Research on the Applications of TBHQ as an Antioxidant

Autoxidation is a complex free-radical chain reaction in which compounds react with atmospheric oxygen at ambient or slightly elevated temperatures, producing free-radical intermediates or final products such as organic peroxides. Typical examples include the rancidity of foods and oils, as well as the aging of rubber and plastics. Although all hydrocarbons are susceptible to autoxidation, the presence of unsaturation—such as in triglycerides—significantly increases the propensity for oxidative degradation.

Tert-butylhydroquinone (TBHQ) is a highly effective phenolic antioxidant commonly used to prevent or retard deterioration caused by autoxidation. In China, TBHQ was approved for use as a food antioxidant in 1991, with a maximum permitted level of 0.2 g/kg, expressed as fat. Currently, TBHQ is widely applied in food, feed, cosmetics, and chemical products, including rubber and printing inks.

1. Applications in Food

During processing and storage, lipids and fat-containing foods undergo autoxidation of unsaturated fatty acids, leading to oxidative rancidity and consequently adverse effects on product quality. TBHQ effectively retards oxidative deterioration and exhibits superior antioxidant performance compared with other commonly used antioxidants. Owing to its high activity, strong efficacy, and favorable cost–performance ratio, TBHQ is widely applied in various food products.

In vegetable oils, TBHQ is recognized as one of the most effective antioxidants. Xu Jinrui ^[1] investigated the effects of three antioxidants on sunflower oil and found that, at the same addition level, their antioxidant effectiveness followed the order: TBHQ > BHT > BHA. In addition, citric acid (CA) showed a synergistic effect with these antioxidants.

Data source: Xu Jinrui, Deng Yifeng, and Lie Likun. Effects of the synergistic action of several antioxidants on the stability of sunflower oil.

 For fried foods, TBHQ exhibits excellent thermal stability and maintains effective antioxidant performance in frying oils and fried products. Gao Pei et al. ^[2] investigated the effect of TBHQ on the oxidative stability of fried peanuts. The results showed that under accelerated oxidation conditions at 37 °C, the acid value and peroxide value of fried peanuts supplemented with 0.1 g/kg TBHQ were significantly lower than those of the control group, and both values remained within international regulatory limits. The predicted shelf life exceeded 12 months, whereas in the control group without antioxidants, the acid value exceeded the acceptable limit by the third month of storage.

2. Applications in Feed

Oxidative rancidity in feed primarily refers to the oxidative degradation of lipids or lipid-soluble components. TBHQ exerts its antioxidant activity by scavenging free radicals in feed and forming stable phenoxy radicals. Its antioxidant efficacy is superior to that of other phenolic antioxidants such as BHT, BHA, propyl gallate (PG), and vitamin E (VE). In addition, vitamin C, citric acid, and phosphates can significantly enhance the antioxidant performance of TBHQ. The combined use of phenolic antioxidants also shows markedly better efficacy than TBHQ used alone.

According to Announcement No. 2625 of the Ministry of Agriculture, the maximum permitted level of TBHQ in feed oils and fats is 0.2 g/kg. When used in combination with other antioxidants, the total addition level in compound feed shall not exceed 0.15 g/kg.

Peng Diwei et al. ^[3] evaluated the antioxidant effect of TBHQ on feed-grade fish oil using an Oxitest oxidation stability analyzer at 90 °C and an oxygen pressure of 6 bar. The results showed that, compared with fish oil without antioxidants, the oxidation induction time increased from 2 h 4 min to 3 h 21 min when 200 mg/kg TBHQ was added, demonstrating that TBHQ significantly improves the oxidative stability of fish oil.

Data source: Peng Diwei, Yang Bineng, Huang Zhen, et al. Study on the Oxidative Stability of Fish Oil for Feed Use.

3. Application in Cosmetics

In cosmetics or personal care products, fragrance and odor have a significant impact on consumer acceptance. The use of appropriate antioxidants such as TBHQ helps deliver products that remain fresh, stable, and protected against oxidative degradation. TBHQ acts as a free-radical scavenger, inhibiting rancidity in creams and lotions as well as the degradation of fragrances.

Due to its excellent oil solubility, TBHQ effectively protects fats and oils, as well as emulsifiers derived from unsaturated fats or oils. It also exhibits good thermal stability and is not easily volatilized under typical cosmetic processing temperatures. For commonly used cosmetic oils and other unsaturated components, TBHQ is more effective than other antioxidants such as BHA, BHT, and propyl gallate.

According to the Inventory of Existing Cosmetic Ingredients in China (2021 Edition), the maximum historical use level of TBHQ in leave-on products is 0.05%.

4. Applications in Other Industries

In addition to its use as an antioxidant for oils and fats in food and feed, TBHQ is also a highly effective industrial antioxidant. It is widely applied in plastics, rubber, printing inks, coatings, unsaturated resins, and other industrial fields. At concentrations ranging from 0.01% to 1.0%, TBHQ is a highly efficient antioxidant for unstable organic liquids such as chlorinated hydrocarbons, oils, ethers, and aldehydes. In certain cases, its antioxidant efficacy is superior to that of hydroquinone.

TBHQ also serves as a very effective polymerization inhibitor during the storage of unsaturated polyesters and other polymeric organic materials. In addition, it functions as an excellent defoaming agent, particularly in the polyethylene industry. It can eliminate “fish-eye” defects in polyvinyl chloride (PVC) products and prevent the aging of PVC materials, thereby extending the service life of PVC products. The typical dosage is 1–2 g/kg.

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