| Peanut is one of the most important economic and oil crops, its nutrition is equal to the eggs, milk, meat and other animal foods. China is the world’s largest peanut production and consumption, with the continuous expansion of peanut production, the demand for peanut in international trade has also increased. But the peanuts are easy to be rancidity and mildew during the storage time and thereby reducing the eating quality, which causes huge loss and bring great harm to the human body. So it has an extremely important significance for the shelf life of the peanut to detect the degree of oxidative rancidity of peanut timely and take effective measures to prevent the further oxidation. This article take the peanut that storage at room temperature as experiment samples, which divided them into no packaging, woven bags and two polyethylene film bags. Measured and analyzed their moisture content, water activity, acid value, peroxide value, conductivity, pests rate, the number of fungal colonies and other indicators and explore the feasibility of rapid non-destructive testing the peanuts’ storage characteristics based on near-infrared spectroscopy. Finally established their predictive models.The study results are as follows:(1) Different storage methods take an effective impact on peanuts’moisture content, water activity and acid value,In the three kinds of storage methods, the difference in no packaging and woven bag peanut is insignificant, but is significant between two-story film packing peanuts and the other two. At the end of the storage, the moisture content of two films peanut was1.14times of the other two, the water activity iwas1.11times of the other two, and the acid value was1.79times of the other two; From the peanut moisture content under different storage conditions, we know that the two-story film packaging can help to reduce the loss of moisture content, but it can effectively boost rancidity deterioration.(2) Different storage methods take an ineffective impact on peroxide value of peanut. The overall trend of peanut in three storage methods are rising with the storage period; the conductivity of two-story film peanuts is of great difference with the other two. At the end of the storage, the conductivity of two-story film is the highest, the woven bags is lower than the film bag and the no packaging is the lowest; the difference of pest rate is significant:no packing bags is the highest, woven bags is lower than the first one and the two-story film is the lowest. The number of fungal colonies of three kinds of packaging peanuts are roughly the same.(3) Use different kinds of the pretreatment methods to deal with the peanut near infrared spectroscopy, measured that by the in the whole spectral range, the optimized spectrum pretreatment method of peanut moisture was first-order derivative,9-point smoothing, R2and RMSECV were0.8786and0.424; he optimized spectrum pretreatment method of peanut water activity, peroxide value, conductivity were first derivative,5-point smoothing and their R2and RMSECV were0.8853and0.0238,0.9057and0.528,0.898and4.07; he optimized spectrum pretreatment method of peanut acid value was first derivative, MSC,9point smoothing, and its R2and RMSECV were0.9698and0.0659.The results show that using near infrared spectroscopy to calibrate storage peanuts’ acid value and peroxide value is accurate, and has a good effect on peanuts’moisture content, water activity, and conductivity, which means the NIRS technique can realize fast and nondestructive detection of the peanut storage characteristics. |
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