## 3 Results and Discussion
### Application of Microencapsulated Probiotics in Apple Juice  
The perception of applying probiotic bacteria into fruit juice can compensate for the nutrition loss due to the manufacturing process. Additionally, the probiotic bacteria also increase the functionality via viable cells that has already been accepted by customers and experts. The cell numbers of fermented and fortified apple juices with different ratios and formulations stored at 4 \({}^{\circ}\)C and 25 \({}^{\circ}\)C for 10 weeks are shown in Figure 8.  
Storage time and storage temperature have a significant effect on the changes of cell numbers of probiotic apple juices during storage. However, the core-to-wall ratio, the formulation and fortification or fermentation methods did not significantly affect the viability of the probiotics. Storage temperature is a factor that influences the viability of probiotics in apple juice. Meanwhile storage at a high temperature, such as room or higher temperature, may initiate some metabolisms by other microbes especially some pathogens that thus will suppress the probiotics, whereas storage at low temperatures, such as at 4 \({}^{\circ}\)C can keep the bacteria alive (Figure 8A-C). Viable cells in all capsules were maintained at the initial levels (approximately 9 Log CFU/g) for a whole storage period (two months). The effect of temperature on the viability of cells can also observed when doing comparison of data in Figure 8C and 8G. Meanwhile the cell number of those samples fermented by microcapsules with core-to-wall ratio 1:1.5 (Figure 8C) was kept unchanged (9 Log CFU/g), whereas it started to decrease from the week 4, and reached 5.04 Log (CFU/g) at the end of storage. It is worth to note that this value is much lower than the viable cell criterium of probiotic products (7 Log CFU/g). Storage time is also a crucial factor that influences the viability of cells. There was no significant difference in the cell numbers during storage of apple juices for 0, 2, 4, and 6 weeks. However, the cell number started to significantly decrease from the 8 th week. This trend was accelerated after week 10 (Figure 8E-H). The cell number apple juice fermented with microcapsules coated by DWP with core-to-wall ratio 1:1 reached even 3.3 Log (CFU/g) at the end of the storage period. Different ratios of core-to-wall as well as WP to DWP did not affect the trend of change of viable cells of both fermented and fortified apple juices stored at temperature 4 \({}^{\circ}\)C. The cell numbers kept constant for the whole storage period (Figure 8A-D). In the case of storage at 25 \({}^{\circ}\)C, the cell numbers of fermented samples with microcapsules coated by pure WP or DWP (Figure 8E,G) as coating materials. Instead, they may influence the dynamics of changes of cell numbers. In addition, these changes were also not affected by fortification and fermentation methods, but generally, the viable cell numbers of fermented samples were significantly higher than fortified samples. Meanwhile, in the fermentation process, the bacteria grew, thus resulted the increase in cell number, whereas it was missed in the case of fortification. The same result was also observed by [PERSON] et al., (2013). However, at the end of the storage process for long time (some months), this is no significant difference in the cell number between two methods (fermentation and fortification). In summary, storage time and temperature are the two main factors that influence the viability of the probiotic cells in apple juice, while the ratio, formulation, fermentation and fortification technologies did not affect it. Storage at 4 \({}^{\circ}\)C is suggested for probiotic apple juice. At this temperature, both fermented or fortified probiotic apple juices can maintain their viable cells more than 6 weeks. Figure 8: Cell number of fermented and fortified apple juices.