Process
Pasteurize or Cold-Fill? How to Decide Based on What's in the Can
Every drink that leaves a filler either gets heat-treated after sealing or goes out the door as-is. The right call depends on what's in the can: how much alcohol, how much acid, how much sugar, and how far the product has to travel before somebody drinks it. Here's how to work through it before you lock a formula and book a run.
The two paths, in plain terms
Fill without heat treatment (cold-fill). The liquid is blended, filtered, carbonated if needed, and sealed. From there, the recipe itself has to keep the product stable: alcohol, acidity, carbonation, low oxygen, and sometimes preservatives.
Tunnel pasteurization. Sealed cans travel through a tunnel of heated water sprays, hold at temperature, then cool back down. Heat reaches the liquid inside the sealed package, so the drink and the can interior get treated together. The dose is measured in pasteurization units (PU), and your formula should spell out the target.
At Tennessee Hills, those are the two options we run. We don't offer hot-fill or flash pasteurization, so if a formulator's spec calls for either, raise it early and we'll talk through whether a tunnel process gets you to the same place. For the mechanics, read our guide to tunnel pasteurization.
Six questions that decide it
Work through these with your formulator. Each one pushes the answer one way or the other.
- How much alcohol is in it? Full-proof spirits generally don't need pasteurization, because the alcohol itself keeps microbes from getting a foothold. As ABV drops into canned-cocktail and seltzer territory, alcohol still helps but carries less of the load on its own.
- How acidic is it? Lower pH makes life harder for most spoilage organisms and for many pathogens. Acidity also determines which process rules apply to some non-alcoholic drinks. Your formulator, and a process authority where one is required, should set your pH target and tell you what process it calls for.
- Is there anything for yeast to eat? Sugar, juice, fruit purée, and honey are all fuel. If a stray yeast cell survives into a sweet, low-alcohol can, it can restart fermentation on the shelf. That means off flavors, rising pressure, and in bad cases, bulged or burst cans.
- Is there a preservative system? Some brands rely on preservatives to stay shelf-stable without heat. Others want a cleaner label. Tunnel pasteurization can make a product shelf-stable without preservatives, which is often the deciding factor for brands chasing a short ingredient list.
- Is it carbonated? Dissolved CO2 and the low oxygen that comes with it slow down some spoilage organisms. Carbonation helps, but on its own it won't stop a yeast problem in a sugary drink.
- Where will it live, and for how long? A drink that ships cold to a few local accounts and sells through fast carries different risk than one sitting in a hot warehouse for months before it reaches a shelf three states away. Wider distribution and longer shelf-life targets push toward heat treatment.
If there's sugar in the can and not much alcohol standing guard, plan on tunnel pasteurization until your formulator and the data say otherwise.
Decision table: drink profile to process
Treat this as general guidance. Your formulator makes the final call for your specific recipe, and where a process authority is required, their letter governs.
| Drink profile | Typical approach | What we test |
|---|---|---|
| Full-proof spirits (750ml glass, 50ml minis) | No heat treatment; the alcohol does the work | Proof/ABV |
| Spirit-forward canned cocktail, little or no sugar or juice | Often filled without heat treatment; confirm with your formulator | ABV, pH, CO2 volumes, DO |
| Lower-ABV RTD with juice, fruit, or sugar | Usually tunnel pasteurized | ABV, pH, Brix, DO, PU, shelf-life trending |
| Hard seltzer or flavored malt beverage | Depends on residual sugar, yeast risk, and distribution; many go through the tunnel for ambient storage | ABV, Brix, CO2 volumes, DO, PU |
| Beer | Varies; many craft beers ship unpasteurized with cold storage and freshness dating, wider footprints may add pasteurization | ABV, CO2 volumes, DO, PU if pasteurized |
| Craft soda or sweetened sparkling drink | Tunnel pasteurization or a preservative system, chosen by your formulator | pH, Brix, CO2 volumes, PU |
| Unsweetened sparkling water | Often filled without heat treatment when ingredients are low-risk; confirm | pH, CO2 volumes, DO |
| Energy and functional drinks | Typically tunnel pasteurized; ask your formulator how heat affects each active ingredient | pH, Brix, PU, shelf-life trending |
| Hemp/THC beverages | Follows the logic of the base drink | Base-drink tests plus THC potency |
What heat changes, and what it doesn't
Pasteurization buys stability and range. It also puts heat into the liquid, and some flavors notice. Delicate citrus, fresh herbs, and some fruit notes can shift a little. A good formulator builds for the process from day 1, so the version you approve at the bench is the version that comes out of the tunnel.
Cold-fill keeps the liquid closer to its bench taste, but it puts more weight on the recipe and on clean production. Sanitation, oxygen control, and tight specs matter more when there's no heat step to back you up.
Either way, heat won't fix a bad formula. A drink with high dissolved oxygen will still stale and fade, pasteurized or not. That's why deoxygenation and nitrogen dosing belong in the same conversation as pasteurization.
How our lab verifies the choice
A process decision only counts if you can prove it held. Our in-house lab, staffed by trained QC techs, checks the numbers that tell you whether a product is stable:
- pH to confirm the batch lands inside the range your formula sets.
- Brix to track sugar content and catch a batch that's drifted sweeter than spec.
- ABV/proof for label accuracy and to confirm the alcohol is doing its share.
- Dissolved oxygen (ppb) because oxygen drives flavor loss and supports some spoilage organisms.
- CO2 volumes to confirm carbonation targets and flag pressure changes.
- PU verification on tunnel-pasteurized runs, so you know the heat dose hit the target your formula set.
- Remote shelf-life trending that tracks pH and DO over time, so a slow drift shows up in the data long before it shows up in a customer complaint.
Every result ties back to your lot numbers in our NetSuite traceability system, alongside ingredient lots, production timestamps, and date codes. If a question ever comes up about a specific pallet, the answer is on file.
How we'd handle it at Tennessee Hills
We start with your formula. Your production-ready spec should define the process, including whether the product gets pasteurized, the PU target if it does, and the pass/fail ranges for pH, Brix, CO2, and DO. If you don't have a formulator yet, we'll recommend vetted third-party formulators we trust.
From there, it runs on the same Bristol line where we can our own beer: deoxygenation, carbonation through the carbo-cooler, nitrogen microdosing, 12oz sleek cans at 50 cans per minute, and tunnel pasteurization when the drink calls for it. Our lab checks the numbers your spec calls for, and we encourage you to be on-site for the first one to approve the liquid, the test docs, and the date coding.
Not sure which side of the line your drink falls on? Bring your formula and your distribution plan, and we'll work through it with you. Request a quote or book a facility tour, or grab the free Co-Packing Blueprint to get your spec ready first.
Want to see it running? Book a tour of our Bristol plant, walk the line your product would run on, and talk specs over lunch off the Smokestillery smoker.
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