Effects of green tea extract nanoencapsulation on the survival of Lactobacillus Casei and Bifidobacterium lactis in symbiotic ice cream

BACKGROUND: The application of natural compounds including green tea extract (GTE) in food preparation and pharmaceutical industries is limited. Nowadays, encapsulation in nanoliposomes could be used as a delivery system to protect compounds during processing and storage. Objectives: In this study, physicochemical characterization of green tea extract encapsulated in nanoliposomes and its prebiotic activities on two probiotic bacteria Lactobacillus casei and Bifidobacterium lactis were evaluated in media and ice cream. Methods: At first, GTE encapsulated in liposomes by thin film layer method and with sonication liposomes reached to nanoscale. For evaluation of the prebiotic activity of nanoliposomal GTE on probiotics, 1% of nanoliposomal GTE in the presence of Lactobacillus casei and Bifidobacterium lactis was added to MRS broth and ice cream. Results: The mean diameter of nanoliposomes was about 44/7± 1/9 nm and had 0/203 ±0/014 polydispersity index. Entrapment eficiency of nanoliposomal GTE under the optimum conditions was 97%. Moreover, addition of 1% nanoliposomal GTE significantly increased the growth rate of Lactobacillus casei and Bifidobacterium lactis in culture media (p<0.05). The lowest reduction of Lactobacillus casei count during storage period was recorded in ice cream containing 1% of nanoliposomal GTE, while the control group showed the reduction of 4/16 log in Lactobacillus casei count. Similarly, addition of 1% of nanoliposomal GTE was most effective on survival of Bifidobacterium lactis in ice cream, since the bacterial count lowered only 0/84 log during the storage compared to 4/4 log reduction in control group. Conclusions:  The considerable effect of nanoliposomal GTE on growth and survival rate probiotics in media and ice cream has been presented in this study and  the use of nanoliposome encapsulation can be proposed as a new method to increase stability of natural compounds, during different processes.