Wheat Germ Drying with Different Time-Temperature Combinations in a Fluidized Bed Dryer

Abstract

The development of an effective drying performance of the fluidized bed dryer (FBD) is crucial to reduce drying costs. The objective of this study was to investigate the drying performance of wheat germ (WG) with different time-temperature combinations in the FBD. The WG was dried at different set temperatures of 80, 100 and 120 °C. The moisture content (MC) and water activity (WA) of WG were measured. A mathematical model was proposed to develop an optimal drying condition. The changes in the MC of WG during drying in the FBD could be divided into the decreased period, the dynamic equilibrium period and the increased period. The product temperature of 45 °C and WA of 0.3 of WG drying could be attained by different time-temperature combinations. The mathematical model, which was developed in conjunction with different time-temperature combinations, could predict the dehydration time and the condensation time of WG for optimization the drying conditions. The WG dehydration at the heating stage and the WG condensation at the cooling stage could also be evaluated by the dehydration flux and the condensation flux, respectively. The optimal drying performance of WG exists in a compromise between promoting dehydration and reducing condensation. Information obtained from the analysis of dehydration flux and condensation flux with experimental data and simulation gave the guidelines for performing an effective drying of WG in the FBD.

Drying Applications during Value-Added Sustainable Processing for Selected Mass-Produced Food Coproducts

“…The wheat germ was dried with two different drying time (4 and 25 min) in a fluidized bed dryer at 80 • C [79]. After the experiment, the data were fitted using programmed mathematic modeling, which can be proven to be compatible with the experiment results [41,81]. In summation, the short drying time was significantly different compared to traditional method about 70% [16].…”

“…The wheat is then ground and sifted into flour, wheat germ, and wheat bran [40]. However, the moisture content of raw wheat germ is about 13% which would cause the lipid oxidation by enzymes easily, leading to the deterioration during storage [41].…”

“…At the same year, Chan and Kuo studied the effect of time and temperature for drying wheat germ drying by using fluidized bed dryer [41]. The results showed that the reduction of moisture content depended on heating time and temperature.…”

“…Meanwhile, the thermal input was reduced as a function of heating time and temperature. Thus, a high temperature with short processing time (120 • C and 3 min) was able to save more energy than the lower temperature and is suitable for the hot and humid climate in Asia, especially, during summer [41,81]. Drying of wheat germ at lower temperature (<80 • C) by using the fluidized bed dryer could be a preferable condition for preserving not only the flavor and color of wheat germ but also the processing energy as compared to drying at higher temperature (>90 • C).…”

Special Issue on Performance Measurement and Optimization for Sustainable Production Processes Improvement

“…Wittner et al [19,20] focused on the air-core-liquid-ring atomization and Chan and Kuo [21] investigated the wheat germ drying performance. Holgado [22] used system engineering approach to performance-based maintenance services design.…”