Nutritional and health benefits of groundnut (peanuts)

Introduction

Groundnut also known as peanut (Arachis hypogeal), is a crop of global importance. It is widely grown in the tropic and subtropics, being important to both small holder and large commercial producers. It is classified as both a grain legume and because of its high oil content. An oil world annual production is about 46 million tonnes per year. Groundnut is a leguminous crop that is best cultivated on sandy–loamy soil. It belongs to the family leguminous of flowering plants.

We all eat groundnut. It can be eaten raw after harvesting. It can be boiled in water, roasted or toasted before eating. It can also be sun–dried, before eating. In eating groundnuts, like any other food, always endeavour to chew it properly before swallowing in order to aid its proper digestion. Groundnut is a complete food or balanced diet as it contains all the six classes of food nutrients – carbohydrates, protein, lipid (fats and oils), some minerals, vitamins A and C in the testa (seed coat) and some water when fresh. Groundnut can be eaten along with some relishes–garri, milk, maize (zea mays), beniseeds (sesame seeds), and bread.

It can be processed as kulikuli for both human and animal feeds. The groundnut plant is a legume and so the root nodules harbor some nitrogen fixing bacteria like nitrosamenas and nitrobacter or rhizobium which convert atmospheric nitrogen into useable forms aside from these, the plant on decay acid organic manure to the soil.Groundnut is considered a very healthy snack. Although small in size, it plays a vital nutritional role and contains amazing health benefit like helping to promote fertility, helps to fight depression, boost memory power, aids in blood sugar regulation and so many others.So, endeavor to eat groundnut, the king of oil seeds, that play a pivotal role to your body and health (Odiba, 2013).

 History of groundnut (peanuts)

Peanuts originated from South America where they have existed for thousands of years. They played an important role in the diet of the Aztees and other native Indian in South America and Mexico. The Spanish and Portuguese explorers who found peanuts growing and Portuguese. Explorers who found peanuts growing in the new world brought them on their voyages to Africa. They flourished in many Africa countries to North America during the beginning of the slave trade, which is how they were first introduced into this region.

In the 19^th century, peanuts experienced a great gain in popularity the U.S. thanks to the efforts of two specific people. The first was George Washington carver, who not only suggested that farmers plants peanuts to replace their cotton field that were destroyed by the ball weevil following the civil war, but also invented more than 300 uses for century, a physician practicing in St. Louis, Missouri created a ground up paste made from peanuts and presented this nutritious high protein, low carbohydrates food to his patient. While he may not have actually invented peanut butter since peanut paste had probably used by many cultures for countries, his new discovery quickly caught on and became, and still remains a very popular food.Today, the leading commercial producers of peanuts are India, China, Nigeria, Indonesia and United States (Smith, 1995).

 Types of groundnut (peanuts)

There are four (4) types of groundnut (peanuts):

1. Spanish groundnut
2. Runner groundnut
3. Virginia groundnut
4. Valencia groundnut.

1. Spanish groundnut (peanuts)

It is known for its red skins, the Spanish groundnut (peanuts) has smaller sized kernels and is used predominantly for peanut candy, salted peanuts and peanut butter. Its reputation of having the nuttiest flavor when roasted is due to its higher oil content. Spanish peanuts are typically grown in the states of Oklahoma and Texas and account for four percent of U.S. production.

2. Runner groundnut (peanuts)

It is attractive and uniform in kernel size (which allows for even roasting), the runner peanuts is most commonly used for making peanuts butter. It has good flavour, butter roasting characteristics and higher yields when compared to Spanish types.

3. Virginia groundnut (peanuts)

The largest of all peanuts, the Virginia peanuts is also known as the ‘ballpark’ peanuts and is often used in groundnut snacks. Virginia peanuts accounts for about 15 percent of total U.S. production and are grown mainly in South Eastern Virginia, North Eastern, North Carolina, South Carolina and West Texas. Virginia are a popular peanuts used for all natural peanut butter.

4. Valencia peanuts

Having three or more kernel per shell, the Valencia has a sweet flavour and is commonly used for all natural peanut butter. Also, they are excellent for use as boiled peanuts. Valencia peanuts are grown mainly in New Mexico and account for less than one percent of U.S production. They are comparatively tall, having a height of 125cm (49in) and a spread of 75cm (30in). The seed are smooth and with no constriction of the shell between seeds. Seeds are oval and tightly crowded into the pods. This types is used heavily for sale roasted and salted in shell peanuts and peanut butter (Schilling, 2013).

 Cultivation of groundnut (peanuts)

Peanuts grow best in light, sandy loam soil with a PH of 5.9 -7. Their capacity to fix nitrogen means that, providing they modulated properly, peanuts benefits little or not at all. From nitrogen – containing fertilizer and they improve soil fertility. Therefore, they are valuable in crop rotations. Also, the yield of the peanuts crop itself is increase in rotations, through reduced diseases, pests and weeds.

