Drying of stingless bees pot-pollen using swirling fluidized bed dryer

High moisture content in stingless bees pot-pollen makes preservation difficult. Since pot-pollen is heat sensitive, using conventional drying techniques below 40 degrees C is time consuming. A fluidized bed dryer (FBD) with swirling distributor is proposed for rapid drying of the pot-pollen while conserving the nutrients. The objectives of this study are to investigate the possibility of using swirling FBD to dry pot-pollen, and to investigate the effect of distributor type and superficial air velocity on pot-pollen drying. Stingless bees pot-pollen from the state of Pahang, Malaysia was dried at different conditions. Three distributor types: perforated, 45 degrees inclination angle, and 67 degrees inclination angle were tested at three superficial air velocities of 1.0 m/s, 1.5 m/s, and 2.0 m/s. Then, moisture content before and after drying were studied. To ensure swirling FBD would preserve the nutrition content of pot-pollen, nuclear magnetic resonance (NMR) analysis on the pot-pollen before and after drying was also carried out. It was found that at higher velocity, the drying rate increased. The 67 degrees swirling distributor has the best drying performance, followed by the 45 degrees swirling and perforated distributor. The highest reduction in moisture content, 13.5% in this study was found when using 67 degrees distributor at 2.0 m/s. This translates to a drying rate of 0.450%/min, about 6.2 times faster than conventional FBD, 5.6 times faster drying rate compared to hot air dryer (HAD) at 45 degrees C, 44.5 times higher than oven drying at 30 degrees C, and also a staggering 225 times quicker than cyclic convective dryer (CCD). It is also comparable to lower power levels of microwave assisted vacuum dryer (MW-VD), without damaging pot-pollen nutrients. The NMR analysis showed no adverse effect due to drying. Hence, it is possible to dry pot-pollen rapidly using swirling FBD without damaging its nutrition content, and using the 67 degrees swirling distributor is preferred.

Automated summary

This study investigates the possibility of using a swirling fluidized bed dryer (FBD) to rapidly dry stingless bees pot-pollen, and explores the influence of distributor type and superficial air velocity on drying efficiency. The findings show that the 67 degrees swirling distributor with a higher air velocity provides the best drying performance.