Can Filling: Tunnel v. Flash Pasteurization ... What’s the difference?

July 06, 2023

Beverages go through many different phases and processes before they’re ready to be filled and put on store shelves. In today’s marketplace, a consumer has seemingly endless beverage and packaging options, each diverse in their physical and chemical states. In order to make your beverages safe for consumption, pasteurization is an essential process.

In the beverage industry, the pasteurization process destroys pathogens that cause spoilage, while increasing product shelf life, all while maintaining consistent quality and freshness.

“Pasteurization is generally recognized as a thermal process by which you heat up the product for a certain amount of time to reduce the level of pathogenic bacteria present in the product,” explained Torben Siggaard, VP of Operations.

Vobev offers two main types of pasteurization in its can filling processes for the purpose of killing microorganisms and pathogens in the beverage and can that can result in spoilage.

Tunnel Pasteurization

Tunnel pasteurization is a widely used method in beverage manufacturing to prolong shelf life and keep products fresh.

Tunnel pasteurization takes cans already filled with the beverage and runs them through a stainless steel tunnel where hot water is sprayed directly onto the finished product.

With tunnel pasteurization, the beverage is filled into cans at 40 °F, then the cans are moved into an enclosed tunnel. Once in the tunnel, they are sprayed with hot water to reach an internal temperature of 160 °F for 10 minutes. After the heating cycle, the cans are sprayed with cold water to cool them down to 100 °F, and dried before they’re packaged in a carton or tray.

“Carbonated, non-carbonated low viscosity, and pulpy products work well in a tunnel,” Siggaard explained. “The time and temperature relationship is very complicated and is very specific to each product. The exact process has to be defined by an official Process Authority organization. These organizations are recognized as the experts in thermal processes.”

Tunnel Pasteurization is an ideal way to pasteurize beverages that are in mass production. It’s also commonly used by drink manufacturers that ship their products regionally or nationally.

Flash Pasteurization

Flash Pasteurization is another type of pasteurization method offered at Vobev. It is also referred to as "high-temperature short-time" (HTST) processing, and is a method of heat pasteurization for certain types of beverages, including fruit and vegatable juices, wine and some dairy products.

The product is handled in a controlled and continuous flow and subjected to heat levels at 195 °F for 30 seconds. The beverage is filled into the can at 185 °F, seamed with an end, turned over for 40 seconds, cooled to 100 °F through a tunnel, before being packaged into a carton or tray.

The amount of heat imparted into the product during the elevated temperature and time period is expressed in Pasteurization Units (PU's). According to Del Vecchio et al, one pasteurization unit is the microorganism death that occurs in a product held at 140 °F for one minute.

A flash pasteurization system will accomplish an economical and microbially stable fill with minimal impacting to the flavor or color of the beverage.

“Flash [pasteurization] is done at a high temperature for a short amount of time,” Siggaard explained. “Tunnel [pasteurization] is performed at a lower temperature for a longer period of time.”

Flash pasteurization of liquid beverages typically uses a two or three stage plate heat exchanger with hot water as the medium. This allows controlled beverage flow and thin film heat transfer which assures the beverage will be evenly heated throughout the process.

“Higher viscosity, non-carbonated and/or non-pulpy products work well in Flash pasteurization,” Siggaard explained.

Siggaard says either pasteurization process is effective, but if the customer has a preference, they can request one process over another, depending on the requirements of their specific product.

Vobev offers customers a turnkey solution when it comes to beverage production, including aluminum can manufacturing, beverage filling and processing, and warehousing.

Vobev has the capability to fill a variety of different products, including waters, carbonated soft drinks, energy drinks, juices and more. Vobev also offers a variety of can sizes, including 7.5 oz sleek, 8.4 oz slim, 12 oz sleek, 12 oz standard, and 16 oz standard. We are flexible in the customer’s choice of how the product is packaged, including trays and cartons in both single and variety pack options.