The sunflower seed is the fruit of the sunflower (Helianthus annuus). The term "sunflower seed" is actually a misnomer when applied to the seed in its pericarp (hull). Botanically speaking, it is more properly referred to as an achene. When dehulled, the edible remainder is called the sunflower kernel.
There are three types of commonly used sunflower seeds. Linoleic (most common), high oleic, and Nusun. Each variety has its own unique levels of monounsaturated, saturated, and polyunsaturated fats. The information in this article refers mainly to the linoleic variety.
For commercial purposes, sunflower seeds are usually classified by the pattern on their husks. If the husk is solid black, the seeds are called black oil sunflower seeds. The crops may be referred to as oilseed sunflower crops. These seeds are usually pressed to extract their oil. Striped sunflower seeds are primarily used for food; as a result, they may be called confectionery sunflower seeds.
|Raw sunflower seeds, intended for planting.|
Sunflower seeds are more commonly eaten as a healthy snack than as part of a meal. They can also be used as garnishes or ingredients in various recipes. The seeds may be sold as in-shell seeds or dehulled kernels. The seeds can also be sprouted and eaten in salads. However, eating expired sunflower seeds may cause stomach irritation such as bloating or diarrhea due to the rotting of the seed.
When in-shell seeds are processed, they are first dried. Afterwards, they may also be roasted or dusted with salt or flour for preservation of flavor. Dehulling is commonly performed by cracking the hull with one's teeth and spitting it out while keeping the kernel in the mouth and eating it.
In-shell sunflower seeds are particularly popular in Mediterranean and Asian countries, including Egypt, Syria, Israel, Turkey, and Malaysia. In Turkey, Syria and Israel they can be bought freshly roasted in shops and markets and are a common stadium food, while in Malaysia they can be bought freshly packed in various roasted flavors. They are also popular in countries worldwide including Russia, Poland, Ukraine, Bulgaria,Romania, Spain, China, Morocco, Iran, Canada and the United States.
Dehulled kernels have been mechanically processed to remove the hull. These kernels may be sold raw or roasted. These dehulled kernels are sometimes added to bread and other baked goods for their flavor. There is also sunflower butter, similar to peanut butter, but utilizing sunflower seeds instead of peanuts. Apart from human consumption, sunflower seeds are also sold as food for pets and wild birds in boxes and small bags.
The hulls, or shells, are mostly composed of cellulose. They decompose slowly. They are sometimes burned as biomass fuel.
Over the past decades sunflower oil has become popular worldwide. The oil may be used as is, or may be processed into polyunsaturated margarines. The oil is typically extracted by applying great pressure to the sunflower seeds and collecting the oil. The protein-rich cake remaining after the seeds have been processed for oil is used as a livestock feed.
The original sunflower oil (linoleic sunflower oil) is high in polyunsaturated fatty acids (about 68% linoleic acid) and low in saturated fats, such as palmitic acid and stearic acid. However, various hybrids have been developed to alter the fatty acid profile of the crop for various purposes.
In the future, sunflower oil could become a renewable bio-source for hydrogen. A team for the University of Leeds has developed a workable method for the extraction of hydrogen from sunflower oil, through a chain of chemical reactions with nickel-based and carbon-based catalysts. However, while the plant's photosynthesis essentially captures the hydrogen, the energy necessary to liberate hydrogen gas from the hydrocarbons from sunflower oil is considerably greater than the energy of the liberated gas. Therefore, although sunflower oil could certainly be used for this purpose, it is not, by any means, a 'free' or even 'eco-friendly' source of energy.
In addition to linoleic acid (an essential fatty acid), sunflower seeds are also an excellent source of dietary fiber, some amino acids (especially tryptophan), vitamin E, B vitamins (especially vitamin B1 or thiamine, vitamin B5 or pantothenic acid and folate / folic acid Additionally, they are rich in cholesterol-lowering phytosterols.[5