Rohu (Labeo rohita ) is a popular fish grown in earthen ponds in most Asian countries, with a production of 2.02 million tonnes and 3.70% of total aquaculture production (FAO 2020). However, it is sold locally in the form of steaks with traditional knives without proper processing and value addition due to the non-availability of proper processing and post-harvest infrastructure. To promote standardised processing and value addition, a small-scale fish filleting machine for rohu fish was designed, developed and tested.
The morphometric measurements and mechanical properties of the rohu fish within the commercial harvesting range (290 g to 2100 g) were used as the basic parameters for the design and development. The machine comprises three main units: (a) conveying, (b) filleting, (c) water spraying and collection. The filleting unit has two parallel disc blades for precise cutting, with adjustable spacing to accommodate a variety of rohu fish backbone thicknesses. The conveying unit employs belt drives and spring-adjusted entry for smooth transport, while the water spraying and collection unit sprays and cleans the filleting blades, ensuring smooth fish movement.
The machine was tested by carrying out a filleting operation using rohu fish within the weight range of 300g to 2000 g. The performance parameters assessed and optimised were capacity (33 ± 1 fish/min), overall filleting efficiency (82.48 ± 0.97%), and energy consumption (93.16 ± 0.28 W-h ). Sensory evaluation of the fillets produced by the machine was performed by a trained panel of 25 members using a hedonic scale (1 to 5) to assess fillet quality in terms of tear, bruise, discolouration, skin condition, and overall acceptability. The ratings for all quality parameters given were within the range of 4 and 5, indicating good quality fillets produced by the machine. The total cost of the machine was Rs. 7000 (as of May 2020). The developed machine is cost-effective (Rs. 0.04/kg of dressed rohu fish) compared to manual filleting (Rs. 1.04/kg of rohu fish) and suits the economic condition of a small or medium freshwater fish processing industry in India and other developing countries.