| In order to study the flavor substances of the characteristic foods of Wuling area and further promote the development of local characteristic food industry,the flavor substances of four characteristic foods was studies in this paper,which including Enshi Tujia Smoked Preserved Pork,Htuynia Cordata,Gongshuibai Pomelo and Badong Ponkan.Four kinds of food flavor substances are comprehensively studied by flavor group methods,such as Odor Activity Value(OAV)analysis,Principal Component Analysis(PCA),and Hierarchical Cluster Analysis(HCA).The main contents of the study were divided into the following four aspects:1.Study on volatile substances of Enshi Tujia Smoked Bacon(ETSB)The volatile substances of ETSB were extracted simultaneously by soxhlet extraction method(SE),steam distillation(SD),simultaneous distillation extraction(SDE)and headspace solid phase microextraction(HS-SPME).Qualitative and quantitative analysis of flavor substances was carried out by gas chromatography-mass spectrometry(GC-MS),and the flavor substances were systematically analyzed by the analysis method of flavor group.The results showed that there were 155 volatile components,including hydrocarbons,alcohols,phenols,aldehydes,ketones,acids,esters,ethers,and other compounds(sulfur,nitrogen,and heterocyclic compounds).The flavor substances were extracted from smoked bacon by four methods.There were 84,56,83 and 64 volatile components were extracted by the four methods.The highest concentration of phenol was 42016.73 ng/g and extracted by HS-SPME.It was found that there were 62 volatile compounds contributed to or modified the formation of ETSB flavor,and phenolic compounds were the compounds with the strongest contribution to ETSB flavor.The method,HS-SPME,was a more suitable extraction method for extracting volatile flavor compounds in bacon.2.Study on volatile substances in different parts of Houttuynia cordataThe differences and characteristics of flavoured substances in different parts(root,leaf and flower ear)of Houttuynia Cordata were studied.HS-SPME combined with GC-MS technique was used to extract volatile substances,and qualitative and quantitative studies were carried out.At the same time,the flavor substances were analyzed by the method of flavor omics.Finally,the formation mechanism of some volatile substances was discussed.The results showed that there were 114 kinds of volatile substances were detected from three different tissue parts of H.Cordata,and there were 70,64 and 63 kinds of volatile substances were detected in the roots,leaves and flower ears,respectively.These volatile substances could be divided into alcohols,phenols,aldehydes,ketones,acids,esters,terpenes and other groups.Furthermore,there were 43 volatile substances with significant flavor.The highest relative content was 2-undecanone(12407.99 ng/g),while the highest OAV(4694)was found in lauraldehyde.It was found that there were significant differences in the types and contents of volatile substances in different tissue parts of Houttuynia Cordata,especially in different states of existence.According to the types of volatile substances and the ways of natural product formation and transformation,the formation process of some volatile substances in Houttuynia Cordata was preliminarily discussed.It was found that terpenoids could be transformed into2-undecanone in Houttuynia Cordata due to its unstable structure.3.Study on volatile substances of Gongshui white pomelo at different growth stagesBy studying the changes of volatile substances in different growth periods of Gongshui white pomelo,dynamic monitoring of the changes of volatile substances in Gongshui white pomelo was carried out.HS-SPME-GC-MS method was used to analyze the types and contents of volatile substances in Gongshuibai Pomelo at different growth stages,including flowering stage,early stage,middle stage and late stage.The results showed that there were 104 volatile substances detected during the four periods,which were divided into terpenes,alcohols,aldehydes,ketones and esters.And the terpenes were the most abundant.Among them,40 compounds own definite aroma,and linalool posses the highest OAV,which would reach to1575587.7 at flowering stage.During the four consecutive growth periods,the number of flavor compounds presented tendencies of increasing firstly,decreasing and final increasing.Most of the changes in the molecular structure of the same compounds,while the content of volatile substances showed an overall decrease.The flavor substances showed six aroma types,which were herb,floral,fruit,wood,chemical and spicy.At the flowering stage,all kinds of smells become obvious,especially floral,fruity,woody and chemical,and the outline of the smell at flowering stage were similar to that at early stage.The contents of volatile substances of pomelo in early and middle stages were similar to each other,while the content of volatile substances in flowering stage was significantly different from the other three stages.Most terpenes,alcohols and some aldehydes were the compounds with high correlation with grapefruit aroma.4.Study on volatile substances in the flesh of Badong Ponkan with different maturityThe changes of the flavor substances of pulp of Badong ponkan during the maturing process(pre-ripening,middle and late ripening)were investigated.The ponkan pulp flavor substances were qualitatively and quantitatively analyzed by using HS-SPME-GC-MS.The flavor compounds with flavor contribution were systematically studied by means of flavor omics analysis.The results showed that there were 45 kinds of volatile substances in the flesh of the three kinds of mature ponkan,including 9 kinds of terpenes,18 kinds of alcohols,6 kinds of aldehydes,7kinds of ketones and 5 kinds of other classes.According to the result,there were 20 types of compounds,including five terpenes,seven alcohols,six aldehydes and two ketones,contributed to the flavor of paraffin fruit,flower,sweet,herbal,chemical and woody flavors.In the early stage of maturity,ponkan showed strong flower-scented,fruity scented and sweet scented.During the maturing period,there were obvious fruit,flower,sweet,chemical and woody flavors in the flesh of ponkan,of which the content of various flavor substances reached to the maximum.And the highest content was alcohol substance,105259.13 ng/g,followed by terpene substance(78231.49 ng/g).In the late ripening stage,the pulp of ponkan presented mainly fruit fragrance,flower fragrance and sweet fragrance.The content of terpenes in ponkan fruit decreased significantly.As the ponkan matured,the smell of its flesh varied from weak to strong and finally weakened.As a result,the species and content of various species of ponkan were relatively unique in the maturing stage,while there was a high similarity between the early and late stages of ponkan.The content of various species basically decreased to the lowest value at the latter stage.This article takes four types of characteristic foods in the Wuling region as the research object,and explains the distribution and flavor characteristics of their volatile substances,which has a promoting effect on the development of the characteristic food industry in the Wuling region. |
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