Intermittent drying of bioproducts--an overview

Area of Science:

• Food Science and Technology
• Bioprocess Engineering
• Materials Science

Background:

• Conventional drying methods supply energy at a constant rate, which can be inefficient and damage heat-sensitive bioproducts.
• Intermittent drying offers a novel approach by adjusting heat input to match material-specific drying kinetics.
• This method is particularly relevant for preserving the quality of foods, pharmaceuticals, and other biomaterials.

Purpose of the Study:

• To explore the principles and benefits of intermittent drying processes for bioproducts.
• To analyze the impact of time-varying heat input on drying kinetics and product quality.
• To review experimental results and mathematical models associated with various intermittent drying techniques.

Main Methods:

• Implementing time-varying heat input, combining different heat transfer modes (convection, conduction, radiation, dielectric).
• Utilizing tempering periods to allow internal heat and moisture diffusion, controlling surface temperature.
• Applying mathematical modeling and experimental validation for diverse biomaterials and dryer types.

Main Results:

• Intermittent drying enhances thermal efficiency and reduces energy consumption compared to continuous methods.
• Improved product quality, including better color and ascorbic acid content, is observed.
• Potential for reduced capital costs in systems like microwave-assisted and heat pump dryers.

Conclusions:

• Intermittent drying is a superior method for preserving the quality of heat-sensitive bioproducts.
• The process offers significant energy savings and can lead to reduced equipment costs.
• Further research and application of intermittent drying strategies are warranted for various biomaterials.