0.8% zedo gum increase in gumminess component wasobserved. At 72 ° C, the number of microencapsulated bacteria remained stable for 10 minutes, and at the 5th minute their count was about 5 log CFU‌/‌ml higher than free bacteria (p <0.05). The amount of acid production was lower and bacterial growth in the microencapsulated bacteria was slower than free bacteria. The microencapsulated bacteria had microbial survival of 2 log CFU/ml more than free bacteria the of 15% (pH = 1.5).