Abstract: In the present study, process optimization for the extraction of polyphenols from pineapple peel residue with ethanol aqueous solution was carried out by Hartley’s experimental design method combined with response surface analysis based on a series of one-factor-at-a-time experiments. A regression model for total polypenhols yield as a function of four factors, namely temperature, extraction time, ethanol concentration and liquid-to-material ratio was built. The importance of the four factors affecting total polypenhols yield declined in the following sequence: temperature, extraction time, liquid-to-material ratio and ethanol concentration. Extraction at 48.4 ℃for 73.6 min with a 46.8-fold volume of 41.6% ethanol aqueous solution yielded the most total polyphenols, reaching 7.77 mg/g, which was basically in accordance with the model-predicted value. In conclusion, the optimized extraction process is reliable and can be used for the development of products based on pineapple peel polyphenols.

Key words: pineapple peel residue, polyphenols, response surface analysis, Hartley s method, extraction