The Genetics of Kiwifruit Flavor and Fragrance
Kiwifruit is appreciated for its distinctive flavor Green fleshed Actinidia chinensis var. deliciosa kiwifruit have a tangy sweet flavor with green notes of citrus and melon. Actinidia chinensis var. chinensis fruit have a more tropical flavor, with hints of mango and berry fruit. The flavors of kiwifruit result from a subtle mixture of volatile organic compounds (VOCs) balanced with both good sweetness and acidity. VOCs have been studied extensively in a range of cultivars by analytical means including GC MS (gas chromatography mass spectrometry) and GC olfactometry analysis, and the major compounds and important odorants have been identified. In most kiwifruit species, esters such as methyl and ethyl butanoates are responsible for the fruity notes, while aldehydes such as hexanal and (E) 2 hexenal contribute green/grassy notes. Species specific compounds such as monoterpenes and strawberry furanone have also been found, as well as certain sulfur compounds that are responsible for tropical notes. Sequestered volatiles may be an important pool of unreleased aroma potential in certain fruit. A detailed account of the genetics, gene regulation, and biosynthesis of these major aroma classes in kiwifruit is presented in the following review.