Open access peer-reviewed chapter
Some examples of vegetable, description, and nutritional value.
Abstract
The incidence of chronic and incurable diseases ravaging humanity today has awakened a resolve for healthy eating and natural living. Mankind generally cultivates diverse foodstuff for survival, multiplication, replenishment, and commercial purposes. Vegetables are a variety of food that provide nourishment of essential vitamins and minerals to the body. The various categories of vegetables cut across leafy, bulb, flower, seed, root, fruit to stem. The variety of colors from different array of vegetables are evidence of the numerous phytochemicals present in vegetables. These phytochemicals have been recorded to help the body fight against diseases and reduce the incidence of occurrence. Metabolic activities of the human body are enhanced when vegetables are consumed in large quantities. Vegetables can be eaten either raw or cooked and play an important role in human nutrition. They are mostly low in fat and carbohydrates, but high in vitamins, minerals, and dietary fiber. Due to the short shelf-life of many vegetables, it is pertinent to handle them in a most hygienic way to prevent the loss of essential nutrients especially the easily volatile group like essential oil, vitamin B, and vitamin C. Handling process of vegetables include canning, freezing, dehydrating and blanching.
Keywords
- health
- nutrients
- phytochemicals
- shelf-life
- vegetables
1. Introduction
The word vegetable is derived from Medieval Latin vegetabilis “growing, flourishing” (i.e. of a plant), a semantic change from a Late Latin meaning “to be enlivening, quickening” while the meaning of “vegetable” refers to as a “plant grown for food” [1].
Vegetables are known as the segments of plants that serve as food to humans and other animals. It is often regarded collectively as edible plant matter, including flowers, fruits, stems, leaves, roots, and seeds.
Vegetable gathering from the wild was done by hunter-gatherers. This evolved to the cultivation of vegetables in several parts of the world during the period 10,000 BC to 7000 BC following the development of a new agricultural way of life. Primarily, plants grown locally would have been cultivated. However, with time, various exotic crops from other regions were introduced to the local market. Presently, the production of most vegetables around the world is highly dependent on the climate and crops may be cultivated as protection for the environments in less appropriate areas. The level of vegetable production varies as a result of the purpose, on the one hand, subsistence farmers supply the needs of their families for food and on the other hand, supply agro-allied businesses.
Moreso, vegetables are edible when raw or cooked and serve an important role in human nutrition because it has low fat and carbohydrates but high in vitamins, minerals, and dietary fiber. Nutrition experts advised people to consume more fruit and vegetable, also recommended five or more portions a day. Generally, vegetables are rich sources of minerals- especially calcium and iron, and vitamins A and C. while nearly all classes of vegetables are adequate as antioxidants and dietary fiber [2].
1.1 Categories of vegetables
There are various descriptions on categories of vegetables namely:
Fruits of some other plants fall into the vegetable group. Such as cucumber, okra, pepper, tomatoes, sweet corn, eggplant, squash.
Leafy vegetables such as brussels sprouts, waterleaf, cabbage, spinach, pumpkin leaves, celery, jute plant, cassava leaves are common examples in this group.
Root vegetables: these are plants whose underground parts are used as vegetables. Examples include beets, carrot, radish, sweet potato, turnips.
Seed vegetables: the seed vegetables are actually the legumes and pods such as beans and peas.
Stem vegetables: these are plants where the shoot parts are considered.
Moreso, the Table 1 below indicate some examples of vegetable, description, and nutritional value.
