Design and experiment on dual rollers peeling machine for satsuma mandarin

Abstract: Citrus is widely planted in China, which can be used to produce a diverse range of products such as orange petal can, orange juice, fruit vinegar and citrus wine. Satsuma mandarin is the main material for most orange products. Currently, peeling the citrus fruit is mainly accomplished by the manual labor, which is definitely labor-intensive and inefficient and results in the high risks of reducing the hygiene and quality of the citrus products. With the increase of labor cost and high requirement of food hygiene, it is necessary for the citrus processing industry to develop an automatic machine to replace the conventional manual peeling method to peel the citrus. In the present study, a dual-roller citrus peeling machine has been designed to quickly peel the Satsuma mandarin. The prototype of the dual-roller citrus peeling machine consists of the frame, the transmission device, the peeling rollers, the scraper, the unloading device and other components. Before being introduced into the machine, the citrus fruits are firstly blanched by the hot steam, ring-cutting and then turned up. Then, the citrus fruits begin to turn over and move forward driven by scraper. In the movement process, the turned up peels of the citrus fruits are gripped by the dual rollers rotating in the opposite directions, and then tore off from the citrus fruits. Three kinds of peeling rollers are designed in this machine, including gear tooth peeling rollers, arc gear tooth peeling rollers and smooth peeling rollers. So the citrus fruits have to go through 3 kinds of processes before leaving the machine. Firstly, the citrus fruits move into the area of the gear tooth peeling rollers. Because of the large gripping force of gear tooth peeling rollers, most of the citrus peels are clipped and stripped. Then the citrus fruits move into the area of the arc gear tooth peeling rollers, and these rollers can provide an appropriate gripping force to continue the peeling of the citrus fruits. It should be noted that the gears in these rollers are designed to have no sharp angle in order to protect the citrus pulps from damage. After this process, almost all of the peels of the citrus fruits are peeled off. Finally, the citrus fruits move into the area of the smooth peeling rollers which can remove the residual peels without damaging the citrus pulps. After these 3 processes, the whole peels of the citrus fruits are peeled off and then the citrus fruits leave the machine. Additionally, 3 kinds of citrus fruits are adopted to assess the peeling performance of the prototype of the dual-roller citrus peeling machine. Results have showed that the peeling efficiency of citrus is about 97.5%-100%, the damage rate of citrus pulps is only 1.82%-2.68%, and the productivity is about 202.5-222.3 kg/h. Clearly, this peeling machine can meet the requirements of the high net rate of citrus peeling and low damage rate of citrus pulps. Besides these, peeling the citrus in this machine is labor-effective and hygeian, obtaining high-quality citrus products compared to the conventional manual peeling method. The machine can run smoothly and reliably, and it can be adopted to peel the citrus fruits with different sizes. So this machine may have a bright future. And the design method of this peeling machine may also offer a new and creative idea for the development of the advanced, stable and high-performance peeling machine.