Fig. 4a and b present details of the microbial viability and the pH throughout the storage period of the fermented sonicated pineapple juice (4 °C/42 days). Fig. 4c and d present data on sugar consumption in the samples. For both samples, pH and viability decreased during the storage period. A sharp drop in pH values was clearly observed for both samples during the first week of storage. This behaviour is consistent with high sugar consumption and indicates that post-acidification occurred at this period. Higher ABT-888 mw acidification and higher sugar consumption was observed

for sweetened juice. Microbial viability was almost linear during the storage period exhibiting higher losses for sweetened sample due to lower pH values. Non-sweetened juice exhibited microbial viability higher than 6 Log CFU/mL for the whole storage period (42 days).

On the other hand, sweetened juice had a shorter shelf life because cell counts were maintained above 6 Log CFU/mL for 28 days. Sugar profile showed the same behaviour observed during the fermentation. Sucrose see more concentration decreased and glucose and fructose increased. Again sucrose hydrolysis rate was faster than the rate of sugar consumption and higher reducing sugar levels were obtained for both samples. In addition to higher acidity, the sweetened juice also had a higher osmotic pressure when compared to the non-sweetened juice, which might have contributed to the lower microbial viability of L. casei during the storage period. Pereira et al. (2011) studied the storage stability of cashew apple juice fermented with L. casei under the same conditions and reported that the microbial viability increased Resveratrol during the storage period, up to 28 days, decreasing thereafter. In probiotic cashew apple juice (non-sweetened), viable cell counts were higher than 8 Log CFU/mL during the 42 days of cold storage, attesting again to the strong effect of food matrix on microbial survival

rates. Despite the probiotic sonicated pineapple juice presenting lower viable cells compared to other juices, a portion of 100 mL of the sweetened juice would reach the recommended ingestion for dairy products of 9 Log CFU if the juice were consumed within 21 days of cold storage. On the other hand, non-sweetened juice presented a longer shelf life (35 days under cold storage). Colour analysis results of fermented and non-fermented sonicated pineapple juice are presented in Table 2. The hue angle (h°) showed variation of less than 5°, indicating that the characteristic colour of the juice (yellow) was maintained throughout the storage period for both samples (non-fermented and fermented). No significant browning was observed during juice storage. This fact is consistent with the values of a∗ parameter that were kept at low negative values (within the yellow range in the colour wheel). Sonication promotes enzyme inactivation, which contributes to the characteristic colour maintenance.