Contents and Changes of Organic Acids and Sugars in Some Varieties of Grapes during Storage at 5°C

Abstract

This study was made on the contents and changes of some organic acids and sugars in some varieties of grapes during storage at low temperature (5±1°C), using high performance liquid chromatography (HPLC) technique. In this experiment, four varieties of grapes, Kyohô, Pione, Muscat of Alexandria (Muscat) and Neo Muscat, were used. The following results were obtained.
1) All varieties of grapes used in this experiment contained malic acid, tartaric acid and citric acid.
2) Black colored grapes, Kyohô and Pione, contained succinic acid, but green colored grapes, Muscat and Neo Muscat, did not.
3) The total organic acid content in four varieties of grapes was found by HPLC to range from 0.8 to 1.5%. During storage of five weeks, organic acid content in Kyohô, Pione and Muscat grapes showed almost no change, while that in Neo Muscat grapes increased gradually.
4) This experiment showed that four varieties of grapes mainly contained fructose and glucose, but sucrose was not detected. Fructose and glucose were contained at a ratio of about 1 : 1.
5) HPLC demonstrated that the total sugar content of four varieties of grapes ranged from 15 to 21 %. During storage, the total sugar content of Kyohô, Pione and Muscat grapes also showed almost no change, while that of Neo Muscat grapes tended to decrease.