Ojike Onyekwere, Uzodinma Eunice Osinachi, Ali Euphemia Ogochukwu, Nweze Blessing C, Okoyeuzu Chigozie F, Eze Chinwendu R
Department of Agricultural and Bioresources Engineering/ African Centre of Excellence for Sustainable Power and Energy Development University of Nigeria Nsukka Nigeria.
Department of Food Science and Technology University of Nigeria Nsukka Nigeria.
Food Sci Nutr. 2021 Nov 10;10(2):388-401. doi: 10.1002/fsn3.2616. eCollection 2022 Feb.
Moisture adsorption isotherm potentials and energy models of leaf grits were investigated. Fresh leaves were dried in sun; passive solar dryer and hot air oven, while proximate composition of the dried and fresh leaves were determined using standard laboratory procedure. Equilibrium moisture content (EMC) of the leaf grits was measured using gravimetric static method. Selected mathematical and statistical models were applied on the experimental data to evaluate data fitting. Energy calculations were done based on the mathematical models. The EMCs of the leaf grits directly increased with water activity (a) at specific temperatures. Adsorption data was better represented by GAB model than others while differential enthalpy decreased as the EMC of the oven sample increased. Differential entropy of all the samples decreased as the EMC increased. The safest monolayer moisture content varied between 7.1036 and 8.0164 gHO/100 g solid, below 40°C, within relative humidity of 10%-50%. Sun and oven leaf grits adsorbed more moisture than solar sample. Proximate contents of the dried leaves showed higher values for protein and ash. Overall results indicated that the leaf grits when properly packaged could be used as spice or tea powder to manage household nutrient security in addition to the use as therapeutic foods.
研究了叶粉的水分吸附等温线势和能量模型。将新鲜叶片在阳光下、被动太阳能干燥器和热风烘箱中干燥，同时使用标准实验室程序测定干燥叶片和新鲜叶片的近似成分。采用重量静态法测定叶粉的平衡水分含量（EMC）。将选定的数学和统计模型应用于实验数据以评估数据拟合情况。基于数学模型进行能量计算。在特定温度下，叶粉的EMC随水分活度（a）直接增加。与其他模型相比，GAB模型对吸附数据的拟合效果更好，而烘箱样品的EMC增加时，微分焓降低。所有样品的微分熵随EMC增加而降低。在40°C以下、相对湿度10%-50%范围内，最安全的单层水分含量在7.1036至8.0164 gH₂O/100 g固体之间。日晒和烘箱干燥的叶粉比太阳能干燥样品吸附更多水分。干燥叶片的近似成分显示蛋白质和灰分含量较高。总体结果表明，叶粉经过适当包装后，除用作治疗性食品外，还可作为香料或茶粉用于保障家庭营养安全。
