Food Science and Technology Project Topics

Proximate Composition of Fermented and Unfermented Sweet Potato-pigeon Pea Weaning Food

Proximate Composition of Fermented and Unfermented Sweet Potato-pigeon Pea Weaning Food

Proximate Composition of Fermented and Unfermented Sweet Potato-pigeon Pea Weaning Food

Chapter One

Aim and Objective of the Study

Thus, the aim of this study was to determine the proximate composition of fermented and unfermented sweet potato- pigeon pea weaning food.

Objectives are:

  1. to produce fermented and unfermented sweet potato-pigeon pea flour
  2. to evaluate proximate composition of the sample.



Sweet Potato (Ipomoea batatas L.)

Ipomoea batatas is the sixth most important food crop in the world and ranked seventh in the total world food production after wheat, maize, rice, potato, barley, and cassava (Islam, 2006). I. batatas or commonly known as sweetpotato originated from the Central America and Mexico and has been dispersed worldwide due to its high yield potential and wide adaptability. Carolus Linnaeus was the first to give the scientific term Convolvulus batatas to the sweetpotato plant in 1753, referring to the plants grown in George Clifford’s garden in the Netherlands.

Ipomoea batatas is a perennial herbaceous dicotyledonous species and is categorised under the Convolvulaceae family, which includes the morning glory (I. purpurae) plant and can be further divided into varieties or cultivars. From the group of approximately 50 genera and more than 100 species in this family, I. batatas is the only group that has major economic importance as food (Woolfe, 2002). Besides I. batatas, Ipomoea aquatica (known locally as Kangkong) is also grown for human consumption and eaten as dishes in China and Malaysia. The increased numbers of Ipomoea batatas varieties took place due to selection by human for domestication. I. batatas is cultivated in more than 100 countries and is an extremely important food crop in developing countries (Wang, 2005). Besides that, the I. batatas are also well adapted to tropical areas where high proportion of poorest people in the world lived.

  1. batatas (sweetpotato), unlike Solanum tuberosum (potato) are not tuber propagated. A tuber can be defined as short, thickened-stem of an underground branch (Kakaty et al., 2002). In contrast, I. batatas produces primary fibrous roots, pencil roots and storage roots and they lack of merismatic buds. The storage roots are attached to the stem by a stalk of thinner roots that is usually initiated at the stem node just below the soil line. Worldwide currently, there are over 6000 varieties of I. batatas and they are basically distinguished by skin colour, flesh colour, and some, by origin (ICP, 2006). The skin colour of I. batatas storage roots typically range from white to brown to red-orange while the flesh colour may be red-orange, orange, yellow or white (more common). Besides that, the flesh of the storage roots can be either soft or firm.

Distribution and Growth Habitat of Ipomoea batatas

Scientists believed that Ipomoea batatas was domesticated more than 5000 years ago. Recent evidence showed that Ipomoea batatas was originated from Central-America although contradicting reports claimed that it was from South America (Natural History Museum, 2007). Ipomoea batatas was widely established in the Americas by the time Europeans first arrived there and was spread to the Old World through various routes. Due to its hardy nature and broad adaptability, Ipomoea batatas successfully spread through Asia and Africa during the 17th and 18th centuries. According to FAOSTAT data, approximately eight million hectares of land were harvested resulting in approximately 107 million tons of Ipomoea batatas roots from more than 100 countries in the year 2010 alone (FAOSTAT, 2012).

Asia is the world’s largest sweetpotato producing region with an annual production of approximately 88 million tons and China contributes about 80% of this amount. Nearly half of these productions were used as animal feed while the remaining was used for human consumption. In contrast, the African region produced about 14 million tons of Ipomoea batatas roots annually but most of this crop is cultivated for human consumption (FAOSTAT, 2012). Previous research on Ipomoea batatas has been focusing on the yield and nutrient improvements in the storage roots although both the Ipomoea batatas roots and tops possess a variety of compounds which are beneficial to human health.

Classification and Taxonomy of Ipomoea batatas

The long-term cultivation and selection of Ipomoea batatas produced many different varieties with different roots skin colours, flesh colours and shapes. Variations can occur both naturally as a result of mutations which will be termed cultivar or through hybridisation by human (known as varieties) (Morton, 2001). Through the advances in biotechnology, Ipomoea batatas roots have been developed for special purposes such as for their high protein, starch or β-carotene contents. Ipomoea batatas varieties are usually distinguished by the size and colour of their fruits. The examples of Ipomoea batatas varieties are Kotobuki (Japanese), Georgia Jet, Fernandez, Red Jewel and Okinawa. Ipomoea batatas can be planted for either their roots and/or forage production, in which yields often depended on the different climate, season and soil conditions (Hartemink et al., 2000; Woolfe, 2002; Antia et al., 2006).

Ipomoea batatas is located in the plant kingdom and belongs to the “Convolvulaceae” family, Ipomoea genus and batatas species and thus termed Ipomoea batatas. While the current method of identification focused on the variations of storage roots to distinguish the Ipomoea batatas varieties, it was found to be time consuming and required the formation of the roots before the different varieties can be identified. Therefore, the leaf of the plant was subsequently used as a new way to distinguish between the different varieties. This method is an economical way to overcome the drawbacks of the previous identification method. Leaves are commonly distinguished based on parameters such as length, width, shape, margin and venation. McEwen (2004) pointed out the variation in the Ipomoea batatas leaves in terms of shape namely cordate shaped with heavily divided single lobed and palmate shaped with seven lobes or more.





Sweet potato (Ipomoea batatas) and Pigeon pea (Cajanus cajam) used in the research work was purchased from a local market in Owo, Ondo State. The samples were processed in Food Processing Laboratory, Rufus Giwa Polytechnic Owo, Ondo State, Nigeria


 Preparation of fermented sweet potato-pigeon pea flour

Fresh sweet potato root were washed, peeled, sliced and pigeon pea seeds were winnowed, sorted, drained. The two cleaned samples (sliced sweet potato root and washed pigeon pea were soaked together i.e fermented together for 72 hours. After 72 hours the fermented samples it was washed, wet milled, sieved, sedimented for 24 hours, drained, sun dried for 3 days and dry milled into powder, sieved and packaged in airtight container for further analysis (Fig. 1).




Table 4.1: Proximate composition of fermented and unfermented sweet potato-pigeon pea weaning food




            The study evaluate the nutritional properties (proximate) of Fermented and unfermented sweet potato-pigeon pea weaning food, the result shows that the moisture, ash, fibre, fat, protein and carbohydrate content of both samples are closely related, but the fermented weaning food was observed to be more nutritious in protein, fibre and moisture content, the moisture content indicate a lesser shelf life compared to unfermented weaning food. The ash, fat and carbohydrate content of the unfermented samples appear to be higher than the fermented samples. Its low moisture content will also contribute to a longer shelf life. In conclusion, both samples possess good nutritional characteristics and are both good for consumption especially for infant.


            From the findings above, it is therefore recommended further study should be conducted on the functional properties of both samples, and food industries in developing countries especially in Nigeria should adopt the formulation of this flour blends, this will increase the chances of fighting malnutrition in children with less capital.


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