The effects of Sucrose/NaCl/Time interactions on the osmotic dehydration of banana slices

Abstract The objective of this work was to study the mass transfer kinetics during the osmotic dehydration of banana slices in an osmotic solution prepared by combining sugar with salt. Two levels of sucrose concentration (50 and 60 °Bx), three levels of NaCl content (0, 5% and 10% w/v) and four time levels (90, 180, 270 and 360 min) were applied according to the full factorial technique. The experiments were carried out with three replications and the means analyzed using response surface methodology (RSM). The experimental data revealed that the water loss increased with increase in time, sucrose and salt contents. According to the data obtained the minimum and maximum water losses observed were 9.0% (at 50 °Bx, 0% salt and 90 min) and 46.5% (at 60 °Bx, 10% salt and 360 min), respectively. Furthermore, a small portion of salt was found to reduce the solids gain while the sugar content and time increased it. The effects of all the parameters were significant for water loss, while only those of sucrose content, time and the interaction of salt with sucrose were significant for solids gain. Based on Fick’s second law, the effective diffusivity of water in banana slices was evaluated in the range from 5.67×10-9 to 9.11×10-9 m 2/s for the solutions studied.摘要 本研究旨在探究香蕉片在糖盐复配渗透液中进行渗透脱水（osmotic dehydration）过程中的传质动力学（mass transfer kinetics）。本实验采用全因子实验设计（full factorial technique），设定了两个蔗糖浓度水平（50与60 °Bx）、三个NaCl含量水平（0、5%与10% w/v）以及四个处理时间水平（90、180、270与360 min）。所有实验均设置三次平行重复，并采用响应面法（response surface methodology, RSM）对实验均值进行统计分析。 实验数据表明，水分流失率随处理时间、蔗糖浓度及NaCl含量的升高而增大。根据所得实验结果，观测到的最小与最大水分流失率分别为9.0%（50 °Bx、0% NaCl、90 min条件下）与46.5%（60 °Bx、10% NaCl、360 min条件下）。 此外，少量NaCl的添加可降低固形物增益，而蔗糖浓度的升高与处理时间的延长则会提升固形物增益。各实验参数对水分流失率均具有显著影响，而仅蔗糖浓度、处理时间以及NaCl与蔗糖的交互作用对固形物增益存在显著影响。 基于菲克第二定律（Fick’s second law），本研究评估得出，在所研究的渗透液体系中，香蕉片内水分的有效扩散系数范围为5.67×10^-9 至9.11×10^-9 m²/s。