Wood pallets have been recognized as a source of haloanisole contaminations for the past 20 years, and the frequency of incidents seems to keep growing. They are most often caused by 2,4,6-tribromoanisole (TBA), gassing-off from wood pallets. TBA has an extremely strong odor, similar to its cousin 2,4,6-trichloroanisole (TCA). Like any other haloanisole, TBA may contaminate winemaking and storage facilities, as well as wine itself.

Upon testing done at ETS, it appears that the problem pallets were made of lumber treated with 2,4,6-tribromophenol (TBP). TBP can be transformed into TBA, either by mold activity, or possibly following fumigation with methyl bromide. This second pathway seems the most plausible when pallets appear to be relatively new and free of any evidence of mold growth. In other words, the worst possible combination would be lumber treated with TBP, then fumigated with methyl bromide.

How can I spot problem pallets?

When receiving a new shipment of cellar or bottling room supplies, beware of TCA-like odors emitted by cardboard packaging, stretch-wrap, or pallets. These odors are often described as “musty/moldy” or “wet cardboard”, also chlorine or bromine-like, reminiscent of a swimming pool or a hot tub. Since TBP is registered as a wood preservative in South America (1), it is advisable to be familiar with the IPPC/ISPM 15 markings on pallets. These markings indicating their country of origin, and the type of treatment used. The mention “MB” (methyl bromide) indicates an increased risk. Heat-treated (HT) pallets indicating a North-American origin are in no way risk-free, however, as pallets may be manufactured from lumber pre-treated with TBP.

Country codes and type of treatment indicated on IPPC/ISPM 15 pallet markings sometimes point to suspect pallets, but not always.

IPPC/ISPM 15 pallet markings indicating a North American origin and heat treatment do not guarantee that a pallet is haloanisole-free.

Why is Harvest a Critical Time?

Haloanisoles are extremely soluble in ethanol. When airborne haloanisoles get in contact with a wine, they readily dissolve into it. 

During harvest, a quick and easy way to unwillingly introduce haloanisoles into wine is by performing a pump-over with aeration, or when using venturis. Indirect contaminations may also happen from hoses or winemaking supplies exposed to halolanisole-contaminated air: they may later contaminate wine getting in contact with them.

Airborne haloanisoles readily contaminate wine during pump-overs.

What Can I Do About It?

In any case, whenever TCA or TBA-like odors are noticed on supplies or pallets, remove them from the premises without delay. In order to confirm the presence of TBA, TBP, or other halogenated compounds, a variety of materials such as cardboard, plastic wraps and wood can be sampled and brought to ETS for analysis. Always feel free to contact us to discuss a course of action.

It is also important to test for airborne haloanisoles using “atmosphere traps”. Haloanisole levels measured with the help of these traps are directly indicative of the risk of wine contamination. Even in the absence of suspected contamination, checking airborne haloanisoles is advisable, at least once a year, especially at the beginning of the harvest season.

Measuring airborne haloanisoles with “atmosphere traps” is prudent at the beginning of the harvest season.

Resources

1. 2,4,6-TRIBROMOPHENOL AND OTHER SIMPLE BROMINATED PHENOLS - P.D. Howe, S. Dobson, an H.M. Malcolm. 2005. Concise International Chemical Assessment Document 66 retrieved on 09/18/2024