Storage And Transportation Characteristic Of Different Moisture Paddy Rice Dealt With Dynamic Temperature And Humidity

Safe storage and transportation of rice is very important because China is the major rice producer and consumer in the world.Through laboratory simulation of dynamic temperature and humidity conditions,the rice quality and moisture migration law of the dynamic storage and transportation conditions are studied.The objective of this paper is to provide reference for the construction of dynamic storage and transportation of rice.Through dynamic temperature and humidity simulation experiment,five moisture content paddy rice(14%,16%,18%,20%,and 22%)were stored and transported for three months respectively at low temperature(fluctuates around 10℃),middle temperature(fluctuates around 20℃)and high temperature(fluctuates around 30 ℃).During the storage and transportation,the changes of microbial growth,physical and chemical quality,cooking quality,regularity of moisture migration and volatile compounds were measured to clarify the influence of temperature and moisture content on paddy rice during storage and transportation.Aerobic plate count increased with prolonged time,the increasing trends of aerobic plate count in different temperatures and moisture content for paddy rice were different.Aerobic plate count increased with rising temperature.The mould number raised with prolonged storage and transportation time and the mould number increased significantly under middle and high temperature.The higher temperature was,the more obviously mould number increased;mould happened at lower levels when 14% and 16% moisture content paddy rice storage and transported at low,middle and high temperature.The mildew occurrence of 18%and higher moisture content paddy rice was significantly higher than 16% and 14% moisture content paddy rice during 15 days storage and transportation at middle and high temperatures.The fatty acid value and the initial moisture content were positively correlated(P<0.01),the higher initial moisture content was,the more obviously fatty acid value of paddy rice increases.The influence of temperature on fatty acid value was particularly apparent,the higher temperature was,the faster fatty acid value rises.Peak viscosity,through viscosity,final viscosity,breakdown,color a,color b,hardness and springiness of paddy rice rise with prolonged storage and transportation time.;Color L and adhesiveness decrease with prolonged storage and transportation time;Setback increases firstly and then decrease or become gently with prolonged storage and transportation time.Amylose content does not change significantly,only decreases at late stage when storaged and transported at high temperature.Peak viscosity,through viscosity,color a,color b and adhesiveness are effected significantly by initial moisture content(P< 0.05);final viscosity,color L,hardness and springiness are effected highly significantly by initial moisture content(P < 0.01);breakdown and setback are not effected significantly by initial moisture content.Peak viscosity,final viscosity,breakdown,setback,color a and hardness are highly significantly by temperature(P < 0.01);through viscosity and adhesiveness are effected significantly by temperature;color L,color a and springiness are not effected significantly by temperature.The low field nuclear magnetic total semaphore t(T2w)decreased with the increase of storage and transportation time,T2 w total semaphore and moisture content exhibited significant linear positive correlation(P < 0.01).As magnetic resonance imaging(MRI)exhibits,moisture mainly concentrates on epidermis and aleurone layer when paddy rice was stored and transported 15 days.After 30 days storage and transportation,surface moisture losses and the moisture distribution became more uniform.The electronic nose can have different response values for the volatile components of rice under different water contents and storage and transportation conditions,and paddy rice under different storage and transportation conditions can be distinguished.The electronic nose sensor have significant correlation with hydrocarbons and alcohols in volatile components,it can detect hydrocarbons and alcohols sensitively.During storage and transportation,many kinds of volatile components of rice are detect by GC-MS,and includes hydrocarbons,alcohols,aldehydes,etones,esters,and hetercyclics.According to the results of GC-MS test,170,180 and 181 kinds of volatile components were detected in Rice under the condition of low,medium and high temperature dynamic storage and transportation condition.The content of ketones increases gradually during rice storage and transportation.At the same time,the content of hydrocarbons decreases.If the content of 1,2-epoxyoctadecane,2,6,10,14-hexadecanetriol,chlorooctadecane,2,6,10,14-tetramethylpentadecane,2-undecane,2-tridecanone increased,the quality of rice probably decreased.The short storage time(15 or 30 days)and transportation of relative high moisture(14%or 16%)paddy rice can improve rice main the texture’s quality.The initial moisture content of paddy rice should be controlled under 16% during a long time transportation with dynamicvariation of the temperature and humidity(around low and middle temperature).