Can Bag-in-Box Plastic Pouches Compete with Glass Bottles for Wine Quality Over Time?

As many of you may already be aware, wine can come in a variety of different packaging types.  While glass is the most traditional packaging material used for wine, there has been a lot of progress made recently in regards to attempting to identify and create new types of packaging that can perform similarly to glass in terms of protecting the wine, many with environmental awareness and sustainability in mind.

Studies and speculation have shown, however, that the type of packaging used may influence the overall quality of the wine.  All else being equal, will the same wine taste different if bottled in glass and at the same time bottled in a plastic bag-in-box pouch?  Does it make a difference what type of plastic is used?

Photo By MichaelGG at en.wikipedia [Public domain], from Wikimedia Commons

Photo By MichaelGG at en.wikipedia [Public domain], from Wikimedia Commons

Does one type of plastic outperform all the others while also being a competitive adversary for glass?  Is plastic a bad idea for wine?  As a side note: I do have many qualms with plastic—most of which are environmental, however, casting that aside for the moment, this post is simply going to discuss plastic as an alternative to glass in wine storage in terms of wine quality and not environmental footprints (though this IS a very important discussion to be had).

There are several different types of plastics used in alternative packaging for wines, with the bag-in-box variety being fairly common to most of the wine consuming regions of the world.  For example, according to the 2008 Australian Bureau of Statistics, more than half of the wine consumed in Australia is packaged in bag-in-box vessels.  Basically, the bag-in-box consists of a welded double plastic bag placed inside a cardboard box for easy storage.  The types of plastics used in these bags can vary, though the outer bag is commonly made with a plastic laminate plus PET, while the inner bag is commonly made with a low density polyethylene (LDPE) or ethylene vinyl acetate (EVA).  The bags are then filled with wine via a vacuum, and any space remaining in the bag is filled with an inert (non-reactive) gas such as nitrogen.  As the wine is poured, the bag collapses in on itself, thus preventing oxygen from entering the container and prematurely oxidizing the wine.

One downside to this type of plastic packaging, strictly from a wine quality perspective, is that some plastics are known to absorb volatile compounds from the liquid within them, thus taking some of the

Photo By Janusz88pl; Inc ru [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Photo By Janusz88pl; Inc ru [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

aromatics out of the wine, potentially lower the overall quality of the wine.  The absorption of these volatile compounds into this kind of plastic packaging also changed depending upon the pH of the liquid inside, as well as the temperature.  These concerns led the authors of the study presented today (printed online prior to print) to examine and analyze the chemical and sensory changes in a dry white wine that had been packaged in glass and in plastic bag-in-box pouches at different time points through a period of 6 months aging time.

 

 

Methods

The white wine used in this experiment was from Vilana variety grapes (Vitis vinifera) grown by the Michalaki winery in Iraklion, Crete, Greece in 2011.   Finished wine was divvied up into three different treatments: one for bottling in glass bottles, and the others for bottling in bag-in-box pouches lined with either LDPE or EVA.  All wine was made from grapes grown at the same vineyard during the same vintage, theoretically under the same conditions.

Bag-in-box wines (5L) were filled first with non-reactive nitrogen to remove oxygen, and then filled with wine.  Glass bottles (1.5 L volume) were dark green and were closed via a screw cap.

Wine samples were collected at 3, 30, 60, 90, and 180 days after bottling/storage.  The following were measured and analyzed for all wine samples: ethanol, titratable acidity, volatile acidity, total SO2, free SO2, pH, color, oxygen permeability, and volatile compounds.

Sensory analyses were conducted by a 7-person panel with wine sensory testing experience.  Specifically, panelists were faculty from the Laboratory of Food Chemistry and Technology in the Department of Chemistry at the University of Ioannina in Greece.  Panelists evaluated wines for appearance/color, odor, and taste on a 1-5 scale (5 being the best, 1 being the worst).  3.5 was chosen as the score that indicated the lower limit of acceptability of a given sample.  Panelists were presented with 3 wines at one time (blind) and asked to evaluate and score each sample.

Results

Titratable Acidity (TA)

  • There was no effect of packaging type on TA up to 60 days of storage.
  • Between 60 and 180 days of storage, TA increased significantly wine stored in LDPE and EVA pouches compared with wine stored in glass.

