Dear Dr. Enig:
What can you tell me about mono- and di-glycerides? I learned from the local company selling cottage cheese (which contains mono- and di-glycerides–almost all brands of cottage cheese contain them) that they receive two batches of MGs and DGs, which come in railroad carloads. Batch I is fully saturated, that is fully hydrogenated oil. Batch II contains a maximum of 50 percent partially hydrogenated oil. So about one-eight of the “stabilizer blend” is partially hydrogenated oil. Doing a calculation, I find that a 24-ounce carton of cottage cheese can contain 0.16 grams trans fatty acids from the MGs and DGs without trans fats being listed on the label.
I have worked at homeless shelters for about 16 years, gathering firsthand a bewildering variety of foodstuffs as donations for the homeless. I estimate that about three-quarters of the common American foodstuffs contain MGs or DGs, often listed several times in the ingredients list. Commercial donuts have five doses of MGs. Seems to me like this is a way for food manufacturers to slip trans fats into their products without labeling them.
Dr. Enig responds:
A mono-glyceride (MG) is made of one fatty acid attached to glycerol, a di-glyceride (DG) is made of two fatty acids attached to a glycerol molecule, and a triglyceride is made of three fatty acids attached to glycerol. Glycerol is the special alcohol that forms the backbone of a triglyceride, which of course is the regular fat or oil molecule. While regular MGs and DGs listed on labels represent one form of surfactant or emulsifier and are usually from the regular oil industry supplies, other surfactants such as ethoxylated mono- or di-glycerides are also used. MGs and DGs work as emulsifiers because one end (the fatty acid) is fat-soluble and the other end (the glycerol) is water soluble.
The terms mono-glycerides and di-glycerides are listed on the labels of most bakery goods, and other processed foods as well as on many frozen food combinations. The MGs and DGs added to bread doughs are usually by-products of fats and oils processing such as partial hydrogenation and various forms of extraction and interesterification processes. Even though they do have some caloric value, they are not counted as fats, and the fatty acids are not identified as having a particular composition. If they are fatty acids with trans bonds, they are not likely to be identified as such, nor would they be identified as any particular fatty acid.
Currently the levels of trans contributed by MGs amd DGs are relatively low, even when they appear several times in the ingredient list. However, as the public becomes more aware of the dangers of trans fats, the industry may be tempted to add more MGs and DGs containing trans fats in order to obtain the qualities they want in a food without having to list trans fats on the label.
Mono-glycerides and di-glycerides are actually normal constituents of digestion of food fats, but the MGs and DGs listed on the labels of our foods are constructed from fats and oils and used as surfactants to make it easier for companies to make their products.
Currently, the real problem with MGs and DGs is that when added to dough, they make it possible to bake very rapidly using machinery without the typical proofing that would be part of a small bakery where items are basically handmade.
One of the most popular shortenings for commercial baking was lard but as surfactants have been developed for use with liquid shortenings, the quality shortenings such as lard and butter have been abandoned for the cheaper oils, which can be made to function almost as well as lard with the added surfactants such as regular MGs and DGs, in addition to the ethoxylated mono-glycerides or sodium steroyl lactylate. These surfactants function as crumb softeners and dough strengtheners and help the volume of the loaf. These are all attributes that a properly made bread can have if it is made in the small bakery or at home without shortcuts.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Fall 2004.