Effects of ethanol pretreatment on drying kinetics and quality attributes of scallop adductors during heat pump drying

Scallop adductors were pretreated with different ethanol concentration, viz., 0, 25, 50, 75, and 100% (coded as CK, E-25, E-50, E-75, and E-100, respectively) to enhance drying efficiency and quality of heat pump dried products. The drying time of scallop adductors was significantly (p < 0.05) reduced by 13.3% for E-100 in comparison to CK at the end of drying process. Low field nuclear magnetic resonance revealed that the immobilized water (T22) was the predominant water status in scallop adductors. With drying proceeding, T22 decreased by more than 60% from initial values in all samples and tended to convert to bound water and/or free water. The Weibull model and Dincer model were well fitted to describe the drying behavior of scallop adductors with high R2 and low RMSE values. The effective moisture diffusivity calculated by Fick’s diffusion model, Weibull model, and Dincer model ranged 9.345 − 9.948 × 10−11, 2.453–2.670 × 10−9, and 9.68–11.45 × 10−9m2 s−1, respectively. The total color difference, shrinkage rate and hardness of dried samples with suitable ethanol concentration pretreatment were lower, and rehydration ratio was higher than those of CK. Ethanol pretreatment could be a promising method to effectively enhance drying efficiency and improve product quality of scallop adductors.