Foam mat drying kinetics of jambolan and acerola mixed pulp

ABSTRACT Acerola and jambolan are fruits with several bioactive compounds of phenolic origin and a product made with these two raw materials appears to be a food with high antioxidant and nutraceutical potential. Therefore, this study aimed to evaluate the foam mat drying of the mixed pulp of jambolan and acerola. Mixed pulp formulations, containing 1.0% albumin with 0.5% xanthan gum (F1), 0.5% carboxymethylcellulose (F2) and 0.5% guar gum (F3), were dehydrated at 50, 60, 70 and 80 °C, with foam mat thickness of 0.5 cm. The elevation of the drying temperature decreased the water content and dehydration time of the samples. Formulation F3 obtained the shortest drying times; all drying models resulted in good adjustments, especially Midilli. Formulation F3 obtained greater effective diffusivity; the activation energy was higher in the F1 combination. The samples with albumin-guar (F3) showed greater enthalpy and entropy and samples with albumin-xanthan gum (F1) showed the highest Gibbs free energy. Foam mat drying is an efficient way of preserving the jambolan and acerola mixed pulp.

【摘要】金虎尾果（acerola）与乌墨果（jambolan）均含有多种酚类来源的生物活性成分，以这两种原料制备的产品展现出较高的抗氧化活性与营养保健潜力。为此，本研究旨在评估乌墨果与金虎尾果混合果浆的泡沫垫干燥（foam mat drying）工艺。本研究制备了3组混合果浆配方：添加1.0%白蛋白与0.5%黄原胶（xanthan gum）的F1组、添加1.0%白蛋白与0.5%羧甲基纤维素（carboxymethylcellulose）的F2组，以及添加1.0%白蛋白与0.5%瓜尔胶（guar gum）的F3组。将各组果浆以0.5 cm的泡沫垫厚度，分别在50、60、70及80 ℃条件下进行脱水干燥。结果显示，升高干燥温度可降低样品的水分含量与脱水时长。其中F3组的脱水时长最短；所有干燥模型均呈现良好的拟合效果，尤以米德利（Midilli）干燥模型为佳。F3组的有效扩散系数（effective diffusivity）更高，而F1组的活化能（activation energy）更高。白蛋白-瓜尔胶复配的F3组样品具备更高的焓（enthalpy）与熵（entropy），而白蛋白-黄原胶复配的F1组样品的吉布斯自由能（Gibbs free energy）最高。综上，泡沫垫干燥法是保留乌墨果与金虎尾果混合果浆品质的高效工艺。