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Establishment And Application Of A Quantitative Method For Pyrazine Components In Aromatic Oils And Fats Based On Multiple Headspace Solid-phase Microextraction

Posted on:2022-03-19Degree:MasterType:Thesis
Country:ChinaCandidate:Z Y XuFull Text:PDF
GTID:2511306602991499Subject:Food Science and Engineering
Abstract/Summary:PDF Full Text Request
Fragrant edible oils have attracted more and more attention because of its unique sensory properties.Sensory property is part of the important indexes affecting edible oil consumption.Pyrazines are one group of the most important flavor compounds in fragrant oils,which endow fragrant oils with roast and nutty.As one of the most common flavor analysis methods,head space-solid phase microextraction(HS-SPME)has many advantages,such as effortless operation and no solvent.At the same time,it has some limitations in the quantitation of volatiles.Therefore,this study took fragrant oils as materials and pyrazines as the target compounds,and established a reliable quantitative method by HS-SPME method:MHS-SPME-GC-MS.SPME-arrow fiber coating and HS-SPME conditions were selected by single factor optimization experiment.The optimal extraction conditions were as follows:PDMS/DVB/CAR was selected as SPME-arrow fiber coating,the pre-incubation temperature of 80℃,the extraction temperature of 50℃,the extraction time of 50 min,the vortex speed during the pre-incubation and extraction of 450 rpm,and the desorption time of 80 s.The extraction efficiency of HS-SPME and SAFE were compared,which proved 13 target pyrazines can be extracted by two methods well,and the response profiles were basically the same.The optimized HS-SPME was utilized to develop and verify the MHS-SPME-GC-MS.Under conditions of R~2>0.75 and 0.4<β<0.95,SPME-arrow fiber was selected as extraction device,and 50 mg was selected as the optimal sample amount to quantify 13 target pyrazines in fragrant oils by MHS-SPME.MHS-SPME combined with external standard and internal standard were verified,and the limit of detection,limit of quantitation,repeatability and recovery were investigated.The performances were as follows:the limits of detection of 13pyrazines were in the range of 3-60μg/kg and the limits of quantification were in the range of6-180μg/kg by using the full-scan/selected ion monitoring mode.The intra-day and intra-day RSD of MHS-SPME external standard and internal standard were all less than 20%,and the recoveries varied from 90%-115%.The repeatability and accuracy were good.The quantitative results of MHS-SPME and stable isotope dilution analysis(SIDA)were compared,and there was no significant difference between the two methods(P>0.05).The newly proposed MHS-SPME-GC-MS method was used to investigate changes of pyrazines in peanut oil during the process of high temperature roasting.The results showed that both the temperature and the time of roasting had effects on the formation of pyrazines.With the increase of roasting temperature,the concentration of pyrazines in peanut oil increased significantly,and 2-methylpyrazine and 2,5-dimethylpyrazine were firstly formed.With the increase of roasting temperature,the methyl-was gradually replaced by the ethyl-,cyclopenta-and isopropenyl-groups.The concentration and species of pyrazines in peanut oil increased significantly with the prolongation of roasting time.Isopropenylpyrazine was the most difficult of the 13 target pyrazines to form.Odor activity value was used to evaluate the contribution of pyrazine to the overall odor quality of peanut oil under different roasting conditions.The results showed that 2-methylpyrazine and 2,5-dimethylpyrazine,which had the highest concentration in roasted peanut oil,were not the right greatest contributor of pyrazines to the overall odor quality.With the condition of not lower than 165℃and not less than 15 min,the greatest contributors of pyrazines to the overall odor quality of peanut oil were 3,5-diethyl-2-methylpyrazine and 2-ethyl-3,5-dimethylpyrazine.2-ethyl-5-methylpyrazine and 2,6-diethylpyrazine also had an effect on roasted peanut oil.
Keywords/Search Tags:Fragrant edible oil, Volatile flavor compounds, Pyrazine, HS-SPME, MHS-SPME-GC-MS, Roasting process
PDF Full Text Request
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