In this study, the effects of supplementary UV radiation during the vegetative period on antioxidant
compounds, antioxidant activity and postharvest quality of broccoli heads during long term storage was
studied. The broccolis were grown under three different doses of supplementary UV radiation (2.2, 8.8
and 16.4 kJ/m2/day) in a soilless system in a glasshouse. Harvested broccoli heads were stored at 0 C in
modified atmosphere packaging for 60 days. The supplementary UV radiation (280e315 nm) during the
vegetative period significantly decreased total carotenoid, the chlorophyll a and chlorophyll b content
but increased the ascorbic acid, total phenolic and flavonoid contents of broccolis. All supplementary UV
treatments slightly reduced the antioxidant activity of the broccolis, however, no remarkable change was
observed between 2.2 and 8.8 kJ/m2 radiation levels. The sinigrin and glucotropaeolin contents of the
broccolis were substantially increased by UV treatments. The prolonged storage period resulted in
decreased ascorbic acid, total phenolic and flavonoid contents, as well as antioxidant activity. Discoloration
of the heads, due to decreased chlorophyll and carotenoid contents, was also observed with prolonged
storage duration. Glucosinolates levels showed an increasing tendency till the 45th day of storage,
and then their levels started to decline. The weight loss of broccoli heads during storage progressively
increased with storage time in all treatments. Total soluble solids, solids content and titratable acidity
decreased continuously during storage. Titratable acidity was not affected by UV radiation doses during
the storage time whereas soluble solids and solids content (dry matter) were significantly affected by UV
doses. Supplementary UV radiation increased the lightness (L*) and chroma (C*) values of the broccoli
heads. Pre-harvest UV radiation during vegetative period seems to be a promising tool for increasing the
beneficial health components of broccolis.