Aromatic constituents analysis of Hongyang kiwifruits from different regions in Guangxi

Abstract: 【Objective】Kiwifruit is known as the“King of fruits”because it is rich in dietary fiber, vitamins, protein and minerals. The market for kiwifruit at home and abroad is huge. China is the world's largest kiwifruit production and consumption country. In recent years, planting area of kiwifruit has expanded rapidly in Guangxi, Yunnan, Guizhou, Jiangxi and other economically underdeveloped provinces (regions) in southern China However, the fruit quality varied with areas of planting. Therefore, improving the quality of kiwifruit is an important task in these areas. Aromatic characteristics are the most important characteristics for kiwifruit quality and are the main concern to consumers. Hongyang is the main variety of kiwifruit grown in Guangxi, but there were few reports on the trend performance of Hongyang in different producing areas. The aroma components of Hongyang from 19 growing regions of Guangxi were determined in order to provide reference for selecting suitable areas for growing kiwifruit in Guangxi.【Methods】Fruit samples were collected from 19 growing regions in Guangxi. Thefruits were harvested when the soluble solid reached 7 Brix. The aroma components of fruit were determined by headspace solid phase extraction (HS- SPME) and gas chromatography- mass spectrometry (GC-MS). The extraction head was 30 μm PDMS/DVB SPME. The data were statistically analyzed by SPSS.19.0, and Origin 2018 was used for heat map.【Results】A total of 71 aroma components were detected from the 19 regions, including 26 esters, 24 terpenes, 4 alcohols, 4 aldehydes, 2 ketones, 2 C13 compounds, 2 C6 compounds, and 7 alkenes. The fruits produced in Leye County of Baise City had the most abundant aroma components, with 26 kinds of aroma components detected, followed by Gongcheng with 24 kinds of components detected. The aroma components of the fruits produced in Dongshan of Quanzhou County in Guilin City were the least, only 9 were detected. The most regions had aroma components ranging from 16 to 20 kinds. The main aroma types of kiwifruit were esters or terpenes, the esters accounting for the total aroma of Hongyang from the 19 regions had large difference, ranging from 8.3% to 99.4%. The terpenes accounting for the total aroma of Hongyang from the 19 regions also had large difference, ranging from 0.5% to 80.9%. Esters was accounting for over 50% of the total aroma in the 12 regions, and terpenes accounting for over 50% of the total aroma components in the 7 regions. The high content of aroma components in Hongyang were ethyl butyrate, methyl butyrate, ethyl caproate, methyl benzoate, ethyl acetate, and eucalyptus, etc. The total aroma content of Hongyang fruits from the 19 regions ranged from 32 to 215 μg · kg- 1 , among them, the fruits from Rongjiang Town of Xin’an County, Guilin City had the highest aroma content, and those from Linchuan County had the lowest aroma content. The esters content of Hongyang from 19 regions ranged from 2.3 to 169.7 μg · kg- 1 , among them, the fruits from Nandan of Hechi City, Mochuan of Xin’an County in Guilin City had the highest aroma content, and those from Longsheng of Longsheng County in Guilin City had the lowest esters content. The main esters in Hongyang were ethyl butyrate, methyl butyrate, ethyl caproate, methyl benzoate, ethyl acetate, butyl butyrate, and methyl quillate etc. The terpenes content of Hongyang fruits from the 19 regions ranged from 0.9 to 134.5 μg·kg-1 . The fruits from Rongjiang of Xin’an County in Guilin City had the most abundant terpenes content, followed by those from Sishui of Longsheng County in Guilin City, and the fruits from Zhongshan of Hezhou City had the lowest terpenes content. The high content of terpenes of Hongyang fruits from the 19 regions were eucalyptol, Dlimonene, 3-carene, o-cymene, γ-Terpinene, β-Pinene etc. Some terpenoids were only detected in the fruit from a few areas. The principal component analysis (PCA) showed that the fruits from Sishui Township in Longsheng County, Rongjiang Town in Xing’an County, Nanbianshan Township in Lingui District, Nandan County in Hechi City and Luocheng County had higher aroma scores.【Conclusion】 The aromatic constituents of the Hongyang kiwifruits from the different regions were analyzed. The comprehensive analysis showed that the aroma of kiwifruit was better in Rongjiang Sishui of Longsheng County, Nanbianshan of Lingui District, Nandan County and Luocheng County, indicating that the climate and soil conditions were favorable for the formation of aroma. The results also showed that the fruits from Dongshan of Quanzhou County in Guilin City and Xiaxia of Linchuang County in Guilin City had the lowest aroma where the conditions might not be suitable for the formation of kiwi aroma. In addition, the climate of some growing areas was favorable for ester formation and some other areas for terpenoids formation. Rongjiang of Xin’an County in Guilin City would be conducive to the formation of esters and terpenoids. The results could provide certain reference for selecting suitable areas for planting kiwifruit in Guangxi.