Research On Quality Characteristics Of "Long An Pomelo" And Origin Identification Technology Of Pomelos From Four Regions

The objective of this paper was to make it clear that the quality characteristics of Long An pomelo, and to discusse the quality differences between Long An pomelo and other kinds of pomelos that come from different regions.80 pomelo samples and 80 soil samples were collected from Sichuan province (Guangan), Chongqing, Fujian (Pinghe) and Guangxi (Rongxian) province of China during the 2012 and 2013 harvest time, respectively. The concentrations of each index in pomelo samples were measured by electronic nose、GC-MS、atomic absorption spectrometer (AAS)、automatic amino acid analyzer (AAA)、ultraviolet-visible spectroscopy、handheld refractometer and some other instruments. Analysis of variance (ANOVA), multiple comparison analysis, principal component analysis (PCA) and linear discriminant analysis (LDA) were applied in data analysis. This study focused on the quality characteristics of Long An pomelo and the characteristics and differences of above determined indicators in pomelo from four regions. Finally, the effective discriminant models were established. The main conclusions were as follows:(1) The content of soluble solids, flavonoids, threonine, glycine, valine, isoleucine, leucine, histidine, copper, iron, manganese and zinc of Long An pomelo from different regions exist significant difference (P< 0.05). By mean value of each index, Long An pomelo which comes from Long An Xiang has the highest nutritional value.(2) The content of pigment and volatile component had significant differences (P< 0.05). It can be used in origin identification. The content of beta carotene of Long An pomelo is the highest, reached 2.58 μg/g; the content of lycopene of Chongqing pomelo is the highest, reached 0.24 μg/g. A total of 81 kinds of volatile components were analysed. D-limonene, germacrene and D-cadinene have the highest reletive content, the content were 38.46%～55.05%,4.35%～7.92% and 0.24%～7.92%, respectively.(3) The conventional physical and chemical index content, amino acids and mineral elements content of pomelo from four regions have significant differences (P< 0.05). The nutritional value of Long An pomelo from Sichuan province is the highest, and the second one is chongqing pomelo. The stability of different traceability techniques is: mineral element fingerprint> organic compound fingerprint> amino acids fingerprint, the discriminant accuracy were 91.74%,90.06% and 89.01%, respectively, these indicators as variance analysis of pomelo were relatively stable. If combine the three kinds of fingerprint analysis technology to classify the pomelo origin, the correct discriminant rate will greatly improve.(4) Using electronic nose non-destructive testing technology analyse the difference of volatile composition of pomelo from four regions, the overall discriminant score contribution rate is 100%. But the scattered point diagram of Chongqing and Fujian are relatively fragmented and overlapping, and its overall correct discrimination rate is 78.42%. It proved that using electronic nose non-destructive testing technology has a certain effect in pomelo origin identification. It can provide a reference for the establishment of agricultural origin traceability technology system.