Research On The Humidity Adjustable Packaging Bag For Grains

Grain safety as a sector in the food safety system has drawn dramatic public attention; hence moisture control plays an important role in grain storage and transportation. When the grain moisture content and the relative humidity in haversack is too high, grain will get mildewed and deteriorated easily. But the grain moisture content is not the lower, the better. Too low moisture content will cause a large drop in grain weight, for which our country will bear an awful economic loss. That is why people make research on reasonable grain packaging.And storage about grain with high moisture content is meaningful.This research refers to four aspects. Firstly, the moisture absorption/desorption properties of representative crops-corns and peanut was studied, so that suitable materials as their moisture-proof packaging materials can be selected. Secondly, seven hygroscopic materials have been chosen from four kinds ot main hygroscopic products for studying their moisture absorption performance. Through comparatively analyzing the moisture absorption/desorption properties of peanuts and selected hygroscopic materials, super absorbent fiber was chosen as raw material to make haversacks. Thirdly, the composite nonwoven packaging material containing SAF fiber was made and its mechanical property was tested. Finally, this report analysed the bag’s moisture-proof performance and compared it with other2kinds of moisture-proof packaging materials.The grain moisture absorption/desorption properties contained, the study between grain moisture content and time when environment temperature and relative humidity was constant, the research on the relations between grain moisture content and RH(relative humidity),searching a suitable equation from several different models to descript the peanuts’ adsorption/desorption isothermal curves and finally the GAB equation was chose.When choosing the best hygroscopic materials, this subject mainly studied the moisture content variation of materials when the absorption rate and RH kept changing. Then the absorption rate and the absorption amount of7materials were analyzed. The report found that the high hygroscopic materials fast absorbed moisture, took a long time to reach moisture balance and can keep high moisture content. The report also compared hygroscopic material’s absorption properties with peanuts’. The hygroscopic material could always absorb more moisture than peanuts in the same environment, which meant hygroscopic materials can get a higher equilibrium moisture content when competing to absorb moisture with peanuts.Mixed the SAF fiber with meld-able fiber PLA and skeleton fiber Viscose, then carded the fiber into web formation and reinforced it into nonwoven materials by needle. The next step was to film mulch the nonwoven materials and sealed the materials’edge to get grain bags. Testing the bags’mechanical performance, then the results showed that this bag can pack5kg of grains.When the temperature and relative humidity was adjusted to RH95%with30℃, put2.5kg of peanuts with13%moisture content into the SAF bag,the jute nonwoven bag and the bag with a desiccant pocket. Then, a15-days’ simulation storage in a stability chamber was conducted. A hygrothermograph recorded15days’ data of RH and temperature. After15days, the moisture content changing of peanuts was tested. Finally, the results showed that nonwoven materials bag made of SAF fiber had a better moisture-proof performance. It reduced10%of RH and made the moisture content of peanuts dropped1.48%.