The application of hydroxytyrosol as a natural antioxidant

Hydroxytyrosol, a natural polyphenolic antioxidant derived from olives, exhibits significant effects in oil preservation. Its mechanism of action and application characteristics are mainly reflected in the following aspects:

I. Antioxidant Mechanism

Oxidative rancidity of oils is the main cause of quality deterioration, manifested as the production of a rancid odor, darkening of color, reduction in nutritional value, and even the formation of harmful substances (such as aldehydes and ketones). Hydroxytyrosol inhibits oil oxidation through multiple pathways:

Scavenging free radicals: The phenolic hydroxyl groups in its molecular structure can provide hydrogen atoms, directly capturing free radicals generated during oil oxidation (e.g., hydroxyl radicals, peroxyl radicals), terminating the free radical chain reaction, and reducing the production of lipid peroxidation products.

Chelating metal ions: Oil oxidation is often catalyzed by transition metal ions such as iron and copper. Hydroxytyrosol can form stable chelates with these metal ions, reducing their catalytic activity and inhibiting the initiation of oxidation reactions at the source.

Protecting the antioxidant system: In oil systems, it can synergistically enhance the activity of other antioxidant components (e.g., vitamin E, tea polyphenols), improving the overall antioxidant efficiency through complementary effects and delaying the oxidation process of oils.

II. Specific Effects in Oil Preservation

Delaying changes in rancidity indicators: Adding hydroxytyrosol to vegetable oils (e.g., olive oil, soybean oil, sunflower oil) can significantly reduce the increase rate of peroxide value (PV), acid value (AV), and p-anisidine value (p-AV). For example, under high-temperature storage or frying conditions, it can reduce the oxidative cleavage of unsaturated fatty acids in oils, extending their shelf life.

Maintaining sensory and nutritional quality: Hydroxytyrosol can inhibit the production of odorous substances (e.g., aldehydes, ketones) from oil oxidation, preserving the original color and flavor of oils. Meanwhile, it reduces the oxidative loss of fat-soluble vitamins (e.g., vitamins A, D, E), retaining the nutritional value of oils.

Adapting to multiple oil types: Hydroxytyrosol exerts antioxidant effects on both vegetable oils (e.g., olive oil, rapeseed oil) and animal fats (e.g., lard, tallow), with particularly significant effects on oils rich in unsaturated fatty acids (e.g., linseed oil, fish oil), as they are more prone to deterioration due to oxidation.

III. Key Influencing Factors in Application

Addition dosage: Its antioxidant effect exhibits a dose-response relationship. Generally, an addition amount of 0.01%~0.1% (mass fraction) in oils can achieve obvious effects. Excessive addition may cause a slight astringent taste in oils, requiring dosage adjustment based on sensory evaluation.

Synergistic effects: When compounded with other antioxidants (e.g., vitamin E, rosemary extract), the antioxidant effect is better than that of a single component. For example, the combination of hydroxytyrosol and vitamin E can enhance free radical scavenging capacity, and compounding with citric acid (a metal ion chelator) can further inhibit metal-catalyzed oxidation reactions.

Processing and storage conditions: During oil refining, high-temperature frying, and other processing processes, the stability of hydroxytyrosol needs to be improved through technologies such as microcapsule embedding to avoid degradation due to high temperature and light. During storage, it should be combined with light-proof and sealed packaging to extend its antioxidant validity period.

IV. Advantages and Application Prospects

Compared with synthetic antioxidants (e.g., BHA, BHT), hydroxytyrosol has advantages such as natural origin, high safety, and good biocompatibility, which is more in line with consumers' demand for "natural and healthy" foods. Currently, it has been applied in high-end edible oils and functional oil products (e.g., blended oils, frying oils), and is particularly competitive in products emphasizing "natural preservation". In the future, by optimizing extraction processes to reduce costs, improving stability, and expanding application scenarios through regulatory certification, hydroxytyrosol is expected to become one of the core natural antioxidants in the field of oil preservation.