Why does aloe vera change its colour?

Thealoe vera is a succulent plant that belongs to the Asphodelaceae family. Its fleshy and thick leaves make it easy to recognise. These leaves contain a gel that is highly valued in cosmetics and often used in the production of skincare and haircare products. The aloe vera is primarily composed of water but also contains enzymes, amino acids and minerals. This composition gives it several of its properties:

• Soothing and anti-inflammatory : aloe vera gel has the ability to inhibit the production of certain pro-inflammatory molecules, thereby helping to calm skin redness and discomfort.

• Antioxidants : this ingredient boosts the production of metallothioneins, proteins with an antioxidant role that limit oxidative stress. The resistance of tissues is enhanced and cellular ageing is slowed down.

• Healing : the application of aloe vera gel aids in speeding up the healing process by promoting the development of new capillary vessels (angiogenesis) and cellular proliferation.

• Moisturisers : The hygroscopic amino acids in the gel limit the evaporation of water on the surface of the epidermis without, however, forming an occlusive film on its surface. The skin thus appears more hydrated and soft.

• Regenerative : the polysaccharides present in the gel enable it to boost the production of collagen and elastin by the fibroblasts, proteins partly responsible for the skin's structure and its suppleness. As a result, the skin gains in tone and elasticity.

• Regulators of microcirculation of blood : this botanical extract can also be used to alleviate issues related to poor blood circulation, such as dark circles or heavy legs.

Aloe vera gel is typically transparent and does not exhibit any specific colour. However, it may occasionally develop a slight yellowish hue over time. This phenomenon can be attributed to the oxidation of the aloe vera gel when exposed to air. Heat can also contribute to the degradation of the gel. This is why it should be stored in a cool place. If its olfactory properties remain unchanged, the application of this gel poses no risk.

However, when the colour change is pronounced and the gel turns from ochre to brown, and/or its smell alters, it is recommended to cease its use.

This is why the aloe vera pulp is immediately stabilised after its extraction. This is achieved by homogenising it with certain substances that neutralise the action of enzymes without destroying them, which are responsible for the rapid oxidation of the gel when exposed to air. In this way, they are always present in the gel and it retains its benefits. Before being incorporated into skincare products, it typically undergoes a second stabilisation for enhanced effectiveness and greater safety.

How to properly store aloe vera gel?

In order to prevent any risk of oxidation or degradation of the aloe vera gel, it must be stored in a hermetically sealed and opaque container. After extraction, the aloe vera gel can be kept for 24 to 48 hours in the refrigerator. However, it is possible to preserve it for a longer period by adding vitamin C and E.

To achieve this, mix the aloe vera gel with one or two of these vitamins (approximately 500 mg of vitamins for 60 mL of gel). This way, you can keep your gel for six months in the refrigerator. One final tip is to freeze it. Aloe vera ice cubes can generally be stored for a year in the freezer.

• SAPLE D. G. & al. Aloe vera: a brief overview. Indian Journal of Dermatology (2008).

• CHUNG J. H. & others. Dietary aloe vera supplementation enhances facial wrinkles and elasticity, and it elevates the expression of the type I procollagen gene in human skin in vivo. Annals of Dermatology (2009).

• Thesis by Margaux ROULLIER. The topical use of aloe vera gel and its healing properties (2015).

• LI J. & al. Aloe vera: a medicinal plant utilised in the healing of skin wounds. Tissue Engineering (2021).