Determination of changes in volatile aroma compounds and some enzyme activities during the maturation of Turkish cv. Kozan orange

In this study, the aroma profile of cv. Kozan yerli orange one of the most important orange varieties in the Mediterranean Region was determined in green, green-yellow and yellow maturity periods, the specific activities of β-glucosidase and alcohol dehydrogenase enzymes were calculated during these maturity periods and their relationship with free volatile compounds was determined. A total of 73 different volatile aroma components, including 14 monoterpenes, 9 sesquiterpenes, 25 aromatic hydrocarbons, 10 aldehydes, 2 high alcohol, 3 ketones, 8 phenol compounds and 1 volatile acid were detected in Kozan yerli orange juice samples by the HS-SPME / GC-MS method.It was determined that the total amount of volatile aroma compounds in yellow oranges reached 3.5 times of the total amount of volatile aroma components in green oranges.The most dominant free volatile components of last maturity period were recorded as l-limonene, valencene α terpinolene, beta ocimene, beta phellandrene. While the specific activity of β-glucosidase and alcohol dehydrogenase enzymes were the highest level in green orange samples; it decreased substantially in the green-yellow orange samples, and reached the lowest level by showing a partial decrease in the yellow orange samples. These enzymes are probably not significant contributors to the increase in the amount of volatile aroma compounds identified during the ripening periods in Kozan yerli orange.