Alternatives to glass for wine packaging: Can plastic perform?(2)
o The mono-layer PET bottle allowed oxygen to transfer into the bottle easily, and oxidized the white wine.
o Bag in Box® and the 18.5cL multi-layer PET bottle displayed oxygen transfer at a rate not as high as the mono-layer PET bottle, however still significant and could alter the sensory characteristics of the wine.
o Glass and the 75cL multi-layer PET bottles were the best barriers to oxygen for white wines.
Carbon Dioxide:
The initial concentration of carbon dioxide was 0.9mg/L.
Bag in Box® and the 18.5cL mono-layer PET bottle had a low CO2 concentration of <0.5g/L.
For all other packaging types, the CO2 concentration ranged from 0.5g/L to 1g/L.
CO2 concentrations were relatively constant for glass bottles and the multi-layer PET bottles.
Sulfur Dioxide:
Note: if free SO2 drops below 10mg/L, white wine will be subject to oxidation and increased browning.
Glass bottles and multi-layer PET bottles contained over 10mg/L free SO2 after 12 months of storage.
The other packaging types had free SO2 levels ranging from 3 to 7mg/L.
OD420:
Note: a decrease in SO2 levels will accelerate the oxidation of a white wine and change the color hue.
The 18.5cL mono-layer PET bottles resulted in clearly oxidized wine after 12 months in storage (OD420 value of 0.155).
Wine from both the 75cL mono-layer PET bottles and the 18.5 multi-layer PET bottles had OD420 values reaching 0.120, which indicates oxidation.
For all other packaging types, there was no sign of oxidation and wine color appeared normal after 18 months of aging.
Volatile Compounds & Oxidation Markers:
3-sulfanylhexan-1-ol decreased in all packaging types after 6 months of aging.
Glass bottles tended to preserve 3-sulfanylhexan-1-ol levels better than the other packaging types.
Choice of packaging influenced the dissolved oxygen level in the bottles and also the redox potential of the wine.
There was an increase in oxidation markers:
o Levels of methional, phenylacetaldehyde, and sotolon were found from highest to lowest in the 18.5 mono-layer PET, 75cL mono-layer PET, Bag in Box®, 18.5cL multi-layer PET, and 75cL multi-layer PET bottles.
o With these packaging types, oxidation markers were found to be above their perception thresholds.
Only aging in the 75cL glass bottles appeared to keep the wine free from oxidation markers.
Sensory Analysis:
Sensory analysis indicated differences in sensory attributes depending upon which type of packaging was used.
o After 6 months, sauvignon character and color intensity was altered in the mono-layer PET, 18.5cL multi-layer PET, and Bag in Box® bottles. This same result was found at 12 and 18 months (and included all mono- and multi-layer bottle types).
White wine sensory quality is highly influenced by packaging type, and is noticeable by 6 months of aging.
Red Wine
Oxygen:
Only Bag in Box® showed increased levels of dissolved oxygen.
All other packaging types showed normal levels of dissolved oxygen for red wine.
Carbon Dioxide:
The initial level of CO2 after bottling was 0.9g/L.
There was a linear decrease of CO2 in the glass and multi-layer PET bottles over time.
o Since CO2 cannot permeate through glass, this decrease was due to gas transfer through the screw cap closure.
The CO2 content was higher in glass bottles than all other packaging types, and was still at acceptable levels after 18 months of aging.
For Bag in Box®, the CO2 levels quickly decreased in the first three months of aging, however remained stable through the rest of the experiment (0.5g/L).
Sulfur Dioxide:
There were decreases in the SO2 levels of wine in all packaging types, though the decrease was less for the glass bottles.
SO2 levels in all packaging (except the glass bottles) was 10mg/L after 18 months of aging (this value is low).
OD420:
The color of the red wines were not influenced by the packaging type.
Sensory Analysis:
There were no differences in any of the sensory attributes for any of the red wines, regardless of packaging type.
Conclusions
Overall, I thought the results of this study were very interesting and potentially important for finding alternative packaging for wine that is both environmental friendly and able to preserve the quality of the wine. It seems as though PET bottles (particularly mono-layered PET bottles) were the less effective in preserving the quality of white wines, as a result of rapid oxidation. The sensory analysis also showed marked decreases in wine quality of bottles created with any packaging material other than glass. I believe based on these results, it’s safe to say that the standard glass bottle is still the best vesicle for storing white wines for over 6 months of time.
The twist in this study, to me, came with the analysis of the red wines. According to the results of this study, no matter what type of packaging used, there were no degrading effects on the overall quality of the red wine. A glass bottle? A plastic bottle? A Bag in Box®? Based on what was found in this study, it doesn’t matter; the wine should taste just fine! Perhaps I’m just naïve, but that blew my mind a little bit!
Of course, more research needs to be done on more varietals of wine, to confirm if all white wines are sensitive to packaging type and all reds unfazed. All in all, I found the results of this study very interesting—what I expected for whites, but totally out of left field for the reds!
What do you all think about this? I’d love to hear your thoughts! Please feel free to comment below!
