Waste Vegetable Oil
Waste vegetable oil (WVO) is simply another name for used cooking oil or in some cases may be used to refer to off spec or expired fresh oils that cannot be used or marketed as intended. WVO is generally used to refer to used cooking oils that are primarily vegetable oil based and have minimum or no animal fats from cooking process. Oil may or may not be processed and will have variable specifications for MIU and FFA.
What buyers test in waste vegetable oil
Waste vegetable oil is fryer oil, or sometimes a fresh oil that went off-spec before anyone cooked with it. The name is used when the fat is mostly from vegetable sources and has little or no meat fat from the griddle. Used cooking oil is the broader kitchen term and can include mixed animal fat. Yellow grease is the commodity name after the oil is collected and graded. The three phrases overlap, and a contract should say which tests apply instead of relying on the nickname.
MIU is moisture, impurities, and unsaponifiables. Moisture is water from a leaking fryer rinse, from rain on an open caddy, or from ice in a drum. Impurities are crumbs, batter, and filter scraps. Unsaponifiables are the fraction that will not become soap or fatty acid methyl ester in the usual reactions. A buyer who makes biodiesel or renewable diesel has to remove water and crumbs before the process. That work costs money, so a wet load is discounted or refused. Keep the lid on. Do not rinse the fryer into the oil tank.
FFA is free fatty acids. Oil breaks down with heat, time, and food moisture. A higher FFA means the oil is more degraded. Some fuel processes tolerate it and some charge for it. Animal fat from a grill raises a different issue: a buyer who ordered a vegetable feedstock may reject a mixed load even when the FFA looks fine. Off-spec fresh oil, the other meaning of waste vegetable oil, is unused oil that failed a color, odor, or shelf-life check. It can be cleaner than fryer oil and still unsaleable as food. Say which one you have.
Sampling is a dip from a mixed tank, not a glance at the top. Water settles. A pretty surface can hide a gallon of water at the bottom. The collector's sample and the plant's sample should describe the same load. Argue from the lab numbers, not from the word yellow.
GREASE.ORG picks up used cooking oil as yellow-grease feedstock and pumps trap waste separately. Trap waste is not waste vegetable oil. It is high in water and food solids and becomes brown grease only after recovery. Keep those tanks apart so a good vegetable load is not downgraded by a gallon of interceptor grease. The price pages show how these grades have been quoted. They do not replace a spec on the pickup ticket.