| Cultivars type | Description | Nutritional value |
|---|---|---|
| An edible green seed pod of the mallow family. | About 90% water in the raw stage. Also contains thiamine, magnesium, folate, iron, copper, niacin, phosphorus, dietary fiber, vitamins C and K. | |
| Leeks are a tasty vegetable that adds a lot of flavor when used in cooking. They are long, with greenish-white stalks reminiscent of green onions, another member of the allium family. | Leek contains carbohydrate, fiber, sugar, fat, protein, vitamin K1, vitamin A, manganese, vitamin C, and folate. | |
| These are fleshy, hollow cylindrical biennial bulb. | Contains carbohydrate, fiber and some amount of vitamins like thiamine, vitamin C, B6, niacin, riboflavin, and minerals like Ca, Fe, Zn, K, Mn. | |
| A perennial flowering bulb. | Carbohydrate, fiber, protein, manganese, vitamin B6, vitamin C, selenium, and calcium. | |
| A biennial plant with pinnate leaves. Consumption assist in weight lose. | Has about 95% water, a very good source of vitamin K with Zn, Na, K, P, Mg Fe, and Cu. | |
| A tall scaly leaves plant with stout stems and feathery foliage. It maybe green, white, or yellow in coloration. | Carbohydrate, fiber, sugar, fat, protein, vitamin K1, A, B1, folate, iron. | |
| Nitrate helps to lower blood pressure. | Contains a lot of nitrates, carbohydrate, fiber, sugar, fat, protein, folate, manganese, potassium, vitamin C, magnesium. | |
| A member of the cruciferous family of vegetables, and it shares some similarities to cabbage and broccoli. Kale has a shout for being one of the healthiest vegetables. | It provides an enormous amount of vitamin K1, beta-carotene, and vitamin C. Also consist of carbohydrate, fiber, fat, protein, manganese, and calcium. | |
| This is a leafy green, red-purple, or pale green vegetable crop. | This has about 96% water, low carbohydrate, fiber, negligible fat, protein. Rich in vitamins K1, C, and B6, folate, manganese. | |
| Resembles miniature cabbage. The edible part is the bud and the leaves. | Contains about 85% water with low carbohydrate, fiber, sugar, fat, and protein with vitamins K, C, and B6, manganese, folate. | |
| From the cabbage family. The flowering head, leaves, and stalk serve as a vegetable. Particularly helpful in preventing cancer. | Contains lots of calories. A rich source of vitamins C and K. Also contains carbohydrate, fiber, sugar, fat, protein, folate, manganese. | |
| Root vegetable cultivated for its fleshy taproot. | Little quantity of carbohydrates and protein. Contains 93% water and vitamins K, A, and C. The boiled leaves contain substantial lutein. | |
| This belongs to the nightingale family and is cultivated for the thick fruit. | Rich in vitamins C, carbohydrate, fiber, sugar, fat, protein, vitamin B6, folate, potassium, manganese. | |
| A broadleaf annual of the Amaranth family. | This is a great source of vitamins A and C, also good in protein, iron, and calcium. | |
| A leafy green vegetable that has a bitter, yet slightly sweet taste. It belongs to the same family of vegetables as radicchio and curly endive. | High in calories, carbohydrates, fiber. Good source of protein, vitamin K, vitamin A, folate, manganese, vitamin C. | |
| The jute plant is used as fiber while the leaves and young fruits serve as a vegetable. | A rich source of vitamin A and C, fiber, zinc, and thiamine. | |
| A creeping vine that bears cylindrical fruits used as vegetables. | Contains 95% of water with carbohydrates and proteins, also minerals such as Ca, Fe, Mg, Mn, K, P, Na, and Zn, with loads of vitamins. | |
| The plump nutritious orange vegetable. | Rich in vitamin C, potassium, fiber. Super rich in provitamin A beta-carotene and vitamin A. | |
| A kind of thistle or prickly flower plant with a cone shape. The edible part is the flower bud before the flower blooms. | Rich source of fiber and reasonably high in vitamins C and K1. Also contains carbohydrate, sugar, fat, protein, folate, magnesium, iron and manganese. | |
| Root vegetables of typical orange color. It’s a biennial plant. | Carbohydrate, fiber, sugar, fat, protein, vitamin A, K1, C, and B6, with diverse minerals. | |
| Tuberous starchy root. There are a variety of forms. | Dietary values include K, Mn, vitamins B6 and C, thiamine, fiber. | |
