Determination And Evaluation Of Naringin, Limonin And Nomilin In Citrus

Citrus is the first fruit crop in the world. It contains large amount of biological active substances which are benefit for human health, such as carotenoids, limonoid, flavonoids and so on. In order to evaluate the content of bitterness substances in citrus fruits and make better use of such germplasm resources in citrus breeding, the contents of limonin, nomilin and naringin were detected by high performance liquid chromatography (HPLC). The main results were as follows:1. The method of limonin, naringin and nomilin detection by HPLC was established. Results showed that these three bitterness substances have a wide range of variability in citrus because the same tissus in different types of citrus, the different citrus varieties in the same group and different tissues of the same variety. In general, pummelo contains the highest level of bitter substances; Phoenix pummelo contains the most and abundant bitter substances and followed by 'Gaoban' pummelo. In the tissues of 'Gaoban' pummelo, bitter substances in albedo and mesocarp were more than those in flavedo and juice sac.2. The content of limonin, nomilin and naringin of 'Guoqing No.1' satsuma mandarin, 'Oroblanco' grapefruit, 'Cara Cara' navel orange and 'Seike' navel orange were measured during fruit development. Results showed that significant decreasing was found in all the 4 variety citrus fruit. Different from navel oranges, a slight recovery about 135 d after full bloom then a subceed decreasing tendency has been found in contents of three substances in pulp of 'Guoqing No.1' satsuma mandarin and 'Oroblanco' grapefruit.3. Limonin, nomilin and naringin in mature fruit of 'Guoqing No.1' satsuma mandarin, 'Guoqing No.3' satsuma mandarin, 'Guanxi' sweet pummelo and 'Shatian' pummelo stored at 4℃and room temperature (about 25℃) were detected respectively. Results showed that: bitterness substances in pulp changed greatly during 20 d to 60 d after storage at room temperature and kept stable after 60 d. bitterness substances in pulp under cold storage was stable before 60 d during storage and increased significantly afterwards. Therefore, in terms of 'Guoqing No.1' satsuma mandarin, 'Guoqing No.3' satsuma mandarin, 'Guanxi' sweet pummelo and 'Shatian' pummelo respectively, consumption before 40 d, 40 d, 20 d and 40 d after storage, little bitterness might be sensed.4. 'Delayed bitterness' in juice of 4 oranges were measured by using HPLC and Electronic-Tongue. Results showed that, in the juice of 'Luzhai' sweet orange (C. sinensis), Tarocco blood orange (C. sinensis) and Newhall navel orange (C. sinensis), the content of limonin increased gradually. A sharp increase of limonin content was found in all those orange juice at 24 h after processing. Analysis of 'delayed bitterness' by Electronic-Tongue in 'Luzhai' sweet orange (C. sinensis) correlate well with data obtained from HPLC and correlated at 0.8670. The results indicated that the fruits of these four orange varieties were not suitable for juice processing.