Mathematical Modeling of Drying Characteristics of Indian Mackerel (Rastrilliger kangurta) in Solar-Biomass Hybrid Cabinet Dryer

Abstract

Eight trials were conducted for drying mackerel by a solar biomass hybrid cabinet dryer (S-BHCD) and open sun drying (OSD) at air temperatures of 32.39–57.69°C, relative humidity 23.9–85.8%, and air flow rate of 0.20–0.60 m/s. The solar radiation ranged between 287 and 898 W/m² during the time of experimentation. At nighttime, drying was carried out by combusting biomass. The initial moisture content of the processed mackerel was 72.50±0.44% (w.b.) and was reduced to the final moisture content of 16.67±0.52% (w.b.) in S-BHCD and 16.92±0.54% (w.b.) in OSD. Eleven drying models were used and the coefficients of determination (R ²) and constants were evaluated by nonlinear regression to estimate the drying curves of dried mackerels. The Midilli model was found to more satisfactorily describe the drying process of mackerel in S-BHCD with R ² of 0.9999, χ² of 0.0000374, and RMSE of 0.0057. In the OSD, a two-term drying model satisfactorily described the drying process with R ² of 0.9996, χ² of 0.0000519, and RMSE of 0.0072. The variation of 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 by using S-BHCD showed very high corresponding coefficients of determination, where all R ² were greater than 0.90, except TBA value. Bacterial count and mold growth were decreased significantly (P < 0.05). There was no discoloration of the product during 4 months of storage. Contour plots of S-BHCD and OSD dried mackerel also showed that for all sensory attributes examined, panelists preferred fish dried with S-BHCD. The organoleptic analysis showed that the S-BHCD drying methods have a highly significant effect (P < 0.01) on texture and overall acceptability. Biochemical, microbial analysis, and sensory evaluation showed that the product was in prime acceptable form for 4 months of storage at ambient temperature.

Keywords:

• Fish drying model
• Mackerel drying
• Open sun drying
• Solar biomass hybrid cabinet dryer

Notes

∗1 WL, 2 IA, 3%s