Research On Air Drying Technology And Quality Control Of Ginger(Zingiber Officinale R.)

Fresh ginger’s moisture content up to 90%,it prone to dehydration atrophy,fibrosis,chilling injury and other phenomena in the preservation process.Heretofore,fresh ginger loss-rate remains high.Drying process is an important means of ginger preservation.The traditional drying industry is energy-intensive,which not agree with the new concept of social and environmental protection development.Therefore,it is of great significance to study the energy-saving drying process of ginger.This study was carried out to investigate the effect factors of dehydration in hot air drying,which were drying temperature,slice thickness,loading capacity,the quality of ginger slices and drying energy consumption were taken as indicators.The optimal constant temperature drying process was obtained through the optimization experiment of three-factor and three-level response surface.LF-NMR technology was used to analyze the water migration rule of ginger slices in constant temperature drying.The main results were as follows:（1）The effects of drying temperature,slice thickness and loading capacity on the drying of ginger were studied by using electricity consumption,color,reconstruction and Gingerol content as indicators.The single factor test was further designed to optimize the constant temperature drying process of ginger,and the optimal drying process was obtained as follows:drying temperature is 66.41℃,slice thickness is 2 mm,loading capacity is 5 kg/m².According to the interactive analysis of response surface,the influence of three factors on energy consumption is as follows:loading capacity>slice thickness>drying temperature（p<0.01）.The drying temperature had a significant effect on Gingerol content（p<0.05）,while the slice thickness and loading capacity had no significant effects.（2）Water migration rule of ginger during the drying process:there are three peaks in the LF-NMR T₂ inversion spectrum of fresh ginger:T₂₁（0.1¹ ms）,T₂₂（1¹0 ms）and T₂₃（10¹,000 ms）,respectively representing the bound water,semi-bound water and free water in fresh gingers,among which free water occupies a large proportion.During the drying process,a large amount of free water was firstly removed,and the proportion of unflowing water and bound water increased.The temperature of ginger slices is the main factor that affects the drying rate.After the evaporation of water on the surface of ginger slices,water in the inner layer migrates outward,and the migration rate is less than the evaporation rate,resulting in excess heat energy.Therefore,the key to optimize the energy-saving drying process is to provide appropriate heat energy supply at different stages.（3）Based on the preliminary test,the conversion point of graded variable-temperature drying of ginger was determined,and the optimal variable-temperature drying process was determined by trial and exploration as follows:80℃（0-60 min）-70℃（60-240 min）-60℃（end）.Takingthe energy consumption and the color,reconstruction and Gingerol content of dried ginger slices as indicators.Compared with the constant temperature drying process,energy consumption of the variable temperature drying mode was reduced by 6.3%.And the dried ginger slices’quality were better than the former:the reconstruction rate was 5.84%,?E was 8.74,browning index was 57.33 and Gingerol content was 21.85 mg/g.