Components of Total Package Oxygen at Bottling
TPO = OIR + HSO + DO
OIR = Oxygen Initial Release from the closure due to compression during bottling
see Closure contributions to total package oxygen includes initial release as well as transmission over time for more details
HSO = Headspace Oxygen
A bottling audit conducted by the AWRI found 60% of TPO is from HSO1
Depends on ullage (volume of fill) and bottle shape/size
Reported HSO values ranged from 0.85 – 2.5 mg depending on the volume of the wine2
Vacuum fillers remove 60-80% of the oxygen from headspace2,3
Cylindrical closures applied without vacuum increases HSO by 1 mg/L1
Use of inert gas in all filling tanks, hoses, etc… decreases HSO
Corks take up more space that screwcaps, leaving less headspace, and therefore contribute less HSO.
DO = Dissolved Oxygen
During pre-bottling activities (cold stabilization, racking/transfer, filtration) and bottling processes themselves, oxygen becomes dissolved in the wine.3
DO is highest at the top of the tank (where the wine interfaces with air) and lowest at the bottom of the tank.3
Best practices keep DO in the tank below 1.0 mg/L for red wines and 0.5 mg/L for white wines before bottling
Sparging the wine with inert gas (nitrogen, CO2) removes dissolved oxgyen1
Within bottling run, DO in the bottle shows a U-shaped curve, with the highest DO at beginning and end and the least DO in the middle2 of the bottling run. Small batches of wine have less wine in the middle of the run, and are more likely to have high DO.
Slow bottling and interruptions during the bottle run increase DO pickup.2,4
References
(1) Oxygen pick-up during packaging - understanding total package oxygen. AWRI. https://www.awri.com.au/industry_support/winemaking_resources/storage-and-packaging/packaging-operations/oxygen-pick-up-during-packaging-understanding-total-package-oxygen/.
(2) Letaif, H. Key Points of the Bottling Process. Wine and Vines 2016, No. May 2016.
(3) Wong, D. P. Taking Control of Total Package Oxygen. Wine Business Monthly 2020, No. March 2020.
(4) Understanding Total Package Oxygen; Fact Sheet: closures and packaging; AWRI, 2019. https://www.awri.com.au/wp-content/uploads/tpo_fact_sheet.pdf.
