Advancement of applied studies of isotope technique in fruits and products geographical origin traceability

Abstract：With the continuous improvement of living standards, the proportion of fruits in the production and consumption of agricultural products is gradually increasing because of its rich nutrition. Its quality and safety become the focus of attention by consumers, and consumers pay more attention to the origin of products, therefore the establishment of a corresponding fruits and products quality and safety traceability system has become inevitable. At present, more and more scholars, both at home and abroad, have devoted themselves to the study of the origin traceability technology of agricultural products, and isotope technology is considered one of the more effective means of provenance analysis of plant products because of its uniqueness. The research in this area started late in our country, and many studies focused on grain, tea, livestock and aquatic products. There were also reports about the origin of fruits and products, but they were not systematic. Isotope fractionation is the basic principle and basis for its traceability. In organisms, isotopes are a natural label for all organisms because of their lack of artificial change, reflecting the external environmental factors of biological growth without changing with chemical additives. This paper compares the commonly used technologies of plant origin for agricultur-al products traceability, along with determining the advantages and disadvantages, analyzes the theoretical basis of the application of isotopes in plant products Origin Traceability Technology, and enumerates the application and characteristics of C, H, O, N, S, Pb, Sr, B and other commonly used approaches in isotope tracing technology. The carbon isotope ratio of 13C/12C primarily depends on plant photosynthesis, carbon dioxide fixation process and plant photosynthetic pathway (C3, C4) , environmental factors (temperature, humidity, rainfall) and physiological factors (stomatal conductance, intercellular CO2 concentration) which are closely related, and primarily reflect the geographic information. Hydrogen isotope ratios 2H/1H and O isotopes 18O/16O are primarily influenced by evaporation, concentration and precipitation processes of water, which primarily reflect geographic information. The nitrogen isotope ratio (~ (15) N/14N) is primarily affected by plant types, chemical fertilizers, climatic conditions, soil conditions and other factors, primarily reflecting marine and terrestrial plant information, agricultural production and so on. The sulfur isotope ratio (~ (34) S/32S) is primarily influenced by bacteria, and the source information is primarily geographical (oceanic) . The lead isotope ratios 207Pb/206Pb and 208Pb/207Pb are primarily affected by the decay of U and Th in minerals and environmental pollution, primarily reflecting geological information, geographical information and sources of environmental pollution. The strontium isotope ratio 87Sr/86Sr is primarily affected by the rock age and Rb/Sr ratio, which reflects geological information and geographic information. The boron isotope ratio (~ (11) B/10B) is primarily affected by different geochemical processes and agricultural chemical fertilizers, primarily reflecting regional information and agricultural production. This paper summarizes the existing application of isotope techniques in the origin of grape, apple, citrus, jujube and other fruits, analyzes its application in the geographical origin of advantages and limitations, and the application of isotope techniques in the origin of fruit and product origin are also proposed. The research and application of isotope technology in fruit and its origin is still at the basic stage, and further research should be carried out in the following areas. First of all, we should look deeply into the application of new isotope indicators, and continue the separation and research of other isotopes, so as to explore the effective source traceability technology and establish the origin traceability database. Secondly, multivariate isotope studies should be strengthened. Now most of the research work is using the application of a single isotope, and stable isotope fingerprint analysis technology, the stability of different isotopes have their own characteristics, its causes and fractionation in traceability of agricultural origin information reflected in different approaches. Therefore, using a single isotope of provenance can play a certain role in identification, however not all sources are easy to distinguish; if we can combine multiple elements of isotope analysis, we will be able to draw more reliable conclusions about origin traceability. Finally, we should focus on the application of multiple technologies. The development of agricultural products traceability technology allows for the quick identification and traceability of fruits and products and increased accuracy becomes possible, but you cannot rely solely on a method which can solve all the problems of fruit origin traceability. This requires us to combine isotope technology with other traceability techniques, such as the analysis method of isotope technology and other mineral elements, isotope technique and multivariate statistical analysis (principal component analysis, variance analysis and cluster analysis) , isotope analysis technology and the organic combination of chemical composition and so on. Research on provenance comprehensive technology must address the needs of different products, to more effectively carry out the fruit and product origin discrimination, in order to promote China's fruit producing research and products traceability technology development, along with promoting the establishment and improvement of a fruit safety traceability system.