Should I be concerned about plastic carboys?

      10 Comments on Should I be concerned about plastic carboys?

I get asked this question quite frequently, as of lately, particularly in light of recent studies linking bisphenol-A (BPA)—the plastic used to line beverage containers and tin food cans—to cancer. The latest research from the Université de Sherbrooke in Québec, Canada and published in Toxicology and Applied Pharmacology reports that BPA can adversely affect development of the fetus in pregnant women.

Until fairly recently, glass carboys were really the only practical containers for fermenting and storing wine available to home winemakers. However, glass carboys are heavy, slippery when wet, and fragile—much wine has been spilled and many people have been injured as the result of accidental breakage.

Light-weight, colorless, clear, durable PET fermentation carboys were introduced at the turn of the century and are replacing glass carboys, which are no longer manufactured in North America. PET plastics (also known as PETE plastics) are copolymers of polymerized polyethylene tere-phthalate and have a recycle number 1. PET belongs to the polyester family of plastics and should not be confused with toxic ortho-phthalate plasticizers such as di(2-ethylhexyl) phthalate, DEHP, and dibutyl phthalate (DBP), which are added to other types of plastics to make them flexible. It is also important to underscore that bisphenol-A (BPA), a notorious endocrine disruptor used to make polycarbonate plastics that have a recycle number of 7, has absolutely nothing to do with the manufacture of PET. Furthermore, rumors that PET containers leach toxins if they are re-used have been scientifically disproved. PET is FDA-approved and considered safe and non-toxic for food and beverage applications.

In sharp contrast to other types of plastic carboys, PET fermentation carboys do not scalp (release, pick up, or transfer) flavors into wines; are specially manufactured to have negligibly low oxygen permeability; are hydrophobic, making them easier to wash than glass; and are not damaged or stained by the washing and sanitizing agents commonly used in winemaking.

So there you go: If you want to switch to PET carboys in your winemaking, you need not worry about bisphenol-A contamination.

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10 thoughts on “Should I be concerned about plastic carboys?”

  1. Bruce Nolte
    I have made wine in both plastic and glass carboys, and I prefer glass. It isn’t an irrational fear of plasticizers leaching into the wine, but a more practical concern. Most of the plastic carboys have some type of ridged or corrugated side. While the wine is settling out, much of the sediment falls on these ledges, and some is dislodged during the racking process. Most glass containers have smooth sides, which means most of the sediment ends up on the bottom, where it belongs.
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    1. Daniel Post author
      “Plastic” carboys I use are made of PET, and I have not experienced the kind of problems you mention, although I can understand how that might happen. It greatly depends though on the type of fining agent you use. Isinglass, for example, is known to cause sediments to “stick” even on glass. Bentonite is great because it’s heavy — that’s what I use for whites.
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  2. Gisela Claassen
    I have now made many, many wines in the plastic carboys, and I am exceptionally happy with them. I haven’t had any adverse effects on the wine. As far as the lees that settle in the ridges, I haven’t had problems when racking off the wine; I do tend to do extra rackings to help clear the wine, although I’ve had wines that just would not clear even in a glass carboy — the lees seemed to “stick” to the side of the glass! I have been lucky enough not to have a glass carboy break on me yet, but I’m happier to avoid that problem. Also, the weight difference is just enough to make it much easier for me to pick up a plastic carboy, but definitely a challenge to pick up a full glass carboy.
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    1. Daniel Post author
      Interesting!
      Lees should not stick to the glass if your carboy (or PET container) is clean, which it should be. Would it be tartrate crystals that you see? Those have more of a tendency to stick to the glass. A light stirring — where you don’t disturb sediment at the bottom — should dislodge particles from the glass. Your fining agent may also be the culprit. I don’t know what you are using; some are better than others. And if your wine is not clearing, there is some problem for sure, eg. high pectin content assuming that the alcoholic/malolactic fermentations have completed.

      Cheers,
      Daniel

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  3. Gisela Claassen
    This happened with the same kit (but not with other wines) that I made several times, but two different years. I do not know what it was about that particular kit that made this happen, but it was always a problem. However, it is one of my favorite whites, so I keep making it, and got a filter for bottling.
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  5. nora barda
    I would like to know how many times can be a plastic tank re used 1) for fermentation container 2) storage of wine.

    Do you know if there is normative for their usage??

    Thank you very much

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    1. Daniel Pambianchi
      First, the plastic must be food grade. If you take good care of it, I.e. You clean/sanitize before/after use, it will last a lifetime for fermenting. It should not be used for long-term storage as plastic breathes, which can oxidize wine.

      Hope this helps.

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  6. Kathy
    In reference to leaving your wine in a plastic carboy until bottling, what is classified as “long-term”? We typically leave our wine in the carboy for about 3 months after adding the clearing agent and until we bottle…is that too long?
    Thank you!
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    1. Daniel Post author
      3 months is ok, not much more. The length of time depends on the type of plastic used and whether the material has been treated with an oxygen barrier. I just read a French study that measured a whole of parameters in wines stored in glass, and two in PET with 1% and 3% oxygen barrier, respectively, for a 12 month period. Although there were differences, the wines in glass and 3%-PET did not show significant changes, but the 1%-PET did.
      Reply ↓

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