Development and Performance Evaluation of a Vacuum-Assisted Stirred Dehumidification Machine for Stingless Bee Honey

Honey is nature's sweetest preservative, a substance so dense with sugar that bacteria and yeast struggle to survive within it. Yet, the honey produced by stingless bees, small insects vital to tropical ecosystems, faces a unique challenge. Unlike the honey of larger, more common bees, stingless bee honey is harvested with a naturally high water content, often holding between thirty and thirty-five percent moisture. This abundance of water turns a potential superfood into a perishable commodity; the extra moisture invites fermentation, causing the honey to spoil quickly and limiting its shelf life. To sell this premium product on a larger scale, producers must remove this excess water without cooking the honey or destroying its delicate nutrients. The traditional methods are slow, energy-intensive, or require expensive industrial machinery that is out of reach for small community farms.

A team of researchers at Princess of Naradhiwas University in Thailand has addressed this bottleneck by building and testing a specialized machine designed to dry honey efficiently on a community scale. Their work focuses on a process that combines three simple physical principles: heat, reduced pressure, and movement. By warming the honey, lowering the air pressure around it to make water evaporate more easily, and stirring the liquid to keep it moving, they created a system that removes moisture rapidly while using less energy than conventional methods. The goal was not just to dry the honey, but to do so in a way that is affordable and practical for local producers, ensuring the final product remains stable and high-quality.

The researchers constructed a compact, ten-liter machine that looks like a stainless steel pot sitting inside a larger jacketed container. The inner pot holds the honey, while the outer jacket circulates hot water to gently warm the contents without burning them. A vacuum pump is attached to the top, capable of sucking the air out of the sealed vessel to create a low-pressure environment. Inside, a motorized stirrer rotates slowly to agitate the thick liquid. To test how well this system worked, the team did not use expensive natural honey for every trial; instead, they prepared a sugar solution that mimicked the moisture and texture of fresh stingless bee honey. They started with a mixture containing thirty-five percent water and aimed to reduce it to twenty percent, the standard for stable honey.

The team ran a series of experiments to see how different settings affected the drying speed. They tested two temperatures, fifty and seventy degrees Celsius, two pressure levels, normal air pressure and a deep vacuum, and two stirring speeds, zero and sixty rotations per minute. The results were striking. When the machine operated under normal air pressure at the lower temperature without stirring, it took an immense one hundred and sixty-eight hours to dry the mixture. In stark contrast, when the researchers applied the vacuum, raised the temperature to seventy degrees, and engaged the stirrer, the same amount of moisture was removed in just nine hours. The vacuum was the most powerful factor, as lowering the pressure allowed the water to boil and evaporate at a much lower temperature, preventing the honey from overheating while speeding up the process.

Beyond just speed, the machine proved to be remarkably efficient with energy. The researchers calculated the cost of electricity required to process each kilogram of honey. Under the best conditions—high heat, deep vacuum, and stirring—the cost dropped to between zero point twelve and zero point fourteen US dollars per kilogram. This was a fraction of the cost incurred when operating at normal pressure, where the energy bill for the same task could be more than ten times higher. The vacuum system allowed the water to leave the honey so quickly that the heating elements and pumps did not need to run for days, saving significant power. The study also tracked the concentration of the honey; as the water vanished, the sugar content rose from sixty-four to seventy-nine degrees on the Brix scale, a standard measure of sweetness and density, confirming that the machine successfully concentrated the product without degrading it.

To help future users predict how long the drying process would take, the researchers developed a mathematical model based on their data. This model acts as a calculator for producers, allowing them to input their desired temperature, pressure, and stirring speed to estimate the drying time before they even start the machine. The model matched their experimental results with high accuracy, suggesting it is a reliable tool for planning production. The study concludes that this vacuum-assisted, stirred approach offers a practical solution for small-scale producers. By combining heat, vacuum, and agitation, they have created a system that transforms a difficult, slow process into a manageable, energy-efficient operation, paving the way for stingless bee honey to reach wider markets while retaining its natural quality.