EFFECT OF DOUBLE PAPER BAGGING ON SUPERFI CIAL SCALD AND VOLATILES ONMUTSU APPLES DURING COLD-STORAGE

Many Japanese apple growers use double paper bags on yellow-colored ap ple cv. Mutsu to enhance red color formation during their growth. To s tudy the effect of the double paper bagging on superficial scald, youn g fruits of the apple cv. Mutsu were shaded individually with commeric ial double paper bags from early June to late September as usual in Ao mori prefecture. These fruits were harvested in late October and store d at 0 degrees C. The incidence of superficial scald between bagged an d unbagged (control) fruits was recorded and the volatiles in their re spective skins during storage were analyzed by gas chromatography-mass spectrometry and gas chromatography. There was less scald in the bagg ed fruit than in the unbagged ones. The same 65 volatiles were identif ied in the skins of the bagged and unbagged fruits during storage. The differences in ratios of the volatile compositions were studied notin g the compositions whose ratios were smaller in the skins of bagged fr uit than those in unbagged ones, and the difference in trans-2-hexenal was largest among the volatiles, followd by n-butyl acetate. No diffe rence was found in alpha-farnesene whose oxidation products are believ ed to cause superficial scald. Exposure of healthy 'Mutsu' apples to t rans-2-hexena, n-butyl acetate, and farnesene (mixed isomers) at 20 de grees C for 20 hours showed that trans-2-hexenal induced scald-like in jury at the lowest concentration; whereas n-butyl acetate produced a s imilar degree of injury at a higher concentration. No symptoms of scal d appeared on fruits exposed to farnesene. Our results suggest that sh ading of double paper bagging reduces the concentrations of trans -2-h exenal and n-butyl acetate with which we experimentally induced scald- like injury to 'Mutsu' apples.