Improving functional properties of Punica Granatum Juice by probiotication using Lactobacillus species

Abstract

Fruit juice enriched with probiotics is increasingly accepted nowadays, mainly due to its health benefits for digestive system and lactose intolerant problem. In the present study, the whole fruit of Punica granatum (pomegranate) was probioticated with selected strains of beneficial bacteria in order to improve the functionality of the juice. Lactobacillus species such as L. plantarum, L. salivarius, L. casei and L. bulgaricus were used for probiotication. Probiotication was optimized based on three parameters; temperature, agitation speed and fermentative pH. The growth profile of Lactobacillus species was observed based on the biomass, pH and lactic acid content in the fermentation broth. The functionality of L. casei probioticated juice was further evaluated using samples from shake flasks and 5 L stirred tank bioreactor. The kinetic profile of L. casei in the pomegranate juice was also determined under the optimized conditions (37 ?, pH 4.0, 0 and 50 rpm). The results indicated that L. casei was the dominant species based on the high biomass, lactic acid and flavonoid content compared to other strains. The specific growth rate of L. casei in shake flasks and bioreactor were 0.083 h-1 and 0.111 h-1, respectively. Probiotication of the juice with L. casei improved the concentration of quercetin-3-glucoside, as well as bioactivities of the juice. The radical scavenging and antidiabetic activities achieved more than 80 % inhibition during exponential phase, concurrently with the increase of biomass (13.0 %), lactic acid concentration (13.3 %) and quercetin-3-glucoside concentration (51.1 %) in the bioreactor samples. The ability of L. casei to rapidly utilize fermentable sugars of pomegranate for growth without further nutrient supplementation has proved the suitability of pomegranate juice as a growth medium for L. casei.