Department of Chemical Engineering, Federal University of Rio Grande do Norte, Natal-RN, Brazil.
Plants for Human Health Institute, Food Bioprocessing & Nutrition Sciences, North Carolina State University, North Carolina Research Campus, Kannapolis, North Carolina, USA.
J Food Sci. 2022 Apr;87(4):1780-1795. doi: 10.1111/1750-3841.16123. Epub 2022 Mar 22.
The objective of this study was to optimize the production of powdered avocado using foam mat drying. In order to achieve this, the effect of Emustab (4, 6, and 8% w/w), goat's milk (10, 15, and 20% w/w), and whipping time (15, 20, and 25 min) on the foam physical properties of avocado pulp were evaluated. In addition, the influence of ethanol pretreatment on the drying kinetics, thermodynamic properties, and physicochemical characteristics of the powders was also assessed. An experimental design 2 with three central points was used in this study and optimized foam conditions were dried at 50, 60, and 70°C, with a fixed air speed of 1.5 m/s. Empirical and diffusive models (boundary conditions of the third type) were adjusted to the experimental data to describe the drying kinetics and to determine the process activation energy and thermodynamic properties. The final products were characterized regarding their physical properties. Optimized foam mat drying conditions were achieved when avocado pulp was whipped for 15 min and 8% of Emustab and 20% of powdered goat milk were used as foaming agents. The use of an ethanol pretreatment and higher drying temperature (70°C) resulted in higher drying rate (1.6 × 10 /min) and shorter processing time (270 min). The ethanol pretreatment reduced the activation energy and Biot number and led to more uniform moisture distribution. The physical properties, such as water content, water activity, bulk, and tapped densities decreased with an increase in drying temperature and pretreatment with ethanol, whereas water absorption capacity increased. PRACTICAL APPLICATION: In this work, new information about the drying kinetics and mass transfer of the foam mat avocado pulp using ethanol as pretreatment is obtained. The results will contribute to the optimization production avocado foaming and powder. Ethanol pretreatment can represent an alternative to minimize the negative impacts on drying process and can be surely suggested as an industrial application.
本研究旨在通过泡沫垫干燥法优化鳄梨粉的生产。为此，评估了 Emustab（4%、6%和 8%w/w）、羊奶（10%、15%和 20%w/w）和搅拌时间（15、20 和 25 分钟）对鳄梨果肉泡沫物理性质的影响。此外，还评估了乙醇预处理对粉末干燥动力学、热力学性质和物理化学特性的影响。本研究采用三因素二次中心组合设计，并优化了泡沫条件，在 50、60 和 70°C 下干燥，空气速度固定在 1.5m/s。采用经验和扩散模型（第三类边界条件）对实验数据进行调整，以描述干燥动力学，并确定过程活化能和热力学性质。最后对终产物的物理性质进行了表征。当鳄梨果肉搅拌 15 分钟，使用 8%Emustab 和 20%羊奶粉作为起泡剂时，可实现优化的泡沫垫干燥条件。使用乙醇预处理和较高的干燥温度（70°C）可提高干燥速率（1.6×10 /min）和缩短加工时间（270 分钟）。乙醇预处理降低了活化能和 Biot 数，并导致更均匀的水分分布。随着干燥温度和乙醇预处理的增加，物理性质如水分含量、水分活度、堆积和振实密度降低，而吸水能力增加。实际应用：在这项工作中，获得了关于使用乙醇作为预处理的泡沫垫鳄梨果肉干燥动力学和传质的新信息。研究结果将有助于优化鳄梨泡沫和粉末的生产。乙醇预处理可以作为一种减少干燥过程负面影响的替代方法，肯定可以作为一种工业应用。
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