Glass vermicelli is made from sweet potato, a deep processing of sweet potato series products. Usually there are three types production process for producing vermicelli, including extrusion molding type, slurry spreading type and leak ladle type. Extrusion molding type is generally used to produce thin vermicelli including instant one. In these few years, with the improvement on the degree of mechanization of its production, many large-scale factories are adopting to use this method to produce vermicelli. For the slurry spreading type, due to the high machine cost, the maximum daily capacity is between 3 to 4 tons. While for the leak ladle type, it is spread over the countryside and towns at north part of the Yellow River in China, the vermicelli produced by this method are deeply loved by local people for many years. Although it has a long history, due to limited research, most existing leak ladle type glass vermicelli making machines are simple, low in automation, poor in sanitation and can’t satisfy the requirements of the national “Food Safety and Sanitation Law”. Therefore, in order to adapt to both large-scale mechanized vermicelli factories and ensure good quality and taste of the products produced, it is necessary to develop "leak ladle" automated large-scale glass vermicelli production equipment to meet market needs.   

The flow of "leak ladle" type for producing glass vermicelli is : Starch (raw material) → Concocting → Mixing → Vacuum Air Extraction → Sifting → Boiling → Cooling → Cutting → Putting-up on Bars → Freezing → Thawing → Drying → Cutting → Packaging → Final Product. Jianli Food Technology and Equipment Research Institute uses patented technology and has developed a leak ladle type glass vermicelli production line for a well-known large domestic food enterprise, the capacity can be 1000 kg/hour . During the production process, it not only ensures that the glass vermicelli to be much stronger toughness and better boiling resistance, maintains the traditional taste, but also achieves automated production and reduces the labor force. 

The concocting process is the key point to the production of leak ladle type glass vermicelli. The moisture content, degree of gelatinization, and toughness of the starch paste are decisive factors in the success of sweet potato starch mixing. Good starch paste should be crystal clear, tough, and highly viscous. Our designed concocting machine automatically adds water according to the amount of starch paste, adopts automatic variable-frequency speed regulation stirring from low speed to high speed, and automatically injects steam to heat the starch paste until it is uniformly gelatinized, reducing errors caused by insufficient experience of operators. It abandons the past method of simply stirring water into a starch milk and then adding boiling water or steam to heat it. It has been proved that through variable-speed stirring, not only can save energy, but also can be fully mixed starch with water, and the starch paste produced can fully meet production requirements. 

The starch is using pneumatic conveyor to convey, enabling the raw material to be continuously and evenly delivered to the multi-stage double-screw continuous mixer, reducing the labor force. Due to the kneading, pinching, pushing and pulling effects of the double-screw stirring on the starch, the starch becomes more flexible, absorbs more water, has stronger viscosity, better boiling resistance and more even feeding, making it easier for the equipment to maintain production continuity. Therefore, this type of double-screw mixer has gradually replaced the single-tank single-shaft paddle mixer and has been used in glass vermicelli production line equipment with good results. 

The boiling process and equipment have gradually developed from traditional methods to new-type boiling machines with automatically lifting lids, energy-saving and environmental protection, easy cleaning, automatic temperature control, and continuous operation. This boiling machine adopts an arc-shaped lid that can be automatically lifted, which is easy and safe to operate. During production, except for the outlet, the entire boiling tank is sealed, and the water vapor is contained within the tank and guided outdoors through the exhaust hood, which not only prevents the water vapor from spilling out indoors and affecting the indoor temperature but also improves the heating speed, ensuring a clean and hygienic working environment. The boiling temperature is controlled by adjusting the opening and closing of the solenoid valve to increase or decrease the intake of steam. At the same time, the filtered steam is directly introduced into the boiling tank to heat the water, achieving faster temperature rise and cost savings. The cooling method uses continuous and uniform water spraying and conveying to cool the vermicelli, which can quickly cool the vermicelli and wash away the gelatinized layer, ensuring the appearance of the vermicelli and facilitating the next process. 

The automatic hanging pole process of vermicelli adopts patented technology, hanging three strings of vermicelli on one pole. The entire process realizes automatic pole feeding, automatic hanging, automatic pressing, and automatic pole conveying. The hanging poles are made of stainless steel round tubes with patterns to reduce the slipping of vermicelli. The cutting blade can move up and down to adjust the cutting length of the vermicelli within a certain range, achieving the optimal hanging length for different product specifications. Each time the vermicelli is hung, a pressing action is performed to ensure that the vermicelli does not slip during the hanging process. When a round tube is filled with three strings of vermicelli, the pressing pole and hanging pole move to a designated position, and the pressing pole returns alone, while the hanging pole is lifted by another conveyor chain to the collection rack and transferred to the freezer through a transfer mechanism. The proximity switch accurately controls the position of the hanging pole, making the entire process seamless. 

The hanging pole automatically runs in the freezer for several hours, and the water droplets on the vermicelli form ice crystals. Then, the hanging pole automatically transfers the vermicelli to the thawing machine. The thawing machine is a closed box with two chains for conveying vermicelli. The upper and sides of the thawing machine are equipped with two rows of water spray nozzles. The ice crystals attached to the vermicelli are washed and melted away by the sprayed water inside the thawing machine, and the vermicelli naturally disperse, with few strands sticking together. The frozen vermicelli has strong toughness, dries quickly, is straight, and easy to package. 

In order to produce vermicelli strictly in accordance with the national "Food Safety and Sanitation Law", unaffected by weather changes, and reduce the labor intensity of workers, large drying machines are used instead of natural drying. The drying machine consists of a machine body, an upper pole manipulator, a lower pole manipulator, a blowing system, a moisture exhaust system, a conveying system, and a heat dissipation system. The entire body is covered with insulation panels, with insulation panel doors on both sides, and transparent glass doors and windows at the entrance and exit for easy observation of the drying and conveying of vermicelli inside the room. The blowing system consists of multiple variable-speed fans, and the moisture exhaust system consists of a variable-speed fan and air ducts, achieving automatic temperature, humidity and speed control. 

The cutting machine for vermicelli also adopts patented technology, which can cut vermicelli to a certain length as needed. The cut vermicelli has less broken pieces, a high yield rate, and is easy to package.

The new leaky ladle type vermicelli production line adopts new electronic control technology and boldly innovates the hanging powder technology that has long plagued people. It not only improves the degree of automation, reduces the labor intensity of workers, but also increases the output of vermicelli. It can be expected that under the condition that this kind of product has a larger market, with the continuous exploration and research and development of the deep processing technology of sweet potato vermicelli, a more intelligent and fully automated "leaky ladle" type sweet potato vermicelli production line will appear in front of people.