| An annual rosette basal leafy plant that grows close to the ground. | Rich source of fibers and phytochemicals but low in calories, sugar, carbohydrates, and fat. Also contains a lot of vitamins such as vitamins A, C K, folate, potassium, calcium, | |
| A perennial wild vine. Belonging to the gymnosperm. | A good source of protein as well as essential and non-essential amino acids. | |
| Herbaceous vine with alternate heart-shaped leaves. | Contains a substantial amount of carbohydrate with negligible fat and rich content of vitamins A, Bs, and C, Mn, and K. | |
| An annual leafy vegetable of the Aster family. | Contain substantial amount of carbohydrate, fiber, protein, vitamin K1, vitamin A, manganese, vitamin C, and folate. | |
| A vegetable with long tapering root. | Contains vitamins B6 and C, Fe, Ca, Mg. The leaves are rich in leucine. While the root is high in dietary fiber carbohydrate and sugar. | |
| Mushroom | These are the flea-shy spore-producing fruiting structure of edible fungi. | Contains much water, carbohydrate, and proteins. Also rich in B vitamins and minerals like Zn, P, and K. |
| An aromatic perennial herb. | Constituents include eugenol, Mg, and essential oil. | |
| Jicama is a kind of bulb/root vegetable which looks a little bit like an onion, with a yellow exterior and a white inner. In terms of taste and texture, it is sweet and crunchy. | This contains carbohydrates, fiber, sugar, protein, vitamin C, potassium, magnesium, manganese, and a negligible amount of fat. Also, consist of a large amount of water. | |
| This is a biennial plant with a rosette with roughly hairy leaves that have a pungent odor when crushed. | Contains a high amount of carbohydrate, dietary fiber, potassium. Also vitamin C, B6, iron, and magnesium. | |
| These are unripe young fruits that are usually in enclosed pods from different cultivars of beans. | A rich source of folic acid fibers and vitamins like A, C, and K. Also a good source of Fe, Mg, P, Ca, and folate. | |
| These are vines useful in culinary. The leaves have a peppery taste and the leaves are green when fresh. | Contains a high level of vitamins C and E. Also contains protein, dietary fiber, and essential oils. | |
| A small spherical seed pod-shaped vegetable. | Has a reasonable amount of carbohydrates, protein, and fiber. Also vitamins A, C, K and thiamine. | |
| An annual or biennial swollen taproot. The abundant anthocyanin gives the characteristic range of skin colors. | High calories, with a low amount of vitamin C, carbohydrate, and protein. | |
| Edible vines with berry. | A major source of antioxidants is lycopene. Also contains 95% water, protein, carbohydrate, fiber, K vitamins B and E. | |
| Belongs to the nightshade family and is cultivated for its purple spongy absorbent fruits. | Fiber, fat, protein, Mg, K, Cu, folate, vitamin C and vitamin B6. | |
| A herbaceous perennial tubers. | Contains phosphorus, calcium, magnesium, zinc. Also a rich source of vitamin B6, vitamin C, and fiber. | |
| An annual leafy vegetable. The leaves are simple, oval to triangular, alternate with broad leaves on the lower part of the stem thinning at the apex. | Rich source of vitamin A, vitamin C, vitamin K, Mg, Mn, folate. Also a good source of B vitamins, vitamin E, potassium, calcium and dietary fiber. | |
| An erect plant with small, broad, and fleshy leaves. | A very good source of vitamins A and C. Also high in Fe and Ca. | |
| Leafy green with impressive nutrient density. Often eaten raw, and have a bitter and slightly peppery taste. Like many vegetables, they have a more pleasant flavor after cooking. | High in Ca and provide a rare source of vitamin E. Also contains carbohydrate, fiber, fat, protein, vitamin K1, A, C. | |
| A shrub and member of the daisy family with elliptical leaves and rough bark. Grows up to 20 cm long. | High protein content, crude fiber. Also contains minerals like NA, Fe, Mg, Zn, Ca, K. | |
| Member of the pea and bean family. An erect annual plant where the seeds in the pod serve as a vegetable. | Carbohydrate, proteins, and fat. High in dietary mineral-like Mg, Fe, Mn, P, folate, and B vitamins. |
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2. Common vegetables and parts used as food
Most vegetables as we all know are different across various continents. Table 2 shows common vegetables, parts used, cultivars, scientific names, and origin.
