Desorption-adsorption isotherms and thermodynamic characteristics of dried fish fillets by combined drying of freeze-heat vacuum pump
LUO Jing, LI Min, GUAN Zhiqiang, ZHANG Ying, LIU Yan
1.College of Food Science and Technology, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Ocean University, Zhanjiang 524088, China; 2.College of Mechanical and Power Engineering, Guangdong Ocean University, Zhanjiang 524088, China
Abstract: In order to explore the quality and later storage stability of tilapia fillets that were dried by pretreatment of ultrasonic assisted polydextrose permeation combined with vacuum freeze-heat pump combined drying, the desorption-adsorption isothermal data of vacuum freeze-heat pump combined drying tilapia fillets were obtain by a static method at 25, 35, and 45 ℃, with the water activity (aw) between 0.111 6-0.843 4. The results of desorption-adsorption isotherms were fitted by 8 common mathematical models, in which the optimal model was used to describe the desorption-sorption isotherms of dried tilapia fillets determined by comparing the coefficient of determination of the models (R2) and root mean square error. The thermodynamic properties of dried tilapia fillets were investigated by the desorption-adsorption isotherm data of dried tilapia fillets at different temperatures. The results showed that the desorption-sorption isotherm of dried tilapia fillets belonged to type Ⅲ, the Peleg is the best model to describe the desorption-adsorption isotherm of tilapia fillets of heat pump combined drying. Meanwhile, there was 16.30% of absolute safe moisture of dried tilapia fillets at 25 ℃, 13.68% of absolute safe moisture at 35 ℃ and 13.64% of absolute safe moisture at 45 ℃, with the relative safe moisture of 22.89% at 25, 19.21% at 35 ℃, and 19.77% at 45 ℃. The net adsorption heat and the differential entropy of dried tilapia fillets were shown to be decreased exponentially with the increase in the equilibrium moisture. The desorption-adsorption processes were driven by the non-spontaneous enthalpy. The findings indicated that the desorption-adsorption isotherm and thermodynamic properties of dried tilapia fillets were affected by different storage temperatures and water activity, which can provide the theoretical basis for the process optimization and storage setting of tilapia fillets drying.
罗静, 李敏, 关志强, 张莹, 刘岩. 基于真空冷冻-热泵联合干制鱼片的解吸-吸附等温线及热力学特性[J]. 大连海洋大学学报, 2021, 36(6): 1050-1058.
LUO Jing, LI Min, GUAN Zhiqiang, ZHANG Ying, LIU Yan. Desorption-adsorption isotherms and thermodynamic characteristics of dried fish fillets by combined drying of freeze-heat vacuum pump. Journal of Dalian Ocean University, 2021, 36(6): 1050-1058.
2021, Vol. 36 
