## 3 Results and Discussion
Similarly, the onset of the intestinal phase caused a pronounced decrease in viable cell content, with less changes 2 h later. This evolution in the viable count during the simulation of the gastrointestinal process is similar to that reported by [PERSON]  
Figure 4: Viable cell counts and survival rate (Rs) of _Lactobacillus reuteri_ along gastric and intestinal stages of the simulated gastrointestinal digestion process in vitro. Fermented lulo jucies at pH 5.5 and 6, non-homogenized (N-HPH) and homogenized at 100 MPa (100 MPa) and 150 MPa (150 MPa) has been included. The solid bars refer to juices with pH 5.5 and the striped bars refer to juices with pH 6. Different letters denote significant differences (\(p\leq 0.05\)). [PERSON] et al. [45] for _Lactobacillus reuteri_ ATCC 55730 in raw and fried tomato puree. As for the enhancement in the microbial strain survival to simulated gastric conditions in HPH juices, reference should be made to their higher content in both total phenols and flavonoids content and to the polyphenols ability to enhance microorganisms' survivability to gastric conditions by protecting them from oxygen toxicity [45,46]. Microbial cells growth in juices at pH 5.5 showed lower tolerance to the drastic conditions of gastric stage than that growth in juices adjusted to pH 6. However, the microbial cell in juices at pH 5.5 showed better survival rate after 2 h in this stage specially when the HPH treatment was applied. The survival rate in intestinal stage was different being higher for microbial cell in juices at pH 5.5 both at the beginning and at the end of the stage. Only, the non-homogenized juices at pH 6 show a different behavior between the initial and final time of intestinal stage. In relation to the HPH treatment, the highest survival was achieved by cells incubated in juices treated at 150 MPa. Overall, the best resistance to simulated gastrointestinal digestion was observed in the juice at pH 5.5 and homogenized at 150 MPa with 82% of survival (calculated as the ratio between the microbial concentration at the end of the intestinal stage and the microbial concentration before in vitro digestion, both referred to the same basis), although in the other juices it was only 5% lower, reaching values of 80-81%. In all cases, levels above 7 \(\log_{10}\) units per mL of juice were reached at the end of the intestinal stage; these are levels above the minimum necessary for a food to exert a probiotic effect [47]. [PERSON] et al. [48] found a survivability of 84-85% of _Lactobacillus acidophilus_ LA-5 in a whey-pineapple beverage (25% whey) at pH 4.3 after simulated gastrointestinal digestion. Moreover, this survival only decreased by 5% after more than 50 days of refrigerated storage. However, in this work, the survival was much higher than that achieved by [PERSON] et al. [49] in mandarin juice at pH 3.7 with _Lactobacillus salivarius subsp.salivarius_, which was only 60%. Among the factors that affect the probiotic bacteria viability in a fruit juice after the gastrointestinal digestion process are the microbial strain and its resistance to acidic conditions and gastric fluids, the fruit juice composition (acidity, carbohydrate content, nitrogen sources, mineral content), and the possible interactions of the probiotic strains with the food matrix component [45]. In this case, it would be both, adaptation of strain to juice acidity and the good nutrient composition of the lulo juice, the main factors responsible for the favorable survival levels obtained after in vitro gastrointestinal digestion. Moreover, the homogenization treatment at 150 MPa would have contributed to the availability of nutrients due to the smaller size of the suspended particles and the greater stability of the cloud.