Infrared drying of coconut (<i>Cocos nucifera L.</i>) fruit

Coconut was dried using infrared drying under different drying process conditions in a central composite design (CCD) of response surface methodology (RSM). Moisture content (%), water activity (aw), pH, free acidity (%), total phenolic content (TPC) (mg GAE/g), color, and FTIR spectrum of the dried samples were analyzed, and the total oil content and fatty acid composition of fresh coconut were determined. Mathematical models were built and an optimization was performed for determining the optimum drying condition. The lowest moisture content (1.80%) and water activity (0.283) values were obtained at 250 W lamp power, 240 min drying time, 15 cm lamp distance, and 10 mm sample thickness. The highest TPC was found to be 209.34 mg GAE/g. ΔE* values of dried samples ranged between 0.28 and 19.12. L* values of the dried samples decreased at higher lamp power and longer drying times, while a* and b* values increased. In fresh coconut oil, medium-chain fatty acids were predominant, specifically lauric acid (C12:0) being the dominant fatty acid at 49.78% of the total fatty acids. An overall desirability of 0.766 was obtained from optimization.