Twist Off Caps: A versatile and economical solution for sealing glass jars

Twist-off caps consist of a metal shell and an inner layer of plastic material that ensures sealing and protects the contents. Their distinguishing feature is the presence of side lugs that latch onto the jar's thread, enabling quick and secure closure. Unlike continuous-thread lids, twist-off caps require special care during closure to avoid errors that might compromise their effectiveness.

One of the most frequent mistakes is over-tightening the cap beyond the required limit. Unlike screw caps, where the end of the thread signals closure, twist-off caps only need to be tightened until a slight resistance is felt. Forcing beyond this point can deform the metal lugs and damage the sealing mechanism.

An overtightened cap can:

• Prevent vacuum formation.
• Damage the internal and external coating, leading to rust.
• Ruin the jar's thread, rendering it unusable.

Practical Tip: When using household vacuum devices, such as vacuum bells, ensure the cap is properly tightened but not excessively so.

Filling jars beyond the indicated capacity is another common issue. Jar capacity is designed to leave headspace below the opening. Filling to the top prevents air from escaping during sealing, obstructing vacuum creation.

Technical Note: The capacity in milliliters reflects the volume of water a container can hold. However, for foods with different densities, such as honey or jam, the actual weight may vary. For instance, a 390 ml honey jar may hold 500 g of product.

For effective sealing, the contact between the jar rim and the cap must be flawless. Residues like oil, water, or food particles can compromise hermeticity. Even small particles, like seeds or food fragments, can deform the cap, allowing air to enter.

Best Practice: Always ensure the jar rim is dry and clean before sealing.

Vacuum sealing is essential to preserve food and prevent the growth of harmful microorganisms. If using twist-off caps with a safety button (click-clack), you can easily check for vacuum presence:

• During the process, the button is pressed down due to pressure.
• Upon opening the jar, the button pops up with a characteristic "click."

If no button is present, specialized equipment can apply consistent pressure to ensure vacuum sealing.

Some difficulties may arise from jar size or compatibility between the cap and jar opening. For example, single-serve jars with smaller openings may require specifically designed caps to ensure uniform pressure. If you frequently encounter vacuum issues with small jars, try using slightly larger jars or consider dedicated machinery.

Proper use of twist-off caps requires attention to detail, which can make a significant difference. Over-tightening, improper filling, or residue presence can compromise sealing and food safety. By following these guidelines, you can safely and effectively package your products, preserving their quality over time.

Remember, food safety starts with good practices—taking a few extra minutes during preparation is better than risking the final result.

In the food industry, where maintaining quality on a large scale is crucial, Tenco offers two innovative solutions for sealing twist-off caps: the Vacuumcap and the Easycap.

• The Vacuumcap is a vacuum sealer designed to seal jars under vacuum conditions, preserving the freshness and quality of the product. This system removes air from inside the jar, creating a mechanical vacuum during sealing. It is especially recommended for delicate products like non-pasteurized sauces and oil-preserved foods.

• The Easycap, on the other hand, is a versatile bench-top pneumatic capper suitable for various twist-off cap sizes. With a production capacity of up to 600 pieces per hour, this machine uses a pneumatic system to precisely regulate the pressure for each cap, ensuring uniform and consistent sealing. This approach minimizes contamination risks and guarantees hermetic sealing, making it ideal for maintaining high safety standards and long-term product preservation.

Both solutions represent excellence in capping technology, meeting diverse production needs with reliable performance and impeccable quality.

Twist-off caps remain a versatile and safe solution for food packaging, whether in artisanal production or industrial lines. Ensuring accurate sealing is essential for delivering a high-quality product to the end consumer. With Tenco equipment, companies can rely on precise and dependable solutions that preserve the freshness and integrity of products until consumption.