For instance, in Texas, peanuts in a three – year rotations with corn yield 50% more than non rotated peanuts. Adequate levels of phosphorus, potassium, calcium, magnesium and micro nutrients are also necessary for good yields to develop well, peanuts need warm weather throughout the growing season. They can be grown with as little as 350mm of water, but for best yields need at least 500mm. depending on growing conditions and the cultivate of peanut, harvest is usually 90 to 130 days after planting for subspecies A, fastigiata types and 120 to 150 days after planting for subspecies A.h hypogaea types. Subspecies A.h hypogeea types yield more and are usually preferred where the growing seasons are long enough.

Peanuts plants continue to produce flowers when pods are developing therefore even when they are ready for harvest, some pods are immature. The timing of harvest is an important decision to maximize yields. If it is too early, too many pods will be unripe.  If too late, the pods will snap off at the stalk, and will remain in the soil. For harvesting, the entire plant, including most of the roots, is removed from the soil. The fruits have wrinkled shells that are constructed between pairs of the one to four (usually two) seeds for pod.

Harvesting occurs in two stages: in mechanized system, a machine is used to cut off the main root of the peanut plant by cutting through the soil just below the level of the peanut pods. The machine lifts the bush from the ground and shakes it, then inverts the bush, leaving the plant upside down on the ground to keep the peanuts to dry slowly to a little less than a third of their original moisture level over a period of three to four days. Traditionally, peanuts were pulled and inverted by hand. After the peanuts have dried sufficiently, they are threshed, removing the peanuts pod from the rest of the bush. It is particularly important that peanuts are dried properly and stored in dry conditions if they are too high they may become infected by mold, fungus, Aspergillus flavus. The fungusreleases a toxic and highly carcinogenic substance aflatoxin (Smith, 1995).

 Uses/composition

Peanuts can be eaten raw, used in recipes or made into oil textile materials and peanuts butter, as well as many other uses. The way peanut are used varies by region. For instance, in some region peanuts are primarily used for snacks, confectionary, and bakery products, where the largest use India is for the production of peanut oil.

Popular confections made from peanuts include salted peanuts, peanut butter (sandwiches, peanut candy bars, peanut butter cookies, cups) peanuts butter and shelled nuts (plain / roasted). Salted peanuts are usually roasted in oil and packed in retail size plastic bags or hermetically sealed cans. Dry roasted salted peanuts are also marketed in significant quantities. Peanuts are often a major ingredient in mixed nuts because of their relative cost compared to Brazil nuts, cashews, walnuts and others. Peanut butter has been a tradition on company trips and the home due to its high protein content and resistance to spoiling. Large quantities are also used in the commercial manufacture of sandwiches, candy and bakery products. Boiled peanuts are a preparation of raw unshelled green peanuts in brine and often eaten as a snack. More recently fried peanut recipes have emerged, both shell and nut to be eaten. Peanuts are also used in a wide variety of cosmetics, plastic, dyes and paints.

Peanut oil

Peanut oil is often used in cooking, because it has a mild flavour and a relatively high smoke point. Due to its high monounsaturated content, it is considered health than saturated oils and is resistant to rancidity. The several types of peanuts oil include: aromatic roasted peanuts oil, refined peanuts oil, extra virgin or cold–pressed peanut oil and peanuts extract. In the United States, refined peanut oil is exempt from allergen labelling laws.

Peanuts flour

Peanut flour is lower in fat than peanut butter and is popular with chefs because its high protein content makes it suitable as a flour enhancer. Peanut flour is used as a gluten – free solution.

Boiled peanut

Boiled peanut are popular snack solution in the United States, as well as in India, China and West Africa.  In the south, boiled peanuts are often prepared in boiling water and sold in street side stands.

Dry–roasted peanut

Dry peanuts can be roasted in the shell or shelled in a home oven if spread out one layer deep in a pan and baked at a temperature of 350^o  for 177^o for 15 to 20mins (shelled) and 20 to 25mins (in shell).

 Nutritional value of peanuts (groundnut)

Nutritional value per 100g (3.502) source USDA national nutrient data base

Energy                                                                2385kj (570kcal)

CARBOHYDRATES                                                   21g

Sugar                                                                                 0.0g

Dietary fibre                                                                  9g

FAT                                                                               48g

Saturated                                                                      7g

Monounsaturated                                                        24g

Polyunsaturated                                                          16g

PROTEIN                                                                     25g

Trytophan                                                                     0.2445g

Threonine                                                                     0.859g

Isoleucine                                                                     0.882g

Lysine                                                                           0.901g

Methionine                                                                             0.308g

Cystine                                                                         0.322g

Phenylaline                                                                  1.300g

