Tunnel Pasteurizers,
Can Warmers & Cooling Systems
Pasteurization Primer
Introduction
CODI is a US-based tunnel pasteurizer manufacturer serving craft and industrial beverage producers. As such, we offer this guide as an introduction into the basics of pasteurization. If you already know what you are looking for, scroll to the bottom of this page for links to our product pages. Pasteurization is a thermal process used to stabilize beverages by controlling microbial activity and extending shelf life after filling. By carefully heating product for a defined time and temperature, pasteurization protects product integrity while maintaining flavor, carbonation, and package quality.
In modern beverage operations, pasteurization is most commonly applied after filling and sealing, ensuring the finished package is microbiologically stable before labeling, packing, and distribution.
Determining the correct pasteurization units for your beverage involves complex science, but you don't need to navigate it alone. The engineers at Codi are experts in this process and will guide you every step of the way.
FAQs for Pasteurization
What is a tunnel pasteurizer?
A tunnel pasteurizer is a continuous system that applies controlled heat over time to packaged beverages (cans or bottles) to reduce spoilage organisms and improve shelf life. Containers pass through temperature zones (heating, holding, cooling) so the thermal load is applied consistently without damaging product quality.
What's the difference between PU control and temperature control?
Temperature control holds the tunnel zones at set temperatures. PU control (Pasteurization Units) manages the cumulative thermal impact applied to the product over time (a function of temperature and exposure). PU control is preferred when you need consistent microbial stability across changing line speeds, ambient conditions, or product temperatures because it targets the process outcome, not just zone temperature.
Why would I need a container warmer?
You typically need a can warmer when cold packaged product is entering a downstream process where condensation or temperature shock causes issues—most commonly labeling, cartoning, or case packing. Warming reduces condensation on cans, improves label adhesion, and helps stabilize packaging performance in humid or cold-fill conditions.
How do I choose between a tunnel pasteurizer vs. a container warmer?
Choose a tunnel pasteurizer when you need verified pasteurization for shelf-life or microbial stability. Choose a warmer/cooler when your primary goal is temperature conditioning—reducing condensation, preventing thermal shock, or stabilizing packaging and downstream equipment—without targeting pasteurization.
Variables to Consider
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Target Pasteurization Units (PUs): Defines how much heat exposure your product requires for shelf stability. The ideal PUs for your product depend on its acidity, alcohol content, and microbial profile. Typically this is determined through industry guidelines or lab validation to ensure product stability and safety.
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Throughput: What are your production requirements? This affects conveyor width, spray density, and total tunnel length.
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Available Space: Simply put, how much space do you have in your facility for the pasteurizer and the conveyance?
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Container Type: Can, bottle, plastic or glass—each absorbs and releases heat differently. What size is your container?
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Heating Method: Steam, hot water loop, or instant hot water?
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Cooling Requirements: What is the ideal product temperature at discharge for downstream packaging or labeling?
Codi engineers will use your requirements to develop the optimal temperature ramp curve (consistent pasteurization while minimizing overexposure and dwell time) for your product.
Each Codi tunnel pasteurizer is engineered around your specific beverage and production requirements. We begin by working with your team to understand the product, target pasteurization units (PU), and line conditions, then configure the pasteurizer to deliver the required thermal load at your desired throughput. Below is an example of our calculation for a customer.
The Inverse Relationship
Higher temperatures require shorter exposure times to achieve the same pasteurization effect. This relationship is exponential, not linear, meaning small increases in temperature dramatically reduce the time needed to reach the same level of microbial control.
In practical terms, pasteurization is about delivering the right amount of heat for the right amount of time—not simply running everything hotter or longer. This gives engineers flexibility to design a process that protects product quality, carbonation, and packaging while still achieving the required level of stability.
This relationship is expressed as: PU = t × 1.393^(T − 60), where temperature has a compounding effect on the pasteurization outcome. By definition, 1 Pasteurization Unit (PU) equals holding a product at 60°C (140°F) for one minute. Different combinations of temperature and time can reach the same PU, allowing the system to be tuned to the specific beverage, container, and line speed.
Regeneration
Regeneration is a heat-recovery process that improves both energy efficiency and temperature stability in a tunnel pasteurizer. Instead of discarding heat after the pasteurization step, the system captures and reuses it.
In a regenerative pasteurizer, hot water leaving the heating zones—where containers are actively being pasteurized—passes through a heat-exchange section. That heat is transferred to the incoming cold water feeding the pre-heat zones.
As a result, containers begin warming before they reach the main heating section. This reduces the amount of energy required to reach target temperatures, smooths temperature transitions for the product and packaging, and helps maintain more consistent pasteurization performance. In simple terms, regeneration recycles heat that would otherwise be wasted, making the process more efficient and more controlled.
Simplified it is this:
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Hot water from the heating zones (where cans are being pasteurized) flows through a heat-exchanger section.
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That heat is transferred to the incoming cold water used in the pre-heating zones.
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This warms the incoming product before it ever reaches the main heating section—recycling heat instead of wasting it.
Here are the benefits of regeneration:
Energy Efficiency: Regenerative systems can reduce heating and cooling energy demand by up to ~60–70% compared to non-regenerative pasteurizers, depending on application and operating conditions.
Operating Cost Savings: By reusing heat instead of generating it, regeneration can deliver tens of thousands of dollars per year in utility savings for typical mid-size beverage operations.
