A fresh produce/prepared food tray sealing machine is an automated device specifically designed for heat-sealing plastic trays (boxes, bowls) with lid film (usually composite plastic film). It not only requires a secure and aesthetically pleasing seal but, more importantly, must be compatible with Modified Atmosphere Packaging (MAP) or vacuum packaging processes to significantly extend the shelf life of fresh food.
Core process: Pre-weighed and portioned fresh produce/prepared food is placed into trays → enters the sealing machine → (optional) vacuuming/filling with a mixed preservation gas (e.g., N₂, CO₂, O₂) → heat-sealing the lid film → cutting → finished product output.
1. Main Types
Based on the preservation process and degree of automation, there are two main types:
1) Modified Atmosphere Packaging (MAP) Sealing Machine
Principle: After removing the air from the container, a mixture of nitrogen, carbon dioxide, and oxygen in a specific ratio is injected to inhibit microbial growth and food oxidation.
Features: It is currently the mainstream choice for high-end fresh produce, salads, and ready-to-eat meals. It can maintain the original color and texture of the food, and the shelf life can reach 5-14 days.
Key indicators: Gas replacement rate (usually required to be ≥99.5%), gas mixing accuracy, and sealing performance.
2) Vacuum Sealing Machine
Principle: The air inside the container is removed as much as possible to create a vacuum state, and then sealed under vacuum or near-vacuum conditions.
Features: Mainly used to inhibit aerobic bacteria and prevent oxidation in meat, aquatic pre-prepared dishes, or some fruits and vegetables. It may affect the shape of fragile ingredients.
Key indicators: Ultimate vacuum degree, vacuuming speed.
2.. Core Structure and Key Technologies
1) Sealing Mold (Sealing Head)
Function: This is the heart of the equipment. The upper mold has heating rods and a sealing knife, while the lower mold is a mold corresponding to the box type.
2) Technology:
Heating Method: Constant temperature heating sealing.
Sealing Pattern: Can be designed as a smooth edge seal or a raised/embossed anti-counterfeiting/easy-tear pattern.
Material: Food-grade stainless steel, with Teflon surface treatment to prevent sticking.
Gas Control System (for Modified Atmosphere Packaging Machines)
Components: Vacuum pump, gas mixing device (proportioner), high-precision flow meter, solenoid valve group.
Key Technology: Able to accurately and quickly mix 2-3 gases in a preset ratio and fill them into the box.
3) Film Conveying and Cutting System
Function: Automatically pulls the lid film and cuts it into individual products after sealing.
Technology: Stepper/servo motor drive, photoelectric eye tracking and positioning to ensure pattern alignment (if using printed film). Cutting methods include hot knife, cold knife, and die cutting.
4) Control System
Core: High-end PLC (such as Siemens, Mitsubishi) and color touch screen.
5) Functions:
Stores multiple sets of product parameters (different box types).
Real-time monitoring and display of vacuum degree, gas concentration, sealing temperature/time, and pressure.
Features self-diagnosis and alarm functions (e.g., gas leakage, insufficient film material, abnormal temperature).
Choosing a suitable fresh produce/prepared food tray sealing machine is essentially choosing the right "freshness preservation technology" and "quality assurance" for your products. It is crucial to conduct "actual product testing," performing continuous tests over an extended period using your own trays, sealing film, and actual products to comprehensively evaluate its preservation effect, sealing success rate, production efficiency, and stability.
