Effect of visible light treatments on postharvest senescence of broccoli (Brassica oleracea L.)

BÜCHERT AM; GÓMEZ LOBATO ME; VILLARREAL NM; CIVELLO PM; MARTÍNEZ GA

Córdoba

Congreso; III Congreso Internacional de Ciencia y Tecnología de los Alimentos.; 2009

MINCYT Cba., CONICET - Universidad Nacional de Córdoba.

Broccoli (Brassica oleracea L.) is a vegetable cultivated for its inflorescences, which are harvested and commercialized while still immature, prior to sepal opening. Harvesting causes severe stress conditions, water and nutrient deficiency and changes in hormone content. As a consequence, an early senescence is initiated, accelerating such process in a significant way. This induces a loss of the superficial green color of the vegetable, which diminishes the commercial acceptance of the product. In this work the effect of visible light treatments on broccoli postharvest senescence were evaluated. Different light intensities were assayed, as well as exposition to continuous and periodic light. In all cases the progress of senescence was evaluated by measuring changes in superficial color. A delay in senescence was observed in all assay conditions, being continuous exposure to a light dose of 25 μmol · m-2 · s-1 the one displaying the greater delay in the loss of green color of the broccoli florets. Comparing Hue (°) values at the end of the treatment with the initial values, florets exposed to continuous light decreased by 19 % while controls stored in darkness decreased by 28%. Consequently, samples treated under these conditions were employed in subsequent assays to determine other senescence-associated parameters. A decrease in chlorophyll content was observed inbroccoli florets exposed to continuous light, as well as lower total and soluble protein content, both with higher values at the end of the experiment in broccoli florets exposed to light in comparison to controls. Another parameter assayed was total and reducing sugar content, and we observed a decrease over the course of senescence, showing an evident delay in material subject to light exposure. Results suggest that storage under continuous low intensity light allows to delay senescence and to improve the quality of harvested broccoli.