Volatile Acidity (VA)

  • VA was not affected by packaging type over the entire 180 day storage period.

pH

  • pH was not affected by packaging type over the entire 180 day storage period (range: 3.35-3.38)

Ethanol

  • Ethanol content was not affected by packaging type over the entire 180 day storage period (11.8% v/v).

Total and Free SO2

  • Total SO2 decreased over the storage period for all packaging types.
  • Total SO2 decreased significantly more in wine stored in either plastic pouch than it did in the glass bottles.
    • Total SO2 loss in glass after 180 days: 26%
    • Total SO2 loss in either plastic after 180 days: 40% (each)
      • The greater SO2 loss in the plastic MIGHT be due to the increased oxygen ingress from the plastic spigot/faucet on the pouch, though this was not explicitly tested.
  • Free SO2 decreased significantly more in wine stored in either plastic pouch than it did in the glass bottles.
    • Free SO2 loss in glass after 180 days: 32%
    • Free SO2 loss in either plastic after 180 days: 83% (each)
  • Free SO2 values below 10mg/L typically indicate risk of increased oxidation in the wine.  This value was reached for both plastic pouches 2 months after bottling.

Color

  • Absorbance at 420nm (an accepted indicator for spoilage in wine) increased for all packaging types with storage time.
  • Up through 90 days, there were no significant differences in absorbance between any of the packaging types.
  • After 180 days, absorbance significantly increased by 43% in wine stored in glass bottles and 62% in wine stored in both of the plastic pouches.

Volatile Compounds

  • 32 volatile compounds were identified in the wine used in this experiment.
  • Wine stored in plastic pouches showed greater losses of volatile compounds compared with wines stored in glass bottles.
    • Wines stored in LDPE pouches showed greater losses of volatile compounds compared with wines stored in EVA pouches (trend was amplified with storage temperature).

Alcohols

  • 1-propanol (“associated with sweet taste”) decreased in all wines over time.
    • Losses were higher in wines stored in plastic pouches compared with glass bottles.
  • Isobutanol (“pleasant aromatic notes”) decreased in all wines over time.
    • Losses were higher in wines stored in LDPE pouches compared with EVA pouches and glass bottles.
  • 3-methyl-1-butanol and 2-methyl-1-butanol decreased in all wines over time.
    • Losses were higher in wines stored in LDPE pouches compared with EVA pouches and glass bottles.
  • Butane-2,3-diol (“sweet and sour tones”) increased similarly in wines in all packaging types over time.
  • 1-Hexanol (“coconut flavors”) decreased similarly in wines in all packaging types over time.
  • 3-methyl-thio-propanol (“potato/cauliflower notes”) decreased similarly in wines in all packaging types over time.
  • 2-phenylethanol (“floral and rose notes”) increased similarly in wines in all packaging types over time.
  • After 180 days, wine stored in glass bottles contained the largest concentrations of alcohols compared with the wines stored in plastic pouches.

Esters

  • Ethyl acetate increased similarly in wines in all packaging types over time.
  • Ethyl lactate (“coconut and creamy notes”) increased in all wines, though between the two plastic pouches, the increase was significantly higher in wines stored in EVA (19%) compared with wines stored in LDPE (7%).
  • 2-ethyl furanate increased similarly in wines in all packaging types over time.
  • Diethyl succinate increased similarly in wines in all packaging types over time.
  • Isoamyl acetate (major contributor to aromatic profile) decreased similarly in wines in all packaging types over time.
  • Ethyl propionate (“floral notes”) remained constant in wines in all packaging types over time.
  • Ethyl butyrate (longer carbon chain) was significantly higher in wines stored in glass bottles compared with wines stored in plastic pouches.
  • Ethyl hexanote and ethyl octanote (major contributors to aromatic profile) were significantly lower in wines stored in plastic pouches compared with wines stored in glass.
    • Ethyl octanote decreased significantly more in LDPE pouches compared with EVA pouches.
  • Hexyl acetate, methyl octanoate, 2-phenyl ethyl acetate, ethyl nonanoate, ethyl decanoate, and isoamyl octanoate all decreased significantly more in LDPE pouches compared with EVA pouches.
  • Total esters were highest in wines stored in glass bottles, 25% lower in wines stored in LDPE pouches, and 10% lower in wines stored in EVA pouches.

