Rational Values of Fish Feed Wet Pelleting Process in the Basket Pelleter

Introduction. The basket pelleter can be used for wet pelleting of plant raw material and producing of small diameter (0.5–2 mm) feed pellets for fish and fish fry. Basket pelleters have not previously been used in aquaculture for preparing feed. The operation process of basket pelleters has not been sufficiently studied and its rational parameters have not the sufficient scientific basis. Aim of the Study. The study is aimed at increasing of water resistance of fish feed pellets by determining the rational parameters of the process of wet pelleting of plant raw materials in the basket pelleter. Materials and Methods. In the basket pelleter, there was pelleted crumbled feed from plant raw material for carp fry. The diameter of pellets was 2 mm. The time of complete disintegration of the feed pellets in water was a criterion for optimizing the wet pelleting process. The values of four parameters were varied during the experiments: raw material moisture, raw material temperature, raw material fineness modulus, and rotation speed of the pelleter movable operating devices. After processing the experimental results, there was obtained the regression equation and there were drawn response surfaces and their two­dimensional sections. The analysis of response surfaces was performed. Results. It has been found that increasing in the values of all factors up to a definite limit increases the water resistance of feed pellets. The effect of raw material temperature on the disintegration time of pellets is less significant than the other three parameters. The optimum value of the disintegration time of pellets in water, equal to 92–96 min, is achieved at the rational ranges of parameters of feed wet pelleting process: raw material moisture 40...42%; fineness modulus of raw material 1,4...1,8 mm (middle grinding); rotation frequency of movable operating elements of basket pelleter 47...51 min–1; raw material temperature 42...56°С. Discussion and Conclusion. There have been found rational parameters of the process of wet pelleting of plant raw materials in a basket pelleter that make it possible to produce pelleted feed for fish and fish fry meeting zootechnical requirements for water resistance. For the process of wet pelleting in the basket pelleter, there have been found the dependences of changing water resistance of pellets on raw material moisture and temperature, and its grinding modulus and rotation speed of movable operating elements. They correspond to similar dependences, which were previously found for the process of dry pelleting in pellet­presses with a vertical ring die.