Abstract

In order to obtain nutritious, low calorie candied pumpkins, of superior quality, air drying kinetics of pretreated pumpkin slices were investigated using three different drying temperatures (40, 60 & 80 °C). Before drying, pumpkins were osmotically treated using different osmotic agents, namely sucrose, oligofructose and their mixture (1:1) in a solution of a constant concentration (70°Brix), at three temperature (75, 85 & 95 °C) for 150 min. Changes in texture (hardness and compression work) were determined during drying and sensory characteristics of the final products were evaluated by trained panelists. A first-order reaction kinetic model was used to predict the drying rate and hardness, in which the rate constant was a function of the process temperature. The results showed that as the drying temperature is increased, the drying constant also increases whereas the equilibrium moisture content of the dehydrated products decreases. The hardness of candied pumpkins was mostly affected by the air drying temperature regardless the osmotic dehydration conditions. Sensory evaluation of the final candied pumpkins, showed a preference for the products osmotically treated by oligofructose.

摘要

为了获得营养丰富、热量低、质量上乘的蜜饯南瓜，我们使用三种不同的干燥温度（40、60 和 80 °C）研究了预处理南瓜片的风干动力学。在干燥之前，南瓜使用不同的渗透剂进行渗透处理，即蔗糖、低聚果糖及其混合物 (1:1) 在恒定浓度 (70°Brix) 的溶液中，在三个温度 (75、85 和 95 °C) 下进行150 分钟 在干燥过程中测定质地的变化（硬度和压缩功），并由训练有素的小组成员评估最终产品的感官特性。一级反应动力学模型用于预测干燥速率和硬度，其中速率常数是过程温度的函数。结果表明，随着干燥温度的升高，干燥常数也增加，而脱水产品的平衡水分含量降低。无论渗透脱水条件如何，蜜饯南瓜的硬度主要受风干温度的影响。对最终蜜饯南瓜的感官评价表明，偏爱经低聚果糖渗透处理的产品。