The Analysis Of Volatile Compounds And Nutrition Composition In Peanut Oil

As a traditional edible vegetable oil in China,peanut oil is fragrant,delicious and rich in some beneficial ingredients,such as oleic acid,linoleic acid and natural vitamin E.At present the main production technologies of peanut oil are hot press and cold press method.Different production process may lead to the difference of volatile components of peanut oil.There is no unified standard about the characteristic flavor compound so far.This paper mainly focuses on nutrient content,volatile compound and the change of volatiles in accelerated oxidation process of hot pressed peanut oil and cold pressed peanut oil.The main contents and results are as follows:1?The acid value,peroxide value and oxidation induction period of peanut oil samples were determined by titration method and Rancimat method.The results showed that the acid value ranged from 0.43 to 1.33 mg/g and most of them were less than 1mg/g;the peroxide value ranged from 0.85 to 7.54mmol/kg and most of them were less than 6mmol/kg;Oxidation induction period were mainly concentrated in 6h.The fatty acid composition and vitamin E content of peanut oil samples were detected by gas chromatography and liquid chromatography respectively.The content of monounsaturated fatty acid ranged from 39.56% to 47.33%,and the major component was oleic acid.The content of polyunsaturated fatty acid ranged from 32.50% to 39.48%,and linoleic acid occupied the largest proportion.The content of saturated fatty acid ranged from 18% to 21.3%,and palmitic acid,stearic acid and arachidic acid were the primary fatty acids.The content of trans fatty acid were very low,about 1%.Two kinds of vitamin E were detected in peanut oil samples,?-vitamin E and ?-vitamin E,the content of the former ranged from 15.6 to 21.8mg/100 g and the latter from 9.36 to 21.91mg/100 g.The content of total vitamin E ranged from 27.44 to 49.98mg/100 g,which was within the scope of the provisions of the codex alimentarius.There is no significant correlation ship between acid value,peroxide value,oxidation induction period and fatty acid component and vitamin E content of samples.2?The extraction conditions for solid phase microextraction were optimized by single factor experiment.Results show that the optimal conditions is balance for 20 min and extracting for 60 min in 80? water bath with DVB/CAR/PDMS fiber.Comparing the extracting efficiency of simultaneous distillation extraction and solid phase microextraction,solid phase micro extraction method has obvious advantage in terms of the quantity,type and flavor contribution of extracting volatile substances,and is more suitable for comprehensive evaluation.3?The volatile component of hot pressed peanut oil and cold pressed peanut oil were measured by GC-MS-O.Total 101 species of volatile substances were identified in hot pressed peanut oil,mainly including pyrazines,aldehydes,furans,alcohols and pyrroles,of which characteristic flavor compounds present green,fatty,nutty and baked.Total 64 species of volatile substances were identified in cold pressed peanut oil,mainly including aldehydes,alcohols,hydrocarbons,furans and ketones,of which characteristic flavor compounds present green and nutty.Hot pressed peanut oil have an advantage over cold pressed peanut oil in terms of the variety and contents of the volatility components.4?The acid value and peroxide value of hot pressed peanut oil and cold pressed peanut oil increased in the process of accelerated oxidation,in addition,the contents of SFA,MUFA and trans fatty acid also increased,while the content of PUFA decreased.The contents of aldehydes,alcohols,ketones and hydrocarbons both in hot pressed peanut oil and in cold pressed peanut oil were on the rise in the process of accelerated oxidation,but the contents of pyrazines and furans were on the decline.Variant trend of volatile components existing all the oxidation process of both two kinds of samples is identical,except hexanol.