Research On Key Flavor Substances Of Flavor Rapeseed Oil

China is a large consumer of edible vegetable oil.Common edible vegetable oils are peanut oil,rapeseed oil,soybean oil,corn oil and so on.Rapeseed oil has a unique flavor,high unsaturated fatty acid content and rich nutritional value.The aroma of flavor rapeseed oil is thick and rich and smooth in the mouth,which is liked by consumers in Yunnan,Guizhou,Hunan,Hubei and other places.At present,it has occupied one-third of the rapeseed oil market and become one of the leading products of rapeseed oil.There are obvious differences in the flavors of flavor rapeseed oil from different origins.In this paper,we collected different rapeseed from several major production areas(Hunan,Hubei,Anhui,Sichuan,Guizhou and Inner Mongolia).And we also analyzed the key flavor substances and their contents of flavor rapeseed oil from the major production areas by using GC-MS.What’s more,we do some research on the flavor quality and flavor substances of these three kinds of process:traditional process,supercritical CO2 extraction process and enzymatic process.A preliminary investigation was conducted to provide reference for controlling the quality and improving the stability of the product of flavor rapeseed oil,which is mainly as following:Firstly,the quality indexes such as transparency,odor,taste,color,acid value,peroxide value,and benzo(a)pyrene were examined in the samples of flavor rapeseed oil prepared from rapeseed raw materials of different origins.The results showed that the erucic acid content of the flavor rapeseed oil prepared from rapeseed oil of Inner Mongolia origin was<3%,while the rest were high erucic acid samples,among which the erucic acid content of the flavor rapeseed oil prepared from rapeseed of Guizhou origin and rapeseed of Sichuan origin was as high as 15.395%and 15.220%.Except for one group of samples with benzo(a)pyrene content slightly exceeding the group standard for flavor rapeseed oil,all the other indexes were in accordance with the national standard for edible vegetable oils and the group standard for flavor rapeseed oil.It indicates that the conditions for the preparation of flavor rapeseed oil by the traditional process are better,but the high temperature or the long time of frying the seeds may lead to the exceedance of benzo(a)pyrene standard.Secondly,by GC-MS analysis,the results of the study showed that the rapeseed of Guizhou and Sichuan origin had high erucic acid content,and their sulfur glycoside degradation products were more diverse and spicy;Hunan and Hubei had more heterocyclic compounds and showed roasted aroma.The flavor compounds of strongly flavored rapeseed oil can be divided into three categories:sulfoside degradation products,oxidized volatiles and heterocyclic compounds.Sulfoside degradation products are pungent;most of the h eterocyclic compounds are related to the Merad reaction and mainly present nutty,sweet,potato and roasted aroma;oxidized volatiles are mainly aldehyd es,olefins,alcohols,acids,esters,ethers,ketones and other compounds,of w hich aldehydes have a low threshold and high content,and are the main flavoring substances in oxidized volatiles,mainly present fatty and greasy aroma.The threshold values of olefins,alcohols,ketones and ethers are high and vary among rapeseed oils of different origins,and their overall relative active eity is between aldehydes and acids and esters.The flavor of rich canola oil is determined by both the threshold value of flavor compounds and the relative percentage content,and the flavor substances with relative activity valu es greater than 1 are its key flavor substances.The key flavor substances of canola oil are:allyl isothiocyanate,4-isothiocyanide-1-butene,phenylpropionitrile,2,4-pentadienenitrile,cyclopropylacetonitrile,3-butene isothiocyanate,2,5dimethylpyrazine,3-ethyl-2,5-dimethylpyrazine,2-ethyl-6-methylpyrazine,2-ethyl-5-methylpyrazine,hexanal,furfural,benzaldehyde,(E)-2-decenal,(E,E)-2,4decadienal,(E,Z)-2,6-nonadienal,(E)-2-nonenal,octanal,furfuraldehyde,etc.H owever,the flavor is the result of all the flavor-presenting substances mixed together,so the flavor characteristics need to be judged in combination with sensory analysis.Finally,the quality indexes such as transparency,odor,taste,color,acid value,peroxide value,fatty acid composition and benzo(a)pyrene of flavor rapeseed oil prepared by different processes were tested and analyzed,and the flavor intensity was comprehensively evaluated by GC-MS detection and analysis technique combined with sensory evaluation.The results showed that the quality index of flavor rapeseed oil prepared by different processes was not much different but the flavor similarity was high.Because of the high cost of supercritical CO2 extraction process,it is not suitable for industrial application,and the cost of enzymatic process is much lower than that of traditional process,but its flavor persistence and safety need to be further studied,and the persistence of flavor retention and production safety can be further investigated.In summary,this research investigated the flavor rapeseed oil prepared from rapeseed of different origins,determined the key flavor substances of the flavor rapeseed oil prepared from rapeseed of different origins,and distinguished the flavor intensity of flavor rapeseed oil prepared from rapeseed of different origins.The spicy flavor of rapeseeds from Guizhou and Sichuan,the roasted flavor of rapeseeds from Hunan and Hubei,and the spicy and roasted flavor of rapeseeds from Anhui and Inner Mongolia were followed.There are obvious differences in the flavor of rapeseed oil prepared from different origins,and appropriate Rapeseed seeds should be selected as raw materials for consumer’s taste preferences in different regions,which is important for the quality,stability and quality evaluation of flavor rapeseed oil products.