Study On Changes Of The Main Components In Citrus Peel At Different Storage Conditions

Citrus peel contains essential oils, pigment, flavonoid, pectin, vitamin, sugar and many kinds of trace elements, and has high nutritive value. But fresh citrus peel was seasonally strong and extremely apt to rot, which caused resources waste and environmental pollution. In order to research the changes of the main components in citrus peel at different storage conditions, satsuma mandarin peel, ponkan peel and pomelo peel were choosen as tested materials. Fresh cirtrus peels were stored at low temperature (-20℃,-40℃) and dried cirtrus peels were stored at room temperature. The content of essential oil, carotenoids, vitamin C, total sugar and total acid in citrus peel were determined regularly during storage. According to the changes and correlation of main components in citrus peel at different storage conditions, then determined the best methods for preserving citrus peels to retain the maximum content of essential oil, carotenoids, vitamin C, total sugar and total acid, and explored the correlation of main components in citrus peel at different storage conditions, which also provided a theory reference for extending storage period and utilizing functional components in citrus peel effectively. The results showed as follows:(1) The content of essential oils in ponkan peel was the highest in three citrus peels, next was pomelo peel, and the lowest content was satsuma mandarin peel. The dominant aroma components in three citrus peels were D-limonene, y-terpinene,3-carene,2-thujene,1R-a-pinene, myrcene, linalool, etc. The results showed that fresh satsuma mandarin peel kept at-40℃, dried ponkan peel and dried pomelo peel stored at room temperature could retain essential oils content.(2) With the different of the breeds and storage conditions, the aroma components of essential oils were different in three citrus peels.The kinds of alkenes and ketones reduced in fresh citrus peel stored at-20; the kinds of alkenes, alcohols, esters, ketones and phenols reduced in fresh citrus peel stored at-40; and the aldehydes reduced in dried citus peel stored at room temperature, but the esters increased.(3) The content of carotenoids in ponkan peel was the highest in three citrus peels, next was satsuma mandarin peel, pomelo peel was the lowest. With extend of storage time; the carotenoids were reduced in citrus peel at different storage conditions. The result showed that fresh citrus peel stored at-40℃were the best storage methods to retain carotenoids content.(4) The study showed that the content of vitamin C in pomelo peel was the highest, and then was ponkan peel, satsuma mandarin was the lowest. The content of total sugar in ponkan peel was the highest, and then was satsuma mandarin peel, pomelo peel was the lowest. The content of total acid in sequence from the highest to the lowest is ponkan peel, satsuma mandarin peel and pomelo peel. Three kinds of fresh citrus peels stored at-40℃were benefit to retain vitamin C and total sugar content. And dried citrus peels stored at room temperature were the better methods to retain total acid content.(5) The study showed that changes of essential oil content in three citrus peels at different storage conditions were existed positive correlation with the changes of carotenoids content and vitamin C content. Changes of carotenoids content were existed significant positive correlation with changes of vitamin C content.