Erythritol. In sugar alcohol, the carbonyl group is replaced by a OH group. Photo by Clara Piccirillo.
“How is erythritol made?”
To answer this question, we will briefly introduce erythritol, explaining what it is and its importance. Then we will talk about the process used at industrial level for its production, describing each step in detail.
What Is Erythritol?
Erythritol is a chemical compound belonging to the family of sugar alcohols. These are molecules which have some characteristics in common with sugars and others with alcohols. Like sugars, they have a hydroxyl group (O–H) on every carbon atom in the chain. However, they differ from the “standard” sugars because they do not have end carbonyl groups (C=O); instead they have end hydroxyl groups, which is characteristic of alcohols.
Erythritol’s formula is shown in the picture above. It can be seen that an OH group is bonded to the first carbon atom of the molecule, instead of a carbonyl.
Why It Is Important?
Erythritol is widely used in the food industry as a sweetener. In fact it has a sweetness of about 60-70 % of that of sucrose (i.e. the normal sugar we use in everyday life). At the same time, however, erythritol is much less calorific; according to the Harvard School of Public Health, a teaspoon of erythritol contains only 0.2 calories, instead of about 4 calories for sucrose.
Fruits like grape contain erythritol. Photo by Diciu.
The main reason for this is that, due to its different chemical structure, erythritol is absorbed much less by our body and, therefore, it gives it almost no energy.
Moreover, some studies showed that erythritol could also be beneficial to our oral health, as it can inhibit plaque formation.
Where Does Erythritol Come From?
Erythritol is a naturally-occurring molecule, we can find it in fruits such as pears, water melons and grapes; it is also present in some drinks like sake and wine, and sauce such as soy sauce.
Due to its large demand, however, the erythritol we use is produced at an industrial level with a fermentation process, using maize/corn as starting material.
Glucose has a carbonyl group. Photo by Clara Piccirillo.
Conversion into Erythritol: More Than One Step
Manufacturers use maize as a source of starch in the production of erythritol; therefore, the first step is the extraction of starch from maize.
Starch is a compound formed by glucose molecules bonded to each other to form long chains. Glucose (see Figure) is one of the most common sugars in nature; it is present, for instance, in the table sugar sucrose.
With a hydrolysis process, the long chains of starch are broken down into the smaller glucose molecules.
At this point, glucose is converted into erythritol with a fermentation process.
Fermentation by a Fungus
Fermentation is a process we are all quite familiar with; probably the most common application is the production of wines from grapes, beer from cereals, and other alcoholic beverages.
From a chemical point of view, during the fermentation one or more sugars are converted into alcohol, by either bacterial strains, yeasts or combinations of both.
In the case of erythritol, a fungus, Moniliella pollinis, performs the fermentation. With this, the glucose carbonyl group is converted into a hydroxyl group and the molecule goes from 6 carbon atoms to just 4.
Purifying Erythritol
At the end of the fermentation, it is essential to “clean” the product, to eliminate all impurities and to obtain high purity erythritol.
Manufacturers accomplish this in several steps, the first one being a cleaning of the fermentation broth by passing the broth through solid material (adsorbents) which can retain some of the impurities.
Subsequently, the broth passes through filters whose pores have quite small dimensions (between 0.01 and 0.1 mm) to completely remove the fungus responsible for the fermentation.
The last step is a crystallization; the broth is cooled down to a temperature which makes erythritol precipitate from the fermentation solution. This means that erythritol becomes a solid which can be separated from the solution. This process may be repeated several times to ensure a high level of purity, generally higher than 99.5 %.
Is Industrial Erythritol Safe?
Erythritol is a compound which the Food and Drugs Administration (FDA) classified as Generally Recognized as Safe (GRAS) for the first time in 1999; in 2001 this status was confirmed. Up to the present day, there is no proven and indisputable evidence showing toxic effects associated with erythritol toxic.
Some people are concerned that industrially-produced erythritol may be “different” from the natural sugar alcohol, and hence possibly dangerous.
These fears, however, are not justified, as erythritol is the same molecule – whatever its origin may be. For our health and/or nutrition, it makes no difference whether erythritol comes from a fruit or from an industrial plant. This is true, of course, assuming that the industrial process was performed properly, implementing the existing legislation on food safety.
Sources
The Harvard School of Public Health. Carbohydrates. Accessed on January 28, 2014.
Monedero V. et al., Perspectives of engineering lactic acid bacteria for biotechnological polyol production. Appl. Microbiol. Biotechnol. (2010), 86, 1003-1015. Accessed on January 28, 2014.
Cargill. Erythritol manufacturing process. Accessed on January 28, 2014.
© Copyright 2024 Clara Piccirillo, PhD, All rights Reserved. Written For: Decoded Science
In my view very informative article. Would you kindly disclose the fermentation method for high yielding erythritol. Besides this method dou you have information regarding electrochemical method? Please do share information.
Thanks in advance.
Vincent Summers says
To some extent, I understand the concern that a man-made compound is somehow different from a naturally occurring compound. In the past, compounds made in a laboratory were passed off as the same as what was found in nature, though in fact, only one of the isomers was the same. And in another way, a compound made by man might be pretty “darn” pure stuff, say 99 or more percent pure, but what was the other fractional percent? So past practices can tarnish future hopes.
Clara Piccirillo, PhD says
I guess you refer to the hydrolysis of the starch into glucose. No raney nickel is used; the hydrolysis is normally done first with a treament in acid, and then with an enzyme.
In any case, for any process, the purification of the final product is essential, to remove all impurities, either from the catalyst or from any reagent.
jbcomps says
Is there a catalyst used for the hydrolysis step, as in production of xylitol? Specifically, i am referring to Reyes Nickel or any other metal catalyst. And if so, are concerns about residues of those metals actually being in the final product actually warranted? Or are they removed from the final product?
Thanks much!
jbcomps says
correction… Raney Nickel… sorry.
Table sugar is 50% glucose and 50% fructose.
How much fructose is Erythritol?
Thank you
Clara Piccirillo, PhD says
There is no fructose in erythritol. Erythritol has a formula different from fructose, see the first figure of the article.
I do not think they use erythritol in Splenda, they use another sweetener (sucralose).
Vincent Summers says
Erythritol even occurs in nature. I’m leery about man-made substances, but a little less so of natural-occurring substances — UNLESS they are not prepared from natural sources, but by man-made processes.
Is erythritol in any way related to what they use in Splenda? Interesting article indeed!