| Peach gum,which is secreted from the bark of Prunus persica(L.)Batsch or Prunus davidiana(Carr.)Franch,is a rare agricultural and sideline product in orchard production.It has the functions of relieving pain,harmonizing blood and replenishing qi,and curing diabetes.At present,peach gum has been widely used in health food,but most of the literatures about peach gum are about the prevention and control of diseases and insect pests,improving tree resistance to reduce the secretion of peach gum,or about the structure and physiological activity mechanism of peach gum polysaccharide.The basic research of peach gum,including the determination of small molecular functional components and pesticide residues,is still relatively weak.In this paper,from these aspects of peach gum to carry out the corresponding research,in order to further tap the application value of peach gum,improve its utilization.Firstly,the chemical components of peach gum were characterized by HPLC-Q-TOF-MS/MS,and the data were analyzed by MS-DIAL software.Compounds were identified by analyzing retention time,mass precision,isotope ratio and MS/MS similarity matching with public database.Results a total of 32 active compounds were identified,including 3 catechols/phenolic acids,5catechins/anthocyanins,20 flavonoids,2 coumarins,1 pentacyclic triterpenoid acid and 1 amino acid like L-carnitine.The extraction conditions and the content of total flavonoids was analyzed by using the ultrasonic-assisted extraction technology.The results showed that the optimum extraction conditions were 70% ethanol,18:1(ml/g)solid-liquid ratio and 60 ? for 1.5 h.Under these conditions,the yield of total flavonoids was 9.35‰ ± 0.1‰.Secondly,this study analyzed the differences of total phenol content and antioxidant activity in the extracts of five different colors peach gum,and the quantitative methods of 18 phenolic components were determined by HPLC-MS/MS.The results showed that the total phenol content and antioxidant activity of variously colored peach gum extracts were significantly different.The deeper the color was,the more the total phenol content and the stronger the antioxidant activity was.The total phenol content in the darkest color group(S5)was 28.23 ?mol/g,which was 7.8 times of the lightest color sample group.18 phenolics were quantitatively analyzed by LC-MS,and the content of hesperetin,naringenin,epicatechin and eriodictyol were the most abundant.Correlation analysis showed that14 of the 18 phenolic compounds had significant positive correlation with total phenols and antioxidant activity.Finally,a method for the simultaneous determination of 43 pesticide residues in173 peach gum samples by HPLC-MS/MS.At the same time,the risk assessment of pesticide residues in peach gum was carried out.The results showed that the linear relationship was good in certain concentration,the correlation coefficient was0.9907-0.9991.The LOD(S/N=3)and the LOQ(S/N=10)were between 0.05?1.80?g/kg and 0.2?2.42 ?g/kg,respectively.Recoveries at two spiked levels of 10 ?g/kg and 100 ?g/kg ranged from 61.77%?119.48% with the RSDs 0.32%?15.75%.It showed the method can be used for the determination of pesticide residues in peach gum.Among 173 peach gum samples,98.8% were detected pesticides,22 out of 44 pesticides were detected,with an average of 2.80 pesticides detected in each sample,and a maximum of 9 pesticides were detected in the same sample.Among the 173 samples,difenoconazole was detected in 95%,chlorpyrifos in 54%,carbendazim in34%,furfuramide in 32% and pyraclostrobin in 19% of 173 samples,which indicated that difenoconazole and chlorpyrifos were widely used in peach trees.According to the risk analysis of chronic dietary intake and the risk ranking of pesticides,the pesticide residues in peach gum were at a low risk level. |
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