EFFECT OF CANNING AND STORAGE ON THE PHENOLIC COMPOSITION OF PEANUTS

ABSTRACT Increased commercialization of boiled peanuts packaged in cans has made it necessary to investigate the effect of canning on the phytochemical composition of this product. Retorting (canning) remains a core processing technology for the extension of shelf life of foods. This study evaluates the effect of canning and storage on the phenolic composition of peanuts. Peanuts canned in 5% brine, retorted and stored for 4 weeks were analyzed for phenolic composition. A total of nine compounds (trans-resveratrol and three conjugates, caffeic acid, luteolin, genistein, quercetin and catechin) were identified in both raw and canned kernels. Quercetin and catechin were not in quantifiable amounts in canned peanut kernels. Concentrations of trans-resveratrol declined initially and stabilized after 2 weeks of storage. The presence of resveratrol in the brine indicates leaching from peanut kernels. Although canning has been shown to be detrimental to certain nutrients, canned peanuts still retained some bioactive polyphenols with antioxidant activity. PRACTICAL APPLICATIONS Retorting and canning of foods still remain important unit processes in food preservation technology as canned products have a longer shelf life compared to other packaged products. This is mainly due to it durability, portability and minimal susceptibility to contamination. While different foods contain various classes of bioactive compounds that have diverse physicochemical properties, it is necessary to investigate the effect of thermal processing on their bioactive constituents. There are several processing methods for peanuts such as roasting (dry- and oil-roasted), boiling and retorting. Of these methods, retorting in cans is the best way to extend the shelf life of boiled peanuts. Previous studies have looked at the effect of roasting and boiling on the phytochemical composition of processed peanuts. This study aims at understanding how retorting affect these bioactive compounds in peanuts.