Peanut Literature Review

LITTERATURE REVIEW

2.5 PEANUTS ORIGIN

The peanut (Arachis hypogea linn) better known worldwide as groundnut and to lesser extent as earthnut, monkey nut and goobers is not a true nut but rather an annual legume much like the bean or pea (Nwokolo;1996: pp.49-63).

It can also be defined as an annual herb belonging to the division papilionaceae of the family leguminosal. The peanut plant is unusual because it flowers above ground and pods containing one to five seeds are produced underground. Peanut need a hot climate for development with moderate rainfall or irrigation and ample sunshine during the growing season. It is suitable for tropical, sub–tropical, Mediterranean and warm temperate climates.

Peanut is the fifth most important oil seed

Peanuts are very high in calories because of their high fat and protein contents. A pound (0.45kg), of peanut brittle, salted peanut or peanut butter contains about 2,800 calories. Cotyledons are the main storage tissues and are concentrated source of protein lipids and dietary energy. Comparatively, the protein content of raw peanut is about 70% of that of raw soybean. Peanuts are generally low in carbohydrate content which is about 21.6g/100% edible portion. These carbohydrates include sugars, starch, crude fiber and pentosans. Peanuts are a reasonable source of dietary minerals especially potassium, phosphorus and magnesium, however they are poor source of fat soluble vitamins like A, D and K. Peanut oil is an excellent source of mono and poly unsaturated fatty acids exceeding the levels of these fatty acids in soybean and corn oil but significantly lower than in sunflower and safflower oil. The oil content of peanut is between 35% and 54.2% of the seed. According to Canola

As in many of the seeds of other grain legumes, the protein is nutritionally inferior to that of the Standard Reference Protein (SFP), which approximates the average amino–acid profile of human proteins because it contains relatively small proportions of lysine, methionine and threonine, and sometimes isoleucine and valine (Pancholy;1958 p.103). As partic, glutanric acids and arginine constitute about 45 percent of the total amino-acids and their proportion is greater than in the SRP (Young; 2002). The proteins of groundnuts have certain unique functional properties, such as low viscosity at relatively high concentrations (5–10percent), good computability with biscuit batter system, white color and bland flavor. The mature kernel contains 20-25 percent carbohydrate, of which about 8–10 percent is cellulose and hemicelluloses, 4 percent is starch and 10

–12 percent is sugar (Patee; 1959:p.33). Sucrose is the principal sugar, varying from 2.86 – 6.35 percent depending on the cultivar. When the kernels are roasted, the sucrose is hydrolyzed to fructose and glucose which then reacts with free amino acids to form the numerous substances which give the characteristic flavor to