Yeast has been used in bread to make the dough rise, but as the need to produce gluten-free bread has grown in recent years, can the same yeast be used? Well, I set out to clarify whether yeast contains gluten, and the answer isn’t as straightforward as I expected!
Yeast has been around for ages, well actually its use in early bread and wine dates back thousands of years. It’s actually a single-cell fungus that evolved from multicellular ancestors, making yeast pretty unique.
Going beyond the past 200 years, yeast was naturally developed in sourdoughs or by capturing it from the air on fruit such as grape skins. The species of yeast used in breadmaking is saccharomyces cerevisiae, however, there are thousands of other yeasts that could be used in breadmaking.
A sourdough starter can contain 3-4 different types of yeast!
There are many ways to produce yeast, the most common manufacturing technique multiplies the fungus on sugar molasses, a waste product of sugar production.
Yeast is added to bread doughs to react with the sugars in the flour to create carbon dioxide gas. The dough’s structure captures the gas to make it rise which is necessary if you want to avoid dense bread.
Yeast also has the ability to follow multiple pathways to produce other products such as water and ethanol. The yeast respiration pathway chosen will depend on oxygen being available or not, as well as other variables that are discussed in the what does yeast do to bread article.
Based on an experiment by Allred LK, Nye-Wood MG, Colgrave MLGluten traces of gluten are found in yeast, however, the amount found is extremely low. Less than 10mg of gluten per 1kg of yeast was found. At such a low level this amount of gluten is not going to cause an issue, especially since the majority will be broken down by enzymes in the dough.
It’s therefore safe to say that fresh and active dried yeasts are gluten-free. Rapid or instant yeasts contain dough improvers which can include wheat gluten to enhance the dough structure.
The inclusion of extra gluten is handy when making bread quickly at home, however this type of yeast is not suitable for celiacs and gluten allergies. Whilst yeast does not need to contain gluten, some yeast brands include it.
Commercial brewers can reuse yeast that’s been used to make previous batches of wheat beer which obviously contains gluten! But, smaller scale and home brewers can purchase dried yeast that does not contain gluten.
If you enjoy the benefits of nutritional yeast, the majority of brands do not contain gluten. However, there are some enriched varieties of nutritional yeast that do have gluten.