Abstract

High moisture content in stingless bees pot-pollen makes preservation difficult. Since pot-pollen is heat sensitive, using conventional drying techniques below 40 °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° inclination angle, and 67° 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° swirling distributor has the best drying performance, followed by the 45° swirling and perforated distributor. The highest reduction in moisture content, 13.5% in this study was found when using 67° 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 °C, 44.5 times higher than oven drying at 30 °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° swirling distributor is preferred.

摘要

无刺蜜蜂花粉中的高水分含量使保存变得困难。由于盆栽花粉对热敏感，因此在 40 °C 以下使用传统干燥技术非常耗时。建议使用带有旋流分配器的流化床干燥器 (FBD) 来快速干燥花粉，同时保存养分。本研究的目的是研究使用旋流 FBD 干燥花粉的可能性，并研究分配器类型和表面风速对花粉干燥的影响。来自马来西亚彭亨州的无刺蜂花粉在不同条件下干燥。在 1.0 m/s、1.5 m/s 和 2.0 m/s 三种表观空气速度下测试了三种分配器类型：穿孔、45° 倾角和 67° 倾角。然后，研究了干燥前后的水分含量。为确保旋转 FBD 能够保留花粉的营养成分，还对干燥前后的花粉进行了核磁共振 (NMR) 分析。发现在更高的速度下，干燥速率增加。67°旋流分布器的干燥性能最好，其次是45°旋流和穿孔分布器。当使用 67° 分布器以 2.0 m/s 时，水分含量降低幅度最大，在本研究中为 13.5%。这转化为 0.450%/min 的干燥速率，比传统 FBD 快约 6.2 倍，与 45°C 热风干燥器 (HAD) 的干燥速率快 5.6 倍，比 30°C 烘箱干燥快 44.5 倍，以及也比循环对流干燥器 (CCD) 快 225 倍。它也可与较低功率水平的微波辅助真空干燥机 (MW-VD) 相媲美，不破坏花粉营养。NMR分析显示没有由于干燥造成的不利影响。因此，可以使用旋流 FBD 快速干燥花粉而不会破坏其营养成分，最好使用 67° 旋流分配器。