Packaging, Carbonation & Oxygen Control

Guide to packaging, carbonation, and oxygen control for homebrewers using Brewfather

Packaging is the final — and often most risk-laden — step in the brewing process. Done well, it preserves your beer's aroma, flavor, and carbonation exactly as you intended. Done poorly, it introduces oxidation, inconsistent carbonation, or contamination that erases weeks of careful work.

This page covers bottling, kegging, priming sugar calculations, carbonation target ranges, dissolved oxygen (DO) control, and how to use Brewfather's packaging tools.

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Before You Package

Always confirm fermentation is complete before packaging. Packaging prematurely — while residual sugar remains — results in overcarbonation and, in severe cases, burst bottles.

Checklist before packaging:

• Gravity is stable at or near predicted FG (two readings 24–48 h apart with no change)

• Diacetyl rest completed (if required)

• Cold crash completed (optional but recommended for clarity)

• All equipment cleaned and sanitized

• Oxygen exposure minimized throughout transfer

Brewfather Tip 🍺: Brewfather's Batch screen shows your expected FG alongside your logged readings. Use this to confirm stability before moving to the packaging step. You can also log your packaging date and method in the Batch notes.

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Bottling vs Kegging

Bottling

Bottling is the traditional homebrewer packaging method. Each bottle undergoes a mini secondary fermentation from priming sugar, producing CO₂ that carbonates the beer.

Advantages:

• Low equipment cost

• Portable and shareable

• Familiar process for most homebrewers

Disadvantages:

• Labor-intensive (sanitize, fill, cap each bottle)

• Higher oxidation risk during transfer and filling

• Longer wait time (typically 1–3 weeks conditioning at room temperature)

• Inconsistent carbonation if sugar is not evenly distributed

Common bottle types:

• 330 mL / 12 oz — standard serving size

• 500 mL — common European format

• 750 mL / 22 oz — bombers, sours, specialty beers

• Swing-top / Grolsch bottles — reusable but inspect gaskets regularly

Kegging

Kegging is the preferred method for consistency, speed, and oxygen control. Beer is transferred to a Cornelius (Corny) keg and force carbonated with CO₂.

Advantages:

• Far lower oxidation risk if purged correctly

• Carbonation in hours (forced) or days (set and forget)

• On-demand serving — no waiting for bottle conditioning

• No sediment in the glass

• Easy to adjust carbonation

Disadvantages:

• Higher upfront equipment cost (keg, regulator, CO₂ tank, lines, faucet)

• Not easily shareable without a draft system

• Requires refrigeration

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Carbonation Targets

Carbonation is measured in volumes of CO₂ — the amount of CO₂ dissolved relative to the liquid volume. One volume means the CO₂ would occupy the same volume as the beer at 0 °C and 1 atm.

Style carbonation ranges

Style	Volumes CO₂
Cask ales / Real ales	0.8–1.5
American stout, porter	1.7–2.3
American amber, pale ale	2.2–2.7
American IPA, DIPA	2.2–2.6
Hefeweizen	3.0–4.5
Pilsner, lager	2.4–2.7
Belgian witbier	2.7–3.3
Saison	2.8–3.5
Lambic / Gueuze	2.5–4.0
Specialty bière de champagne / highly sparkling beers	4.0+ (specialty process)

Source: Adapted from BJCP Style Guidelines (2021) and Noonan (1996).

A general "default" for most ales is 2.3–2.5 volumes. When in doubt, use the midpoint of your style's range.

Safety note: Standard longneck beer bottles are usually best kept around ~2.2–3.0 volumes. Carbonation above that typically requires heavy Belgian/champagne-rated bottles and closures.

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Bottle Conditioning (Priming Sugar)

How it works

When priming sugar is added to flat, fully fermented beer and bottles are sealed, residual yeast ferments the sugar, producing CO₂ in a sealed environment. The gas dissolves into the beer, creating carbonation.

