The Composition of Strawberry Aroma as Influenced by Cultivar, Maturity, and Storage

The aroma of fresh strawberries is composed of a mixture of volatile compounds with no single compound responsible for the characteristic strawberry aroma. Volatiles produced in strawberries are predominately esters, although alcohols, ketones, and aldehydes are also present in smaller quantities. The major volatiles contributing to aroma include ethyl butanoate, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, ethyl hexanoate, methyl butanoate, linalool, and methyl hexanoate. There are qualitative and quantitative differences in volatile composition between cultivars. Headspace concentration of volatiles from 5 cultivars were 0.4, 1.7, 5.6, 5.8, and 14.3 mol·m –3 for `Honeoye', `Cavendish', `Micmac', `Kent', and `Annapolis', respectively. During fruit maturation on the plant, aroma volatile synthesis coincides with color formation, and continues to increase until the fruit is over-ripe. Volatile concentration increases about 4-fold in the 24-hr period required for fruit to ripen from 50% red to fully red on the plant. Volatile composition continues to change after harvest and is affected by storage temperature, atmosphere composition, and light. The concentration of ethyl esters increases while methyl esters remain constant in fruit held at 0°C, but, when fruit are warmed to 15°C, the reverse is true. Holding strawberries in 10 to 20 kPa of CO 2 may increase concentrations of ethyl esters in the fruit. Light increases the production of volatiles in stored strawberries. Methods to control strawberry aroma will be discussed.