Introduction

Globally, there are many under-utilized fruits that have been found to be a rich source of essential components of nutritional advantage, this includes carbohydrates, proteins, vitamins and micronutrients. These are regarded as under-used because they are not popularly consumed outside their geographical origins and their nutritional benefits are not sufficiently explored. Cultural and societal beliefs and myths also stand as a challenge to these limitations such as the classification of such fruits as food for the poor’. However, this hinders the exploration of these fruits for their medicinal, economic, dietary/ nutritional, and environmental benefits. The Canistel (Pouteria campechiana) is also known as egg-fruits or the yellow sapote. The name egg-fruits is derived from its appearance which is in the shape of hard-boiled egg yolks. It is indigenous to Central America and can also be found in tropical and subtropical regions. Phytochemicals that are beneficial to human health have been found to be present in the different parts of the plant, this includes their nuts, seeds, and fruits. These phytochemicals have been found to provide beneficial curative effects on many diseases. The ripened canistel fruit can be eaten fresh or processed into other forms such as Jam, ice creams, custards, and milkshakes.^1,2

Nutritional composition of Canistel

According to the World Health Organization (WHO), at least 400 g of fruits and vegetables must be ingested for the maintenance of good health. These fruits and vegetables can be consumed raw or in various processed forms such as jams, drinks, and cakes.³

In spite of its nutritional and therapeutic advantages, Canistel is a neglected fruit in comparison to many others all over the world. Unfortunately, the under-utilization and inadequate knowledge about canistel further extend into inadequate knowledge of its biochemistry. Consequently, there is limited data on the benefits of the canistel fruit and this stands as an obstacle in the consideration of canistel fruit in the food diversification efforts. It has higher carotenoid content when compared to the sweet potato which is popular for its very high carotenoid content. The canistel has carotenoid content as high as 2300 mg/100 g. This carotenoid content is effective in the avitaminosis treatment and it is an affordable management option with fewer side effects due to its natural origins. It is also beneficial due to its antioxidant effect due to its dihydromyricetin, catechin, epicatechin, ascorbic acid, beta carotene and polyphenolic contents. These are responsible for the many more benefits of the canistel such as the antihypertensive and antidiabetic effects, and bone and joint strengthening benefits.

Canistel contains essential amino acids such as L-Valine, L-Phenylalanine, L-Isoleucine, L-Lysine, L-Leucine, L-Histidine, and L-Threonine. Additionally, some non-essential amino acids present in canistel include; L-Glutamic acid, L-Alanine, L-Serine, L-Aspartic acid, L-Proline, and L-Tyrosine.^3,4

The antioxidant effects of canistel are relatively higher than many other under-utilized fruits. This tropical fruit has a wide range of medicinal uses which include the treatment of epilepsy, coronary heart diseases, liver disease, cancer prevention, treatment of cataracts, anaemia management, cold and flu management, skin diseases among others. These effects have been attributed to its broad content of functional compounds.⁵

A 2016 study by Elsayed et al concluded that the canistel leaves and seeds possess effective analgesic and anti-inflammatory effects. A desired quality to this is the added advantage that they do not predispose the patient to gastric ulcers as found in synthetic non-steroidal anti-inflammatory drugs (NSAIDs) such as indomethacin, rather they have gastro-protective effects against ulcers. This is due to the presence of flavonoids and phenolic compounds.⁶

Recent scientific studies have shown that the compound myricitrin in the leaf of canistel has a poisonous effect on Aedes aegypti as well as Culex quinquefasciatus species of mosquitoes at every stage of their life cycle. This makes them a potential active component in mosquito-repellant products such as creams, gels, and sprays.

The egg fruit contains many minerals, including phosphorus, copper, iron, potassium, calcium, sodium, magnesium, and zinc with potassium being the mineral with the highest component. The phenolic compounds present which varies in concentration depending on the parts of the plant are able to remove toxic free radicals from the body and protect against degenerative and life-threatening diseases such as cancer.

The antimicrobial activity of oil extract from the canistel has also been reported. The anti-microbial effect is potent against Gram-positive as well as Gram-negative organisms.⁷

Storage of the Canistel products

The canistel fruit is rich in water content which makes its storage quite a challenge because of the risk of attack by spoilage organisms. It is essential to properly store these fruits to preserve their quality and ensure they retain their safety and potency after harvesting. It is recommended that canistel products be stored at low temperatures (as low as four degrees centegrade), pre-treatment with 2% sodium chloride and calcium chloride solution has also been found to confer longer shelf life on the canistel fruits.⁷

Summary

Canistel (Pouteria campechiana) has significantly high nutritional and medicinal values, however, it is grossly under-utilized and limited data is available on its biochemical contents. This has been attributed to geographical regions of cultivation, limited information, cultural and socio-economic beliefs and myths. More studies need to be carried out to assess the fruit and its limitless possibilities. This is because, with the ever-increasing population growth of global populations, it is important for food diversification efforts to be increased and explored more effectively. This will ensure the nutrient-dense foods/ fruits such as the canistel are made available, and accessible to everyone.

Despite being a neglected fruit, canistel is rich in essential nutrients, including carbohydrates, proteins, vitamins, and micronutrients. The fruit's high carotenoid levels go as high as 2300 mg/ 100 g. Canistel also shows antioxidant effects due to compounds like dihydromyricetin, catechin, and ascorbic acid, offering benefits such as cardio-protective and anti-diabetic effects. Furthermore, Canistel contains essential and non-essential amino acids essential for human health. Studies suggest its medicinal uses, including treatment for epilepsy, coronary heart diseases, and cancer prevention. Canistel are best preserved in low temperatures to preserve their quality and safety for human consumption.