Correlation Analysis Of Nutrition And Sensory Quality Of Walnut And Its Storage

This study focused on determine nutritional qualities and sensory qualities of 28 main walnut cultivars in China,which further revealed composition differences of walnuts and its internal correlations.The cultivars with high composition differences were chosen for storage experiments to investigate dynamic changes of walnut qualities at different temperature.The findings were as follows:(1)The nutritional qualities of 28 walnut cultivars were significantly different(p < 0.05).The significant differences of total polyphenol,total flavanoids,Ni?Co?Ba and ?-tocopherols were up to 66%,65%,51%,42%,40% and 40%,respectively.Moreover,there were significant differences among cultivars in total flavonoids,total polyphenols and Co in same producing areas of walnuts,while significant differences among regions were found for total flavonoids,total polyphenols,oleic acid,Mn,Ba,Co and Ni in the same cultivars.(2)The study of sensory qualities(kernel color and volatiles)showed that gray values of28 walnut cultivars were between 61.99-115.46 and the cultivar with deep color(61.99,the minimum gray value)of walnut kernel was “Xinxin 2”,while light color cultivar(115.46,the maximum gray value)was “Xilin 3”.Methane,sulfides,organic sulfides,nitrogen oxides and ethanol were abundant odorant components in walnut kernels according to the analysis of electronic nose.The response values of M6,M7,M9,M2 and M8 were 5.71-12.23,3.54-7.25,3.59-7.05,1.91-4.61 and 2.11-3.76,respectively.The result was submitted to cluster analysis that 28 walnut cultivars were classified into three groups.In every group,the representative cultivars for “Liao 1,Jinlong 1 and Liaoruifeng” were chosen to determine volatiles by headspace gas chromatography-mass spectrometry,indicating that D-limonene,?-pinene,styrene,p-xylene and nonanal were the most volatile substances in walnut.Styrene(content:9.06%-17.93%)was the most abundant terpenes in walnuts.Linear discriminant analysis(LDA)further achieved the accurate discrimination of walnut cultivars with total contribution rate of95.99%(LD1,91.35% and LD2,4.64%).(3)The correlation analysis showed that there were great internal relationships between walnut nutrition and sensory qualities.There were significant positive correlations between amino acids and some mineral elements(r > 0.501,p < 0.01),while some antioxidant components and saturated fatty acids were negatively correlated with most amino acids(-0.754? r ?-0.500,p < 0.01).The kernel color(R,G,B and gray value)was positively correlated with phenylalanine,methionine,Ba(r > 0.506,p < 0.01),and negatively correlated with Na(-0.522 ? r ?-0.501,p < 0.01).Some volatile substances in walnuts had positive correlations with nutritional qualities.The aromatic groups of volatile substances had a significant positive correlation with phenylalanine(r =1.000,p < 0.01),and aldehyde ketones have a significant positive correlation with Ti(r =1.000,p < 0.01).The correlation between walnut nutrition and sensory qualities can provide basic data for walnut breeding in the future and provide reference for creating characteristic walnut products.(4)According to the temperature gradient of-25?,5?,20?,50? for 180 days in storage,temperature change has great effect on total polyphenol,total flavanoids,the kernel color were significant high,ranged 0.07% to 27.34%.However,temperature change has little effect on?-tocopherol and the content of essential amino acids.Result showed that walnut was suitable for storage at low temperature(-25?).Cultivar ‘Liaoruifeng,Liao 1,Liao 4,Liao 7and Jizhuamian' had great advantage in storage.