Ethyl carbamate and spirits dossier: what solutions for rum and cachaça exports?

The boom in the rum market over the last few years is the result of ingenious marketing campaigns: brut de fût, old vintages, single cask, limited editions.... The success is such that it is even becoming very difficult for the creators of new brands to obtain supplies, especially for agricultural rum.

This wave of premiumisation is resulting in a generalised increase in prices and consequently in quality.. But the industry that benefits from this craze cannot ignore the consumer's need to be reassured about what they are putting in their drinks. 

The latter are becoming more and more specialized, especially in the world of rum. For example, the question of adding sugar often comes up in the forums, as do organic, traceability and authenticity, which are all subjects of interest to these new consumers.

But as we hunt for endocrine disruptors and other carcinogens, the presence of ethyl carbamate in rum could come back to the fore.. Indeed, after having been at the centre of the distillers' preoccupations in the 80's, a period during which research was initiated to understand its appearance, the subject has since fallen into oblivion.

Would we want to forget about this problem so that we don't play the spoilsport? One can ask the question when reading Matt Strickland's article on ethyl carbamate written in October 2019: "It's Time to Take Ethyl Carbamate Seriously Again" (distilling.com).

Canada and the USA have since set limits beyond which rum cannot be marketed. But what would happen if the regulations were to change and become even stricter?

One more time, the Spirits Valley can meet this challenge. Because it houses technicians with the necessary know-how to act and allow the distilleries to adapt to legislation and consumer expectations.

Ethyl carbamate (EC), also known as urethane, is a compound found in foods such as bread, soy sauce and fermented beverages (beer, wine, wine spirits, sugar cane-based spirits), and it's a known carcinogen.

Interestingly, Wikipedia tells us that prior to 1943, it was used as a cancer drug until it was discovered to cause cancer itself in laboratory mice. Most countries stopped using it except Japan, until 1975. During this period, it is estimated that about 100 million injections were administered, but no studies were done to evaluate its effects on patients. Similarly, it was used as a tranquilizer in the United States in the 1950s .

During the 1980s, ethyl carbamate became a major concern for distillers, brewers and winemakers because of its discovery in spirits. Particularly in whisky and armagnac, where the most successful studies were carried out during this decade thanks to Professors Cook and Bertrand. This led governments to get involved by imposing regulatory limits on the amount of ethyl carbamate allowed in spirits.

Canada was the first state to take the problem seriously, following analyses of stone fruit spirits imported from Germany as early as 1986. Other countries, including Czechoslovakia, followed suit and adopted the Canadian codex alimentarius. While most products are below the threshold allowed in the USA (125 ppb* - voluntary limit used by the industry) and in Canada (150 ppb - limit imposed by the government, including the SAQ), a number of spirits that meet and exceed these limits are returned to the shipper or destroyed.

* expressed in ppb: parts per billion

Thus, to understand the issue of ethyl carbamate in spirits, it is necessary to ask the following questions: how is it formed? What are the precursors? How can its formation be reduced?
 

FT is formed when both the urea produced by yeast and ethanol, a key element in our industry, are heated. We thus obtain ethyl carbamate: CO (NH2) 2 + C2H5OH + Heat CH3CH2OCNH2.

Yeasts produce urea via amino acid metabolism: the amino acid arginine is broken down into ornithine and urea (see diagram below). The enzyme responsible for this process is encoded by the CAR1 gene. Indeed, when this gene is eliminated, urea production decreases. Hence the temptation to genetically modify yeasts = GMOs...

But it is not so simple to systematically reduce FT in the production of spirits. The first reason is that the CAR1 gene does not work for all the enzymes involved in urea production. Secondly, the use of genetically modified yeast is risky because the long-term health effects of GMOs are not known. Moreover, this is not in line with the search for authenticity, food safety and sustainable development desired by the consumers of 2020. Finally, urea is only one of the many precursors of FT.

So to better understand what is at stake in rum, let's look at whisky, fruit brandies and Armagnac, where the first studies were carried out to reduce the precursors that lead to the production of EC.

A) Concerning whisky in Scotland: the article "Ethyl Carbamat in function in grain based spirits" published in the Journal of the Institude of Brewing by Mc Kenzie (1990) highlights the work of R. Cook which allows to identify the action of cyanide in whisky.

In barley, the main precursor is a glycosidic nitrile (GN) called epiheterodentrin (EPH). EPH belongs to a family of compounds called cyanogenic glycosides, a sugar (glycoside) attached to a cyanide-based compound (cyanogen). EPH is enzymatically converted to cyanide in a two-step process. First, a β-glucosidase (naturally present in grain) cleaves the glucoside component and leaves the isobutyraldehyde cyanohydrin (IBAC). Cyanide appears when IBAC is exposed to the heat of fermentation or distillation.

As a result, the Scotch whisky industry selects barley and malt varieties with less EPH to limit the existence of precursors.
 

