Effect of microencapsulation on probiotic viability in 3D printed cookies based on confectionary\'s waste

The survival of probiotics in food products face various challenges during the production process. One of the emerging processes in the production of food products is 3D printing. The effect of this process on the viability of probiotics has not been studied so far. In this research, the effect of micro-encapsulation on cell viability during the process of 3D printing and cookie baking (based on waste from confectionery products) was investigated. First, the conditions for the production of micro-capsules were optimized by modulating the percentage of sodium alginate and calcium chloride solutions. Then, the effect of micro-encapsulation with different concentrations of micro-capsules (10, 5, 0% w/w) on the firmness of the dough texture was also investigated as an important factor in the printability of the dough. Finally, the cell viability was evaluated during the printing and baking process (150°C and 180°C for 10 minutes). The results of the microscopic images showed that with the increase in the concentration of sodium alginate and calcium chloride solution, the uniformity and sphericity of the micro-capsule increases. The efficiency of alginate-based micro-encapsulation in this method was 89.41%. The optimal concentration of micro-capsules in order to have the desired printability of baked dough, was reported as 5% w/w. Microencapsulation increased the survival rate of probiotics during 3D printing and baking. The survival percentage of microencapsulated probiotics (T2) after 3D printing and baking (150°C temperature) was 96.86% and 62.58%, respectively. Meanwhile, the survival percentage for the sample containing free cells (T1) was reported 60.77% and 43.05%, respectively. However, no viable probiotic cells were observed in both free and encapsulated cells conditions at 180°C.