I’ve been intolerant of eggs for a long time. My more recent discovery that eating propylene glycol has been causing me symptoms like stomach upset have led me to reexamine my food intolerances. Here’s what I learned about eggs:
- Eggs directly from a bird are covered with a biological coating known as the cuticle. This coating protects the porous shell from bacterial contamination by blocking the pores.
- Eggs sold in Europe are legally required to be unwashed. This preserves the cuticle to prevent bacterial incursion. It allows the eggs to be stored on the counter rather than in the fridge (and it is better that they be stored that way), and while they don’t last as long, consumers can see by the cleanliness of the eggs whether birds are kept in clean conditions. Because there can still be bacteria on the outside of the eggs, people should wash their hands after touching them.
- By comparison, eggs sold in North America are legally required to be washed prior to sale. The government believes that this will prevent bacterial spread. When the cuticle is washed off the egg, it becomes extremely permeable to bacteria and chemicals, which is why it is required to be dried as quickly as possible. This treatment makes it necessary to store the eggs refrigerated.
- Egg washing typically involves a surfactant and defoamer. Egg wash chemicals are proprietary in nature, but one defoamer ingredient list I was able to find included 10% silicone-based organic (carbon-containing) rinse (polysiloxane) and 1% propylene glycol. All chemicals used on eggs during this process are required to be recognized as safe food additives, which includes propylene glycol. These chemicals are applied when the egg is at its most porous.
- It is common practice to feed commercial laying chickens feed containing propylene glycol. This allows them to lay more eggs without losing too much body fat. The resulting eggs are lower in fat than those from chickens who have not been fed propylene glycol. Science claims that the propylene glycol is metabolized (chemically changed by the body into other things) before it can become a part of the meat, or muscle tissue, but in the short term (a few hours) after eating the feed, the propylene glycol can be excreted by the chicken.
I couldn’t find any certainty of egg contamination by propylene glycol or other chemicals, because I couldn’t find any comprehensive chemical analysis of commercial eggs from chickens fed this diet, after egg washing. I do have a couple of suspicions:
- In North America, chemicals including propylene glycol are applied to the egg when it is at its most porous, so it is reasonable to believe that some of these chemicals *could* get into the egg, possibly in quantity. This is especially likely considering the requirement by the governments that egg wash chemicals be food safe additives. Why require the wash chemicals to be food safe if they don’t get into the egg?
- The requirement to wash the eggs means that even free-range, organic eggs, sold by a neighbourhood roadside stand would be affected, if sold in North America.
- If propylene glycol prevents chickens from putting as much of their body fat into eggs, is some of the fat that would normally be in the eggs being replaced by propylene glycol?
I would love to see a study done, with a full chemical analysis performed on natural vs. commercial, chemical-treated eggs, so that we could confirm or deny these theories. I do hope to try an unwashed egg from a free-range, organically-raised chicken or duck, and suffer the consequences if necessary, as soon as I can get closer to the farm during an appropriate time of the year. I’ll update after I have a chance to try.
In the meantime, are there more of you out there who are allergic to propylene glycol, including through food, and are intolerant of eggs? Comment below.