In a new petition to FDA, the US wine industry has asked the agency to switch to a different method for calculating carbohydrates in wine, a move that wine makers say would give consumers a more accurate representation of wines' carbohydrate content.

Filed June 8 by the Wine Institute, which represents California wineries, and WineAmerica, the National Association of American Wineries, the petition states the method FDA currently uses "significantly" overstates the level of carbohydrates in wine.

"This overstatement disproportionately harms wine in the marketplace," the wine groups said in the petition.

To avoid that, and to prevent unfair comparisons of the carbohydrate content in wine versus that in other alcoholic beverages, the groups are asking FDA to amend its regulations, permitting use of an accurate "quantitation and summation of sugars" approach as an approved method for calculating total carbohydrate content in wine and wine-based beverages.

"Carbohydrate declarations need to be accurately expressed, both to be in accordance with regulations and so as not to misrepresent or mislead consumers," the two wine industry groups wrote in the petition.

This is an important issue for the wine industry, even though FDA currently does not require all wines to provide nutrition information on all wine labels, stressed Robert Koch, the Wine Institute's president and CEO, and James Trezise, president of WineAmerica, who signed the petition.

In some cases, winemakers offer nutrition label information voluntarily and for the benefit of consumers. Additionally, wine producers must include nutrition labeling, including carbohydrate content, on all wines that contain less than 7% alcohol by volume, Koch and Trezise noted.

And under the new menu labeling requirements that went into effect in May 2018, chain restaurants and other similar food establishments are required to provide written information for standard menu items specifying the amounts of several nutrients, including total carbohydrates, if consumers request the information, the petition said.

Specifically, the two wine groups take issue with the FDA regulation governing nutrition labeling of food outlined in 21 CFR §101.9, which requires that total carbohydrate content of wine be calculated using a specific "by difference" method described by Merrill and Watt in Energy Value of Foods: Basis and Derivation found in USDA's Agriculture Handbook No. 74.

Current methods inaccurately represent carbs in wine, petition says

But the use of that method has limitations and it becomes problematic when applied to wine, the wine groups told FDA.

"Notably, the carbohydrate by difference method was designed to determine the energy content of foods and not to measure carbohydrates. The calculation was designed for its robustness in the energy calculations, as any errors in protein determination are offset by a higher or lower carbohydrate energy value," Koch and Trezise explained.

And when applied to wine, the "by difference" method renders inaccurate results, as the method estimates carbohydrate content by including non-carbohydrate compounds, such as organic acids and glycerol. As a result carbohydrate levels in wine become significantly overestimated, which provides consumers with inaccurate information and may lead them to make "ill-informed" choices in relation to wine, the wine groups said.

"Wine contains a high relative concentration of organic acids and glycerol, resulting in an inaccurate and significant over-estimation of total carbohydrate when estimated using the carbohydrate by difference method," Koch and Trezise said in the petition. "Wine Institute and WineAmerica believe that the organic acids and glycerol in wine are not carbohydrates and thus should not be included as carbohydrates in nutrition information for consumers."

Glycerol, organic acids should not count as carbs for wine

Among the minor components of wine, glycerol and fixed acids together represent nearly two-thirds of wine's composition, the petition noted.

And even the authors of Handbook No.74 acknowledged that "addition to the true carbohydrates, this 'difference' fraction may include such compounds as organic acids," the wine groups said.

"In other words, the authors acknowledged that organic acids are not true carbohydrates," Koch and Trezise wrote. "On page 6, the authors confirm this, and point out that, in those foods containing abundant organic acids, a separate estimation of those acids should be made when determining energy values, because they are chemically distinct from carbohydrates and have different heats of combustion."

Also, the Handbook lists grapes as one of the foods for which the carbohydrate by difference method "will not give accurate results, in view of the abundant content of organic acids in grapes," the wine groups said.

"The authors of Handbook 74 recognized that organic acids should not be counted as carbohydrates and that the carbohydrate by difference method is not accurate for foods with a high organic acid content."

The petition applies similar arguments for glycerol (glycerin) with the wine groups arguing that it should not be classified as a sugar alcohol and, therefore, not as a carbohydrate.

"Generally speaking, sugar alcohols are composed of 5- or 6-carbon chains, since they are derived from 5-carbon or 6-carbon sugars (pentoses and hexoses, respectively). Glycerol, however, is only a 3-carbon polyol," the groups said.

FDA appears to have recognized that glycerol is not a sugar alcohol because the Federal Register notice of FDA's final nutritional labeling rule "specifies the calories per gram that are to be used for each of the 'sugar alcohols.' However, that list does not include glycerol," the petition said.

Glycerol metabolizes differently than sugars, and while glucose "travels through the bloodstream and is generally metabolized intracellularly in every cell in the body for energy, glycerol kinase, the predominant enzyme responsible for glycerol metabolism is primarily present in the liver, indicating that most of the glycerol would be metabolized there," the petition noted.

"While a portion of ingested glycerol, whether consumed as glycerol per se, or as a triglyceride, may be converted to glucose via gluconeogenic pathways, such is also the case for many other food components such as organic carboxylates (i.e., lactate), and amino acids (e.g., alanine, and glutamine), which are not classified as carbohydrates," the wine groups stated.

Summation of sugars - a more accurate way to estimate wine's carb content

Based on these arguments, the wine groups' petition argues that an approach based on the summation of sugars would be a more appropriate method for calculating the level of carbohydrates in wine. Analytical technology has advanced significantly since Handbook No.74 was written in 1973, and a new method for the analytical determination of glucose and fructose in wine has been developed that allows for more exact calculation of the level of carbohydrates.

"This new method has been accepted by the AOAC as Official Method 985.09," the petition said. The method is based on an enzymatic reaction, utilizing the enzyme hexokinase to catalyze a reaction with glucose and fructose.

"This creates compounds that undergo further reactions to form a very specific chemical that can then be selectively analyzed using a simple spectrophotometer, common in most laboratories. This highly selective method provides a much more accurate quantitation of glucose and fructose than earlier analytical approaches."

Additionally, the analysis of sugars using High Performance Liquid Chromatography (HPLC) is another method that was developed after the publication of Handbook 74, the petition noted.

"In an effort to address the inaccuracy inherent in the carbohydrate by difference method, the Wine Institute commissioned the development of an HPLC method for the measurement of sugars, which was accepted by the AOAC as First Action 2013.12 and published in the Journal of the AOAC International in 2014," the petition said.

Considering that such methods are available and fix inaccuracies in the current methodology for calculating carbohydrate content, the Wine Institute and WineAmerica have requested that FDA amend subparagraph (c)(6) in 21 CFR §101.9, Nutrition Labeling of Food, and allow the summation of sugars to be used for calculating carbohydrate content in the case of wine and wine-based beverage products.

"As we have shown, the inaccurate method as currently prescribed disproportionately harms wine in the marketplace and is misleading to consumers," Koch and Trezise told FDA.

"The Wine Institute and WineAmerica respectfully ask the Commissioner to review this Citizen Petition and move to implement the requested amendment to 21 CFR §101.9(c)(6) expeditiously so that wineries may provide consistent, accurate, and fair declarations of carbohydrate content in wine to consumers, while meeting the requirements of 27 CFR §4.39 (a)(1)."

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This article was published by S&P Global Commodity Insights and not by S&P Global Ratings, which is a separately managed division of S&P Global.