The impacts of vacuum microwave drying on osmosis dehydration of tilapia fillets

Hot‐air (HAD), vacuum microwave (VMD), osmosis microwave (O‐MD), and osmosis vacuum microwave (O‐VMD) drying were applied to investigate the effects of osmosis dehydration and vacuum microwave on the quality and structure of tilapia fillets. Shrinkage ratio, rehydration rate, color, hardness, elasticity, microstructure, per‐unit energy consumption, and main nutritional components of tilapia fillets were compared over the four drying methods. Moisture content was quickly decreased by osmotic pretreatment. Fillets were dehydrated in a short time via microwave conditions (3 min by O‐MD; 11 min by O‐VMD). A vacuum environment promoted the formation of porous structures inside the fish fillets. As for nutrient composition, shrinkage rate, rehydration rate, hardness and elasticity, O‐VMD fillets and VMD fillets had similar performance. The composite drying method of O‐VMD improved the quality of the product and had comparatively better in terms of microstructure, per‐unit energy consumption (24.04 kJ/g) and color change (13.8). Thus, tilapia fillets produced by O‐VMD were of higher quality. Meanwhile, this study provided a reference for further research. PRACTICAL APPLICATIONS: The purpose of dehydration is to decrease the moisture content to a low level at which microbial spoilage and quality deterioration are minimized. Drying is a traditional dehydration method in fish processing, able to deactivate the enzymes and remove the moisture to inhibit the growth of microorganisms. Vacuum microwave drying (VMD) uses microwave heating to dry the material under a vacuum environment with a low boiling point, a new technology in modern food processing that was developed to improve the quality of products. Few published studies have applied osmosis vacuum microwave drying to fish processing. Therefore, the aim of this work was to study the effects of vacuum and osmosis pretreatment on fillets drying process. Provided data can be applied for comparing the effects of different drying methods on tilapia fillet quality.