The temperature prediction of some botanical beverages,concentrated juices and purees of orange and pineapple during ohmic heating

In this research, 10 kinds of botanical beverages, concentrated juices and purees of orange and pineapple were heated applying a static ohmic heating system. The objectives were (1) to develop the mathematical models for predicting the temperature changes of these samples during ohmic heating and (2) to compare between the qualities of ohmically-heated and conventionally-heated specimens. The results indicated that the mathematical models can precisely predict the temperature variations of the concentrated purees during ohmic heating although the heat losses to the surroundings and evaporated moisture are neglected. However, the temperature estimation of botanical beverages and concentrated juices were more accurate if the heat losses to the surroundings and evaporated moisture were included in the mathematical models. Furthermore, at the same heating rate the ohmic and conventional heating methods resulted in the insignificant difference in the sensorial qualities and remaining vitamin C contents of orange and pineapple juices.     

Study of hybrid dryer prototype and its application in pregerminated rough rice drying

In this study, a hybrid dyer, combining heat pump drying (HPD) with fluidized bed drying (FBD) concepts were designed and fabricated. The pregerminated rough rice (pre-GRR) was dried in multistage using this hybrid dryer to compare with the single-stage drying by hot air dryer. The objectives were to test the application of this hybrid dryer and determine the suitable drying condition for pre-GRR. The result indicated that the punched plate distributor was the most suitable distributor. The pre-GRR should be dried by the three-stage drying method using either FBD or HPD at 45°C in the last stage to obtain higher head rice yield, lower fissure grain, and better color values than their counterparts. The scanning electron micrographs proved that starch gelatinization occurred when applying FBD at temperatures between 100 and 140°C causing the adhesive connections inside the kernels and subsequent decrease in fissures.