Evaluation Of Some Nutraceutical Properties Of Lesser Known Functional Foods In Ghana

ABSTRACT

Functional foods are foods that possess other health benefits apart from their regular nutritional benefits. A functional food may contain nutraceutical properties, which have components, responsible for curing or preventing a disease or disorder. There are several indigenous foods in Ghana that have been purported to possess functional properties.

The claim to functionality of some of these indigenous foods are based on folklore but the scientific backing to these claims may not be known. It is therefore important to find out foods that Ghanaians consider to be functional. Some of these may have their properties reported in literature. However, some may not be popular and so may not have been well studied. The aim of this study was to identify some of these lesser known foods and determine their nutraceutical properties. It also sought to find out, if there were correlations between the health claims of such foods with their nutraceutical properties. Since most of the local Ghanaian foods are cooked before eating, it is also necessary to know the effect of heat on their nutraceutical contents.

A consumer survey was carried out in two major market centres in Accra to determine and select some indigenous functional foods. Analysis were carried out on selected samples to determine their total phenolic content, phytochemical profile (flavonoids, alkaloids, saponins) and antioxidant scavenging capacity. The samples were then blanched at different time regimes to determine the effect of heat on the physicochemical properties.

The results revealed that foods such as turkey berries, cocoyam leaves, and fruit of Tetrapleura tetraptera, calabash nutmegs, bissap, water leaf, fermented African locust beans, cassava leaves, anise, orange leaves, soursop leaves, pawpaw leaves, and melon seeds were considered as functional foods. These foods were easily accessible in their communities. From those interviewed, 18% reported as having consumed some of these functional foods on a daily basis. Another 18% reported that they consumed some of them occasionally. About

iii

16% consumed them on a monthly basis, 15% twice a week, and 9% three or more times a week.

Seven indigenous food samples selected for nutraceutical analysis were bitter kola, Calabash nutmeg, alligator pepper, cloves, fruit of Tetrapleura tetraptera, anise and Ashanti black pepper. For antioxidant scavenging capacity, cloves recorded 0.933%, Ashanti black pepper, 0.798%, bitter kola, 0.877%, anise, 0.789%, fruit of tetrapleura tetraptera, 0.867%, alligator pepper, 0.928% with calabash nutmeg having 0.709%. Bitter kola had a total phenolic content of 45.223mgGAE/g but Alligator pepper recorded levels of total phenolic content at 2.236 mg GAE/g. Total phenolic content and antioxidant scavenging capacity of the food samples were directly proportional to each other such that food samples that recorded high levels of phenolics also recorded a high level of free radical scavenging capacity. For phytochemicals, bitter kola recorded levels of alkaloids at 0.670. Cloves had on the other hand had alkaloid levels of 0.236. Ashanti black pepper had high flavonoid levels (8.250). Bitter kola recorded very high saponin content of 12.470, but low flavonoid levels of 2.040. Cloves recorded low flavonoid contents (1.886).

It can be concluded that the above indigenous foods have appreciable amounts of phenolic compounds, phytochemicals (alkaloids, saponins and flavonoids) and antioxidants which are bioactive compounds responsible for the functionality of foods. The bioactive compounds identified are to be responsible for the various medicinal and pharmacological properties of the selected food samples. This supported the claim by those interviewed that those foods have medicinal or curative properties.

There was a general decline in the levels of phytochemicals with respect to blanching time. The reduction occurred gradually but there was no significant difference in the values with heating time. Heating therefore had no effect on the levels of bioactive compounds present in the food.