Brewer's Yeast in Wet Pet Food: Retort Performance and How to Specify It

Brewer's yeast earns its place in wet pet food as a savory flavor base, a protein source and a natural carrier of B vitamins. The retort is where it gets tested. In a Kansas State canned cat food trial, thiamin naturally present in a brewer's yeast survived the retort better than in the other yeasts tested, and yeast diets held thiamin steadier in storage.

Why do wet food formulators use brewer's yeast?

Most wet recipes are built on meat, liver and water, so the dry ingredients have to work hard in small amounts. Brewer's yeast does three jobs at once. It adds a savory note that pets accept well, it carries protein (our dried brewer's yeast is specified at 40 to 46% crude protein), and it brings B vitamins that were already in the yeast cell when it left the brewery.

Cats are the main reason formulators care. In a two-bowl test on dry food, cats preferred a yeast diet by about two to one, which we cover in our palatability guide. Wet food has its own sensory rules, but the reason to trial yeast is the same: it is a familiar flavor with a clean label name.

What happens to brewer's yeast in the retort?

Canned and pouched pet food is a low-acid food in a hermetically sealed container. In the US, 21 CFR 500.23 applies the thermal processing rules of 21 CFR part 113 to these products when they are intended as food for animals. Every can goes through a validated heat process, and thiamin (vitamin B1) is the nutrient formulators watch most closely through it.

Dainton and colleagues at Kansas State University tested this directly. They screened six yeast ingredients for thiamin, then put three of them into a canned cat food at a commercial cannery. The cans were retorted at a 123°C target for 63 minutes. The authors note the average lethality of 79 minutes was well above a typical commercial process of about 12 to 14 minutes, so the results below reflect a stricter process than most plants run.

Source: Dainton et al., PLoS ONE, 2022. Retention calculated from the relative losses reported by the authors.

The brewer's yeast labelled BY held its thiamin best of the three yeasts. The authors wrote that thiamin intrinsic to BY "had the most favorable thermal processing survival". For a formulator the practical reading is simple: brewer's yeast adds naturally occurring thiamin alongside the vitamin premix, which stays in the recipe.

Thiamin content differs between yeast products, so ask your supplier for a typical value before the first trial. In the same screen, the spray-dried brewer's yeast held 36.8 mg/kg of thiamin on a dry matter basis. TBESBY's most recent independent analysis reported 49 mg/kg of vitamin B1 as received.

Does yeast help thiamin hold up in storage?

The same team ran a second study on what happens after the retort. Cans were stored for six months in an uncontrolled commercial warehouse in Kansas, from October to April, and thiamin was measured every month.

Source: Dainton et al., Frontiers in Veterinary Science, 2022.

The authors concluded that the three yeast ingredients helped stabilize thiamin during storage, while the premix-only diet lost 17.8% of its thiamin over six months. The study ran for six months of a typical canned cat food shelf life, in an uncontrolled commercial warehouse.

How much brewer's yeast goes into a wet recipe?

Both trials used brewer's yeast at 5% of the formula as fed, which is a practical reference point for a first bench trial. Your own level depends on the flavor target, the protein budget and the cost per can. Start at the trial level, run it through your own retort schedule, and measure what you care about in the finished can rather than in the raw ingredient.

If you also make dry food or treats, the same yeast can usually serve all three lines, which keeps the supplier list short. Our guides to brewer's yeast in cat food and dog treats cover those formats.

What should a wet food buyer specify?

Agree the basics in writing before the first container, then check the first delivery against them. These are the values we publish for TBESBY dried brewer's yeast.

Beyond the spec sheet, wet food plants usually ask a few more questions:

• Is the yeast inactivated, and is that stated on the specification?
• What particle size does it have, and will it disperse in your batter or gravy without lumps?
• Which nutrients will you verify in your own lab after the retort?
• Can the supplier support the documents your market needs, such as FDA registration for the US or feed material labelling for the EU and UK?

Our safety specs guide lists the contaminant limits pet food buyers in the US and EU usually ask about.

Where does TBESBY fit?

TBESBY is dried brewer's yeast made from fresh brewer's yeast from leading international breweries in Vietnam, dried at our own facilities in Vietnam and shipped to pet food and animal nutrition importers in the UK, EU, Australia and the US. You can see the full specification on our product page and how we work with pet food makers on our brewer's yeast for pet food page.

If you are planning a wet food trial, tell us about your recipe and we will send the documents your QA team needs.

Sources

• Dainton AN et al. (2022). Composition and thermal processing evaluation of yeast ingredients as thiamin sources compared to a standard vitamin premix for canned cat food. PLoS ONE 17(8): e0271600.
• Dainton AN et al. (2022). Impacts of vitamin premix and/or yeast ingredient inclusion in a canned cat food on thiamin retention during 6 months of storage. Frontiers in Veterinary Science 9: 1090695.
• 21 CFR 500.23, Thermally processed low-acid foods packaged in hermetically sealed containers (eCFR).