Aroma Synergy And Mechanism Of September Red Navel Orange Based On Molecular Structure

Navel orange belongs to the genus citrus in Rutaceae,which is full in taste,rich in juice,bright in color,fresh and pleasant in aroma,and extremely high in nutritional value,and it is deeply loved by consumers.In this paper,at first,the aroma characteristics of September red navel orange(SRO)pulp(OPU)and peel(OPE)were deeply analyzed.On this basis,the interaction between key aroma compounds and fragrances in SRO was studied by using a variety of aroma interaction research methods combined with support vector machine(SVM).Furthermore,a synergistic analysis method for aroma of fruits was established,and the effects of molecular structural characteristics such as chain length,functional groups and substituent positions of volatile substances in fruits on aroma synergy were evaluated by this method.Firstly,the volatile components and aroma characteristics of OPU and OPE were investigated and compared by headspace solid phase microextraction with gas chromatography-mass spectrometry(HS-SPME-GC-MS),gas chromatography-olfactometry(HS-SPME-GC-O),aroma activity value(OAV)and quantitative descriptive analysis(QDA),combined with aroma recombination and omission experiments.The results showed that terpenes,alcohols and aldehydes were found as the major volatile compounds in SRO.Meanwhile,23 key aroma components were detected,with 15 of them present in both OPU and OPE,and the concentration of the 15 substances in OPE was 1-1700 times higher than in OPU.Among the six main fragrances identified in OPU and OPE,“fruity”,“green”,“floral”,and “woody” in OPE were significantly stronger than that in OPU(p<0.05).Finally,(E)-2-pentenal,ethyl butyrate,(E)-2-decenal,styrene,(Z)-3-hexen-1-ol,(Z)-2-hexen-1-ol,linalool,nerol,γ-terpinene and acetic acid were summarized as the key aroma compounds by aroma recombination and omission experiments.Secondly,the interaction between the key aroma substances or fragrances and fruit fragrances was compared with different methods.Meanwhile,the results were modeled and verified by SVM,and the synergetic research methods were selected for the characteristic aroma in fruits based on the model.The results showed that experimental results of S-curve,σ-τ diagram and U-model were more accurate for the fruit characteristic aroma interaction of binary and ternary systems.Therefore,in the aroma synergy study,Therefore,S-curve,σ-τdiagram and U model combined with SVM(polynomial kernel)were selected for experiments.Finally,the influence of molecular structural characteristics such as chain length,functional group and substituent position on aroma synergy was studied according to the optimized research method.It was found that OAV value had a significant effect on the interaction between aroma substances.In addition,among the several fruits studied,aroma substances with similar molecular structures were more likely to be synergistic,and the greater the difference in chain length of similar substances,the more significant the synergistic effect.Generally,alcohol and aldehyde were more likely to synergy,and the presence or absence of substituents and position changes had no significant effect on aroma synergy.The study on the synergistic effect of aroma substances with similar molecular structure will provide a further reference for the study of the mechanism of aroma interaction.