Factors that influence volatile ester biosynthesis in 'Delicious' apples.
Miller, T. W.; Fellman, J. K.; Mattheis, J. P.; Mattinson, D. S.;
Acta Horticulturae Year: 1998 Issue: No. 464 Pages: 195-200 Ref: 27 ref.
1998
บทคัดย่อ
The effect of the intensity of light reaching fruit surfaces, cultivar and maturity on amounts of the principal aroma and flavour volatiles (acetate esters) emitted from Delicious apple fruits, and the relationship between anthocyanin accumulation and acetate ester emission, were studied. Light treatments of full sun (FS), 53% FS, 19% FS and <1% FS were created by season-long bagging of 2 strains of Delicious fruits (Starkrimson and Topred) with shade cloth. Anthocyanin levels decreased with decreased light exposure, with Topred fruits generally accumulating more anthocyanin than Starkrimson fruits. Contents of all flavonoid classes were also reduced as light level decreased. Volatile ester emissions were strongly affected by light exposure, with maxima occurring below 100% FS. Ester emission from Starkrimson fruits at 179 days after full bloom (DAFB) was roughly twice that from Topred fruits in both years. The primary ester of both strains at all light exposures was 2-methyl butyl acetate, acco
unting for 50 to 75% of total ester content, with butyl and hexyl acetates as secondary components. Fruit position on the canopy also affected fruit colour and aroma/flavour. Western and southern aspect fruits generally emitted more esters than northern and eastern aspect fruits; anthocyanin accumulation was maximal in fruits from northern and eastern aspects. Differences in ester, anthocyanin and flavonoid content due to light exposure in the canopy were as seen in the main study. The data suggest that anthocyanin accumulation and volatile ester formation increase together with increasing light exposure, but at higher light exposures, continued increases in anthocyanin production come at the expense of acetate ester biosynthesis. For these strains, this happened between 53% FS and FS. Results suggest that Delicious apples managed for maximum colour have less volatile content and less potential for volatile development.