Sustainability Impact: Lower energy consumption translates to a meaningfully reduced carbon footprint, supporting sustainability goals without changing product or throughput.
Now for a real example - below is a bird's eye view of a Codi pasteurizer under construction. You can see the piping that flows from one zone into another.
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Heating Methods
Tunnel pasteurizers require a reliable way to heat process water to precise temperatures and maintain those temperatures across multiple zones. There are three common approaches: steam heating, hot water reservoir systems, and instant (on-demand) hot water systems. Each has tradeoffs related to efficiency, control, footprint, and operating complexity.
Steam Heating
How it works: Steam is generated in a boiler and used to heat the pasteurizer water—either by direct steam injection into spray water or indirectly through a heat exchanger. The heated water is then circulated through the pasteurizer zones.
Advantages
Very fast heat-up capability
High thermal capacity, well suited for high-throughput lines
Proven, widely used technology
Effective at reaching high temperatures quickly
Considerations
Requires boiler infrastructure and steam distribution
Higher regulatory oversight (boiler permits, inspections)
Often requires licensed operators
Additional maintenance for steam traps, valves, and condensate handling
Best suited for: Facilities that already have steam available, operate at high volumes, or require rapid thermal response.
Hot Water (Reservoir-Based) Heating
How it works: Water is heated and stored in insulated tanks at set temperatures. These tanks feed the pasteurizer zones, often cascading water from hotter zones to cooler zones to improve energy efficiency.
Advantages
Lower operating pressure than steam systems
Stable, consistent temperature control
Reduced thermal shock—important for glass containers
Lower regulatory burden than steam
Can recover and reuse heat between zones
Considerations
Requires multiple water tanks
Larger physical footprint
Slower response to major temperature or throughput changes
More plumbing and components to maintain
Best suited for: Mid-size operations, glass bottle lines, or facilities with space for tanks and steady operating conditions.
Instant (On-Demand) Hot Water Heating
How it works: A centralized heat exchanger heats water only as needed. Instead of storing large volumes of hot water, the system produces hot water on demand and mixes it into each zone to achieve the target temperature.
Advantages
High energy efficiency (minimal standby losses)
Excellent temperature precision
Smaller footprint than tank-based systems
Simplified maintenance (fewer tanks and components)
Modern controls integrate well with PU-based control strategies
Considerations
Higher upfront capital cost
More sophisticated controls required
Single heat source introduces a potential single point of failure
Backup or redundancy planning may be required
Best suited for: New installations, energy-conscious operations, or facilities prioritizing efficiency, control, and ease of operation.
Let's Summarize:
Steam Heating
Fastest heat-up; ideal for high-throughput lines
Requires boiler infrastructure and regulatory oversight
Best when steam is already available onsite
Hot Water (Tank-Based)
Stable, gentle heating with good temperature control
Larger footprint and slower response to change
Well-suited for steady operations and glass containers
Instant Hot Water (On-Demand)
Highest efficiency and most precise control
Smaller footprint with modern controls
Higher upfront cost, lower operating complexity
Codi's Tunnel Pasteurizer, Warmer, Cooler Line Up
See below for Codi's overview of Tunnel Pasteurizer, Warmers and Coolers. The pasteurizer page will provide a more in depth look at some different configurations. Keep in mind that tunnel pasteurizers are application specific and highly customized. We are happy to walk you through the process and to provide a straightforward solution.
Steam Heating
Direct or Indirect Steam Injection
HOW IT WORKS
Steam is injected directly into spray water or used through external heat exchanges to rapidly heat the water in pasteurizer zones.
ADVANTAGES
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Rapid heating capability
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High heat capacity at 100*C+
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Efficient heat transfer
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External exchangers offer energy savings
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Proven, traditional technology
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High-pressure boilers need licensed operator
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Constant monitoring of safety devices
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Higher infrastructure requirements
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More regulatory management
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Potential condensate management
CONSIDERATIONS
Facilities with existing steam infrastructure, high-volume operations, or sites with on-staff boiler operations.
Best for:
Hot Water
Tank-Based Reservoir System
HOW IT WORKS
Pre-heated water reservoirs maintain set temperatures for each zone. Water cascades between tanks to maximize efficiency.
ADVANTAGES
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Lower pressure requirements
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Surplus water cascades to reduce water loss
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Reduces thermal shock for glass
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More stable temperature control
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Less regulatory complexity
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Requires multiple water tanks
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Larger footprint needed
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Slower heat-up tiumes
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More complex plumbing
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Higher maintenance (multiple tasks)
CONSIDERATIONS
Mid-size operations, glass bottle lines requiring gentle heating, facilites with space for tank installation
Best for:
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Requires multiple water tanks
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Larger footprint needed
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Slower heat-up times
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More complex plumbing
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High maintenance (multiple tasks)
Steam Heating
Direct or Indirect Steam Injection
HOW IT WORKS
Single centralized heat exchanger heats water to maximum temperature, then mixes with process water at each zone as needed.
ADVANTAGES
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Single heat source for entire system
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Most energy efficient design
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Easier maintenance (one system)
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Precise temperature control
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Modern control system
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Higher intial investment
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Requires sophisticated controls
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Single point of failure risk
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May need backup systems
CONSIDERATIONS
Facilities with existing steam infrastructure, high-volume operations, or sites with on-staff boiler operations.
