Total polar compounds decide when frying oil must leave the kitchen. How Indian FBOs test TPC and then sell UCO under RUCO.
What TPC measures
Polar compounds form as oil breaks down in heat. They are the health reason FSSAI set 25 percent. Colour alone is not TPC.
Practical testing
Brand SOP: hours, product mix, filtration, plus a rapid TPC strip or meter. Calibrate against a lab if you run a chain. Do not wait until the oil smells burnt.
After the fail
Cool, filter, store, list on BioTradX. That moment is a sale, not a disposal cost, if you have a RUCO buyer.
Do not cheat the test
Topping up with fresh oil to 'pass' TPC and keep frying is the behaviour RUCO was written to stop.