Green thumb
Fruits of tropical soursop tree have many benefits
Commonly known as soursop, Annona muricata is a tropical fruit tree found growing naturally in the tropical regions of Central America. The soursop tree was originally brought to North Queensland, along with many other fruits and grasses, by early European explorers such as George Dalrymple.
Dalrymple was the proverbial “Johnny Appleseed”; during his exploration journeys around Far North Queensland, he planted trial plots of tropical crops he thought would sustain a European colony. Unfortunately, many of the plants Dalrymple introduced have become weeds.
As a child growing up in Far North Queensland, I remember that almost every backyard had a chicken coup, and planted within was a selection of fruit trees and nearly always a soursop.
I loved climbing the strong branches of the old soursop tree and reaching out to pick the soft mature fruits – they were the size of footballs and could weigh over 6kg; it needed strong hands to grab hold of the prickly fruits. When fully ripe, the creamy, sweet-sour flesh tastes like yoghurt ice cream; I loved it then and now, and have eaten soursop fruits all my life.
A few years ago claims were made that the soursop fruit and extracts from the leaves of the tree could cure some cancers; there is no medical evidence to substantiate this claim. However, the flesh of the fruit is loaded with fibre, which is needed for bowel and gut health.
The fruit is covered in a thin, prickly, green inedible skin and the flesh of the fruit contains many seeds which cannot be eaten. Understanding how to remove the skin and extract the seeds easily is the secret to making the best use of the fruits.
Harvest the soursop fruits only when they are fully mature, usually when they respond slightly to a light squeeze. At this stage, the fruits will ripen fully within 24 hours.
There is only a small window of perfect ripeness during which time is easy to process the fruits. When the fruit is soft but still firm, cut a level slice from the bottom and top of the fruit. Stand the fruit on a board and peel the skin away – it should peel away easily without breaking.
The seeds are located around the core of the fruits. With a sharp knife, cut a slice from each of the four sides, noting where the core of the fruit sits in the somewhat lopsided fruit. The seeds should be visible around the core and the external slices should be without seed.
Hold the core firmly and with a fork remove the seeds from the remainder of the flesh – discard the seeds and pull the remaining fruit away from the core. Discard the core of the fruit as it is not edible.
The flesh can be thinly sliced and dried as a fruit snack, or can be placed in a blender with coconut cream to make a refreshing drink or ice cream, or the juice reinvented as a refreshing sherbet.
The soursop tree is easy to grow; it does best in the hot, humid, loamy soils of lowland Northern Australia, where the monsoon reigns. Good drainage is ideal for this tree although it will tolerate short periods of inundation.
Soursop is mostly grown from seedling trees which fruit within three years or when the biomass of the tree has grown within a height of about 4m.
Regular mulching and regular applications of organic fertiliser will benefit the tree’s growth, and the quality and quantity of the fruit.
The soursop tree can be pruned to remove lateral branches, allowing light to reach the centre of the tree and stimulate fruiting buds and their pollinators. The tree’s height can be reduced to around 4m to enable easy fruit harvest.
Scale insects can be a problem. When observed, spray the fruits, leaves and branches of the tree with pest oil or insecticidal soap, either of which will control both scale and mealy bug.
Fruit fly control is necessary in summer with one bait station for every three fruit trees being sufficient to manage these pests.
The root system of the soursop tree is not invasive and if the tree is kept pruned, it is an ideal tropical fruit tree for a small yard.