What is the oily layer on the outside of an apple

The luster of the oil on the surface of apples is usually natural fruit wax or artificial edible wax, which is a normal phenomenon. Fruit wax mainly comes from five sources: natural secreted wax, artificial coating preservation wax, pesticide residue wax, transportation and storage wax, and variety specific wax.

1. Natural secretion of wax

Apple epidermal cells naturally secrete a layer of hydrophobic wax, mainly composed of hydrocarbons and ester compounds. This wax can reduce water evaporation, prevent microbial invasion, and gradually form during fruit ripening. The wax thickness of different varieties of apples varies significantly, for example, the wax layer of Red Fuji apples is usually thicker than that of Gala apples.

2. Artificially coated fresh-keeping wax

Some apples are waxed after harvesting, commonly using food grade materials such as insect glue and palm wax. This process can delay respiration and maintain fruit hardness, and the Codex Alimentarius Commission allows the use of specific types of edible wax. China has strict standards for wax coating technology, requiring the use of additives that comply with national food safety standards.

III. Pesticide Residue Wax

Copper pesticides such as Bordeaux mixture used during the planting process may form a blue-green waxy film after drying. These substances need to be thoroughly rinsed with running water and can be purchased with organic certified products or peeled for consumption. The pesticide residue level of apples sold through legitimate channels usually meets national standards.

4. Transportation and storage of wax

During cold chain transportation, some apples are sprayed with microcrystalline wax to prevent frostbite. Improper humidity control during cold storage may also lead to abnormal accumulation of fruit wax. It is recommended to clean with warm water and a soft bristled brush before consumption to effectively remove excess wax on the surface.

Fifth, Variety characteristics Wax

Specific varieties such as snake fruit naturally have a thicker wax layer, and wax secretion is more vigorous in environments with sufficient light. The wax of these apples is a characteristic of the variety and does not affect their safety for consumption. Apples with thicker wax layers are usually more resistant to storage, but may affect the taste experience.

Before consuming waxed apples, it is recommended to rinse them with warm water. For stubborn wax, gently rub the surface with a small amount of salt. When choosing apples, there is no need to overly pursue appearance brightness, as naturally glossy apples are often fresher. For children or individuals with weak digestive function, priority should be given to consuming without skin. If you find that the wax layer has a pungent chemical odor or sticking to your hands, you should avoid purchasing. Keeping apples ventilated and dry during daily storage can effectively reduce the oxidation and deterioration of surface wax.