Drying Kinetics and Quality Characteristics of Indian Mackerel (Rastrelliger kanagurta) in Solar–Electrical Hybrid Dryer

The aim of the study was to investigate the drying kinetics and quality characteristics of Indian mackerel dried under solar–electrical hybrid dryer (S-EHD). Fresh Indian mackerel fishes (Rastrelliger kanagurta) were cleaned, cut into butterfly fillets, and salted overnight using a dry salting method (salt-to-fish ratio, 1:3). The salted mackerel was dried in a S-EHD at the air temperature of 45–55°C, relative humidity of 47–62%, and air velocity of 0.60–0.80 m/s. Open sun drying (OSD) of salted Indian mackerel was conducted to compare with S-EHD. The moisture content of the salted mackerel (61.5% w.b.) was reduced to 31.8% (w.b.) under S-EHD and 30.25% (w.b) under OSD in 8 and 32 h, respectively. The drying rate curve showed that mackerel drying occurred under falling-rate drying period in both the drying methods. A drying efficiency of 23.81% was observed for salted Indian mackerel drying under S-EHD. Diffusion approach and two-term models were selected to accurately predict the drying behavior of mackerel under S-EHD and OSD, respectively. Total volatile base nitrogen (TVB-N), trimethylamine, and thiobarbituric acid analysis of dried samples revealed that the mackerel dried under S-EHD was better than OSD. In the sensory analysis, samples dried under S-EHD recorded highest overall acceptability score.