The color of aloe vera varies significantly across its distinct layers. Aloe vera is a succulent prized globally for its medicinal and cosmetic properties, particularly the soothing substance found inside its thick leaves. To understand the true color of aloe, one must distinguish between the outer leaf, the inner gel, and the various color changes that signal a plant’s health or occur during commercial processing.
The Color of the Aloe Vera Leaves
The exterior of a healthy, mature Aloe vera leaf displays a grayish-green or blue-green hue. This coloration is due to the presence of chlorophyll, the pigment that allows the plant to perform photosynthesis and produce energy. The leaves are covered with a waxy cuticle layer, which gives them a dull or matte finish and helps the succulent retain moisture in arid conditions. The leaves grow in a rosette pattern and feature serrated edges with small, pale spines.
The Color of the Inner Gel
The most sought-after component of the plant is the inner leaf fillet, known as the aloe gel. When freshly extracted, the gel is transparent or translucent, resembling clear, gelatinous water. This clarity is due to the absence of chlorophyll and other plant pigments found in the outer rind. The inner fillet is a mucilaginous parenchyma tissue, composed of over 98% water, with the remaining solids consisting primarily of complex polysaccharides such as acemannan.
Why Aloe Colors Indicate Plant Health
The outer leaf’s color can shift in response to environmental conditions, serving as a visual indicator of the plant’s well-being. A change from the standard green to reddish-brown, yellow, or even a deep bronze is a stress response. When exposed to intense, direct sunlight, prolonged drought, or cold temperatures, the plant produces reddish-purple pigments called anthocyanins to protect its tissues from damage. This color change is a defensive measure, allowing the plant to conserve energy and water until conditions improve.
Separately, a bright yellow liquid, known as aloe latex or aloin, is found in the pericyclic cells located just beneath the leaf rind. This bitter, yellowish-brown exudate is the plant’s natural defense mechanism against herbivores. Aloin is an anthraquinone glycoside with potent laxative properties, and its presence is easily noticeable when a leaf is cut, as the yellow fluid will seep out before the clear gel. It is important to drain this yellow layer before using the inner gel, as it can be an irritant.
Color in Commercial Aloe Products
Commercial aloe products, such as gels and juices, often appear slightly different from the fresh, clear gel. Many products are processed using a decolorization step, which involves carbon filtration to remove the bitter, yellow aloin compound. If this process is thorough, the resulting juice or gel should be colorless and odorless.
However, some commercially available products may exhibit a pale yellow, light green, or even amber tint. Light yellowing can occur naturally due to slight oxidation or be an artifact of the harvesting season, as gel harvested during dry periods may contain more naturally occurring pigments. Conversely, products that are artificially green often contain added coloring agents like FD&C blue and yellow dyes, despite the authentic inner gel being colorless.