Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2005
Publication Date: 7/1/2005
Citation: Drake, S.R., Eisele, T.A., Elvfing, D., Drake, M.A., Drake, S.L., Visser, D. 2005. Effects of the bioregulators avg and eth on brix, carbohydrate acid and mineral concentrations in 'scarletspur' delicious apple juice. Hortscience. 40:1421-1424.
Interpretive Summary: Bioregulators have been widely used for multiple purposes in tree fruit production. Many physiological processes in tree fruits can be influenced by exogenous application of such products. There is little, if any, information on the compositional characterization of apple juice from apples treated with bioregulators, even though there has been extensive characterization of apple juice from non-treated apples. This study was conducted over three crop seasons using 'Scarletspur Delicious' apples. Ethephon (ETH) or aminoethoxyvinylglycine (AVG) were applied alone or in combination. ETH alone increased the Brix, sucrose and sorbitol content of apple juice, but reduced the fructose content. ETH reduced total acidity and reduced individual acid (quinic and malic) contents. AVG alone reduced both Brix and sucrose content of apple juice, but had no influence on either total acidity or individual acid contents. Combinations of ETH and AVG tended to counteract the influence of either one used alone on Brix, individual carbohydrates, total acidity and individual acids. Increased juice Brix values coupled with reduced total acidity would improve the overall solids/acids ratio, thereby having a strong positive influence in the sensory quality of apple juice. Mineral content of apple juice was not influenced by the application of either ETH or AVG.
Technical Abstract: This study was conducted over three crop seasons using 'Scarletspur Delicious' apple trees on MM.111 rootstock. Ethephon [Ethrel(R), ETH] or aminoethoxyvinylglycine [AVG, ReTain(R)] were applied alone or in combination. AVG was applied four weeks before first harvest (WBFH) and ETH at either one and/or two WBFH. Apples were harvested at commercial maturity and again after four weeks; Brix, total acidity, carbohydrates, acids and mineral contents were determined on apple juice. ETH alone increased the Brix, surcose and sorbitol content of 'Delicious' apple juice and at the same time reduced the fructose content. Both longer preharvest exposure to, and higher concentrations of, ETH had a stronger influence than application closer to harvest and/or at lesser amounts. Time of ETH application tended to influence individual carbohydrates more so than amount of ETH applied. ETH reduced total acidity and also reduced apple juice individual acid (quinic and malic) contents with longer preharvest exposure or higher concentrations. AVG reduced both Brix and sucrose content of 'Delicious' apple juice, but had no influence on either total acidity or individual acid contents. Combinations of AVG and ETH tended to counteract the influence of either one used alone on total Brix, carbohydrates, total acidity and individual acids. Mineral content of 'Delicious' apple juice was not strongly influenced by application of either ETH or AVG.