Recent developments of drying techniques for aquatic products: With emphasis on drying process monitoring with innovative methods

Fresh aquatic products are highly perishable after harvest due to their high water content, high protein level, high endogenous enzyme activity, and high growth rates of microorganism. Drying has been proven a successful preservation method for aquatic products by removing water. The conventional sun drying is energy-saving and environment-friendly, but time-consuming and low efficiency. This paper reviews the recent developments in drying technologies for aquatic products including hot-air drying, heat pump drying, infrared radiation drying, freeze drying, microwave drying and hybrid drying methods, with an emphasis of the advantages for different drying techniques to improve the drying efficiency and product quality. Especially, the advances of innovative detection technologies for the drying process monitoring are analyzed and discussed, including near infrared spectroscopy, computer vision system, hyperspectral imaging, low-field nuclear magnetic resonance and magnetic resonance imaging. These analytical techniques can effectively monitor the quality change and improve the drying quality of the aquatic products. Finally, the development trends of drying technologies and monitoring methods for aquatic product in the future are proposed.