Wood-eating yeast in cat food is okay

If you are concerned about sustainability and the environment and most people aren't in my judgement you might be interested to know that a wood-eating yeast in cat food has been found to be highly palatable and digestible. 

Torula yeast. Picture believed to be in the public domain.

It's a fungus and it can be used as a pet food ingredient. The yeast is called torula yeast (Cyberlindnera jadinii). It feeds on woody biomass and that's useful because there's a lot of forests being cut down and therefore a lot of biomasses lying around facilities which can be used to grow this yeast.

Apparently, it is easy to manipulate and extrude and therefore it can be converted into a pet food ingredient conveniently. It doesn't contain allergens or heavy metals, but it does provide amino acids. Unbeknown to many cat owners some cat foods contain heavy metals.

Torula yeast is approved as an ingredient by the AAFCO in America. It has a safe history of use. A Kansas State University study compared cat food made with torula yeast and others made with chicken meal, soybean meal and pea protein extract. 

It came out of the tests well on my reading of a summary of the study. Crude protein digestibility is similar to the other three ingredients. Chicken meal had a higher gross energy digestibility than the yeast, but the fungus was similar to the other diets.

When torula yeast is deactivated and dried it looks like a powder. It adds a smoky flavour to foods. It has a meat-like taste. It's been added to dog food, cat food and human food. And therefore, cat food manufacturers who claim that they only use human grade ingredients can add torula yeast without lying!

In human food the yeast sometimes substitutes monosodium glutamate as a flavour enhancer. It can improve the texture and flavour of many foods. As I understand it torula yeast is sprayed onto dry cat and dog food as a flavour enhancer.

For those people who do actually read the label for the ingredients of cat food, if they bump into torula yeast as an ingredient they should not be concerned on my understanding and having carried out some research. But this advice is provided without liability! Please do your own research ✔️😎.