Scald development and the levels of alpha-farnesene and conjugated triene hydroperoxides in apple peel after treatment with sucrose ester-based coatings in combination with food-approved antioxidants

Ascorbyl palmitate and n-propyl gallate were applied either separately or together to 'Granny Smith' apples (Malus domestica Borkh.) as a possible treatment to control scald development. The antioxidants were applied as formulations with Semperfresh (a sucrose ester-based fruit coating). Their effect on scald development and also on alpha-farnesene and conjugated triene hydroperoxide (CTH) levels was compared to that of diphenylamine (DPA). After four months storage at 0 degrees C and ten days at 20 degrees C, untreated apples were affected on 10-25% of their surface area. Apples treated with ascorbyl palmitate plus Semperfresh delayed scald development during the assessment at room temperature, while DPA provided almost complete control. After six months at 0 degrees C and then ten days at room temperature, DPA-treated apples were only slightly scalded, whereas all the other apples were severely scalded. After four months storage, the beneficial effect of DPA treatment was accompanied by a slightly higher alpha-farnesene level than that of the control, and by CTH levels one third to one half than those of the control. Compared to the DPA treatment, coating with ascorbyl palmitate plus Semperfresh led to similar levels of CTH, but the alpha-farnesene level was much lower. It is concluded that the limited scald control obtained with Semperfresh plus ascorbyl palmitate, unlike the greater control seen with DPA, is not due to an inhibition of alpha-farnesene oxidation to CTH.