Response Surface Methodology to Optimize Microwave Sterilization of Palm Fruit

Abstract

This study employed response surface methodology (RSM) to optimize microwave sterilization (MS) of oil palm fruit (OPF). RSM used experimental design CCD (central composite design) arrangement with three experimental factors: mass (330-1171 g), microwave power (80-800 Watt) and sterilization time (5.3-18.7 minutes) as main variables. This study adjusted significant level to 5% error (α = 0.05) with confidence level of 95%. MS affected moisture loss during MS significantly indicated by p-value experimental factors less than 0.05. The p-value of mass, power and time were 0.0001, 0.001, and 0.002 respectively. RSM provided predictive model to evaluate effect of sterilization time, mass and microwave power to moisture loss. Evaluation on normalized curve of MS treatment and lack of fit test of predictive model resulted p-value of 0.011 or less than 0.05 indicated no deviation of experimental data with the model. Determination of optimum condition for MS was conducted by evaluated the surface and contour plots obtained from response surface study. The optimum condition of MS was obtained from combination of heating 350.7 g palm fruit using microwave power of 639.29 W for 18.728 minutes. The moisture loss during optimum MS treatment was observed approximately 32.07%.