Hydrocolloid coating pretreatment makes explosion puffing drying applicable in protein-rich foods – A case study of scallop adductors

Explosion puffing drying (EPD) is rarely employed in protein-rich foods due to insufficient puffing driving force. Therefore, hydrocolloid coating pretreatment was performed to evaluate the feasibility of EPD application in scallop adductors. The transverse relaxation time (T2) of scallop adductors was determined by low-field nuclear magnetic resonance (LF-NMR). Average drying rate, puffing degree (Pd), rehydration rate (Rr), total color difference (ΔE), hardness, and brittleness of puffing-dried scallop adductors were also analyzed. Coating before pre-drying and coating twice significantly improved quality characteristics of scallop adductors. After pre-drying, T2 of loosely bound water (T21) appeared with coating pretreatment, which increased the freedom degree and mobility of water molecules, thereby improving the quality of scallop adductors. T2 of the immobilized water (T22) and the proportion of tightly bound water (mT2b) had a significant correlation with Pd, ΔE, hardness, and brittleness. Coating pretreatment contributes to the enhanced quality of puffing-dried scallop adductors.