Effects Of Different Storage Methods Of Fengdan’ Seeds On The Components And Contents Of Volatiles In Seed Oil

With the progress of time,people’s requirements for food safety,nutrition and health are increasing,and the demand for high-quality oils and fats is also increasing.Peony seed oil for oil has high nutritional value and has great benefits to human health.Research on the quality of edible vegetable oil has became one of the current research hotspots.As an important part of oil flavor,volatile matter is an important indicator for evaluating oil quality and plays a key role in the sensory evaluation of oil.In order to explore the variation law of volatiles in’Fengdan’ grains under different storage conditions,find out the best conditions for ’Fengdan’grain storage,and provide reference for postharvest storage and processing of oil-use’Fengdan’ grains.In this study,the oil peony ’Fengdan’ grains were used as materials,and the Fengdan grains were stored post-harvest in four storage methods: room temperature bulk,room temperature vacuum packaging,4 ?C refrigerated bulk,and-20 ?C frozen bulk,For 180 days,during the storage period of ’Fengdan’ grains,the volatiles of the extracted seed oil and the activities of key metabolic enzymes of ’Fengdan’ grain volatiles were measured every 30 days,and the effects of different storage methods were compared to determine the suitable postharvest Fengdan grains storage environment.The main research contents and results are as follows:(1)The extraction conditions of volatiles from ’Fengdan’ seed oil were optimized by solid-phase microextraction(SPME)combined with gas chromatography-mass spectrometry(GC-MS).The total peak area of the detected volatiles was used as an indicator.The optimal extraction conditions for SPME were obtained as follows: the sample amount was 4.0 g,the equilibration time was 40 min,the extraction time was 20 min,and the extraction temperature was 80 ℃.(2)89,68,75,and 71 volatiles were detected in the seed oil of ’Fengdan’ grains stored at room temperature,vacuum,4 ℃ and-20 ℃,respectively,mainly esters and alcohols,alkanes,aldehydes,olefins,ketones,acids,phenols,amines and heterocyclic substances.During the storage process,the relative contents of alkanes,esters and heterocyclic substances account for a relatively high proportion,the relative contents of acids and amines fluctuate greatly,while the relative contents of aldehydes,alcohols,phenols,olefins and ketones Relatively low content.Preliminary thought that 2,3-dihydrothiophene,valeric acid,acetic acid,propionic acid,dimethylaniline,benzaldehyde,trimethylcyclohexanone,5-glutaraldehyde-2-one,cyclodecanone,1-(2-Hydroxyphenyl)ethanone was the main contributor to the flavor deterioration of ’Fengdan’ grains during storage.The key flavor compounds shared by the four treatments of room temperature,vacuum,4 ℃ and-20 ℃ in different storage periods were phenylethyl alcohol,methyl benzoate,ethyl benzoate,styrene,benzaldehyde;2-pentyl Furan and nonanal are the unique key flavor substances under room temperature storage conditions;acetophenone is the unique key flavor substances under-20 ℃ storage conditions.The grain storage effect of ‘Fengdan’ was as follows:-20 ℃>4 ℃>vacuum>room temperature.(3)Low temperature can effectively inhibit the activities of key enzymes in metabolic pathways such as esters,alcohols,and aldehydes.Under different storage conditions,the activities of grain alcohol acyltransferase(AAT),alcohol dehydrogenase(ADH)and hydroperoxide lyase(HPL)in ‘Fengdan’ showed a fluctuating trend as a whole.There was a significant correlation between the volatiles and key metabolic enzymes of seed oil extracted from different storage treatments of ’Fengdan’ grains.Among them,AAT activity was positively correlated with esters and negatively correlated with alcohols under room temperature storage treatment,and HPL activity was negatively correlated with alcohols and aldehydes;AAT activity was positively correlated with esters under 4 ℃ storage treatment;-20 ℃ AAT and ADH activities were positively correlated with aldehydes under storage treatment,and HPL activities were positively correlated with alcohols and aldehydes.To sum up,the volatiles of the seed oil extracted from the seeds of ‘Fengdan’ during storage were different under different storage conditions,which were mainly affected by the temperature and oxygen content of the storage environment,as well as the combined effect of the two.By comparing the differences between the four storage methods,the grains of‘Fengdan’ should not be stored for more than 120 d at room temperature and in a vacuum environment,should not be stored for more than 150 d at 4 ℃,and should not exceed 180 d at-20 ℃.Low temperature can effectively inhibit the activities of key enzymes in metabolic pathways such as esters,alcohols,and aldehydes.There was a significant correlation between the volatiles and key metabolic enzymes of seed oil extracted from different storage treatments of ’Fengdan’ grains.In order to reduce the quality decline of ’Fengdan’ grains during storage,in production,Fengdan grains can be air-dried and then stored in frozen storage to avoid losses caused by deterioration of oil or finished oil.