Tyrosine                                                                       1.020g

Valine                                                                            1.052g

Arginine                                                                        3.001g

Histidine                                                                        0.634g

Alanine                                                                         0.997g

Aspartic acid                                                                3.060g

Glutamic  acid                                                              5.243g

Glycine                                                                         1.512g

Proline                                                                          1.107g

Serine                                                                           1.236g

VITAMIN                                                                      

Thiamine (B1)                                                              0.6mg

Riboflavin (B2)                                                             0.3mg (25%)

Niacin (B2)                                                                             12.9mg (86%

Pontothenic acid (B5)                                                 1.8mg (36%)

Vitamin B6                                                                    0.3mg (23%)

Folate (B1)                                                                   2461g (62%)

Vitamin C                                                                      0.0mg (0%)

Vitamin E                                                                      6.6mg (44%)

MINERALS

Calcium                                                                        62mg (6%)

Iron                                                                                2mg (15%)

Magnesium                                                                  184mg (52%)

Manganese                                                                  2.0mg (95%)

Phosphorus                                                                 336mg (48%)

Zinc                                                                               3.3mg (35%)

Other constituents

Water                                                                            4.26g

Health benefits of groundnut (peanuts)

Groundnut also known as peanuts, are considered a very healthy snack. Although small in size it plays a vital nutritional role and contains amazing health benefits.

1. Help promote fertility (folate)

Peanuts contain a good amount of folate. Repeated studies have shown that women who had a daily intake of 400 microgram of folic acid before and during early pregnancy reduced their risk of having a baby born with a serious neural tube defect by up to 70%.

2. Help fight depression (tryptophan)

Peanuts are good sources of tryptophan, an essential amino acid before which is important for the production of serotonin, one of the key brain chemical involved in mood regulation. When depression occur a decreased amount of serotonin may be released from the nerve cells in the brain. Tryptophan may raise serotonin antidepressant effects when there is an increased amount of serotonin in the blood.

3. Boosts memory power (vitamin B₃)

What can be found in peanuts that gave them the brain food tag is due to their vitamin B₃ or niacin content whose many health benefits include normal brain functioning and boosting memory power.

4. Aid in blood sugar regulation (manganese)

One-fourth cups of peanuts can supply the body with 35% of the DV. of manganese, a mineral which plays a role in fat and carbohydrate metabolism, calcium absorption and blood sugar regulation.

5. Cancer protection a form of phytosterol called beta sitoserol (SIT)

Is found in high concentration in some plants oils, seeds and legumes including peanuts. Phytosterol not only protects against cardiovascular disease by interfering with the absorption of cholesterol, they also protect against cancer by inhibiting tumour growth.

6. Helps prevent gallstones

It may come as a surprise that peanuts can help prevent gallstones but 20 years of studies have shown that eating I ounce of nuts, peanut or peanut butter a week lowers the risk of developing gallstones by 25%

7. Help lower cholesterol levels (copper)

The same nutrient which gives peanuts their memory enhancing power also helps lower and control cholesterols levels. Added to that is their copper contents which aid in reducing bad cholesterol and increase good cholesterol levels.

8. Lower risk of weight gain

Eating nuts regularly is associated with a lowered risk of weight gain. Research has shown that people who eat nuts at least twice weekly are at a lower risk of weight gain.

9. Lower risk of heart disease

Numerous studies have shown that regular nuts consumption is linked to reduced risk of cardiovascular and coronary heart disease.

10. Protects skin

Vitamin E in peanuts helps in maintaining the integrity of cells of mucous membrane and the skin. This protects them free radicals which cause great damage (Odiba, 2013).

Conclusion

Based on the nutritional and health benefit of groundnut, it is therefore important that the awareness on the health and nutritional benefit of groundnut should be made known to both young and old in our country. Since groundnut is cheap and available all year round, it plays a pivotal role in our health.

References

Carver, G. W. (2015). How to grow the peanut and 105 ways of preparing it for human consumption. London:Tuskegee Institute

Keith, W. (2010).Occurrence of resveratrol in edible peanuts. J Agric Food Chem, 48 (4), 1243–1246.

McFarland, M. (2009). Texas peanut production guide. Texas: A&M University

Northstone, K. & Golding, J. (2003).Factors associated with the development of peanut allergy in childhood. New England Journal of Medicine, 348 (11), 977–85.

Odiba, A. A. (2013). Food and your health. Akure: Adura Publishing

Ozcan, M. M. (2010).Some nutritional characteristics of kernel and oil of peanut (arachis hypogaea L.). J Oleo Sci, 59 (1), 1–5.

Schilling, R. (2013). L’arachide histoire et perspectives”. L’arachide histoire et perspectives. Nice: Agropolis Museum

Smith, C. (1995). Crop production: evolution, history and technology. New York: John Wiley and Sons.