Tracking Technology On Radish Locality Based On Stable Isotope Ratio And Mineral Element Content

With the demanding on geographical best-selling of agricultural products in recent years,radish with geographical indication represents the new excellent agricultural product,and promotes local development on agriculture.However,the tracking technology on radish locality should be improved,by which discerning the landmarks of radish products and enhancing the consumers’trust in the authenticity of radish locality.This paper and analyzed177 samples,which belonging to 10 radishes species in 8 sub-regions in Tianjin,Henan and Shandong provinces.The soluble sugar and radish contents,stable isotope ratios of carbon and nitrogen,and contents of 18 mineral elements,including Co,Cd,As,Ni,Mo,Cr,B,Ba,Ca,Cu,Fe,Mg,Mn,Na,P,Sr,Zn and Se,were determined.The results are listed as follows:（1）Appearance characteristics and nutritional components of fleshy radish roots at different growth periods and environments.The succulent root weight of radish constantly increased with the prolongation of radish growth,while the soluble sugar and sulforaphane contents increased first and then decreased slowly at the same time.Both of the soluble sugar and sulforaphane reached to the maximum contents at 91-100 days,corresponded with the values of 1.22%and 134.22μg/g,respectively,and then decreased gradually.Comparatively,the change of sulforaphane content was significantly higher than those of soluble sugar content.Except the diameter,the weight,length,soluble sugar content and sulforaphane content of radish grown in the shed were higher than those grown outside the shed,among which the soluble sugar contents varied more significantly.（2）Sulforaphane,soluble sugar and stable isotopes in different species and localities of radish.The contents of soluble sugar and sulforaphane varied significantly in different species and locations（p<0.05）,among which the highest contents of soluble sugar（1.08%）and sulforaphane（128.98μg/g）were detected in Qixing radish,and the content of soluble sugar and sulforaphane were lower contents of soluble sugar（0.57%）and sulforaphane（39.07μg/g）were contained in Pohe radish.The soluble sugar content in radish decreased in turn of Tianjin,Shandong and Henan,while the sulforaphane content followed the turn of Tianjin,Henan and Shandong from high to low.Although theδ¹³C in radish varied obviously in different provinces and sub-regions,it was hard to discern the producing locations because of small total variations ofδ¹³C.Meanwhile,δ¹⁵N was suggested to be applied in tracking locations of radish for the higher variations ofδ¹⁵N in sub-regions.（3）Discrimination model on landmark radish based on mineral compositions.Inductively coupled plasma mass spectrometry（ICP-MS）was used to determine the contents of 18 mineral elements,including Co,Cd,As,Ni,Mo,Cr,B,Ba,Ca,Cu,Fe,Mg,Mn,Na,P,Sr,Zn and Se.The contents of 9 elements,including Na,Ca,Mg,Fe,Sr,Zn,B,Mn and As,varied significantly among the 3 provinces（p<0.05）.In order to further discern the landmark radish,partial least squares discriminant analysis（PLS-DA）and linear discriminant analysis（LDA）were used to establish the tracking models of radish producing locations based on the geographical mineral contents.The results showed that PLS-DA model generally discerned 86.44%of the radish on producing locations,with lower misjudgment in3 provinces.LDA model presented a better discrimination on the producing locations with a more accuracy of 92.09%and 93.79%respectively.（4）Screened characteristic factors on radish landmarks by partial least squares discriminant analysis（PLS-DA）.After screening the factors of soluble sugar and sulforaphane contents,mineral elements,stable isotope ratio of carbon and nitrogen,and considering the VIP variables,13 parameters of Na,Ca,Mg,Ni,Sr,As,B,Cd,Co,sulforaphane,Mn,soluble sugar and Cr could be applied to distinguish the radish locality.