As a naturally sweet, low-calorie, and healthy sugar substitute, stevia's core value lies in the steviol glycosides in its leaves. These glycosides are heat-sensitive and extremely sensitive to processing temperatures. Traditional air-drying or rough drying can easily lead to glycoside degradation and browning of the leaves, significantly reducing their economic value. Modern precision drying processes, by simulating optimal drying conditions, are key to preserving this "natural sweetness."

Pretreatment: Efficient Cleaning and Surface Dehydration
Fresh stevia leaves and stems must first be vigorously cleaned to remove stems, old leaves, and impurities, preserving as many intact leaves as possible. Subsequently, a combination of air bubble cleaning and powerful spraying is used to thoroughly remove surface sediment and microorganisms. After cleaning, the leaves must be centrifuged to quickly remove surface water, reducing the initial moisture content from 75%-80% to approximately 65%. This paves the way for uniform and efficient drying and significantly reduces subsequent energy consumption.

Core Technology: Low-Temperature, Slow Drying to Lock in Glycosides
Steviosides are easily decomposed and inactivated under sustained high temperatures, so the entire drying process must adhere to the principles of "low temperature, high air volume, and rapid dehumidification."

Phase 1 (Color Fixation): Initial temperature set at 50-55°C for 2-3 hours. This stage aims to rapidly evaporate free moisture from the leaf surface using low to medium temperatures, while simultaneously inhibiting polyphenol oxidase (PPO) activity, preventing enzymatic browning and securing a vibrant green color.

Phase 2 (Main Drying): Slightly increase the temperature to 55-60°C, with maximum air volume and dehumidification enabled. This phase is the primary dehydration stage, rapidly reducing the leaf moisture content from 65% to around 15%. Strong, penetrating hot air prevents the stagnation of hot and humid air, which can lead to yellowing and mold.

Phase 3 (Final Drying): Return the temperature to 50-52°C and dry slowly at a low speed. The final moisture content of the leaves is steadily reduced to 8%-10%. This stage requires extreme patience. Slow, low-temperature drying ensures complete evaporation of moisture from the leaves without overheating and charring, preserving the activity and purity of the steviol glycosides to the greatest extent possible.
Critical Control Points and Quality Linkages
Temperature is crucial: The material temperature must not exceed 62°C throughout the drying process, otherwise the steviol glycoside content (especially Reb A content) will drop sharply.
Uniform spreading is key: We recommend using a multi-layer mesh belt dryer, laying the leaves no thicker than 5 cm and rotating them regularly to ensure that the hot air penetrates every leaf thoroughly and achieves uniform drying.
Balance between color and sweetness: Emerald green leaves generally indicate higher quality and glycoside retention. Yellowing or blackening of the leaves after drying indicates a loss of process control and the loss of active ingredients.

The superior value of modern drying technology


Dried stevia leaves using scientific drying processes can achieve a total steviol glycoside retention rate exceeding 90%, and the STV% content is significantly higher than traditional air-dried methods (typically below 70%). This not only directly improves the procurement quality and economic benefits of raw materials, but also provides downstream extraction companies with high-quality, highly active raw materials, solidifying the market competitiveness of natural sweetener products. Intelligent drying equipment enables large-scale, standardized, and clean production, and is the only way to modernize and upgrade the stevia industry.