Kirkland Signature Roasted Turkey Breast and Yeast Extract

Product warning for Kirkland Signature Roasted Turkey Breast. This product is labeled gluten-free and it contains yeast extract. Based on email correspondence with Costco, the yeast extract in this product may be brewer’s yeast sourced from the beer brewing process.

(Brewer’s yeast from the beer brewing process is known as spent brewer’s yeast– what’s left of yeast once it has been used to make beer. Consequently, spent brewer’s yeast may include gluten from malt and grain.)

Correspondence from Costco:

“Our supplier uses PHR-YL is a phosphate replacer [sic]. This replacer is designed to replicate the functionalities of phosphates such as texture, water-holding capacity, and yield without using synthetic phosphates. PHR-YL includes yeast extract and citrus extract.”

“The sources of the PHR-YL are as follows:

Yeast Extract:

-Bakers Yeast: Derived from Saccharomyces cerevisiae.

–Brewers Yeast: Also Saccharomyces cerevisiae, but sourced from beer brewing processes.

-Torula Yeast: Comes from Candida Utilis used for its savory flavor.

Citrus Extract: Lemon, Lime, Orange”

We have advised Costco that spent brewer’s yeast is not considered gluten-free. The information has been passed along to the Kirkland Signature team and their buyer is supposed to be in touch. When we learn more, we will pass it along.

Recommendations:

Historically, Gluten Free Watchdog has recommended that Individuals with celiac disease avoid products NOT labeled gluten-free containing the ingredient “yeast extract” unless the manufacturer confirms the source to be gluten-free.

If you are concerned about the yeast extract in a product labeled gluten-free, you may want to reach out to the manufacturer to ask about the source. However, in our experience, manufacturers may view this information as proprietary. We lucked out with Costco—they have been very transparent about sharing information provided by their supplier.

You can also choose products certified gluten-free whenever possible. Products certified by GFCO, for example, can’t contain yeast extract grown in “culture media that contained proteins from wheat, rye, barley, or oats.”

Source: GFCO Manual 2025.1

Testing products containing yeast extract:

The competitive R5 ELISA is used to assess foods for fermented or hydrolyzed gluten. Unfortunately, this assay has many limitations. If gluten is detected, this may be cause for concern. If gluten fragments are not detected, it is not possible to know if the result is a false negative. According to the FDA, gluten could be present in a form that is not detectable by the competitive R5 ELISA. For more information, please see https://www.glutenfreewatchdog.org/news/what-the-fda-has-to-say-about-testing-for-gluten/

Labeling:

In the US, there is no requirement for barley to be declared in the ingredients list if the word “barley” is not part of the common or usual name of an ingredient. This is why we need manufacturers to be transparent about ingredients.

The USDA was made aware of the apparent misbranding of Kirkland Signature Roasted Turkey Breast.

Thank you to the GFWD subscriber who reached out about this product and provided photos.