[Guanabana (Spanish); Graviola (Brazil); Annona muricata]
Native to the West Indies, soursop is now the most grown Annona throughout the tropics. The fruits are relatively large, up to 12 inches long and 6 inches in diameter, thin skinned and covered with tiny spines which rub off easily. The larger photo specimen was 6 inches long, 3-3/4 inches diameter and weighed 6-3/4 ounces.
Most soursop is processed into ice cream, sherbets and beverages. The flesh is a trace fibrous and there are a lot of seeds, but the flavor is intensely floral and quite enjoyable. It has been described as like Strawberry and Pineapple with notes of Citrus and Coconut or Banana. The fruit has a sweet-sour balance similar to Tamarind.
More on Annonas.
Buying: Fresh Soursops have just started to appear in markets in Southern California, but at a very steep price. The photo specimens were purchased for 2016 US $11.99 / pound. I have also bought whole frozen soursops from the feezer cases of a large Philippine market in Los Angeles (Eagle Rock, actually) but they are not as pleasant as the fresh ones. I have also purchased Soursop canned in syrup which was quite nice, but I haven't seen it for years.
Ripening: If they are hard, they can be set out on a counter for a few days. They are ripe when they have just a little give, similar to a green Avocado. They can be eaten with a spoon.
Health & Nutrition:
Vitamins: Soursop has significant amounts of Vitamins C, B1 and B2, and Minerals Magnesium, Phosphorus and Potassium.
Neurotoxin: Soursop seeds contain Annonacin, a degenerative neurotoxin which produces a form of Parkinsons disease. It is still unknown if the flesh contains annonacin sufficient to be a problem for people who consume soursop regularly. Further study is indicated.
Cancer: "Health Food" businesses are selling Soursop capsules under the name "Graviola" as a cure for cancer. There isn't the slightest trace of any scientific or medical evidence that Graviola capsules have any anti-cancer activity (Memorial Sloan-Kettering Cancer Center, Cancer Research UK, U.S. Federal Trade Commission). On the other hand, no large scale human trials have been performed, so the claims have not been rigorously disproven, however unlikely they may be.
Seed Oil: Soursop seed oil has traditionally been used for many medicinal purposes, and is used in lotions to relieve various skin disorders.