Peanut and its Nutrition Values
Peanuts(Arachis hypogaea L.) belong to the legume family and grow underground, thus referred to as groundnuts. Peanut has high protein content (usually more than 20%) and high oil content (usually more than 40%). It is also a nutritious source of fats, carbohydrates, Vitamin E and minerals such as calcium, phosphorus, iron, zinc, magnesium, and potassium. Groundnut can thus help overcome severe nutritional deficiencies in Tanzania where over 40% of children under five in the rural areas are malnourished and their development retarded.
Groundnut Production in Tanzania
Commercial groundnut production in Tanzania started in 1946 at Kongwa (Dodoma), Urambo (Tabora) and Nachingwea (Mtwara) under the Groundnut Scheme. However, the scheme failed and was subsequently abandoned in 1951.
Currently major groundnuts growing regions include Dodoma, Tabora, Shinyanga, Singida, Mtwara, and Mwanza. Groundnut is usually intercropped with cereals or cassava. 11 varieties of groundnuts have been released to date, and Pendo is very popular.
Groundnut is grown by smallholder farmers in Tanzania, providing both food and income for households. Nearly 1 million smallholder farmers grow groundnuts. Most groundnut farmers grow less than 1 hectare of groundnuts on their farm. Since peanut is one of the key sources of household nutrients, women are mostly found as paying more laboring in producing the crop.
In 2013, Tanzania ranked 9th in the world for peanut production, producing 785000 tons of peanuts, which is harvested on an area of 740000 hectares, accounting for 1.7% of global production. However, the yield is still low, producing 1.06 tons per hectare in 2013, ranked 69th in the world. Reasons for low yields include drought, diseases and lack of improved varieties.
Export Market of Groundnuts in Tanzania
Groundnuts in Tanzania are exported mainly as shelled nuts. Even though the country could be among the world’s top 10 groundnut exporters, it receives the lowest price of the top 20 countries. Export markets are constrained by stringent aflatoxin standards set by importing countries.
Farmers do not have incentives nor do they have the ability to grow aflatoxin free groundnuts.
Peanuts Deep Processing Industry Analysis in Tanzania
Peanuts industry in Tanzania has inadequate value addition and agro-processing activities. There are a few large groundnut exporters operating in Tanzania, but the processing part is performed elsewhere, usually in the companies country of origin.
Groundnut is one of the major oilseeds produced in Tanzania. However, there is virtually no oil produced commercially from groundnut in this country, since groundnuts in nut form have higher value than converted into oil. It is not economical to press groundnuts to extract edible oil as there are several cheaper sources such as sunflower seeds.
Most of the groundnuts are consumed as snacks in the following forms: Raw nuts; Roasted salted and non salted nuts; Roasted spiced peanuts; Stir fried peanuts mixed with other foodstuffs. Some groundnuts are ground into powder, which can be done by a peanut powder grinding machine. Kashata is peanut brittle traditionally sold by street vendors in Tanzania along with black coffee.
Groundnut processing and shelling equipment are often Chinese made as they are often the most inexpensive. Farmers prefer new technologies which are simple and tend to avoid devices that may require frequent adjustments.
Peanut pods after harvesting should be dried to a safe moisture level to prevent the growth of microorganisms, particularly moulds that produce aflatoxins. Tests were carried out for drying groundnuts in batch dryers and maximum temperature was 54°C in single layer of sacks to reduce moisture content from 48% to 8%. Groundnuts were also dried in tray dryer and two feet deep freshly harvested pods were dried at air temperature of 38°C from moisture content of 48% to 8%. Simple twin tray dryers were also used driven by diesel engine. In continuous flow dryers, temperature of hot air was also maintained at 38°C.
Freshly harvested peanuts should be cleaned and sorted to remove damaged nuts and other foreign matter. By using density separators or air legs, light pods can be removed and slotted screens are used to remove pre-shelled kernels.
At the shelling plant, the peanuts undergo a sorting process to remove defective kernels. Blanching used together with gravity tables and manual or electronic sorting is very efficient in removing aflatoxin-contaminated kernels. Color sorting combined with blanching can reduce 90% aflatoxin contamination.
Tanzania Peanut Butter Production
Peanut butter is traditionally used for cooking purposes in many homes in rural Tanzania. It is used in preparation of side dishes and is also cooked with vegetables, pearled sorghum and maize. Commercially produced peanut butter is used as a spread on bread especially by the urban middle classes. Tanzania groundnuts can make good paste.
Peanut butter can be produced in the following steps:
1. Cleaning of peanut kernels
Shelled peanuts are cleaned by winnowing and blowing away the light particles and removing broken and infested nuts by hand.
In this step, adequate heat is required to ensure cooking of the nuts, while uniform roasting should be achieved. This step may take 10 to 30 minutes to obtain uniform golden coloured (light brown to brown) nuts.
The roasted nuts are cooled before going to the next step.
4. Peeling and sorting
Peanuts after roasting have brittle skin and can be removed easily. Roasted peanut peeling machine is recommended for this process. Two rotating rollers in the peeling chamber remove the red coat, which is then sucked by air fan. The peeling rate can be 98%. After peeling, burnt nuts and other nuts with undesirable qualities are removed.
There exist different types of peanut butter taking smoothness into consideration. In Tanzania, a finely ground, smooth paste is preferred. The kernels are ground in peanut butter machie or in a hand operated plate mill which is available in the local market.
In this step, ground paste is mixed with other ingredients such as vegetable oil, sugar, salt and stabilizer. Vegetable oil such as corn, sunflower or groundnut is heated to 80–90°C and added with a quantity of 2-5% to improve the spreadability. Some manufacturers add 6% of sugar or maltose and 1.7% salt to improve the flavor. Peanut stabilizer is added at a quantity of 2–3% to reduce oil-meal separation. The paste is then heated to about 80°C to ensure that the stabilizer melts and is well blended into the paste.
The butter is filled hot into containers that have been cleaned and sterilized. Full-automatic filling machine is recommended for this process, which features automatic bottle loading, filling and discharging.