Food Science and Technology Project Topics

The Effect of Soyabean Supplement on the Physicochemical and Sensory Properties of Garri

The Effect of Soybean Supplement on the Physicochemical and Sensory Properties of Garri

The Effect of Soybean Supplement on the Physicochemical and Sensory Properties of Garri

Chapter One

Objective of the Study

The main aim and objective of the study is to examine the effects of pigeon pea supplementation on the physicochemical and sensory properties of garri

Other specific objectives include:

  • Production of garri from cassava (Manihot esculenta Crantz)
  • Production of flour from soybean and lastly
  • To supplement soybean flour with garri


CASSAVA (Manihot esculenta Crantz)

Overview of Cassava

Cassava is an important source of food and income throughout the tropics, including Africa, Asia and Latin America. About 600 million people in Africa, Asia and Latin America depend on the plant for their survival, deriving calories and income from the roots and leaves (IFAD, 2008). Cassava production in Africa has more than tripled since 1961, from 33 million metric tons per year to 101 million metric tons, making the continent the largest producer in the world (IFAD, 2008). Advantages of cassava as a crop include flexibility in planting and harvesting time, drought tolerance, and ability of cassava to grow and produce in low nutrient soils, where cereals and other crops do not grow well (IFAD, 2008).

In Malawi, cassava is the most important root crop. Cassava plays an important role as a cash crop for smallholder farmers, middlemen, as well as sellers in various markets, and is gradually becoming an important industrial crop (Akingbala et al., 2005). It is grown country wide and is a staple food crop for more than 30% of the population along the central and northern lake shore areas of Lake Malawi and the Shire highlands (Akingbala et al., 2005). Country wide, cassava is used as a food supplement, a main part of breakfast, and snack food (Akingbala et al., 2005). Cassava leaves are an excellent source of protein compared to legumes and are commonly consumed as vegetables in many parts of the country. The fresh cassava leavescontain 17-18% dry weight protein. The leaves are particularly important in the dry season when other green vegetables are in short supply.

 Nutritional Value of Cassava

Cassava is commonly known to be a good and cheap source of carbohydrates. After sugarcane, it is considered to be the highest producer of carbohydrates among crop plants. The protein, vitamin and mineral contents in cassava are very low. In addition, it lacks essential amino acids such as lysine (Balagopalan et al., 1992). In general, cassava is often considered inferior to maize and wheat because of its low levels of proteins, vitamins and minerals. The low protein content necessitates fortification of cassava flour with legume flour in order to improve the protein content of the end product.

Cyanogen Content of Cassava

All cassava plant parts, apart from the seeds, contain cyanogenic glycosides (CG), a chemical substance responsible for bitterness of cassava roots and toxicity in humans. Cultivars with<100mg CG kg-1 fresh weight cassava are called “sweet”, while cultivars with 100 to 500 mg CG kg-1 are “bitter” cassava (Wheatley et al., 1993). The most abundant CG in cassava isLinamarin (85%), with lesser amounts of Lataustralin. Total CG concentration depends on cultivar, environmental conditions during growth, agronomic practices and plant age (McMahon et al., 1995). Linamarin is synthesized in the leaf and transported to the roots. It is therefore a standard practice to process bitter cassava roots to remove CG before consumption to avoid food poisoning. Hydrogen cyanide gas (HCN) is released from CG when cassava tubers are macerated as in chewing or grating. According to McMahon et al. (1995), juice extraction, fermentation, frying or a combination of these processing treatments aid in reducing the HCN concentrations to safe levels. Akingbala et al. (2005) reported about 95% decrease in HCN content after grating and nearly 98% decrease after fermentation of cassava.

 Processing of Cassava Roots

            Processing cassava roots into different food forms helps to stabilize shelf-life, improve quality and detoxify the roots (Falade and Akingbala, 2010). Additionally, processing can also increase or decrease the quality attributes of the processed products. Studies have shown that during traditional processing over 40% of the produce is lost on drying. This is because the products are usually dried on bare floor where they are exposed to various contaminants such as dust and birds. However, these contaminations can be avoided by modifying the production and drying process, adherence to food sanitary and hygienic practices (Falade and Akingbala, 2010).

The products from cassava root are either processed into unfermented or fermented foods and drinks, but their processing methods such as boiling, steaming, roasting as well as the form (solid, semi-solid or liquid) in which they are consumed differ (Falade and Akingbala, 2010). The processed products from the root can be used for industrial purposes or for consumer foods. Some of the unfermented products are common in some African countries while others are available in several regions of the world and they include the following.





Soybean (Glycine max) and Cassava roots (Manihot esculenta) was purchased at the main market (Oja Oba) in Owo, Ondo State. The cassava was processed in the processing laboratory of food science and technology, the chemicals and wares used in analyzing the effects of Soybean (Glycine max) supplementation on physicochemical and sensory properties of Garri were gotten from the chemistry laboratory of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo State, Nigeria.


The soybean flour was prepared according to the method described by Ihekoronye and Ngoddy (2005) as shown in Figure 1. During preparation, the soybeans were sorted and weighed, then it was soaked in tap water for 8 hours. Thereafter, the seeds were drained, boiled for 30 minutes, it was then dehulled manually to remove the seed coats and was washed and drained it was then sundried for two days. The dried seeds were milled and sieved, the sieved soybean flour was then packaged into an air tight container.




Table 4.1: Proximate composition of garri fortified with soybean flour





            Soybean is well-known for its nutritional value; soyflour used to fortify garri in order to enhance its nutritive value as well as to increase is sensory attributes. The result shows that the research work is successful, the protein content of Sample A disagree with earlier researches since cassava contain less than 1.50% protein. Sample D have the best outcome in terms of protein, moisture, fat, fibre and ash content, and also contain some considerable quantity of carbohydrate. The functional properties help to conclude that the samples are of good qualities, although Sample A was rated best. Regarding the sensory attributes of the samples, Sample A (control sample) have the best outcome and is generally accepted due to it’s colour, texture and appearance. In conclusion the fortification of Garri with soy flour should be approved up to 85% for garri and 15% for soy flour.


Based on the findings of the research work, it is therefore recommended that the use of soy flour up to 15% with Garri produced from cassava should be encouraged in order to enhance the nutrition and qualities of Garri and to help control malnutrition in society at large, since Garri is widely consumed by almost all the people in Nigeria.


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