Optimization and test of the working parameters of the cutting disc for the whole-skin peeling system of snakehead

This study aims to reduce the damage to fish skin during the whole-skin peeling process. The integrity of the whole fish skin can also be achieved after peeling. A single-factor orthogonal test was carried out to optimize the cutting disc parameters in the self-built whole-skin peeling device of snakehead. Test results showed that the parameters of the cutting disc posed a significant effect on the whole-skin peeling process of snakehead. In addition, the cutting steps greatly contributed to the subsequent separation steps during skin and flesh peeling. Hence, the cutting disc parameters indirectly dominated the development of the fish industry. Taking snakehead with the typical morphological characteristics as the testing object, a systematic investigation was made to determine the relationships between the cutting performance and the cutting disc parameters in the cutting tests. Sensory evaluation and cutting index were used as the evaluation criteria, indicating the cutting quality and the injury degree of fish skin. Specifically, the higher the sensory score was, the higher the deep processing value of the fish skin was obtained. The cutting index represented the loss of fish skin after cutting, where the higher the cutting index was, the less waste of fish skin was. The testing factors were set as the cutting disc tooth structure (skewed, straight, and toothless cutting disc), and cutting disc rotation direction (consequent cutting and converse cutting). An optimal combination was achieved in the range of cutting disc diameter, thickness, and rotational speed were 60-140 mm, 1.0-2.0 mm, and 1 500-3 500 r/min, according to the equipment parameters and the morphological characteristics of the snakehead. Some factors with a significant influence in the single-factor test were selected for the orthogonal test. The single-factor test showed that the toothless cutting disc performed the best cutting performance, and the converse cutting was better than the consequent cutting. When the cutting discs with a diameter range of 60-100 mm were used, the cut of the fish skin was smooth and the cutting index presented a relatively high value after cutting. The optimal range of cutting disc thickness was 1.2-1.8 mm, leading to the high cutting index value and sensory evaluation score. Furthermore, the low rotation speed was used to prevent the fish skin from being cut through completely under the same conditions. As such, the cutting effect was gradually improved, as the rotation speed increased. The orthogonal test showed that the diameter and thickness of the cutting disc were the primary factors for the sensory evaluation, whereas, the diameter and rotation speed of the cutting disc were the primary factors for the cutting index. The best parameters were achieved in the cutting process of the whole skin peeling for the snakehead: the cutting disc diameter, thickness, and rotation speed were 80 mm, 1.2 mm, and 3 000 r/min, respectively. The parameter optimization tests demonstrated that the cutting disc with the optimal parameter combination performed the best in the validation test on the whole-skin peeling device of snakehead, indicating the excellent cutting effect. Specifically, there were smooth incisions without outstanding damage, while the sensory score of the incision reached 9.30 points and the cutting index reached 9.15. The cutting disc with the optimal parameter combination fully met the process requirements of whole-skin peeling of snakehead. The finding can provide theoretical support for the development of the whole fish skin peeling device.