Organic Acids

  • Organic acids significantly increased in glass bottles over the 180 day storage period.
  • Hexanoic, octanoic, and decanoic acids were significantly lower in wines stored in plastic pouches compared with wines stored in glass bottles (with LDPE pouches having even lower levels of these acids than EVA pouches).
  • Acetic acid significantly increased in wines stored in glass bottles, while levels remained constant in wines stored in plastic pouches.
  • Organic acids were highest in wines stored in glass bottles, while wines stored in plastic pouches had significantly lower levels (48% loss for LDPE pouches and 32% loss for EVA pouches).

Aldehydes

  • Furfural increased similarly in wines in all packaging types over time.

Terpenes

  • Limonene concentrations significantly decreased in all packaging types over time, though it decreased more in the two plastic pouches than it did in the glass bottles.
  • Linalool decreased similarly in wines in all packaging types over time.
  • Total terpene levels were highest in wines stored in glass bottles, while wines stored in plastic pouches had significantly lower levels (22% loss for LDPE pouches and 11% loss for EVA pouches).

Total Volatiles

  • Total volatile concentrations were highest in wines stored in glass bottles, followed by wines stored in EVA pouches, and finally followed by wines stored in LDPE pouches.

Sensory Analysis

  • Wine samples were collected for sensory analysis at 3, 30, 60, 90, and 180 of storage.
  • After 30 days of storage, wines stored in glass bottles received an average score of 4.5 out of 5 (“rich in floral notes”).
    • Wines stored in EVA pouches received an average score of 4.1.
    • Wines stored in LDPE pouches received an average score of 3.7 (described as “off flavor” and “plastic tasting”).
  • After 60 days of storage, wines in both the LDPE and EVA pouches were scored as “poor” in aroma and had “flat” tastes
  • After 90 days of storage, wines in both the LDPE and EVA pouches were scored as “slightly oxidized” and also had a change in color.
  • After 180 days of storage, wines in the glass bottles received an average score of 3.9 (“acceptable”), while wines in the plastic pouches received average scores less than 3.5 (“unacceptable”).
  • Panelists noted significant sensory changes in the wines in as little as 30 days.

Conclusions

The results of this study are pretty clear, in my opinion.  The Vilana wines in this experiment fared significantly better over a 180 day storage period than wines stored in two different types of plastic pouches/bag-in-box.  The wines in the glass bottles appeared to retain the most aromatic and flavor

Photo By Cjp24 (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Photo By Cjp24 (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

characteristics, while the wines in the plastic pouches lost a lot of these characteristics which is possibly due to absorption of these compounds by the plastic.  Expert panelists noted that even as little as 30 days was all that it took to note a significant sensory difference between wines stored in glass bottles compared to wines stored in plastic bag-in-box pouches.

Between the two different types of plastic bag-in-box pouches, the results of this study would clearly indicate that pouches lined with LDPE present significantly poorer protection to the wine over storage time, and that this type of plastic appears to absorb many more of these compounds than the EVA-lined pouches or the glass bottles.  While wines stored in EVA-lined bag-in-box pouches still resulted in lower quality wines over the 180 day storage period, they performed at least marginally better than the LDPE-lined bag-in-box pouches.  Of course, after the 180 day storage period, the sensory analysis indicated that both plastic bag-in-box pouches yielded unacceptable wine, so really, there is no winner here in terms of which of the two plastics is better for preserving wine quality.

Even though the study mentioned they also tested the effects of storage temperature, it was not the primary focus of the study and therefore was not presented very clearly.  I would like to see a study making storage temperature one of the primary outcome measures, so we could see how these plastics perform at different storage temperatures.  Perhaps wine quality would be preserved at a different temperature than what is usually recommended for glass bottles?  Maybe, maybe not.

I would also be curious to know how “average” consumers would score these wines.  While the experts

Photo Copyright R. Yeamans (2014)

Photo Copyright R. Yeamans (2014)

found clear sensory differences, would the average consumer be able to notice these differences?

In a nutshell, the moral of this story is that bag-in-box wines stored in plastic bags lined with either LDPE or EVA are not appropriate for long-term storage.  While the design of the bag-in-box pouches is to minimize oxidation by using vacuum technology to keep oxygen out, the material of the bag seems to create a myriad of other problems, specifically those related to absorption of aromatic and flavor compounds out of the wine and into the plastic.

