Taurine Loss in Cooking: 10%, 30%, Then 10%

Heat takes taurine out of cat food in measurable steps: 10% to 20% in ordinary cooking, up to 30% across a high-temperature extrusion run, and another 10% after 7 days in the fridge. That is why a food that starts with 2,000 mg/kg can reach the bowl at 1,260 mg/kg, and why commercial cans are dosed at roughly 1,000 mg/kg above the stated requirement instead of at the requirement itself. Cats cannot make taurine from cysteine the way dogs do, so every loss lands on the diet.

Why a cat cannot absorb the shortfall

Cats lack enough of the enzyme activity needed to convert cysteine to taurine, and they lose taurine continuously through bile acid conjugation, which uses taurine rather than glycine. So the requirement has to be met daily, not averaged over a month. The AAFCO minimum is 0.10% taurine on a dry matter basis for extruded food and 0.20% DM for canned food, and the canned figure is double for one reason only: retorting destroys part of what was added.

Put in daily terms, a 4 kg cat eating 60 g of dry matter at 0.10% DM takes in about 60 mg of taurine a day. Most complete foods land at 2 to 4 times that, which is the margin that keeps a cat safe when a batch runs hot or a bag sits open for 6 weeks.

The 10% to 20% cooking loss

Home cooking is where owners lose the most without noticing. Simmering chicken at 100°C for 30 minutes costs about 10% of taurine; pressure-cooking the same meat at 121°C for 30 to 45 minutes costs 20% or more; and if you pour the cooking water away, you add a leaching loss on top because taurine is water-soluble. Baking at 180°C for 25 minutes sits in the middle at 10% to 15%. None of those numbers is a crisis on its own. Stack 3 of them across a week of meal prep and a diet that started at requirement is now at 70% of it.

Two habits cut the loss: keep the cooking liquid and pour it back over the meat, and add the taurine supplement after the food has cooled below 40°C rather than before cooking. A supplement stirred into a 90°C stew is paying for taurine the cat never eats.

Extrusion: the 30% run

Dry food is made by pushing a dough through a preconditioner at 90°C to 100°C for 60 to 120 seconds, then through the extruder barrel at 120°C to 150°C for 20 to 60 seconds under pressure. That combination is the harshest treatment in pet food, and it is where the 30% figure comes from. What decides the final number is whether taurine goes into the dough or onto the kibble as a coating. Post-extrusion coating loses under 5%, which is why most large manufacturers now split the dose, putting 60% to 70% in the coating and the rest in the base mix.

A kibble that tests at 0.12% DM after extrusion started at roughly 0.17% DM in the dough. That is the arithmetic to keep in mind when a label states a guaranteed analysis rather than a finished-product test.

Storage: 10% more after 7 days

Opened canned food loses about 10% of its taurine over 7 days at 4°C, and the loss is not linear: most of it happens in the first 48 hours as the surface oxidizes. A 400 g can fed over 4 days is fine. A 1 kg batch of homemade food eaten across 3 weeks is not, because the 10% per week compounds to roughly 27% by day 21. Freezing at -18°C for 30 days costs about 5%, which makes portioning and freezing the better habit than refrigerating a big pot.

Dry food is a slower story. An opened bag at 22°C to 25°C and 60% humidity holds its taurine for about 6 weeks, then drifts down 5% to 10% by week 12 as fat oxidizes and the coating degrades. Store it sealed, in the dark, and finish a 3 kg bag within 8 weeks.

The 1,000 mg/kg addition, checked

1,000 mg/kg is the common supplemental dose in canned formulas, and it is not the same as 1,000 mg/kg of food as eaten. In a 78% moisture can, 1,000 mg/kg as-fed equals 0.45% DM, more than 4 times the 0.10% DM minimum. In a 92% DM kibble, the same 1,000 mg/kg as-fed equals 0.11% DM, which is barely above the floor. This is why copying a can's inclusion rate into a dry recipe is a mistake, and why homemade diets are usually specified in milligrams per day instead: roughly 250 to 500 mg of taurine per day for an adult cat, with any higher amount for a cat with diagnosed dilated cardiomyopathy (DCM) set by the vet from repeat echocardiograms.

Losses from 2,000 mg/kg, by process

Process	Temperature and time	Taurine lost	Left from 2,000 mg/kg
Simmering	100°C, 30 min	10%	1,800 mg/kg
Baking	180°C, 25 min	15%	1,700 mg/kg
Pressure cooking	121°C, 30 min	20%	1,600 mg/kg
Extrusion, taurine in the dough	130°C, 30 sec	30%	1,400 mg/kg
Extrusion plus 7 days at 4°C	130°C then 4°C	37%	1,260 mg/kg
Post-extrusion coating	Ambient spray	under 5%	1,900 mg/kg

The 37% row is 30% plus 10% of what remains, not 40%: 1,400 × 0.9 = 1,260. Because losses combine differently, two labs can test one recipe 8% apart, so a label number is a target, not a measurement.

What deficiency looks like, and when to test

Taurine deficiency in cats shows up in 3 places: the heart, where dilated cardiomyopathy causes exercise intolerance and fluid in the chest; the retina, where a horizontal band of degeneration appears near the optic disc and vision loss is permanent; and reproduction, where queens cycle poorly and litters are small. Whole-blood taurine below 200 nmol/mL is the usual cutoff for deficiency, with 200 to 250 nmol/mL called equivocal. A cat with a new murmur, a cat that tires on the stairs, and any cat on a homemade or vegan diet should be tested rather than supplemented blind. Cardiomyopathy needs an echocardiogram, and no amount of taurine reverses retinal damage that is already visible.

For the requirement itself, read /food/taurine-in-cat-food/; for how moisture and processing differ between formats, see /food/wet-vs-dry-food/. Before you add any human supplement or energy drink to a cat's bowl, check the ingredient against /tools/toxic/, because several contain caffeine or xylitol.

5 habits that keep the number up

Buy food with a taurine guarantee of at least 0.10% DM for dry and 0.20% DM for canned, and check the date code.
Keep cooking liquid in the bowl instead of down the sink, and add supplements below 40°C.
Portion homemade food into 3 to 4 day units and freeze at -18°C instead of refrigerating a week of food.
Finish an opened can within 4 days and an opened 3 kg bag within 8 weeks.
Test whole-blood taurine before starting a supplement if the cat is on a homemade diet, and repeat at 12 weeks.

Terms mentioned in this article

DM AAFCO DCM

Frequently asked

Does freezing homemade cat food destroy taurine?

Far less than refrigeration does. At -18°C for 30 days the loss is about 5%, while 7 days at 4°C costs about 10% and 3 weeks of refrigeration compounds to roughly 27%. Portion cooked food into 3 to 4 day units and freeze the rest, then thaw one unit at a time in the fridge.

Is 1,000 mg/kg enough taurine in dry food?

Only just. In a 92% dry matter kibble, 1,000 mg/kg as fed converts to 0.11% DM, which clears the 0.10% DM minimum by a hair and leaves no room for extrusion or storage loss. The same 1,000 mg/kg in a 78% moisture can equals 0.45% DM, so the two formats cannot share an inclusion rate.

Can a taurine supplement reverse heart disease in my cat?

It can help only when the cardiomyopathy is taurine-deficient in origin, and even then it works alongside cardiac medication, not instead of it. A cat with a murmur or breathlessness needs an echocardiogram and a whole-blood taurine test first. Retinal degeneration from taurine deficiency does not recover at all.