B) Stone fruit spirits: distillers in Germany or Alsace are used to managing the risk of cyanide and the European regulation 2016/22 governs the distillation of these spirits. Because the stones of these fruits contain a compound called amygdalin, which was once considered a cure for cancer. The amygdalin can be broken down during fermentation into glucose benzaldehyde. Since the amygdalin is contained in the pits, the pits do not have to be broken down for the reaction to occur (a maximum of 5% broken pits is tolerated).

Similarly, the EC content increases during ageing while it remains stable in wine spirits. It is therefore important to check the EC levels over time, as these vary according to the quantity of precursors present and the storage conditions after distillation.

C) Wine brandies: Professor Bertrand is the initiator of important research on behalf of the BNIA at Eauze because Armagnac is confronted with high EC contents.

The copper still is used as a catalyst during continuous distillation while a double distillation will allow to rectify the precursors and to divide by 4 the EC content. He concludes that the precursors must be treated as quickly as possible before they are transformed, right from the alembic outlet with resins. The EC content is already formed after 15 minutes and reaches a peak after 48 hours and cannot be treated ("Elimination du précurseur du carbamate d'éthyle dans les eaux-de-vie de vin" by Bertrand A., Bertschk , Segur M.C, Institut d'Œnologie, Université de Bordeaux II, 1988).
 

The following are therefore the areas in which rum producers can take action to best prevent EC concentration exceedances:

• Varieties of canes
• The most advantageous terroirs
• Chemicals used in crops
• Appropriate yeasts
• Fermentation temperature
• Distillation method and temperature
• Alcohol Concentration
• The acidity
• The pH
• The light
• Storage conditions (heat,...)
• The potential release of used barrels used for aging

Sometimes this is not enough to fully control EC production and it is not uncommon for rum farm houses to give up, discouraged by red tape. They finally decide not to export all their products to Canada or the United States and to select only the barrels that are compliant for these markets .

After an 11-year absence, a non-French brand of agricultural rum is once again distributed by the SAQ in Quebec, with a laconic press release from the SAQ explaining the spirit's return to favour: "It seems that the manufacturing process has been modified so that it is now possible to better control the ethyl carbamate level. The sample presented to us was in compliance with Health Canada standards".

However, other prestigious brands are still not available on the Canadian market, much to the despair of niche spirits consumers.

In an article in Rumporter on rum in Canada, Yan Aubé gives an overview of the complications encountered by French agricultural rums compared to molasses rums, with the EC limit favouring the latter category. : "In order to comply with this rule, several distilleries have to make considerable changes to their establishments. Investment that is generally too large for the market share they will obtain in North America. Having said that, some manage to find the right path and make themselves available, much to the delight of the amateurs. Just look at the products of Bielle, PMG, Longueteau, Trois Rivières, La Mauny, Saint James and even Issan! But once again, the big winners in terms of sales are still molasses rums like Captain Morgan, El Dorado, Kraken, Appleton and Plantation" (Rumporter, Yan Aubé, 25/11/2016).

In fact, each distillery accessing the North American market must select the rums in its catalogue that can be marketed according to the quantities of EC they contain. This explains the presence of holes in the lists of available products of these brands in the territories concerned. In addition, care must be taken to ensure that the batches selected by the SAQ, for example, remain compliant over time since the quantity of FT in the barrel may increase and records may take 9 months from the time the Quebec organization analyzes the rum sample and begins to place orders (Interview with Annie des Groseillers, Rumporter, September 2020).

However, there is still a card to be played for the distilleries which have the greatest difficulty to control the appearance of FT and which cannot incur huge costs to ship a few batches of agricultural rum, even if the stated ambition is toaccelerate sales in North America. This joker's name is Jean-Luc Braud and he's based in Spirits Valley.
 

Faced with costly investments and legislation that could be tempted to tighten the net, the company Spirits Drink Consult of Gensac, headed by engineer Jean-Luc Braud, offers a proven and economical solution.

Taking up the work of Professor Bertrand in the early 2000s, he carried out numerous tests with resins placed at the outlet of the still. The information gathered enabled him to establish a process that could be adapted to the production conditions specific to each distillery, according to the type of still, the quantity to be distilled and the average flow rate.

From there, it is possible to establish a tailor-made protocol with the cellar master of the distillery who will determine the appropriate resin and the quantity to be used, directly at the outlet of the alembic. There is not enough time to move the alcohol to another site to carry out the operation.

Already adopted by several customers, this filtration technique does not alter the taste qualities of the product and will also be of interest to Asian fermented rice spirits and baijiu.

Companies interested in the ethyl carbamate treatment method can contact directly Jean-Luc braud of Spirits Drink Consult (jlbraud@gmail.com) or My Spirit Factory (myspiritfactory@gmail.com).

JÉRÔME SAVOYE

I would like to thank Dr. Evelyne Chanson of EC Consulting for her precious advice in writing this article.