Residual CO₂

Beer already contains dissolved CO₂ from fermentation. The amount depends on the highest temperature reached during and after fermentation (not the final temperature). This residual CO₂ must be accounted for in your priming calculation — otherwise the beer will be over-carbonated.

Priming sugar calculation (simplified)

The formula basis:

Sugar needed = (Target CO₂ − Residual CO₂) × Batch volume × Sugar factor

Different priming sugars have different fermentability and sugar content:

Priming Sugar	Approximate equivalent to 1 g Sucrose
Sucrose (table sugar)	1.0 g
Dextrose / corn sugar (monohydrate)	1.09 g
Dry Malt Extract (DME)	~1.47 g
Honey	~1.25 g (variable — depends on composition)

Brewfather Tip 🍺: Use Brewfather's built-in Carbonation Calculator in the Batch screen. Enter your batch volume, target CO₂ volumes, fermentation temperature (highest temp beer reached), and priming sugar type. Brewfather automatically calculates the correct weight of sugar, accounting for residual CO₂. You can also set a default carbonation target per style in your Recipe settings.

Priming best practices

1. Dissolve priming sugar in a small amount of boiling water (e.g., 250 mL), boil for 5 minutes, cool, and add to the bottling bucket before siphoning beer on top to ensure even distribution.

2. Condition at room temperature — 18–22 °C (64–72 °F) — for 2–3 weeks to allow carbonation to develop fully.

3. Test a bottle at 1 week and 2 weeks: chill a single bottle and open to check carbonation level.

4. Chill before opening — CO₂ is more soluble at lower temperatures and beer will be less foamy.

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Force Carbonation (Kegging)

Force carbonation involves pressurizing the keg with CO₂ to dissolve gas into the beer. Two common approaches:

1. Set-and-forget

Set the regulator to your target serving pressure (based on temperature and desired volumes) and wait ~7–14 days. CO₂ slowly absorbs into the beer. This produces the most stable and consistent carbonation.

2. Fast carbonation (burst carbonation)

Apply ~20–30 PSI for 12–36 hours, then reduce to serving pressure and let the keg stabilize. Useful for rapid turnaround, but easier to overshoot than set-and-forget.

Caution: Over-carbonating with burst carbonation is easy. Vent and taste-test frequently.

CO₂ pressure / temperature chart

The relationship between serving temperature, pressure, and carbonation volumes follows Henry's Law:

Serving Temp	~2.3 vol CO₂	~2.5 vol CO₂	~3.0 vol CO₂
1 °C (34 °F)	~7 PSI	~9 PSI	~14 PSI
4 °C (39 °F)	~10 PSI	~12 PSI	~17 PSI
7 °C (45 °F)	~13 PSI	~15 PSI	~21 PSI
10 °C (50 °F)	~15 PSI	~18 PSI	~24 PSI

Values are approximate. Use a dedicated CO₂ chart or calculator for precision.

Brewfather Tip 🍺: Brewfather's Carbonation Calculator supports both bottle priming and forced carbonation. For kegging, enter your keg temperature and target volumes to get the recommended serving pressure.

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Dissolved Oxygen & Oxidation Control

Oxygen is the enemy of packaged beer. Even small amounts of dissolved oxygen (DO) on the cold side of brewing cause:

• Staling — papery, cardboard, oxidized flavors

• Color darkening

• Loss of hop aroma (especially relevant for IPAs and NEIPAs)

• Shortened shelf life

DO thresholds

DO Level	Impact
< 50 ppb (0.05 ppm)	Excellent (common commercial target zone)
50–100 ppb	Good, but hop-forward beers can fade faster
100–250 ppb	Elevated risk of detectable staling over weeks
> 250 ppb	High risk of rapid staling

Most homebrewers cannot measure DO directly without expensive equipment. The practical approach is process discipline to minimize exposure.

