Pre-bottling wine adjustments and specifications

This page provides a summary of typical pre-bottling wine analysis targets drawn from AGW’s Packaging Guidelines, several wine packaging operation’s client specifications and the minimal levels recommended by Rankine (1989). Note that these values will vary based on wine composition, as well as the intended filtration level, the intended shelf-life of a product or any intended export destination, and are thus meant as a general guide only. Some wineries will have lower tolerances or targets for some measures. Some countries will also require analysis to be done by a particular method (e.g. measuring sugar as reducing sugars versus as glucose+fructose enzymatic analysis).

If wine is to be packaged at a contract packaging facility, the facility may request that the wine is both heat and cold stable before it can be processed. The facility might also request the wine be cellar bright or below a certain turbidity (NTU) level before bottling, to prevent costly filtration blockages.

Wine can be bottled un-fined and unfiltered but may still be subject to other specifications such as turbidity. For example, if exporting wine to Ontario, Canada, the LCBO has the following turbidity specifications (Wine Australia, accessed November 2019):

Turbidity maximum

  • white wine: 5 NTU
  • red wine: 10 NTU
  • rosé wine: 8 NTU

with exceptions where the wine is unfiltered, as follows:

  • unfiltered white wine >12% alcohol and <6 g/L reducing sugars 6-10 NTU
  • unfiltered red wine >13% alcohol and <6 g/L reducing sugars 11-25 NTU
  • unfiltered rosé wine >12% alcohol and <6 g/L reducing sugars 9-15 NTU

The wine must be identified on the label as unfiltered (either on the label or a written declaration from the winery). Turbidity for red wine between 26 – 40 NTU is acceptable if all criteria are met and the wine has no visible sediment and the sample has an acceptable microbiological assessment (no evidence of microbiological activity during a sterility assessment)

When exporting wine to a particular country, it is vitally important to understand and adjust the wine specifications where required, as well as abiding by the allowed additives and processing aids, according to that country’s regulations. This information can be found within the ‘Wine Standards’ link within each country’s Export Market Guide on Wine Australia Export Market Guides website.

It is also advised that while not all countries have specifications for copper and/or calcium concentrations, winemakers should check the wine composition to ensure these concentrations are within acceptable levels, in order to prevent metal-induced hazes or calcium tartrate instabilities that are not removed during normal cold stabilisation techniques.

Typical pre-bottling wine analysis targets for key parameters

Analysis Units White table wine Red table wine Cask white wine Cask red wine Sweet wine
Free SO21 mg/L 28-32 28-32 40-55 30-45 15
Total SO21 mg/L 50-150 130-150 150
Ascorbic acid mg/L 50-100 100-150
Volatile acidity g/L <0.8
Dissolved oxygen mg/L <1.0
Dissolved carbon dioxide g/L 0.8-1.2 <0.5 <0.7 <0.7
Turbidity NTU <1.0 <1.0 <1.0 <1.0
Heat stability pass/fail pass pass pass pass pass
Cold stability pass/fail pass pass pass pass pass
Copper mg/L <0.50 <0.50 <0.50 <0.50 <0.50
Calcium mg/L <80 <80 <80 <80 <80

1Free sulfur dioxide concentration should be considered based on wine pH

Once a final wine blend has been prepared and final adjustments made, the wine may undergo analysis at key timepoints. A guide is presented in the table below. If wine is sent from a winery to a packaging facility, a holdback sample should be taken from the tanker after loading and stored until the wine is bottled, analysed, tasted and deemed acceptable. The receiving packaging facility will then conduct several checks to ensure the wine has not spoilt, been tainted or been diluted. The facility will generally also confirm the wine’s heat and cold stability.

The pre-bottling approval is where most analysis is performed and is signed off by all appropriate parties. The wine may then be analysed again if sent to a bottling line tank where final gas adjustments may be made.

As the wine is packaged in real time, the first bottles off the line are measured to check packaging set-up conformance, gas uptake, dilution, taints and any adjustments made if needed. A sample is taken some time into the bottling run, often after about 30 minutes, as a representative sample for post-bottling analysis. Holdback samples from the run are also often taken at this time and stored until the wine is in market. These samples can be used as a reference if a complaint is received about the wine in-market.

If there are any tank changes during a bottling run, then some of these steps may be repeated.

Analyses taken at different stages in packaging a wine

Tanker Pre-bottling approval Bottling tank First fill ½ hour into a bottling run
Sterility optional optional
Specific gravity
Free SO2
Total SO2
Ascorbic acid
Glucose +fructose
Volatile acidity
Dissolved oxygen
Dissolved carbon dioxide
Heat stability
Cold stability