Influência da luz pulsada sobre a fisiologia e a qualidade pós-colheita de acerola (Malpighia emarginata DC)

Abstract

Physiologically mature acerola ‘Okinawa’ were submitted to Pulsed light (PL) radiation (0.6 J.cm-2), stored at 10 ºC and evaluated at days 0, 1, 4, 10 and 16 for firmness and associated variables, oxidative stress marker and constituents of antioxidant metabolism, respiration and ethylene metabolism, polyamine metabolism, color and phenolic metabolism and vitamin C content. When compared to the control of untreated fruits, PL treatment reduced climacteric respiratory peak in 5% lower (P< 0.05) with 78.6 mL.Kg-1.h-1 and delayed ethylene peak to day 3 with 2.65 µL.Kg-1.h-1. PL-treated acerola were significantly firmer 12%, at day 10 and lost 13.4% less weight with no significant differences in color attributes lightness and chroma. Oxidative stress marker H2O2 was significantly lower in PL-treated fruit and antioxidant enzymes SOD and CAT activities were stimulated. The lower ROS content reflected in lower membrane lipid peroxidation degree, while cell wall hydrolytic activity was also inhibited, contributing to greater firmness. PL reduced ethylene precursor free ACC content in 20% and inhibited ACO activity in 16%. Polyamines putrescine and spermidine levels were 21% and 12% higher, respectively, than control due to stimulus of its synthesis (ADC activity) and inhibition of its degradation (DAO activity). PL-treatment resulted in significantly (P< 0.05) higher total vitamin C and AsA levels. LP treatment resulted higher polyphenol content due to withted the enhanced synthesis by PAL.Therefore, PL, under the conditions here applied, influenced acerola physiology not as a stress agent, but as an elicitor of the antioxidant defense system preventing possible oxidative damages due to unbalance between ROS production and scavenging mechanisms, promoting quality during storage.