Changes Of Peanuts Chemical Component Under Different Packing Materials And Storage Condition

Peanut is an important oil crop and economic crop in China,and it is also one of the important export agricultural products.The fat content of peanut is as high as 46%~57%.Stored improperly,peanut may get rancid easily,which affects the taste and results in the deterioration of sensory and physicochemical indexes of peanut quality.Therefore,to increase economic benefits and prolong the storage and preservation period of peanuts,it is of great importance to screen the best preservation conditions and suitable packaging materials through experiments.In this study,peanut kernel was stored at three different conditions: room temperature(7-25℃),light(18-22℃),constant temperature and humidity(temperature setting 39℃,and humidity 91%RH-93%RH).Firstly,the peanut kernel was roasted and fried.Then saved in vacuum,the peanut kernel was packaged in three kinds of materials: aluminum foil bag(polyethylene / polypropylene / aluminum foil),composite bag(polyethylene / nylon / polypropylene)and poly vinylidene chloride(polyvinylidene chloride bag).During the period of storage,samples were extracted regularly to detect the acid value,peroxide value,carbonyl value,TBA value and water activity.These five indexes of the samples were analyzed.By the same time,the sensory evaluation was applied.According to the experimental data,the following conclusions are drawn:(1)Light can result in remarkable increase in acid value,peroxide value,carbonyl value and TBA value.Therefore,the light has obvious effect on promoting the preservation process of peanut kernel rancidity.As a result,in the process of preservation of peanuts,light should be avoided as much as possible.(2)Temperature has a significant effect on the hydrolytic rancidity and oxidative rancidity of fatty acids in peanut seeds.Combined with actual situations,peanut kernels can be stored at a low temperature.(3)During the storage period,peanut acid value,peroxide value,TBA value and carbonyl value have increased by different levels.Peroxide value,carbonyl value and TBA increased faster while acid value slower.(4)During the storage period,hydrolytic rancidity and oxidative rancidity occur simultaneously.While the effect of oxidative rancidity on the quality of peanuts is much greater than that of hydrolytic rancidity,oxidative rancidity works as the main rancid control type.(5)Under the same storage conditions,the effect of different packaging materials on the acid value,peroxide value and sensory quality of peanuts is very significant.The product standards of PVDC bags,aluminum foil bags and composite bags vary greatly.Among them,the PVDC bags and aluminum foil bags have excellent oxygen,moisture and light barriers,and the difference between the two bags differs not very much.But due to the high cost of aluminum foil bags and the lack of intuitive sales,PVDC bags are more marketable.