COVERING CAULIFLOWER CURDS DURING GROWTH REDUCES FLORET FLAVONOIDS AND IMPROVES QUALITY

Cauliflower (Brassica oleracea) curds are of better quality, and therefore more marketable, when they are white and free from blemishes. As the production of pigments in plants can be stimulated by exposure to light, cauliflower curds were covered with either their leaves or "Tyvek", a spunbounded olefin material, during curd growth to minimise the light transmitted. In a spectrophotometer, Tyvek and leaves transmitted <1% of light, as compared to deionised water, over the spectral range 200-800 nm. In a field experiment at Medina, Western Australia, covered curds were whiter and had 20% (Tyvek) or 40% (leaves) of the concentration of flavonoids in the florets (estimated by absorbance at 366 nm) of the curds grown without covers. The carotenoid concentration did not differ significantly (P > 0.05) between covered and uncovered curds. Under the conditions of the field experiment management of curd quality required pre-harvest protection from light to reduce flavonoid production.