Effects Of Raw Materials And Production Processes And Storage Conditions On Flavor And Comprehensive Quality Of Oils

Edible oil in China as one of the important daily necessities,consumption of the recent years has increased year by year,and aromatic rapeseed oil and aromatic peanut oil,and other aromatic oil,is welcome and loved by the majority of consumers,in recent years for the consumption is also increasing.The sensory and flavor of aromatic oils is affected by several factors,such as aromatic oil processing technology,oil storage conditions,quality and varieties of oilseeds.At present,there are many studies about aromatic oils,but most of them focus on the influence of the processing process on the volatile components of aromatic oil,while there are few studies on the influence of varieties of oilseeds on the volatile components and comprehensive quality of aromatic oils,and there are also few studies on the comprehensive quality of oils during storage and the use of volatile components of oils for identification and analysis.In this study,we firstly used common oilseed varieties(canola rapeseed,common rapeseed,high oleic peanut and common peanut)as raw materials to investigate the specific differences of oilseed varieties on the comprehensive quality and volatile components of aromatic rapeseed oil and aromatic peanut oil,then used chemometric methods to determine the influence of different oilseeds on the comprehensive quality and volatile components of aromatic oils;then the differences of volatile components between aromatic and refined oils were investigated,and the possibility of using volatile components identify and analyze refined oils mixed with aromatic oils was studied;eventually,the oxidative stability of aromatic and refined rapeseed oils and the influence of different temperatures and antioxidants during storage on the comprehensive quality and volatile components of aromatic and refined rapeseed oils were investigated.(1)Two oilseeds of four species(canola rapeseed,common rapeseed,common peanut,and high oleic peanut)were selected as raw materials to produce aromatic rapeseed oil and aromatic peanut oil under the same conditions,and the volatile components in the different oils were analyzed using two extraction methods,solvent-assisted evaporation(SAFE)and simultaneous distillation extraction(SDE),combined with a gas chromatography mass spectrometry device(GC-MS).The crude fat,crude protein and amino acid composition of the oil as well as the acid value,peroxide value,fatty acid composition,vitamin E,sterols and sensory evaluation of the oils were also analyzed,and eventually the key volatile components causing the differences between different oils were determined using chemometric methods with odor activity values.The results showed that the highest content of Canola rapeseed oil was phenolic substances,about three times higher than that of traditional rapeseed oil,while the highest content of traditional rapeseed oil was sulfur glycoside degradation products,about44 times higher than that of double-low rapeseed oil.18 key volatile components of the two types of aromatic rapeseed oils were identified using chemometrics combined with odor activity values,and the sulfur glycoside degradation compounds and aldehyde products,which caused the key differences between the two oils,were identified.These substances were found in higher levels in traditional rapeseed oil and combined with sensory analysis showed that these compounds had an important effect on the pungency and oiliness of the oil.The content of heterocyclic substances in common peanut oil was higher than that in high oleic peanut oil,with pyrazines and furans both about twice as high as in high oleic peanut oil.After further analysis of the volatile components using chemometric methods and odor activity values,19 key volatile components causing the flavor differences between common peanut oil and high oleic acid peanut oil were finally identified,of which pyrazines and aldehydes were the main substances causing the differences between the two peanut oils,combined with sensory evaluation showed that the entire flavor of common peanut oil was superior to that of high oleic acid peanut oil,and these substances caused the sensory differences between common peanut oil and high oleic peanut oil.In a comprehensive view,oilseed varieties have an important influence on sensory flavor,volatile components,nutritional composition and comprehensive indexes of oils and fats,while the sensory flavor of aromatic oils made from common peanut and common rapeseed is better.(2)The fatty acid composition and volatile components and sensory evaluation of adulterated aromatic rapeseed oil and adulterated aromatic peanut oil at different volume ratios(5%,10%,15%,20%,25%,30%,35%,45%,50%)were determined.It was found that sensory evaluation and fatty acid composition were not effective in the identification of adulterated aromatic oils and fats.The volatile components were extracted using a solvent-assisted evaporation device in combination with a gas chromatography-mass spectrometry device and analyzed by principal component analysis(PCA)for the adulterated aromatic rapeseed oil and aromatic peanut oil.The results showed that the volatile components of refined oil and aromatic oil were significantly different,and when more than 20% of refined oil was added to the aromatic oil,it would be significantly different from the original aromatic oil,and the change of volatile components of aromatic peanut oil was more obvious.The results of the partial least squares regression analysis showed good results in identifying adulterated rapeseed oil and adulterated peanut oil,and the results of the prediction model using volatile components showed that PLS could identify the proportion of refined rapeseed oil adulterated in concentrated rapeseed oil,and the prediction accuracy was 0.828 and 0.76 for adulterated rapeseed oil and adulterated peanut oil,respectively,and identified the key volatile components that caused the difference between adulterated and aromatic oils.In conclusion,the use of volatile components combined with chemometric analysis to identify the proportion of refined rapeseed oil and refined peanut oil added to adulterated aromatic rapeseed oil and adulterated aromatic peanut oil is good enough to meet the needs of identifying adulterated aromatic oils.