TBHQ is one of the most effective synthetic antioxidants available for protecting unsaturated fats and oils from oxidative degradation. Unlike BHA and BHT, TBHQ performs especially well in vegetable oils (soy, canola, sunflower, palm) and fried food applications where it suppresses off-flavor development, color degradation, and free-radical-driven polymerization during frying and extended storage. It delivers excellent carry-through protection (survives frying to remain active in the finished fried product). Regulatory: FDA 21 CFR 172.185 with max use level 0.02% (200 mg/kg) of the fat/oil content, EU E319 approval with similar limits, and approved by JECFA with ADI 0.7 mg/kg body weight.
Often combined with citric acid and BHA/BHT for synergistic antioxidant systems. Produced by tert-butylation of hydroquinone with isobutylene. Typical purity ≥ 99%. Applications include vegetable oils, shortenings, frying fats, snack foods, convenience foods, pet food, and cosmetics.