Oxygen control best practices

Transfers:

• Purge all vessels with CO₂ before transferring beer

• Keep liquid below liquid — avoid splashing; use a silicone transfer tube pressed to the bottom of the receiving vessel

• Purge transfer hoses by flushing with CO₂ or StarSan before use

Kegging:

• Purge the keg with CO₂ (pressurize and vent 3–4 times) before filling

• Fill from the bottom with the dip tube, not the top

• Purge headspace immediately after filling

Bottling:

• Use a spring-loaded bottle filler (racking cane) to fill from the bottom

• Fill to the lip with the bottling wand inserted; when the wand is removed, it leaves typical headspace

• Fill quickly and cap immediately

• Minimize pouring/splashing at every step

Dry hopping:

• Hop additions post-fermentation introduce oxygen via the vessel opening

• Purge the dry hop with CO₂ before adding if possible

• Consider adding hops via a pressurized hop rocket or through a closed system

Brewfather Tip 🍺: Log your packaging process in the Brewfather Batch screen — note whether you purged lines and vessels, your transfer method, and any concerns. This creates a record to correlate with flavor notes at drinking time and improve your process for future batches.

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Spunding (Natural Carbonation in Kegs)

Spunding is the practice of sealing the fermenter or keg with a spunding valve at a calculated point in fermentation, trapping naturally produced CO₂ to carbonate the beer. This:

• Eliminates the need for priming sugar

• Can produce very fine, stable carbonation

• Reduces oxidation risk (beer never de-pressurizes between fermenter and keg)

How to spund:

1. Monitor gravity during fermentation

2. When ~3–5 gravity points remain above FG (common starting point; adjust by temperature/target volumes), attach a spunding valve set to your target carbonation pressure

3. Allow fermentation to complete under pressure

Spunding pressure targets mirror force carbonation targets — use a CO₂ pressure/temperature chart at your fermentation temperature.

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Common Packaging Problems

Problem	Likely Cause	Solution
Flat beer (bottles)	Too little priming sugar; yeast not viable; bottled at too low temp	Re-prime with dissolved sugar; store warmer
Overcarbonated bottles	Too much priming sugar; bottled before FG reached	Open carefully; refrigerate; consider re-sealing after venting
Gushing bottles	Wild yeast or bacterial contamination	Sanitation review; discard batch if severe
Oxidized/stale flavor	Oxygen introduction during transfer or packaging	Review cold-side oxygen practices; purge vessels with CO₂
Foam in keg (excessive)	Over-carbonated; serving lines too short/warm; dirty lines	Reduce pressure; use longer serving lines; clean keg lines
Sediment in bottles	Bottle conditioning yeast — normal	Chill and pour carefully; leave last few mL in bottle

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Packaging Checklist

Use this checklist before every packaging session:

• Gravity confirmed stable at target FG

• Beer has completed diacetyl rest if needed

• All equipment cleaned and sanitized (bottles, caps, keg, lines, filler)

• CO₂ tank has sufficient pressure

• Receiving vessel purged with CO₂

• Priming sugar calculated and prepared (bottling) or regulator set (kegging)

• Transfer hoses flushed / purged

• Batch logged in Brewfather with packaging date and method

Brewfather Tip 🍺: Brewfather's Batch screen has a dedicated Packaging step where you can log the packaging date, method (bottles/keg), carbonation target, and packaging notes. Use this religiously — it's invaluable for understanding shelf life, identifying oxidation patterns, and improving your cold-side process over time.

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Sources

• Palmer, J. (2017). How to Brew (4th ed.). Brewers Publications.

• Noonan, G. (1996). New Brewing Lager Beer. Brewers Publications.

• Kunze, W. (2014). Technology Brewing and Malting (5th ed.). VLB Berlin.

• BJCP Style Guidelines (2021). BJCP Style Guidelines

• American Homebrewers Association — A Balancing Act: How to Balance Your Home Draft System

• Brewers Association — Draught Beer Carbonation

• Fix, G. (1999). Principles of Brewing Science (2nd ed.). Brewers Publications.

• Huige, N. & Henke, J. (1994). "Dissolved oxygen and beer quality." MBAA Technical Quarterly, 31(1).