Effects Of Temperature In Combination With Controlled Atmosphere Storage On The Quality Of Hazelnuts

Hazelnuts,as a raw material which is widely used in various foods,is one kind of rich-nutritious nut.In this paper,the Corylus heterophylla Fisch.x Corylusacellana L'liaozhen 3'hazelnut was used to study the change of lipid quality of nut in different storage conditions and the effect of storage environment temperature and atmosphere composition on main lipid quality of hazelnut.It will provide theoretical basis to find out the suitable storage conditions for different target of storage and transportation.The main results were as followed:(1)The fat content of hazelnut was about 60.79 g·100g-1 which will be 57.06 g·100g-1 after baking.9 kinds of fatty acids,palmic acid,palmitic acid,pearl acid,stearic acid,oleic acid,linoleic acid,linolenic acid,arachidic acid and arachidonic acid were main composition in hazelnut fatty acid.The relative contents of saturated fatty acid was less than 8%,mainly for palmitic acid,whose relative content was about 5%,followed was stearic acid.The relative contents of unsaturated fatty acids was more than 92%,mainly for oleic acid,whose relative content is about 80%,followed was linoleic acid.The kinds of fatty acid of hazelnuts lipid were the same but the fatty acid content were different to some extent in different storage conditions during storage time.(2)The acid value,iodine value,peroxide value and saponification value were separately 0.21 mg·g-1,72.49 g·100g-1,0.41meq·kg-1 and 133 mg NaOH·g-1 in raw hazelnut oil while the acid value,iodine value,peroxide value and saponification value were separately 0.32 mg·g-1,iodine value is 64.62 g·100g-1,peroxide value is 0.63 meq·kg-1,and saponification value is 103mgNaOH·g-1 in cooked hazelnut oil.After baking,cooked hazelnut oil acid value and peroxide value were significantly higher than those of raw hazelnut,but the other two values were lower than those of raw hazelnuts.This shows that heat treatment can cause bad effects to hazelnut oil quality(3)With the extension of storage time,the hazelnut oil acid value and peroxide value were increased obviously,iodine value was declined,and the change of saponification value did not have a certain regularity.The acid value and peroxide value were the highest but the iodine value was the lowest storage in room temperature condition.Temperature in combining with low oxygen(5%O2)and nitrogen-controlled(100%N2)can effectively controlled the increasing of acid value and peroxide value and decreasing of iodine value.The effect of room temperature storage with low oxygen and nitrogen-controlled was the same with 10? storage and the effect of 10? storage with low oxygen and nitrogen-controlled was the same with 5 ? cold storage.The effect of nitrogen-controlled storage was better than that low oxygen storage.Low temperature,low oxygen and nitrogen-controlled treatment can effectively slow down the process of oil oxidation.It can also effectively restrain the increasing of acid value and peroxide valueand the decreasing of iodine value.(4)In keeping with the hazelnuts under the premise of good quality,room temperature storage is suitable for short-term storage,less than 6 months;10? storage with low oxygen can prolong the shelf life of the hazelnuts certainly;5 ? cold storage can realize anniversary of storage.