Refractance window drying of fish silage : an initial investigation into the effects of physicochemical properties on drying efficiency and nutritional quality

The goal of this study was to investigate changes in nutritional quality of fish silage during refractance window (RW) drying. Furthermore, the effect of protein hydrolysis-degree of fish silage on production efficiency (%-moisture evaporated and production rate) was determined. To acquire a dried product, fish silage was conveyed (30 cm/min) on a polyester film over a water bath of 55 degrees C. Moisture content decreased from 747 +/- 24 g/kg to 101 +/- 33 g/kg, with only a slight increase in TBARS, from 3.7 +/- 1.0 mg/kg to 6.3 +/- 0.8 mg/kg. End-product consistency seemed to be affected by application thickness, ambient conditions and protein hydrolysis-degree. Additionally, a higher protein hydrolysis-degree increased evaporation efficiency, resulting in moisture contents of 135 +/- 10 g/kg, 101 +/- 12 g/kg, and 67 +/- 24 g/kg, for low-DH, medium-DH, and high-DH, respectively; though production rate decreased, producing dry matter outputs of 1.60 +/- 0.06 kg/h, 1.21 +/- 0.03 kg/h, and 1.05 +/- 0.06 kg/h, respectively, possibly caused by an increased availability of free water and a reduced application thickness. RW-drying seems to be an effective way of rapidly drying fish silage under gentle conditions.The goal of this study was to investigate changes in nutritional quality of fish silage during refractance window (RW) drying. Furthermore, the effect of protein hydrolysis-degree of fish silage on production efficiency (%-moisture evaporated and production rate) was determined. To acquire a dried product, fish silage was conveyed (30 cm/min) on a polyester film over a water bath of 55 degrees C. Moisture content decreased from 747 +/- 24 g/kg to 101 +/- 33 g/kg, with only a slight increase in TBARS, from 3.7 +/- 1.0 mg/kg to 6.3 +/- 0.8 mg/kg. End-product consistency seemed to be affected by application thickness, ambient conditions and protein hydrolysis-degree. Additionally, a higher protein hydrolysis-degree increased evaporation efficiency, resulting in moisture contents of 135 +/- 10 g/kg, 101 +/- 12 g/kg, and 67 +/- 24 g/kg, for low-DH, medium-DH, and high-DH, respectively; though production rate decreased, producing dry matter outputs of 1.60 +/- 0.06 kg/h, 1.21 +/- 0.03 kg/h, and 1.05 +/- 0.06 kg/h, respectively, possibly caused by an increased availability of free water and a reduced application thickness. RW-drying seems to be an effective way of rapidly drying fish silage under gentle conditions.A