Dynamic Analysis Of Aroma Components In Different Parts Of Apple Fruits

The two apple cultivars ('Delicious'and'Nagafu No.2') were used as materials in this study. The aroma components of apples were measured by head-space solid phase microextraction (HS-SPME) and gas chromatograph-mass spectrometry (GC-MS) for studying the change of aroma components in the peel and pulp of apples during fruit maturation, and in the peel, pulp and full fruits of apples at different storage time. Fruit firmness and the content of soluble solid were measured in order to analyze the relationship between the storage quality and aroma components. The main results were as follows:1. The main aroma components of unripe apple fruit comprised C6 aldehydes and alcohols such as 2-hexenal, hexanal, (E)-2-hexen-l-ol. Esters and some alcohols showed a major increase during fruit maturation. The categories of aroma compounds in apple peel were significantly more than those observed in pulp during fruit maturation, and the relative content of volatiles showed a great difference.2.58 and 65 aroma components were respectively determined at maturity in the peel of'Delicious'and'Nagafu No.2',41 and 45 components in the pulp. The majority of aroma components were determined to be esters, aldehydes and alcohols in two apple cultivars, among which the categories of esters were significantly higher.2-Methyl-l-butyl acetate, hexanal,1-hexanol, butyl hexanoate and 2-methyl-l-butanol were main aroma components in the peel of'Delicious'. In the pulp of'Delicious'aroma comprised 2-methyl-1-butyl acetate, 1-butanol,2-methyl-1-butanol,1-hexanol and hexyl acetate.2-Hexenal,2-methyl-1-butyl acetate, hexyl 2-methyl-butanoate,1-hexanol and a-farnesene were main aroma components in the peel of'Nagafu No.2'.2-Methyl-l-butyl acetate,2-hexenal,2-methyl-l-butanol, 1-hexanol and hexyl acetate were important to the pulp flavor of'Nagafu No.2'.3.50 and 49 aroma components were respectively determined at maturity in the full fruits of'Delicious'and'Nagafu No.2'. There were 30 kinds of esters in 38 common aroma components of two apple cultivars. Acetate esters are the most aboundant aromas, such as 2-methyl-l-butyl acetate, butyl acetate, hexyl acetate, propyl acetate and so on, the content being 70.81% and 52.60% respectively. Acetate esters were thought to contribute significantly to the unique aroma of two apple cultivars.2-Methyl-1-butyl acetate, butyl acetate, hexyl acetate, hexyl 2-methyl-butanoate and butyl hexanoate were main aroma components in the full fruits of'Delicious'.2-Methyl-l-butyl acetate, butyl acetate, hexyl 2-methyl-butanoate, butyl hexanoate and hexyl acetate were main aroma components in the full fruits of'Nagafu No.2'.4. Esters were increased first and decreased afterwards in the full fruits of two apple cultivars, and the peak of esters appeared at 20 days during ambient temperature (15-25℃) storage. Esters were obviously increasing in the peel and pulp of'Delicious'along with the storage time, but aldehydes and alcohols were decreasing. Esters showed a major decrease in the peel and pulp of'Nagafu No.2'; aldehydes were decreasing in the peel, while those were increasing in the pulp; the change regularity of relative content of alcohols were increased first and decreased afterwards.5. Fruit firmness depressed as storage time prolong, while the relative content of ethyl esters showed a major increase in the peel, pulp and full fruits of apples. Among them, the contents of ethyl acetate, ethyl propanoate, ethyl butanoate, ethyl hexanoate and ethyl 2-methylbutanoate were increasing greater. Ethyl esters in the peel and pulp of apples had no correlation with the content of soluble solid.