If you do decide to purchase bag-in-box wines, which can be great in certain situations, pay attention to what the pouch is made out of, and if it’s made of LDPE or EVA plastics, try to make sure than the wine hasn’t been sitting around in that box for a month or more, and try to drink it within a few weeks of purchase.

I’d be curious to hear your thoughts on this topic.  What other tests would you like to have seen done in this experiment?  What are your thoughts on the bag-in-box container design?  Please feel free to leave any and all of your comments in the comment box below!

Source: Revi, M., Badeka, A., Kontakos, S., and Kontominas, M.G. 2014. Effect of packaging material on enological parameters and volatile compounds of dry white wine. Food Chemistry 152: 331-339.

8 comments for “Can Bag-in-Box Plastic Pouches Compete with Glass Bottles for Wine Quality Over Time?

  1. Jeff
    February 17, 2014 at 9:34 am

    From a consumer’s perspective, my wife and I will sometimes buy boxed wine like the Bota Box. We recognize it for what it is…easy drinking, value priced wine. Its something we have around to consume with pizza, etc. or to share with friends who are less picky when it comes to wine.

    However, we also have a small stash of our finer wines that we reserve for a more special occasion or a nicely prepared meal. There is a noticeable quality difference, but storage is not an issue as this wine typically doesn’t stay around very long in our house.

    • Becca
      February 17, 2014 at 10:50 pm

      Thanks for sharing your experiences, Jeff! My fiance and I, too, are no stranger to the boxed wine (ahhhh the lives of a PhD graduate student and his betrothed….). I think you probably represent most people, in that when you buy a bag-in-box wine, it’s not one that you plan on keeping around for a long period of time!

  2. February 17, 2014 at 4:28 pm

    Great write-up Becca! I have never really paid attention to what the pouch is made out of, so I’ll be sure to look for this information the next time ;’) On a side note, I am wondering how one can tell how long the box has been siting on the shelf. I know that many box wines have expiration dates but this won’t tell us how long the box has been sitting on the shelf unless of course the box collects dust!

    ~Pamela
    http://enobytes.com

    • Becca
      February 17, 2014 at 10:52 pm

      Thank you for reading and commenting, Pamela!

      That’s a great question about knowing how long the box has been on the shelf….short of an expiration or bottling date (which I *think* the latter may be on there….well, maybe….I don’t know exactly), dust, or going to ask when the last shipment came into the store, it’s going to be really hard to say. I’ll have to check next time I’m in the store to see if there is a bottling/”born on” date anywhere, though I’m guessing these things probably move fast enough that it’s not too much of an issue for the average Joe (though may be for more seasoned palates, I suppose).

  3. Lisa
    February 18, 2014 at 11:54 am

    Does any one know what the storage conditions were for the wines tested, i.e. temperature and humidity?
    Thanks

    • Becca
      February 20, 2014 at 6:34 pm

      Hi Lisa!

      My apologies for the delayed response!

      I took a look at the article again and the only thing they mentioned about storage conditions was that they were stored in a temperature-controlled cabinet at 20C (+/- 1C). Nothing mentioned about humidity anywhere in the paper!

      Hope this helps!

  4. Andy
    February 18, 2014 at 10:52 pm

    This trial seems at odds with what American wine producers find in that millions of bag-in-box wines are opened every month, with very happy consumers. That the wines bottled in glass and sealed with air-tight screw caps lost 32% of free SO2 and 26% loss of total SO2 in a short time suggests that the base wine had high dissolved oxygen level (DO2) levels. Do you know what was the DO2 at bottling?

    • Becca
      February 20, 2014 at 6:39 pm

      Hi Andy! Sorry for the delayed response!

      You’re right—-it does seem a little at odds with actual consumer behavior. One thing that could be a factor is that there are many different types plastic or other material used in these bag-in-boxes that weren’t tested in this experiment and that actually fare much better in terms of wine quality over time.

      Also, it’s possible that the differences detected in this study by wine experts would not be significant enough for the average consumer to detect.

      Finally, maybe these bag-in-boxes move fast enough such that they are consumed before any off-characteristics are noticeable?

      It does not appear that they tested the DO2 at bottling (or if they did, they didn’t report it).

      Thank you for your great insights and comments!

What do you think about this topic?