芒果片真空预处理联合超声辅助渗透脱水的传质动力学及品质分析

Mass Transfer Kinetics and Quality Analysis of Mango under Vacuum Pretreated and Ultrasound Assisted Osmotic Dehydration

摘要:

为解决芒果果脯生产过程中传质效率低、加工时间长的问题，该文研究了脉冲真空预处理联合超声辅助渗透脱水对芒果传质动力学、质量特性和微观结构的影响。结果表明：脉冲真空预处理联合超声辅助渗透脱水组的芒果失水率（54.43%）最高，较常规渗透脱水、脉冲真空预处理渗透脱水、超声辅助渗透脱水组分别高45.85%、14.06%、29.38%，增固率（12.81%）较常规渗透脱水、超声辅助渗透脱水、脉冲真空预处理渗透脱水组分别高90.03%、53.43%、32.06%。用Azuara模型拟合渗透脱水过程中失水率和增固率的变化，高回归系数（R2>0.97）和低RMSE表明Azuara模型可以较好拟合芒果渗透脱水过程，预测脉冲真空预处理联合超声辅助渗透脱水组的平衡脱水率、增固率最高，分别为65.06%和23.35%。测定色泽和质构，发现超声辅助渗透脱水组、脉冲真空预处理联合超声辅助渗透脱水组芒果硬度值显著低于常规渗透脱水组和脉冲真空预处理渗透脱水组（p<0.05），而芒果色泽得到了较好保护。通过扫描电镜的观察，发现超声处理使芒果细胞壁塌陷与变形、细胞横截面积变小、微孔增多。此外，真空对芒果硬度和微观结构的影响均较小。综上，脉冲真空预处理联合超声辅助渗透脱水通过改变芒果细胞结构、增加传质微通道，提高了渗透脱水的效率，缩短加工时间，可以较好保护芒果色泽，但会导致硬度的下降。

Abstract:

To improve mass transfer efficiency and reduce production duration, the effects of the pulsed vacuum pretreated and ultrasound assisted osmotic dehydration (VUOD) on the mass transfer kinetics, quality and microstructure of mangoes were investigated. In terms of mass transfer efficiency, the results showed that the water loss (54.43%) of the VUOD samples was the highest, which was 45.85%, 14.06%, 29.38% higher than that in the traditional osmotic dehydration (OD), ultrasound assisted osmotic dehydration (UOD) and pulsed vacuum pretreated osmotic dehydration (VOD) samples, respectively, and the solid gain (12.81%) of the VUOD samples was 90.03%, 53.43% and 32.06% higher than that in the OD, UOD and VOD groups, respectively. The high regression coefficient (R2>0.9) and low RMSE value represented the suitability of Azuara model for describing WL and SG of osmo dehydrated mangoes. The model predicted that the equilibrium value of WL and SG of VUOD were the highest, which were 65.06% and 23.35% respectively. The hardness of the mangoes in the UOD and VUOD groups were significantly lower than those in the OD and VOD groups (p<0.05), while the color of mangoes was well protected. The results of scanning electron microscope (SEM) showed that ultrasound treatment caused a significant collapse in cell wall, the decrease in cross-sectional area and the formation of the microscopic pores. Meanwhile, vacuum pretreatment had little effect on the hardness, color and microstructure of mangoes. Overall, VUOD improved the efficiency of osmotic dehydration by changing the cell structure, increasing the mass transfer microchannels which can better protect the color of mangoes but result in a decrease in hardness.