| Part used | Cultivars | Scientific name | Origin |
|---|---|---|---|
| Bulbs | Garlic | Asia | |
| Bulbs, leaves | Onion, spring, scallion, shallot | Asia and Africa | |
| Fruits | Pepper, bell pepper, sweet pepper | North and South America, Africa | |
| Fruits | Cucumber | Southern Asia | |
| Fruits | Tomatoes | South America | |
| Fruits | Eggplant | South and East Asia | |
| Fruits, flowers | Pumpkin. Squash, marrow, zucchini, | Mesoamerica | |
| Flower, bud | Artichoke | Mediterranean area and North Africa | |
| Leaf sheath | Leek, elephant garlic | Europe and Middle East | |
| Leaves | Clove basil | Africa and Southern Asia | |
| Leaves | Arugula | Mediterranean and Middle-East | |
| Leaves | Spinach | Central and Southwest Asia | |
| Leaves | Lagos spinach (also known as quail grass, soko, celosia or feather cockscomb) | Central and West Africa | |
| Leaves | Fluted gourd, fluted pumpkin, ‘Ugwu’ | West Africa | |
| Leaves | Kale | Eastern Mediterranean and Asia | |
| Leaves | Bitter leaf | Tropical Africa | |
| Leaves | Waterleaf, Florida spinach, Lagos bologi, sweetheart, potherb, fame flower | Central and South America, Caribbean, West Africa | |
| Leaves | Uziza leaves, Ashanti pepper leaves, Benin pepper leaves | West Africa | |
| Leaves | Eru, wild spinach | Tropical Africa | |
| Leaves, axillary buds, stems, flower heads | Cabbage, Brussel sprouts, cauliflower, broccoli, kale, kohlrabi, collard greens | Europe | |
| Leaves, seed | Jute plant, Jew’s mallow, buch okra, nalta jute, jute mallow | Tropical Asia and Africa | |
| Leaves, stem, seed oil | Lettuce, celtuce | Egypt | |
| Pods, seeds | Green bean, French bean runner bean, haricot bean, lima bean | Central and South America | |
| Pods, seeds | Broad beans | Mediterranean and Middle East | |
| Pods, seeds, sprout | Pea, snap pea, snow pea, split pea | Mediterranean and Middle East | |
| Root | Parsnip | Eurasia | |
| Root, leaves | Beetroot, sea beet, Swiss chard, sugar beet | Europe and Near East | |
| Root, leaves | Turnip, Chinese cabbage, napa cabbage, bokchoy | Asia | |
| Root, leaves, stems | Carrot | Persia | |
| Seed pods, seed oil, sprouting, roots, leaves | Radish, daikon, seed pod varieties | South Eastern Asia | |
| Seed, pod | Okra, ladies’ fingers | West Africa, South Asia, and Ethiopia | |
| Tubers | Yam | Tropical Africa | |
| Tubers | Cassava | South America | |
| Tubers | Potato | South America | |
| Tubers, leaves, shoots | Sweet potato | Central and South America |
2.1 Health benefit of vegetables
Some of the under listed health benefits of vegetables were mentioned by [6] and they include:
Vegetables act as suppliers of dietary fibers and are important sources of essential vitamins, minerals, and trace elements.
They also serve as antioxidants and loads of vitamins such as A, C, and E. A diet laden with vegetables leads to a reduction in the terminal incidence of cancer, stroke, cardiovascular disease, and other chronic ailments.
The fiber contents of vegetables can assist in keeping hunger in check because it fills the stomach.
Vegetables have a positive effect on the blood sugar of consumers.
Consumption of vegetables also assists in the control of high cholesterol levels and blood pressure in the body.
It aids to reduce inflammation and aid digestion.
Generally, vegetables have a positive effect on the blood sugar of consumers.
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3. Description on therapeutic benefits of phytochemicals in vegetables
The words “Phytochemicals” often called secondary metabolites are non-nutritive chemical compounds produced by plants via several chemical pathways. Recent studies have demonstrated that a large number of phytochemicals can be beneficial to the function of human cells. Several studies also indicate the effects of phytochemical-rich foods on health. While phytochemicals can help to improve health.
