Study On Quality Evaluation Of Wushan Plum

In recent years,with the rapid development of Chongqing plum industry,as one of the characteristic agricultural products in Chongqing,Wushan plum was widely loved by people because of its sweet taste and tender meat.However,there was only a"word-of-mouth effect"on the quality of Wushan plum and lack of scientific quality evaluation at present.In this paper,55 Wushan plums were picked from the 5 planting areas of Wushan including Ganyuan and Quanfa village in Quchi township?Pingtai village in Daxi township?Shuimo village in Miaoyu town and Longwan village in Tonggu town,which were used as experiment material,and a total of 42 indicators were measured to determine the physical properties,nutritional function quality and safety,comprehensively evaluated the quality of Wushan plum from the aspects of color,falvor,nutrition,function and safety.The quality difference of Wushan plum under different altitude was analyzed,the comprehensive quality of Wushan plum was evaluated by CA and PCA.The results were as follows:1.In terms of color,the L*value of Wushan plum ranged from 37.68±4.02 to52.52±2.13,the a*value ranged from-9.33±1.12 to 4.74±0.91,the b*value ranged from 32.16±2.47 to 70.64±6.22,the hardness ranged from 8.58±1.14 to 59.66±4.22 N,the edible rate ranged from 94.14±2.17 to 98.12±0.44%,the browning degree ranged from 0.132±0.006 to 0.833±0.010.In terms of sugars,the content of total sugar ranged from 12.58±0.61 to 19.67±0.52 g/100 g,the content of reducing sugar ranged from5.36±0.34 to 10.80±0.08 g/100 g,the content of glucose,fructose and sucrose ranged from 2.69±0.06 to 7.71±0.23 g/100 g,from 0.89±0.17 to 1.19±0.40 g/100 g,and from3.23 to 10.95 g/100 g,respectively.In terms of acid substances,the content of total acid ranged from 0.37±0.00 to 0.92±0.19%,The contents of tartaric acid,malic acid,citric acid and succinic acid ranged from 1.23±0.06 to 5.64±0.16 mg/g,from 3.21±0.05 to20.17±0.87 mg/g,from 0.23±0.02 to 2.71±0.20 mg/g,from 0.27±0.01 to 0.79±0.01mg/g,respectively.The content of soluble solid ranged from 10.52±0.53 to 19.47±1.61%,and the solid-acid ratio and sugar-acid ratio ranged from 13.60 to 43.61 and 13.60 to43.61 respectively.In terms of nutrition and function,the water mass fraction ranged from 80.88±0.31 to 89.48±0.12%,the content of Vc ranged from 4.44±0.04 to7.44±0.43 mg/100 g,the content of V_B1 and V_B2 ranged from 0.005±0.002 to0.058±0.003 mg/100 g and 0.013±0.001 to 0.040±0.003 mg/100 g,respectively,the content of?-carotene ranged from 0.087±0.007 to 0.594±0.019 mg/100 g.The content of Ca ranged ranged from 125.34±4.11 to 286.56±26.22 mg/kg,the content of Fe ranged from 0.68±0.02 to 7.50±0.44 mg/kg,the content of Zn ranged from 0.09±0.00 to1.15±0.07 mg/kg,the content of Se ranged from 0.45±0.01 to 7.71±0.46?g/kg,the content of soluble protein ranged from 1.14±0.21 to 1.58±0.18 g/kg,the content of crude fiber ranged from 0.34±0.01 to 0.65±0.02%,the content of?-aminobutyric acid ranged from 17.82±2.82 to 32.98±4.31 mg/100 g.The contents of polyphenols and flavonoids ranged from 105.11±7.29 to 301.42±3.10 mg GAE/100 g and from18.69±0.74 to 111.89±4.79 mg RE/100 g,respectively.In terms of antioxidant capacity,DPPH radical scavenging rates ranged from 20.67±0.54 to 75.69±4.57?mol V_C/g,ABTS value ranged from 1.31±0.02 to 4.87±0.02?mol V_C/g,and FRAP value ranged from 0.93±0.02 to 2.43±0.08?mol V_C/g.Compared with other varieties of plum,Wushan plum contained higher levels of sugar substance,soluble solid,solid-acid ratio,sugar-acid ratio and lower levels of acid substance,showing better taste and flavor quality,and riched in nutritional and functional components,with better antioxidant capacity.The contents of 4 harmful elements(Hg,Cd,Pb and As)and 2 pesticide residue indexes(imidacloprid and cypermethrin)did not exceed the relevant standards,and the safety reached the standard.Among the 5 planting areas in wushan,plum from Ganyuan and Quanfa had higher level of flavor,nutrition and functional components than those from Pingtai,Shuimo and Longwan,and the quality of plum from the 2 areas was relatively better.2.Through correlation analysis,it was concluded that altitude had a very significant positive correlation with hardness,moisture and total acid(P<0.01),and had a very significant negative correlation with edible rate,soluble solids,solid-acid ratio,sugar-acid ratio,V_B1,V_B2,?-carotene,Ca,DPPH value and ABTS value(P<0.01),and was significantly positively correlated with?-aminobutyric acid and FRAP value(P<0.05),and was significantly negatively correlated with L*,a*and amber acid(P<0.05).The higher altitude,the lower soluble solids,solid-acid ratio,sugar-acid ratio and the higher the total acid content of Wushan plum,the taste,flavor and nutritional function of Wushan plum were relatively poor,indicating that altitude was one of the important factors affecting the quality of Wushan plum.3.CA clustered 55 Wushan plum samples into 3 categories.The first category clustered 13 plum samples had poor taste and quality,which could be used as raw materials for plum products processing;The second category clustered 16 plum samples were slightly inferior in flavor and taste,but riched in intrinsic nutritional complement;The third category clustered 26 plum samples had good flavor quality and nutritional function quality.The third category of plums were from Ganyuan and Quanfa,which indicated that the comprehensive quality of most plums in Ganyuan and Quanfa were better than that in Pingtai,Shuimo and Longwan.4.11 comprehensive evaluation indexes were extracted from PCA,and the cumulative variance contribution rate reached 76.880%.11 core indexes of solid acid ratio,sucrose,V_B1,tartaric acid,glucose,b*value,browning degree,succinic acid,Fe,Se and VC were selected to evaluate the comprehensive quality of Wushan plum.The results obtained from the principal component score were basically consistent with the clustering results.By establishing the scoring equation of Wushan plum comprehensive quality evaluation model,and comparing the comprehensive quality of Wushan plum in5 planting areas,the comprehensive quality of Wushan plum in 5 planting areas from high to low was:Ganyuan>Quanfa>Pingtai>Longwan>Shuimo,the comprehensive quality of Wushan plum in Quchi township was the best.The result was also consistent with the actual"word of mouth".5.According to the measurement results and the actual demand of Wushan County,,the comprehensive quality index and reference value of Wushan Quchi plum quality were formulated:soluble solid content?12%,total acid content?0.7%,solid-acid ratio?17,total sugar content?13 g/100 g,sugar-acid ratio?18.