Citrus속 과일의 이화학적 성분 비교연구

Abstract

ABSTRACT

A Comparative Study of the Physicochemical Composition of Citrus Fruits

Hong, Young Shin Advisor : Prof. Kim, Kyong-Su, Ph.D. Department of Food and Nutrition Graduate School of Chosun University

This study was conducted on major citrus fruits widely consumed in South Korea and in fact worldwide. In this connection, in this study, various mineral content and nutrients contained in the edible part of the citrus fruits were analyzed by using ICP-MS, ICP-OES and HPLC. The volatile flavor components from citrus fruits were extracted by SDE, and analyzed by GC/MS. In addition, among the citrus fruits, orange which depends on imports of large quantities, confirmed the changes of volatile flavor components in fruit pulp and peel irradiated with electron beams at 1, 3 and 5 kGy dose.

Ⅰ. Analysis of organic and inorganic compounds from Citrus Fruits

Citric and Malic acids were the highest fruits content of lemon with 4.70% and 1.98%, respectively. The content of succinic acid (0.46%) was the highest in yuzu while grapefruit showed the highest content of tartaric acid as 0.20%. Among all the samples, Redhyang showed the highest content (12.33%) of free sugar. Sucrose was 8.38% in Redhyang, fructose was 3.94% in kumquat, and glucose was detected the highest (2.61%) in orange. The content of vitamin C was found in the range of 23.64∼108.44 mg/kg. The peel of citrus fruits showed high levels of hesperidin and naringin than in pulp. In most of the number of samples, mineral content(mg/100g) such as Ca, K, P and Mg were found in the ranges of 10.57∼75.29, 95.13∼270.38, 9.27∼47.30 and 8.21∼26.42 mg/100g. Ca showed the highest content(mg/100g) 75.29 in yuzu, K (270.38) in lime, P (47.30) in yuzu, Mg (26.42) in yuzu and kumquat (20.99), Na (10.62) in yuzu and Fe (2.51) in orange. The content of Co and Ba were observed the highest in Redhyang, Ni and Ga in kumquat, and Cr and Se in grapefruit.

Ⅱ. Volatile flavor profile of major aromatic spices from Citrus Fruits

Components that have been identified in the pulp of various samples were; Cheonhyehyang 63 species (22.95 mg/kg), Hallabong 48 species (22.86 mg/kg), Jinjihyang 33 species (9.12 mg/kg), Hwanggeumhyang 76 species (130.10 mg/kg ), Redhyang 60 species (37.21 mg/kg), Orange 96 species (120.55 mg/kg) and 86 species grapefruit (195.60 mg/kg). Limonene was found to be the major flavor component of the citrus fruits with the highest percentage (69.31%) in Hwanggeumhyang pulp while in other citrus fruits, it was detected at a lower range of 31.92%∼48.90%. The main flavor components identified in the pulp were; limonene, nonanal, 3-methyl-1-butanol, heptanal, camphene and valencene.

Aroma components were identified in the peel of Cheonhyehyang 104 species (4939.77 mg/kg), Hallabong 97 species (3286.38 mg/kg), Jinjihyang 105 species (3317.56 mg/kg), Hwanggeumhyang 102 species (4293.39 mg/kg), Redhyang 108 (4049.94 mg/kg), Orange 109 species (4510.81 mg/kg) and grapefruits 124 species (4223.68 mg/kg). Limonene was the most common content of peel, showing high peak area for each fruit in the range of 42.57%∼66.70%. The main volatile components of the peel detected were; limonene, sabinene, β-myrcene, α-pinene, β-pinene, linalool, 4-terpineol, α-terpineol, (E)-β-ocimene and γ-terpinene

The volatile component of the 93 species (622.24 mg/kg) of kumquat, 108 (2209.37 mg/kg) of lime, 105 (3024.76 mg/kg) of lemon and 105 (3713.73 mg/kg) of yuzu were analyzed, in which the content of limonene was the most common. The peak areas were 63.53%, 24.90%, 40.37% and 35.00% for kumquat, lime, lemon and yuzu, respectively.

Ⅲ. Effects of irradiation on volatile flavor profile of major aromatic spices from Citrus Fruits

The composition of the volatile components of the electron beam irradiated and non-irradiated samples did not show significant differences. However, changes in small amounts were observed. In the electron beam irradiated samples, the specific flavor components were not detected. The content of limonene in non-irradiated samples was identified at 65.31 mg/kg, but the irradiated samples at a dose of 1 kGy showed decreased content of limonene.

Volatile compounds were identified in a total of 109 species (4510.81 mg/kg) of orange peel while only 123 species were studied for electron beam irradiation. The irradiation was increased at a dose of 1, 3 and 5 kGy each 5447.13, 6361.75 and 7054.02 mg/kg. Limonene content increased at a dose of 3 and 5 kGy while β-myrcene, α-pinene were reduced in all of the irradiated samples.

In this study, the changes of volatile flavor components of fruit pulp, and peel of orange by electron beam irradiation, confirmed that the profile of volatile aroma components is influenced by irradiation only in terms of quantitative changes. The electron beam irradiation dose in the citrus fruits was judged to be appropriate within a maximum 1.