Also, phytochemical substances are found in plant-based foods such as fruits, vegetables, whole grains, nuts, seeds, and legumes. They give plants their color, flavor, and aroma. There are thousands of different phytochemicals in which scientists are discovering the different roles they play in human health. Much of the current evidence on the benefits of phytochemicals came from observing people who eat mainly plant-based diets. These people have been shown to have significantly lower rates of certain types of cancers and heart disease [7, 8]. Phytochemicals may have the potential to:
Aid the function of the immune system
Protect cells and DNA from damage that may lead to cancer
Improve the health conditions
Reduce inflammation
Slow the growth rate of some cancer cells
Help regulate hormones
You will find some examples of specific phytochemicals and their potential benefits, along with some of the foods in which they are found in Table 3.
| Phytochemical | Foods | Potential benefit |
|---|---|---|
| Carotenoids (beta carotene, lycopene) | Cooked tomatoes, orange squash, carrots, sweet potatoes, and green plants, such as broccoli. | May inhibit cancer cell growth, reduce risk of cardiovascular disease, and boost immunity. |
| Flavonoids | Berries, apples, citrus fruits, soybeans, coffee, tea, walnuts, whole grains. | May fight inflammation, decrease damage to DNA, and reduce tumor growth. |
| Anthocyanins | Berries | It may help lower blood pressure. |
| Isothiocyanates (sulforaphane) | Cruciferous vegetables, such as broccoli, cauliflower, and kale. | May protect against cancer and cardiovascular disease. |
| Lutein and zeaxanthin | Dark, leafy greens, such as spinach and chard. | May promote eye health. |
Each plant food has many different phytochemicals; for instance, there are more than 100 phytochemicals in carrots alone. You may not find a single food item with all the essential nutrients. There is a need to include a little portion of every food in your diet for great health benefits. Different phytochemicals have different functions in the body, and many of them complement one another. Evidence shows that taking phytochemicals in supplement form may not provide the same benefits as eating whole plant foods, because phytochemicals in supplements may not be as easily absorbed by the body as those from food sources. So the best way to have a variety of phytochemicals and other essential nutrients in the diet is to eat a rainbow of plant-based foods. The fruits and vegetables with deeper and brighter colors or with stronger flavors are often the best sources of phytochemicals. Larger concentrations of phytochemicals are also often found in the skins or peels of fruits and vegetables [8].
3.1 Preparing vegetables for healthy living
Most essential nutrients in vegetables can easily be washed and bleached off thorough preparatory procedures. Preparing food to preserve the nutrients for maximum effect ensures healthy eating. Soluble nutrients such as vitamins B and C can easily be lost during preparation [9, 10]. Following the required preservative, methods to keep nutrients in food intact enable us to gain access to the nutrients embedded in the vegetables. Useful tips to follow in preparing vegetables include:
Handling is essential for keeping vegetables fresh and healthy for consumption. Therefore, wash your hands before handling or preparing the vegetables for consumption or commercial purposes.
It is very important to wash vegetables before consuming them.
Use of healthy cooking methods like broiling, grilling, steaming, and roasting. As much as it is possible deep frying should be avoided because it leads to the destruction of the nutrients and addition of fats to the vegetable.
Ensure you cook vegetables at a safe temperature using a food thermometer. To avoid contaminants, it is essential to refrigerate within 2 h of purchase or harvest. You may as prepare.
Vegetables should be cooked in little water for a short period to prevent the soluble nutrients from being washed off.
Avoid dicing or cutting into small chunks. This can lead to the wash off of the nutrients such as the B and C vitamins.
Avoid using salt as flavor instead use a variety of spices.
Avoid packaged or processed vegetables because these are likely to contain salt, sugar, and fats.
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4. Methods of processing and preserving the vegetable
Due to the different growing and harvesting seasons of different vegetables at different locations, the production, availability, and consumption of fresh vegetables are as diverse as there are different cultures and people in the different parts of the world. The main reason for processing is to prolong the shelf life through the prevention of microbial spoilage and natural physiological deterioration of the plant cells [9, 11].
According to [10] processing and preserving are essential keys for foods product in order to avoid spoilage of such items. Some methods of processing and preserving vegetables can be:
Freezing
Canning
Blanching
Fermenting
Packaging
Dehydration
Irradiation
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