Background Introduction
In modern food packaging, especially in the packaging of dairy products such as cheese sticks, it is crucial to ensure the freshness, barrier and safety of the product. Cheese sticks are highly susceptible to oxygen and moisture in the air due to their high protein content and humid characteristics, which leads to oxidation and deterioration. Therefore, in order to extend the shelf life and maintain the freshness of the product, the outer packaging of the cheese stick not only needs to have high barrier properties, but also needs to meet food contact safety standards.
In order to solve these problems, a well-known food manufacturer chose to use PP/EVOH/PP high barrier sheet for thermoforming packaging of cheese sticks. Due to its multi-layer structure design, this type of sheet can effectively prevent the intrusion of oxygen, moisture and other external factors, ensuring the quality stability of cheese sticks during transportation and storage.
Material Introduction
PP/EVOH/PP high barrier sheet is a multi-layer composite material that combines the excellent properties of polypropylene (PP) and ethylene-vinyl alcohol copolymer (EVOH):
Polypropylene (PP): As the outer and inner layers of the sheet, PP has good thermoforming properties and mechanical strength. At the same time, it is non-toxic and odorless and meets food contact standards. PP material also has excellent chemical resistance and can resist the erosion of acids, alkalis and organic solvents.
Ethylene-vinyl alcohol copolymer (EVOH): As the middle layer of the sheet, EVOH is known for its excellent gas barrier properties and can effectively prevent the penetration of oxygen and other gases. The combination of EVOH and PP greatly improves the barrier properties of the overall sheet, especially in food packaging that needs to be kept fresh for a long time.
The design of this composite structure gives PP/EVOH/PP sheet a significant advantage in maintaining the freshness and flavor of cheese sticks.
Project Challenges
Thermoforming packaging of cheese sticks needs to meet the following key challenges:
High oxygen barrier requirements: The milk fat and protein in cheese sticks are easily affected by oxygen, resulting in oxidation and deterioration, which in turn affects the taste and shelf life. Therefore, the packaging material needs to have extremely high oxygen barrier properties.
Moisture barrier requirements: Moisture is also an important factor affecting the quality of cheese sticks. Excessive moisture will cause the cheese to soften and affect the taste, so moisture needs to be effectively blocked.
Adaptability of thermoforming process: Since the manufacturer chose the thermoforming process for packaging, the forming performance of the material needs to be excellent, especially to ensure that it is not easy to break or deform during the forming process.
Food safety and environmental protection requirements: The packaging material must comply with international food safety standards, such as FDA and EU standards. At the same time, the material must have certain environmental protection properties and be recyclable.
Solution
Based on the above challenges, PP/EVOH/PP high barrier sheet was selected for thermoforming packaging:
Improved barrier performance: The addition of the EVOH layer greatly improves the gas barrier performance of the sheet, especially the barrier effect for oxygen. The experimental results show that cheese sticks packaged with PP/EVOH/PP sheets can be kept fresh longer at room temperature, and the shelf life of cheese sticks is extended by more than 30% compared with traditional packaging materials.
Moisture barrier performance: The PP layer not only provides good performance for thermoforming, but also has excellent moisture barrier performance, which can effectively prevent cheese from getting damp.
Forming and sealing performance: PP/EVOH/PP sheets show good plasticity and operability during thermoforming. On high-speed production lines, the material maintains a stable thickness and uniform sealing effect, avoiding leakage problems caused by uneven materials.
Food safety and recyclability: Both PP and EVOH are food-grade certified materials that meet global food packaging safety standards. In addition, the PP layer can be recycled separately, which increases the environmental friendliness of the packaging material.
Final results
After a period of production testing and market feedback, customers showed extremely high satisfaction with PP/EVOH/PP high barrier sheets. The main feedback is as follows:
Significant preservation effect: The cheese sticks can stay fresh for a long time in the package, avoiding changes in taste caused by oxidation.
Improved production efficiency: The material performs well in the thermoforming process, the yield rate is greatly improved, and the loss caused by unqualified materials is reduced.
Good feedback from consumers: Due to the strong and high barrier properties of the packaging shell, consumers can feel the freshness and high taste of the cheese sticks when opening the package, and customer satisfaction is greatly improved.
Customer feedback
“We have been looking for a packaging material that can extend the shelf life of cheese sticks while meeting our high standards for food safety. The use of PP/EVOH/PP high barrier sheet not only solves our challenges in oxygen and moisture barrier, but also greatly improves our efficiency on the production line and reduces the scrap rate. Consumers also have very good feedback on the new packaging, and the taste and freshness of the cheese sticks have been significantly improved. We are very satisfied with this cooperation.” ——Customer feedback
Conclusion
The multi-layer structure design of PP/EVOH/PP high barrier sheet makes it an ideal choice for thermoforming packaging of cheese stick shells. It can not only effectively block oxygen and moisture, extend the shelf life of cheese sticks, but also has good thermoforming performance and food safety. In future food packaging applications, this material will be more and more widely favored.
