Mathematical modeling and quality characteristics of Indian mackerel (Rastrilliger Kangurta) dried in solar cabinet dryer

Eight trials were conducted for drying mackerel in solar cabinet dryer and open sun. The initial moisture content of mackerel was 71.83±0.53%, which reduced to 16.75±0.81% in solar cabinet dryer (SCD) and 16.83±1.43% in open sun drying (OSD). Eleven drying models were used and the coefficients of determination (R²) and non linear regressions were employed to establish drying curves. The Midilli model satisfactorily described drying process of mackerel in SCD with R² = 0.9993; Χ²= 0.000082 and RMSE = 0.0127. In the OSD, two term drying model was satisfactorily describing the drying process with R² of 0.9996; Χ² of 0.0000519 and root mean square error (RMSE) = 0.0072. Free fatty acid (FFA), Peroxide value (PV), Thiobarbituric acid (TBA), Total volatile bases nitrogen (TVB-N), Trimethylamine nitrogen (TMA-N) and histamine contents of dried mackerel prepared by using SCD, showed high coefficients of determination, wherein the R² were greater than 0.85, except that for TBA and TMA-N. Bacterial count and mold growth significantly (P&lt;0.05) decreased, and there was no discoloration of the SCD product during four months of storage. On the other hand, open sun dried product showed discoloration after four month of storage, Fishes which were dried with SCD were preferred by the panelists during sensory evaluation. The organoleptic evaluation showed that the SCD drying method had significant (P&lt;0.05) effect on texture and overall acceptability of the product. Dry mackerel, stored at ambient temperature, was acceptable to the sensory panel until 134 and <97 days in case of SCD and OSD, respectively. The shelf-life of dried mackerel from local fish markets was <43 days.