Drying of ground fish slices using superheated steam combined with hot air

Abstract

The objectives of this research were to study the changes in the moisture of ground fish slices during drying with superheated steam combined with hot air, and to compare the physical properties (in terms of color, hardness, toughness and shrinkage) as well as sensory evaluation of dried fish slices. Two drying methods were performed (i.e., superheated steam drying at 140 ?C combined with hot air drying at 110 ?C (SSD+HAD), and hot air drying at 110 ?C combined with superheated steam drying at 220 ?C and hot air drying at 110 ?C (HAD+SSD+HAD)). The ground fish samples were produced at sizes of 50?50?1.3 and50?50?2.2 mm (WDH). The samples with the initial moisture content of around 205-215% dry basis were dried until the final moisture content of about 20% dry basis. Results showed that the samples with 1.3 mm thickness had shorter drying times than those with 2.2 mm thickness. The samples dried by SSD+HAD and HAD+SSD+HAD were similar in the drying time. In term of qualities, it was seen that the lightness of dried samples decreased, but the hardness, toughness, and shrinkage percentage of dried samples increased when the samples thickness increased. Dried samples obtained from SSD+HAD had higher lightness, hardness and toughness, but had lower percentage of shrinkage than those obtained from HAD+SSD+HAD. Moreover, it was found that dried samples obtained from HAD+SSD+HAD had the highest sensory scores.