Is it safe to make yogurt in a plastic Instant Pot insert?
Use caution. Warm dairy held for hours is better in glass or stainless steel than a plastic insert.
What's actually in it
Yogurt ferments warm for hours. It is wet, slightly acidic, and often made from milk with fat. That is a lot of contact time for a plastic insert.
The better setup is simple: use the stainless steel inner pot, or set glass jars in a water bath inside the cooker.
What the research says
A 2025 study in J Environ Health Sci Eng tested yogurt and buttermilk samples and found microplastics and phthalic acid esters. The average phthalic acid ester concentration in yogurt samples ranged from 5.79 to 11.36 micrograms per liter.
A 2013 study in Int J Environ Res Public Health tested phthalate migration from plastic food containers into liquid food simulants during microwave use. DBP migration increased with longer heating time and prolonged container use.
Those studies do not test your exact Instant Pot insert. They do support the safer habit: keep warm dairy in glass or stainless steel, especially when the food sits for hours.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Microplastics and phthalate esters in yogurt and buttermilk samples: characterization and health risk assessment. | J Environ Health Sci Eng | 2025 |
| Analysis of phthalate migration to food simulants in plastic containers during microwave operations. | Int J Environ Res Public Health | 2013 |