Spray drying of orange peel extracts: Yield, total phenolic content, and economic evaluation

• Microwave-assisted extraction and spray drying were used to produce orange peel extract powder.
• A peak yield trend and high recoveries of phenolic compounds were found during spray drying.
• The combined process is economically feasible.
• The powder selling price, the labor cost and the orange peel cost are the three most important costs.

Orange peel extract powders were produced using two steps: microwave-assisted extraction and spray drying. The extraction solvent-to-solid ratio has been found to significantly affect the level of total phenolic compounds in the extract and powder. Under the outlet air temperatures between 43 and 79 °C, spray drying of orange peel extracts resulted in a peak yield trend (between 75% and 92%) and high TPC (total phenolic content) recoveries. An evaluation of economics has also been conducted, suggesting that this process is economically feasible, with profits of 6.1 USD/kg and 8.8 USD/kg for solvent to solid ratios of 2 and 14, respectively. The uncertainty analysis of the economics showed that the selling price, the labor cost and the orange peel cost are the three most important parameters compared with the costs of electricity, natural gas, and water.