Enhancing the quality of stingless bee honey (SBH) is crucial due to its naturally high moisture content, which can lead to fermentation and spoilage. Various innovative dehydration techniques have been developed to reduce moisture content while preserving or enhancing the honey’s nutritional and functional properties.
Dehydration Techniques for Moisture Reduction
1. Vacuum Drying
Vacuum drying at temperatures between 40–60°C effectively reduces SBH moisture content to below 17%, thereby inhibiting microbial growth and fermentation. This method also enhances antioxidant properties, increasing total phenolic and flavonoid contents, and improves antioxidant capacities such as ABTS and FRAP values.
2. Freeze-Drying (Lyophilization)
Freeze-drying at −54°C achieves moisture levels as low as 5%, significantly extending shelf life. However, this process can alter carbon isotope ratios, which may affect authenticity assessments.
3. Microwave Heating
Microwave heating at a power level of 60 for 60 seconds can reduce moisture content to approximately 15%, meeting safety standards. This rapid method also increases total phenolic content, enhancing the honey’s antioxidant properties.
4. Thermosonication
Combining mild heat with ultrasonic waves, thermosonication reduces moisture content by about 16.6%. While it enhances total phenolic content, it may not achieve moisture levels below 17% without extended processing.
5. UV-C Assisted Drying
UV-C treatment at 254 nm can lower moisture content to around 17.4% within 120 minutes. However, this method may increase hydroxymethylfurfural (HMF) levels beyond acceptable limits, potentially affecting honey quality.
6. Passive Diffusion (Clay Pot Storage)
Storing SBH in clay pots at elevated temperatures (e.g., 35°C) facilitates moisture reduction through passive diffusion. This traditional method can decrease moisture content by up to 24.2% over several days, though it may not consistently achieve levels below 17%.
Quality Assessment and Authentication
Near-infrared spectroscopy (NIR) combined with chemometric analysis offers a rapid, non-destructive method for assessing SBH moisture content and detecting adulteration. This technique provides accurate predictions, aligning closely with traditional refractometric methods.
Impact on Physicochemical Properties
Dehydration methods not only reduce moisture content but also influence other physicochemical properties of SBH:
- Total Phenolic Content (TPC): Methods like vacuum drying and microwave heating significantly increase TPC, enhancing antioxidant capacity.
- Hydroxymethylfurfural (HMF) Levels: While some dehydration processes may raise HMF levels, maintaining processing temperatures and durations within optimal ranges ensures HMF remains below the permissible limit of 40 mg/kg.
- pH and Water Activity: Effective dehydration stabilizes pH and reduces water activity, contributing to improved shelf life and safety.