Differences In Nutritional Quality And Geographical Origin Traceability Of Walnuts

This study compared the oil contents,fatty acid composition,amino acid composition,mineral element in"Wen 185","Xiangling",and total 29 planted cultivars walnuts from China.At the same time,40 samples of walnut from 5 areas in China were collected,and the nutritional composition and stable isotope were used to trace the walnut from different regions.The contents of oil contents,fatty acids,amino acids,antioxidant components,minerals,and heavy metals in walnuts from different regions and different cultivars in China were determined by chromatography method,spectrophotometry method and mass spectrometry method.The results showed that the content of oil and unsaturated fatty acid in 29 cultivars walnuts were ranged from 54.87%to 66.26%and 90.89%to 92.00%,respectively.The content of total amino acids,total polyphenols,total flavonoids and tocopherol were 14.61?20.52g/100g,13.34?49.36 mg/g,5.53?27.79 mg/g and 31.29?53.84 g/100g,respectively.The Ca,K,Mg,and P contents of 29 cultivars walnuts were 1021.66?1853.73 mg/kg,2727.49?4597.91mg/kg,1435.64?1867.42 mg/kg,3017.53?4100.75 mg/kg,respectively."Lipin 1"contained the highest oil content,"Liaoning 7"and"Liaoning 10"contained the highest oleic acid content as well as"Lvling"contained the highest linoleic acid;amino acid content in"Liaoruifeng"significant higher than?p<0.05?the other cultivars;"Jinlong 1"provided higher total polyphenolys content,total flavonoids content,and tocopherols;"Jinbaoxiang 1"and"Jinbaoxiang 2"showed higher minerals content than others walnut cultivars.The content of oil,unsaturated fatty acid and total amino acids in walnuts samples from five producing areas?Gansu,Hebei,Guangxi,Sichuan,Xinjiang?of China were ranged from61.47%to 63.13%,89.28%to 92.85%,and respectively.The content of amino acids,total phenols,total flavonoids and tocopherol in walnuts samples from five producing areas of China were 14.61?20.52 g/100g,13.34?49.36 mg/g,5.53?27.79 mg/g and 31.29?53.84 g/100g,respectively.The Ca,K,Mg,and P contents in walnuts samples from five producing areas of China were 656.52?1608.90 mg/kg,2781.63?3775.31 mg/kg,1381.78?1733.36 mg/kg,3406.28?3610.60 mg/kg,respectively.The mean concentrations of Pb,As,Cd,and Cd in walnut from different producing areas were 19.11?0.031?g/kg,5.06?36.34?g/kg,262.54?450.30?g/kg,3.44?4.45?g/kg,respectively.According to the health risks assessment models recommended by the Unites States Environmental Protection Agency?USEPA?,the total hazard quotients??THQs?of four heavy metals for adults were ranaged 9.88?31.60%and for children were ranged 23.72?75.84%,respectively,which were not more than 100%.The?¹³C,?¹⁵N,?²H,and?¹⁸O values of the walnut from five producing areas were from-24.34?-23.25‰?0.11?5.66‰?-98.42?-62.30‰,and 14.70?28.81‰,respectively.Based on the differences of nutritional composition and stable isotope,different chemometrics methods were used to trace the geographical origin of walnut samples from five producing areas of China.The results showed that the identification accuracy of the traceability model based on different nutritional compositions combinations and different stable isotope combinations were 80?97.5%and 17.5?84.6%respectively,which indicated that the nutritional compositions have the better traceability than stable isotopse for walnuts samples from five producing areas.When the origin traceability model of walnuts samples was established based on stable isotope,the discrimination correct rate of linear discriminant analysis?LDA??17.5?84.6%?was higher than that of neural network?15.4%?82.5%?.However,the discrimination correct rate of the neural network method?80?97.5%?was higher than that of the LDA method?67.5?97.5%?when establishing the origin traceability model based on the nutritional compositions.In a word,the neural network method combined with nutritional components is suitable for the establishment of walnuts geographical origin traceability.