Application of response surface methodology for the co-optimization of extraction and probiotication of phenolic compounds from pomegranate fruit peels (Punica granatum L.)

Currently, the synergistic interactions between plant polyphenols and probiotic bacteria are gaining interest with diverse perspectives of applications of both functional ingredients. This study aims to explore and optimize the interaction between pomegranate peel polyphenols and the probiotic strain Lactobacillus rhamnosus ATCC 53103, throughout the co-optimization of the extraction/probiotication techniques. In this context, the response surface methodology (RSM) was applied to find the suitable extraction conditions to obtain phenolic extracts exhibiting a synergistic interaction when fermented with the probiotic strain. A ß-Cyclodextrin ultrasound-assisted extraction technique has been applied for pomegranate polyphenols extraction, followed by the probiotic fermentation of extracts. Results of RSM indicate that for all chosen design responses, the experimental values are in good agreement with the predicted one, with R squared values above 0.8 for all prediction models. Using optimal conditions predicted by the desirability function, it has been found that after probiotication of optimized phenolic extracts, the growth of probiotic strain at presence of polyphenols was possible. Moreover, a significant (p < 0.05) improvement of in vitro antioxidant activity of probioticated extracts was confirmed (an increase on in vitro free radical scavenging activity up to 51.37%). Results of this study, demonstrate for the first time, the feasibility of RSM approach to perform simultaneously the optimization of extraction and probiotication processes of phenolic compounds with the perspective to develop a new bioprocess aiming to produce functional food ingredient or novel nutraceutical products containing both bioactive polyphenols and beneficial probiotic bacteria.