MODELING USING A NEW THIN-LAYER DRYING MODEL AND DRYING CHARACTERISTICS OF SWEET BASIL (OCIMUM BASLICUM LINN.) USING TRAY AND HEAT PUMP-ASSISTED DEHUMIDIFIED DRYING

摘要

The maturity of Thai sweet basil was based on leaf area, % inhibition and total phenolics. Desorption isotherms for sweet basil leaves were performed. It was found that the modified Henderson model showed the best fit to both fresh and blanched sweet basil leaves for Xe = f(Xe,T). Sweet basil leaves were pretreated by blanching prior to drying under three temperatures of 40, 50 and 60C in tray and heat pump-dehumidified (HPD) dryers. The three-parameter model was the most effective model in describing sweet basil leaf drying. The drying constant was related to air temperature using the Arrhenius model. Effective moisture diffusivities increased with increasing temperature and blanching treatment, as well as the HPD dryer. Quality evaluation by % inhibition, total phenolics, rehydration ratio and ΔE* showed that the best quality resulted from sweet basil leaves pretreated by blanching and dried at 40C in HPD dryer.