Influence of ripening stage on phytochemicals and antioxidant activity of prickly pear (O. megacantha 'Liria')
2018
Rios-Alegria, E. | Mercado-Silva, E. | Mondragon, J. C. | Vazquez-Barrios, M. E. | Rivera-Pastrana, D. M.
Mexico is the center of origin of several cactus species with potential benefits for human health including prickly pear fruit (Opuntia sp.), which is a widely distributed and exploited phylogenetic resource. However, few studies directed to evaluate physicochemical and phytochemical changes during ripening process and postharvest storage of this fruit have been reported. The objective of this work was to evaluate quality parameters (weight loss, size, total soluble solids-TSS, firmness, color), phytochemical composition (betacianins, betaxanthins and total phenols and antioxidant capacity (DPPH assay) of Opuntia megacantha 'Liria' fruit, harvested at two ripening stages (75% (A) and 100% (B) color surface development) at the Bajío region of Mexico (San Luis de la Paz, Gto.). Fruit was stored for 45 days at 12°C and 98% RH, and samples were taken at 15, 21 and 45 days and after transfer at room temperature (RT) for 3 days (25±2°C). No differences were found on TSS, internal or external color, firmness and weight between samples of both ripening stages. Although, betacianin and betaxanthin contents were significantly affected by ripening stage, reaching maximum values (10 and 3 mg 100 g-1 fw, respectively) in fruit of stage B at the end of storage (45 d at 12°C + 3 d at RT). While, highest total phenols content was found in samples from ripening stage A (110 gallic acid mg 100 g-1 fw) after transfer to room temperature. Even though no significant differences on antioxidant activity were found between ripening stages (752-961 µM trolox equivalents g-1 dw), highest levels were determined in stage A samples at the end of storage, and a positive correlation with total phenols content was observed for all samples. Fruit harvested at ripening stage A, maintain and even increased phenol content and antioxidant capacity during postharvest storage.
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