(3)The oxidative stability of aromatic rapeseed oil and refined rapeseed oil was investigated by accelerated oxidation experiments using the schaal method.Further principal component analysis(PCA),orthogonal partial least squares(OPLS)and heat map clustering analysis were used to investigate the specific changes of volatile components of the rapeseed oils during accelerated oxidation and to identify the key volatile components during storage using chemometric methods.The oxidative stability of aromatic rapeseed oil and refined rapeseed oil was investigated by accelerated oxidation experiments using the Schaal method.Further principal component analysis(PCA),orthogonal partial least squares(OPLS)and heat map clustering analysis were used to investigate the specific changes of volatile components of the oils during accelerated oxidation and to identify the key volatile components during storage using chemometric methods.The predicted shelf-lives of blank concentrated rapeseed oil and concentrated rapeseed oil with antioxidants were 65 and 256 days,respectively,using the national standard limit for rapeseed oil(?5.0mmol/Kg)as the standard,while the corresponding predicted shelf-life of refined rapeseed oil were 52.6 and 254.2 days.During accelerated oxidation storage,the acid value of rapeseed oil did not change significantly and did not exceed the national standard;the loss rates of vitamin E in blank and TBHQ-added concentrated rapeseed oil were 9.9% and 35%,respectively,while the corresponding loss rates of vitamin E in refined rapeseed oil were 9.9% and 36%,respectively;the loss rates of sterols in blank and TBHQ-added concentrated rapeseed oil were 1.32% and 1.32%,respectively,during storage until the peroxide value exceeded the standard.The loss rates were 1.32% and0.93% for blank and TBHQ-added concentrated rapeseed oil,respectively,while the corresponding loss rates of vitamin E in refined rapeseed oil were 2.21% and 5.21%,respectively,with little change compared to the vitamin E sterol content.The volatile components were also analyzed by simultaneous distillation extraction combined with gas chromatography,and the total content of aldehydes and ketones in rapeseed oil increased with the increasing storage time and oxidation,while the degradation products of sulfur glycosides and phenolics in the aromatic rapeseed oil showed gradual loss with the increasing storage time.The addition of antioxidants could delays the production of aldehydes and ketones,but at the same time,tert-butyl-p-benzoquinone,a harmful substance,was produced.In addition,the addition of antioxidants had no significant effect on delaying the loss of sulfur glycoside degradation products and phenolics,and finally the key volatile components were determined using chemometric methods.In general,the volatile components of rapeseed oil changed dramatically with the degree of oxidation,and the addition of TBHQ also had an important effect on the entire volatile components of the oil,while there were some differences in the change patterns of volatile components between aromatic rapeseed oil and refined rapeseed oil.(4)The experiment of storage of aromatic rapeseed oil and refined rapeseed oil with the addition of TBHQ in a constant temperature oven,as well as the analysis and study of the trends of basic indexes,vitamin E,and volatile components under different temperature storage conditions were conducted.The results shows that temperature has a significant effect on the Comprehensive quality of aromatic rapeseed oil and refined rapeseed oil,blank and TBHQ added aromatic rapeseed oil and refined rapeseed oil stored at 45? and 25? for 112 days and 196 days,respectively,and the acid value of blank aromatic rapeseed oil and refined rapeseed oil stored at 15? for 196 days was exceeded,but the rise at 45? was significantly greater and the addition of TBHQ oil delayed the increase of acid value.Both the blank rapeseed oil and refined rapeseed oil stored at 45? for 112 days exceeded the national standard limit in 49 days;the peroxide value of both aromatic rapeseed oil and refined rapeseed oil stored at 25? for 196 days without the addition of antioxidants exceeded the national standard limit in 112 days;both rapeseed oil and refined rapeseed oil stored at 15? exceeded the national standard limit in 196 days,while both the 45? and 25? with the addition of TBHQ Both the concentrated rapeseed oil and refined rapeseed oil with TBHQ added at 45?and 25? did not exceed the limit of the national standard.The effect of different storage temperatures on the vitamin E content also differed.In the period of storage at 112 days,the loss rates of vitamin E for 45°C blank and TBHQ-added concentrated rapeseed oil,25°C blank and TBHQ-added concentrated rapeseed oil,and 15°C blank concentrated rapeseed oil were46.79%,32.89%,32.94%,21.8%,and 17.08%,respectively;The loss rates of refined rapeseed oil were 42.57%,34.89%,26.50%,20.59%,and 12.93%,respectively;after studying the volatile components of aromatic rapeseed oil and refined rapeseed oil,it was found that the content of aldehydes and quinones increased with storage time,and the degradation products of sulfur glycosides in aromatic rapeseed oil and phenolics in refined rapeseed oil both showed a decreasing trend.After principal component analysis,it was found that there was a significant difference between the blank aromatic rapeseed oil stored at 45? and 25? and the aromatic rapeseed oil with added antioxidants,and the difference gradually became larger as the storage time was extended,while the difference between the blank aromatic rapeseed oil stored at 45? and 25? and the refined rapeseed oil with added antioxidants was larger compared with the aromatic rapeseed oil,which indicated that the antioxidants in the refined rapeseed oil had a greater effect on the volatile components.Further OPLS analysis of volatile components showed that the changes of volatile components in aromatic rapeseed oil stored at 15°C were closer to aromatic rapeseed oil with antioxidant addition,while for refined rapeseed oil the changes of volatile components were better than those with antioxidant addition at 15°C,and the retention effect of volatile components at 15°C was closer or better than that of antioxidant addition,which indicated that the effect of temperature on volatile components is significantly greater.In general,the effect of temperature on the quality and volatile components of fats and oils is more obvious,and the effect of low-temperature storage on the retention of volatile components of rapeseed oils is better than that of adding antioxidants,and the low temperature can delay the oxidation of rapeseed oils and the rise of acid value and the loss of nutrients.