There are 3 main types of cumin seed available: amber, black and white.
The amber seeds closely resemble caraway, fennel and ajwain seeds, and are a light yellow brown in colour with ridges and oblong in shape. These are the most common variation used in cuisines.
White cumin seeds are similar to amber seeds, just a bit paler. You can substitute white and amber if you only have one type available.
The black seeds are really a very dark brown in colour, they are lighter and sweeter than the other cumin and work well in creamy foods, rice dishes and the more unusual spice blends of Northern India and Persia.
Black cumin seeds are often mistaken for nigella seeds, when in fact they are very different spices.
Health benefits of cumin
The health benefits of cumin include digestion, piles, insomnia, respiratory disorders, asthma, bronchitis, common cold, lactation, anemia, skin disorders, boils, immunity, and cancer.
Digestion: Cumin is extremely good for digestion and related problems. Cumin is also Carminative i.e. relieves from you from gas troubles and thereby improves digestion and appetite. Due to its essential oils, magnesium and sodium content, it promotes digestion and also gives relief in stomach-ache when taken with hot water (like aqua ptycotis and mint).
Piles: The main reason behind piles is constipation added with infections in the wound in the anal tract, which again is caused by constipation. Cumin, because of its dietary fiber content and carminative, stimulating, anti fungal and anti microbial properties due to the presence of essential oils comprising mainly of Cuminaldehyde and certain pyrazines, acts as a natural laxative in powdered form, helps healing up of infections or wounds in the digestive & excretory system and speeds up digestion too.
Insomnia: This is a very peculiar property of cumin. It is a stimulant as well as a relaxant at the same time. This property cannot be attributed to a single component alone, just as causes of insomnia cannot be attributed to a single cause.
Common Cold: Common Cold is a viral infection which affects our body frequently when our immune system goes weak. Again, the essential oils present in cumin act as disinfectants and help fight viral infections which cause common cold. Cumin also does not let cough formation in the respiratory system as it is supposed to be hot and dries up the excess mucus. Cumin is rich in iron and has considerable amount of vitamin-C, which are essential for a good immunity and keeps infections away.
Anemia: cumin is very rich in iron (above 66 mg. in each 100 grams) which is more than 5 times the daily requirement of iron for an adult. This iron is the main constituent of haemoglobin in the red blood corpuscles of blood. It is haemoglobin which transfers oxygen (as oxide of iron) to the body-cells and whose deficiency causes anemia. So, cumin can be a nutritious additive to daily diet for anemic people.
Skin Disorders: Almost all of us know that vitamin-E is good for skin.
Boils: Boils are just outlets for removal of toxic substances and foreign matters such as microbes etc. from the body.
Immunity: abundance of iron, presence of essential oils and vitamin-C & vitamin-A in cumin boosts up our immune system.
Cancer: Cumin itself has detoxifying and chemo-preventive properties and accelerates secretion of detoxifying and anti-carcinogenic enzymes from the glands, as it does to other secretions. As well as, it has nice anti oxidants like vitamin-C and vitamin-A in it, in addition to those essential oils, which, besides having countless other benefits, have anti carcinogenic properties too. It is particularly good for cancer of colon.