Abano Ernest Ekow, Akanson Joshua, Kizzie-Hayford Nazir
Department of Agricultural Engineering, School of Agriculture, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana.
Department of Biochemistry, School of Biological Science, College of Agriculture and Natural Sciences, University of Cape Coast, Cape Coast, Ghana.
Int J Food Sci. 2021 Apr 3;2021:8870001. doi: 10.1155/2021/8870001. eCollection 2021.
The objective of this study was to provide the optimum drying conditions to produce high-quality dried tiger nuts using hot-air drying. For this, we evaluated the effect of the whole, halved, and pulverized tiger nuts and air temperature (50 to 70°C) on the drying kinetics and quality of tiger nuts. The drying process generally followed a constant rate in the first 3 hours and a falling regime. We found the optimum drying conditions for tiger nuts to be crushed before convective hot-air drying at a temperature of 70°C. At this optimum condition, the predicted drying time, vitamin C content, reducing sugars, browning, brightness, redness, and yellowness was 780 min, 22.9 mg/100 mg dry weight, 157.01 mg/100 g dry weight, 0.21 Abs unit, 56.97, 1.6, and 17.0, respectively. The tiger nut's reducing sugars increased from the 130.8 mg/100 dry weight in the raw tiger nuts to between 133.11 and 158.18 mg/100 dry weight after drying. The vitamin C degradation rate was highest in the uncut tiger nuts (32-35%) while in the halved and the pulverized samples, it was between 12 and 17%. The crushed samples' effective moisture removal increased between 5.6- and 6.75-fold at the different air temperatures than that of the intact tiger nuts. The activation energy was 18.17 kJ/mol for the unbroken, 14.78 kJ/mol for the halved, and 26.61 kJ/mol for the pulverized tiger nut samples. The model MR = 0.997 exp(-0.02 ) + 0.0000056 was the most suitable thin-layer drying model among the models examined for convective hot-air drying of tiger nuts. It is advisable to crush tiger nut before hot-air drying to produce better-quality flour for making milk beverages, cakes, biscuits, bread, porridge, and tiger nut-based breakfast cereals.
本研究的目的是提供最佳干燥条件，以利用热风干燥生产高质量的干虎坚果。为此，我们评估了完整、对半切开和粉碎的虎坚果以及空气温度（50至70°C）对虎坚果干燥动力学和品质的影响。干燥过程通常在前3小时遵循恒速阶段，之后进入降速阶段。我们发现虎坚果的最佳干燥条件是在70°C的对流热风干燥前进行粉碎。在这个最佳条件下，预测的干燥时间、维生素C含量、还原糖、褐变、亮度、红度和黄度分别为780分钟、22.9毫克/100毫克干重、157.01毫克/100克干重、0.21吸光度单位、56.97、1.6和17.0。虎坚果的还原糖从生虎坚果中的130.8毫克/100干重增加到干燥后的133.11至158.18毫克/100干重之间。未切割的虎坚果中维生素C降解率最高（32 - 35%），而对半切开和粉碎的样品中，降解率在12%至17%之间。在不同空气温度下，粉碎样品的有效水分去除量比完整虎坚果增加了5.6至6.75倍。完整虎坚果样品的活化能为18.17千焦/摩尔，对半切开的为14.78千焦/摩尔，粉碎的为26.61千焦/摩尔。在为虎坚果对流热风干燥所研究的模型中，模型MR = 0.997 exp(-0.02) + 0.0000056是最合适的薄层干燥模型。建议在热风干燥前将虎坚果粉碎，以生产出质量更好的面粉，用于制作牛奶饮料、蛋糕、饼干、面包、粥和以虎坚果为基础的早餐谷物。
