Synthesis and oxidation of alpha -farnesene during high and low O2 storage of apple cultivars differing in scald susceptibility.
Whitaker, B. D.; Solomos, T.; Harrison, D. J.;
Acta Horticulturae Year: 1998 Issue: No. 464 Pages: 165-170 Ref: 9 ref.
1998
บทคัดย่อ
Apple fruits of high (Granny Smith; GS), moderate (Red Delicious; RD) and low (Gala; GA) susceptibility to superficial scald were stored for up to 6 months at 0 deg C under high (100%) or low (1.5%) O2 or in air. Hexane extracts of peel samples were analysed for alpha -farnesene and its major oxidation product, a conjugated trienol, using an HPLC method which allows simultaneous detection at 232 and 269 nm, respectively. Identification of the compounds was confirmed by UV spectrometry, HPLC with diode array detection, and GC-MS. In general, alpha -farnesene and trienol content correlated with scald susceptibility. Levels of both isoprenoids were over 20-fold higher in GS compared with GA fruits, the latter having only trace amounts. Farnesene content peaked in both GS and RD fruits at 2 months, whereas trienol rose sharply from 1 to 4 months. Production of farnesene and trienol increased at higher O2 levels in all 3 cultivars. The amount of trienol was more closely correlated with O2 concentrati
on. GS fruits stored under 100% O2 were completely "bronzed" after 3 months and had a high level of ethanol. Two lots of RD fruits harvested one week apart differed markedly in their rate and amount of farnesene and trienol production. Fruits from the earlier harvest had higher levels of both compounds at all times. The results support the hypothesis that susceptibility to scald in a given cultivar is a function of farnesene production and its subsequent autoxidation to conjugated trienols.