Torula Yeast vs Brewer’s Yeast: What Pet Food Buyers Should Compare

Torula yeast and brewer’s yeast are both inactive, dried yeasts used as protein and flavour ingredients in pet food. The difference is origin. Brewer’s yeast is Saccharomyces recovered from beer brewing. Torula is Candida utilis grown on purpose, often on wood sugars. They carry different feed names, protein minimums and supply models.

Both names can turn up on the same ingredient shortlist, sometimes as substitutes for each other. They are not the same ingredient, and a buyer who swaps one for the other needs to change the label name, the specification and, often, the inclusion rate. This guide puts the two side by side.

What is the difference between torula yeast and brewer’s yeast?

The organism and the way it is produced. Brewer’s yeast does its first job in a brewery. Once fermentation is finished, the yeast is separated from the beer, inactivated and dried. Torula yeast is cultivated for its own sake as a nutritional yeast. The commercial torula used in a 2022 Kansas State University cat food trial was grown on forestry by-products from the timber industry.

US feed definitions keep them apart. California’s feed regulation, which follows the standard feed ingredient definitions, describes the two as follows:

The protein minimum in the definition is a legal floor, not a typical value. Commercial brewer’s yeast is usually sold well above 35%.

How do they compare on protein and composition?

Typical values overlap more than the definitions suggest. Feedipedia’s data sheet for brewer’s yeast, built on 108 samples, gives an average of 48.9% crude protein on a dry matter basis, with a range of 39.3 to 56.8%. Lysine averages 6.3% of protein and ash 7.0% of dry matter.

The torula sample analysed in the Kansas State trial had 54.6% crude protein, 8.4% ash and 6.2% acid-hydrolyzed fat on a dry matter basis, plus 18.4% total dietary fibre. The authors noted that this sample’s fat was higher than in other torula reports, so treat it as one product’s analysis.

Because the fat methods differ, do not compare those two fat figures directly. Ask any supplier to report fat by the same method your lab uses.

What does the research show for torula in pet food?

The Kansas State trial replaced part of the chicken meal in an extruded cat diet with torula yeast at 20%, and compared it with two plant-protein diets at the same level. Crude protein digestibility was 89.9% for the torula diet, similar to the others. In two-bowl tests, cats chose the torula diet first 36 times to 4 against the chicken meal diet.

Stools were softer on the torula diet, and the authors suggested keeping torula at about 20% of the diet or less for that reason. The torula diet also expanded more in the extruder and gave the softest kibble.

The study tells you how torula behaves as a major protein source. Brewer’s yeast is more often used at a few percent of the recipe. A 2025 dog study, for example, fed dried brewer’s yeast at 1.5% of the diet and looked at gut bacteria rather than protein replacement. For typical use levels in dry and wet formats, see brewer’s yeast in pet food.

Which one should you specify?

It depends on the job the yeast has to do in your recipe and how you want to buy it.

What should be on the specification sheet?

Whichever yeast you choose, the spec sheet should let you prove what you bought. At minimum, ask for:

• The organism, by genus and species, and confirmation that the yeast is inactivated.
• The production route: brewery co-product or cultivated, and the drying method.
• Crude protein, moisture and ash as guaranteed limits, with the test methods.
• Fat with the method named, since ether extract and acid hydrolysis give different numbers.
• Shelf life, packing and storage conditions.
• Registrations and certifications relevant to your market.

For reference, TBESBY dried brewer’s yeast is drum dried at our own facilities in Vietnam from fresh brewer’s yeast supplied by leading international breweries in Vietnam. Protein is 40 to 46%, moisture below 10%, ash below 6% and fibre at most 1.5%, with a 12-month shelf life in 25 kg bags or jumbo bags of 600 to 1,200 kg. The product is non-GMO, and the company is U.S. FDA registered and ISO 22000:2018 certified. Details are on our product page.

Sources

1. California Code of Regulations, Title 3, §2801 Yeast Products (definitions of dried yeast, brewers dried yeast and torula dried yeast). regulations.justia.com
2. Heuzé V, Thiollet H, Tran G, Edouard N, Lessire M, Lebas F. Brewers yeast. Feedipedia, a programme by INRAE, CIRAD, AFZ and FAO. 2018. feedipedia.org/node/72
3. Holt DA, Aldrich CG. Evaluation of Torula yeast as a protein source in extruded feline diets. J Anim Sci. 2022;100:skac327. doi:10.1093/jas/skac327
4. De La Guardia Hidrogo VM, et al. In vitro fermentation characteristics of dietary fibers using fecal inoculum from dogs consuming a dried brewers yeast product. Animals. 2025;15(21):3117. doi:10.3390/ani15213117

Related reading: brewer’s yeast in plant-based and vegan pet food, where yeast often carries a larger share of the protein.

Compare our specification with yours

Send us your yeast specification and we will tell you how our dried brewer’s yeast compares, line by line. Contact the TBESBY team, or read more about brewer’s yeast for pet food.