Chitosan was used for nanoencapsulation of Lactobacillus acidophilus as Probiotic bacteria. In vitro experiments were conducted with the objective of investigating the survival of the bacterial cells in gastro-intestinal conditions. The results demonstrated that the size of chitosan nanoparticles noticeably increased by increasing chitosan concentration from 0. 05 to 0. 5 g/mL. Encapsulation of the cells caused a decrease at the leakage of Probiotic bacteria when compared to free bacteria. However, the number of Probiotic cells reduced from 3. 27 to 3. 23 log CFU/mL in gestural acid condition in contrast to free cells which they approximately dropped from 3. 3 to 3 log CFU/mL after 120 min. Good Probiotic viability and stability was also obtained by nanocapsulation of Lactobacillus acidophilus in intestinal juice. At this condition, the initial capsulated cells numbers were 3. 28 log CFU/mL which after placing in biliary salt condition for 120 min, it reached to 3. 23 log CFU/mL. On the other hand, the free bacteria cells reduced from 3. 3 to 2. 97 log CFU/mL in intestinal environment. Overall, nanocapsulation of Probiotic bacteria plays a pivotal role in enhancing the viability and survival of them against gastro-intestinal environmental conditions.

Introduction: Because of many health benefits, production and cosumption of Probiotic products was incresead worldwide. Viability of Probiotic bacteria and sensory propperties are important factors in quality of Probiotic yoghurt. Many factor can affect the sensory property and survival of Probiotic bacteric in yoghurt. Thus, the aim of this study was to assess the the viability of Probiotic bacteria and sensory properties of two kinds of Probiotic yoghurts. Methods: Two kinds of Probiotic yoghurts named as MY 1821 and ABY3 were made using commercial starter culures according to manufacturer instruction. Viability of Probiotic bacteria (lactobacillus acidophilus, bifidibacteria and lactobacillis casei) and sensory properties (flavour, mouthfeel, appearance and texture) of yoghut were assessed during 21-days at 7 days interval. statistical analysis was carreid out using T-test and ANOVA (repeated measure) in SPSS software. P value less than 0. 05 was considered as significant. Results: At the end of experiments the number of lactobacillus acidophilus and bifidobacteria were 7. 42± 0. 04 and 6. 90 ± 0. 06 log cfu/gr in MY1821 and 6. 45 ± 0. 11 and 6. 16 in ABY3 and the number of lactobacillis casei was 7. 55± 0. 04 log cfu/gr in MY 1821. population of lactobacillus acidophilus and bifidobacteria decreased by 1. 1 and 0. 48 log cfu/gr in MY 1821 And 0. 89 and 1. 38 cfu/gr in ABY3 yoghurts. Viability of L. casei also reduced and by 0. 55 Log cfu/gr in MY 1821 yoghurt. At the end of experiments the mean score for flavour, mouthfeel, appearance and texture were 21. 2± 3. 09, 12. 36 ± 1. 80, 7. 2± 1. 1. 01, 3. 86± 0. 35 in MY 1821 yoghurt and 17. 6± 4. 22, 10. 73± 2. 46, 6. 66± 0. 97 and 3. 33± 0. 49 in ABY3 yoghurt respectively. Conclusion: The number of Probiotic bacteria at the end of storage were above the criteria determined by Iran national standard. The result of sensory evaluation showed that the prepared yoghurt had good to excellent acceptance. Thus using these starter cultures by diary industry is recommended. Because of helth benefits of Probiotics, consumption of these products for their high population of Probiotic bacteria can improve the public health.

Yoghurt is a popular healthy food, consumed by many people. The popularity of this product made it possible to use it as a base in order to produce Probiotic preparations. Prebiotics are used for better growth and survival of Probiotic bacteria as well as to improve organoleptic, rheological and technological properties of Probiotic yoghurt. The aim of this research was to study physicochemical changes and survival of Probiotic bacteria in synbiotic yoghurt. In this study, prebiotics including Lactulose, Inulin and Oligofructose were used separately and Probiotic bacterium Lactobacillus casei was used to prepare the yoghurt. Samples were stored at 4oC for 21 days and during this time pH, acidity, syneresis and Probiotic counts were investigated and compared to the control (Probiotic yoghurt without prebiotics). The results showed that the highest pH, the most Probiotic counts and the highest taste and texture scores were related to the sample which had Inulin. In contrast the control sample had the least Probiotic count and the lowest score concerned with taste and texture. This sample had the least percent of syneresis which wasn't significantly different from others. The most and the least acidity were related to the control sample and the yoghurt containing Lactulose, respectively. The results suggested positive effect of synbiotic in Probiotic yoghurt. Based on this study, since prebiotics improve physicochemical properties and enhance Probiotic bacteria survival they can be incorporated in yoghurt formulation. The results show that Inulin has a better effect on physicochemical changes and Probiotic bacteria survival as compared to other prebiotics.

The aim of this study was to investigate the impacts of NaCl, bile salts, and their combinations on the viability of Lactobacillus casei in Probiotic yogurt. For this purpose, the antibacterial activity of NaCl and bile salts was investigated via the microdilution technique by determining the minimum inhibitory concentration (MIC) against L. casei. Further, the stress effects of 50% MIC on NaCl and bile salts on the L. casei were examined by comparing the stress treatments with the control in terms of the L. casei population, pH, acidity, and syneresis percentage in Probiotic yogurt during storage in the refrigerator for 28 days. According to the results, the L. casei population and pH decreased in all the treatments during the storage time, such that the intensity of the decrease in the control treatment was lesser than in other stress treatments (p<0. 05). The acidity and percentage of syneresis during the storage time increased for all the treatments, with the increase being less in control than in the other stress treatments (p<0. 05). The control scored the highest in the sensory evaluation (p<0. 05). In conclusion, applying stresses below the MIC had a negative effect on the survival of L. casei in the Probiotic yogurt until the end of 28 days and the outcome was not as expected.

Nowadays, a refresh interest is rising to extend the viability of Probiotics by direct incorporation of them in edible coats and films to prevent lethal phase transition in food processing and storage. In current study, four Probiotic bacterial strains (Lactobacillus acidophilus, L. casei, L. rhamnosus and Bifidobacterium bifidum) were used for the immobilisation in edible film based carboxymethyl cellulose (CMC) during 42 days of storage at 25 ᵒ C and 4 ᵒ C respectively. Results showed a clear decrease in bacterial cell viability. But, viability of L. acidophilus and L. rhamnosus were always in the range of recommended levels at 4 ᵒ C during the storage (106– 107 CFU/g). CMC-based edible films could act as a suitable carrier for some Probiotic strains in food packaging during refrigerated temperatures.