Fruits and vegetables, fats and oils, frying and health

A fruit, in botany, is the ripened ovary of a flower containing seeds. In cookery, “fruit” usually means the sweet, juicy fruits eaten raw or as dessert, while savoury fruits (tomato, okra, garden egg, pepper, cucumber) are treated as vegetables.

Structure

• Skin (epicarp): protects; contains colour pigments, flavour oils (orange peel) and some vitamins and fibre.
• Flesh (mesocarp): the juicy edible part: water, sugars, acids, vitamin C, pectin.
• Endocarp: hard stone in drupes (mango, ube) or segments in citrus.
• Seeds: some edible (pawpaw seeds as a pepper substitute, watermelon seeds dried as egusi-type “egusi bara” in some areas).

Composition and nutritive value

• Water 80 to 90% in most fresh fruits.
• Sugars (fructose, glucose, sucrose) give energy and sweetness; starch in unripe fruit turns to sugar on ripening.
• Vitamin C: very high in guava, cashew apple, citrus, pawpaw, pineapple, baobab pulp.
• Carotene (provitamin A): mango, pawpaw, ripe plantain, yellow and orange fruits.
• Minerals: potassium (banana, plantain, dates).
• Fibre: pectin and cellulose.
• Organic acids (citric, malic, tartaric) give sharpness and help preserve.
• Very low protein and fat, except avocado (high in unsaturated fat) and coconut (saturated fat).

Seasonality in Nigeria

Mango (mostly dry season, roughly February to May), agbalumo/udara (African star apple, roughly December to April), cashew (dry season), oranges (most abundant late in the year), pineapple (available most of the year, peaking in the rains), watermelon (dry season, from the north). Buying in season is cheaper and gives better quality.

Uses of fruits in meals

• Raw as dessert or snack (oranges peeled on the street, sliced pawpaw, pineapple).
• Appetisers: fruit cocktail, melon balls, grapefruit halves.
• Drinks: juices, smoothies, zobo with pineapple peel and ginger.
• Cooked: stewed fruit, baked banana, fruit pies, crumbles, plantain dishes.
• Preserves: jams, marmalade, jellies, dried mango and pineapple, candied peel.
• Garnish and decoration: orange twists, lime wedges, cherries on cakes.
• Tenderising: pawpaw and pineapple enzymes in meat dishes.
• Flavouring: lime juice in pepper soup, tamarind in some northern drinks and sauces.

Ripening and climacteric fruits

Some fruits (banana, plantain, mango, pawpaw, avocado, tomato) continue to ripen after harvest because they produce ethylene; they can be picked mature-green and ripened later. Others (orange, pineapple, watermelon, cashew apple) do not ripen further after picking and must be harvested ripe. Artificial ripening with calcium carbide, used by some traders, is unsafe because carbide may contain arsenic and phosphorus impurities.