Kukui nut oil is extracted from the seeds of the kukui nut. It is also called kemiri nut or candle nut and grows on the kukui nut tree, which has the Latin name Aleurites moluccanus. Like the kukui nut, the kukui nut tree has many names. It is called the light nut tree, lumbang tree, Indian walnut, bankul nut tree, or candlenut and belongs to the spurge family. The kukui nut tree is an evergreen and fast-growing tree that can reach a height of up to 20 meters and more. A broad tree top characterizes the Kukui tree. Its outer bark layer is dark gray, while the bark is grey-brown and hairy. Its leaves are arranged alternately on a petiole, which is usually 6 to 12 centimeters long and can sometimes reach 22 centimeters. The upper side of the leaves is intensely shiny and has a dark green color. Underneath, there are bright, shimmering, silver-colored star-shaped hairs. The candlenut tree has white flowers. The female flowers can reach a length of up to eleven millimeters, while the male flowers are smaller at seven millimeters. The small, bell-shaped flowers are arranged in many inflorescences at the top of the branches. The kukui tree is also known as the "candle-nut tree" because of its flowerage. The kukui nut is hairy and has a diameter of up to six centimeters, while the shell is around six millimeters thick. Four longitudinal ribs break up the almost spherical shape. The skin is olive green but can also be reddish. Inside are one or two stony seeds, the shell of which is complex and leathery. The seeds are rounded, wrinkly, and brown-black.
The kukui nut tree is native to Hawaii and is on mountain slopes and canyons. In addition, kukui nut trees are also found in Polynesia, southern Asia, Australia, and Sri Lanka. Nowadays, their range extends from India to China and Southeast Asia to New Zealand. The kukui nut tree is rarely found in tropical regions because it prefers a relatively dry tropical climate, where it lives at altitudes of up to one thousand two hundred meters. It loves warmer temperatures and is sensitive to frost. According to its distribution area, the Hawaiians use kukui nut oil to protect themselves against wind and sun, which is part of traditional Hawaiian medicine. In addition, the noil is also characteristic of Hawaiian Lomi Lomi Massage. Because the kukui nut is rich in oils, it is often used as a seasoning in Southeast Asian cuisine. The sweetish nutty taste also acts as a flavor enhancer. In the countries of origin, kukui nut oil is traditionally used to make soap, candles, and lamp oil, with the kernels being lit untreated. The wood of the kukui nut tree is less important because it is soft and not very durable. Under no circumstances should kukui nuts be eaten raw, as this can result in abdominal cramps, diarrhea, and vomiting.
A mature kukui tree can produce up to 35 to 45 kilograms of fruit per year, from which the valuable kukui nut oil is extracted. It is done by cold or hot pressing. The kukui nut oil is then gently filtered and cleaned or refined. The oil is light yellow to orange, while its odor is acidic and slightly grassy.
Ideally, kukui nut oil is obtained by cold pressing, which refers to the oily cores not being pre-treated with heat. However, pressing and rubbing can generate heat during manufacturing, though this must not exceed 40 degrees Celsius. The oil yield is lower during cold pressing, which makes cold-pressed oil more expensive. The peculiarity of cold pressing is that these oils are not refined but filtered and dried. The remaining water is then removed during the drying process. Antioxidants such as vitamins A, E, and C can be added to stabilize it. The advantage of cold pressing is that the high quality of the oil, the polyunsaturated fatty acids, and the vitamins and minerals it contains remain unharmed due to the delicate production process. When kukui nut oil is hot-pressed, most of the antioxidants, vitamins, and minerals it contains are destroyed. It is because during hot pressing, the fruits of the kukui nut tree are crushed, heated, and the oil is pressed. It can also be followed by the extraction process, in which the remaining oil is removed from the fruit. It is done using a solvent, which is then separated from the oil again by distillation. As a result, numerous undesirable contents and accompanying substances get into the nut oil, which is removed through refining. Hot pressing is significantly more complex than cold pressing and leads to the loss of valuable ingredients. For this reason, cold pressing deserves preference.
To understand the application and effects of kukui nut oil, it is essential to know the ingredients. The oil is characterized by a very high content of unsaturated fatty acids, up to 90 percent of which are linoleic and linolenic acids. It makes the kukui nut oil one of the top oils with the highest fatty acid content. Omega-3 and omega-6 fatty acids are rich in vitamins A, B, and E and contain phytohormones such as beta-sitosterol, campesterol, and stigmasterol. Due to these ingredients, the kukui nut oil has numerous positive effects on the skin and hair. It is anti-inflammatory wound-healing moisturizing relieves pain and prevents the aging process. Studies have proven the anti-inflammatory properties of kukui nut oil, especially in inflammatory skin diseases and arthritis. The high content of essential fatty acids has a moisturizing effect, making it ideal for dry skin and relieving psoriasis, neurodermatitis, and eczema. The nut oil is also suitable for caring for sensitive and impure skin. The unsaturated fatty acids can also support the build-up of the body's epidermal ceramides and thus contribute to the regeneration of the skin barrier. As a result, the body's moisture is retained. The skin's texture can be improved with kukui nut oil, as the skin quickly absorbs the nut oil without leaving a greasy feeling. The extra portion of lipids protects the skin from harmful environmental influences and moisture loss, as it also has a natural sun protection factor of up to ten. Because of these properties - relieving inflammation and improving blood circulation - it is also believed to have an analgesic effect. The vitamins and minerals in kukui nut oil support wound healing and positively improve scar appearance.
Kukui nut oil also helps reduce the appearance of fine lines and wrinkles due to its antioxidant properties, slowing down the aging process. It is also due to the high proportion of vitamin A and linolenic acid, which have a moisture-regulating and skin-tightening effect. Among other things, the kukui nut oil can strengthen the connective tissue and prevent stretch marks.
Kukui nut oil is suitable for skin care and hair care. A small dose of nut oil moisturizes the hair. It becomes soft, supple, and shiny, reducing problems such as hair breakage or split ends. You can use the oil for massages as it penetrates the skin quickly without leaving any residue and has a relaxing effect. It promotes blood circulation and relieves muscle tension. Due to its natural UV filter, the kukui nut oil offers natural protection against the sun's harmful rays, with a sun protection factor of around 10. The oil is also used in aromatherapy. Its light and nutty scent helps increase general well-being and reduce stress.