Optimization of Fermentation Factors for Vinegar Production from Prickly Pears using Response Surface Methodology (RSM)

Abstract

Background: Prickly pears are abundant in the Aurès region but are intended only for direct human consumption, due to the limited processing of this highly perishable fruit. To enhance the use of this precious resource, prickly pear vinegar [Opuntia ficus indica L. Miller], enriched with seed powder, can be produced by a double biological fermentation process, first alcoholic then acetic. Methods: The Response Surface Methodology (RSM) was employed to optimize acetic fermentation process. This study investigated the influence of two independent variables, fermentation time and amount of added seed powder, on the chemical changes that affect five parameters (reducing sugar, ethanol, acetic acid, total phenolic and free radical scavenging activity) of vinegar obtained by the traditional method “Orléans”. Result: The fermentation time had a significant impact on all chemical properties examined, while the amount of added seed powder had a significant impact only on total phenolic contents and free radical scavenging activity. At the optimal point (fermentation time= 248.81 h and seed powder= 35.52%), the vinegar produced contained 1.73±0.31% reducing sugar, 0.42±0.02% ethanol, 5.55±0.5% acetic acid, 1670.14±2.9 mg GAE/L total phenolic and 61.33±0.45 mg AA/100 mL free radical scavenging activity. As a result, prickly pear vinegar enriched with seed powder was successfully made. It has a high level of bioactive components and a strong antioxidant potential, so it can be used as a functional food.