摘要
采用基于环境相对湿度可控的微波干燥系统,探究相对湿度对山楂微波干燥过程的影响。在物料干燥温度60℃的条件下,研究恒定湿度(相对湿度5%、30%、50%、70%)和阶段变湿[CRP(恒速阶段)、FRP(降速阶段)分别保持相对湿度5%、30%、50%]共10种方案下山楂的干燥特性;利用Weibull函数进行干燥动力学分析并计算有效水分扩散系数(Deff);基于复水性、色差、VC含量和感官品质,评估不同干燥条件下干制品品质。结果表明:恒定湿度条件及阶段变湿条件下,干燥时间均随相对湿度的下降而缩短,其中,相对湿度5%条件下干燥时间比相对湿度70%条件下缩短了51.62%;FRP阶段降湿可显著缩短干燥时间。Weibull函数可很好地拟合山楂干燥过程,Deff随相对湿度的下降而增大,验证了降低相对湿度可增强干燥过程中水分扩散速率,其中FRP阶段降湿对水分有效扩散系数的提升更为明显。恒定相对湿度30%和阶段变湿(恒速阶段相对湿度50%、降速阶段相对湿度30%)条件下干制品色差、VC含量和感官品质较好。
Microwave drying system based on controllable relative humidity was adopted to investigate the effect of environmental relative humidity on the microwave drying process of hawthorn.Under the condition of material drying temperature of 60℃,the drying characteristics of hawthorn were studied under 10 schemes including constant humidity(relative humidity of 5%,30%,50%and 70%)and phase humidification relative humidity of 5%,30%and 50%.The phase humidification was divided into constant rate period(CRP)and falling rate period(FRP).Weibull function was used to fit the drying curve and calculate moisture diffusion coefficient(Deff).The quality of dried products under different drying conditions was evaluated based on rehydration,color difference,VC content and sensory scores.The results showed that the drying time was shortened with the decrease of relative humidity under constant humidity and phase humidification,and the drying time was shortened by 51.62%under the condition of 5%relative humidity compared with that under the condition of 70%relative humidity.Dehumidification at FRP stage could significantly shorten the drying time.Weibull model could fit the drying curves of hawthorn under different conditions accurately.Deff increased with the decrease of relative humidity,which verified that reducing relative humidity could enhance the water diffusion rate in the drying process.Dehumidification at FRP stage has a more obvious improvement on the Deff.The color difference,VC content and sensory scores of dried products were better under the conditions of constant relative humidity of 30%and phase humidification(relative humidity of 50%at CRP stage,relative humidity of 30$at FRP stage).
作者
刘明宝
李静
何方健
裴永胜
李臻峰
LIU Ming-bao;LI Jing;HE Fang-jian;PEI Yong-sheng;LI Zhen-feng(School of Mechanical Engineering,Jiangnan University,Wuxi 214122,China;Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology,Wuxi 214122,China)
出处
《江苏农业学报》
CSCD
北大核心
2020年第2期487-493,共7页
Jiangsu Journal of Agricultural Sciences
基金
国家青年自然科学基金项目(21606109)。
关键词
山楂
微波干燥
相对湿度
干燥速率
品质
hawthorn
microwave drying
relative humidity
drying rate
quality
