Effect of Various Temperatures on the Nutritional Composition of Fermented African Locust Bean (Parkia Biglobosa) Seeds
Objectives of the Study
This study was carried out to know the effect of temperature variation on the nutritional composition and to bring out the optimum temperature that would yield the best nutrient composition for the fermentation of Iru.
Origin and Distribution of African Locust Bean
The African locust bean tree, Parkia biglobosa is a perennial legume tree which belongs to the subfamily Mimosoidaea and family Leguminosae. It grows in the savannah region of West Africa up to the southern edge of the Sahel zone 13o N (Campbell-Platt, 2000). These trees are normally cultivated but can be seen in populations of two or more in the savannah region of Nigeria (Schnell, 2007; Hopkins, 2003). The various types of African locust bean tree are Parkia clappertoniana, Parkia bicolor, Parkia filicoidea and Parkia biglobosa.
A matured African locust bean tree of 20 to 30 years can bear about a ton and above of harvested fruits. Musa (2001) reported that the tree can start to bear fruits from five to seven years after planting. The tree is about 7 to 20 metres high and bears pods that occur in large bunches and vary from 120 to 300 mm in length.
African locust bean tree fruits during the months of December to March of the year. The fruits are ready for harvest in April and have many leguminous pods each with a tough pericarp. The pods contain yellow powdery pulp in which seeds are embedded. The seeds have hard, black testa making them less vulnerable to insects and rodent infestation (Oladele et al., 2005, Oyewole et al., 2006, Oni, 2000). At maturity the pod length averages 232 mm ( 173 ≤ L ≥ 290 mm) with a mean diameter of about 15 mm ( 10 ≤ d ≥ 20 mm) (Oni, 2000).
Use and Importance of African Locust Bean Tree
The Parkia trees play a vital ecological role in recycling of nutrients from deep soils, by holding the soil particles to prevent soil erosion with the aid of roots. The trees also provide shades for farmers (Campbell-Platt, 2000). Parkia tree is used as timber for making pestles, mortars, bows, hoe handles and seats (Hagos, 2002; Irvine, 2001). The fruit may also be used as an ingredient for the preparation of various stews, soups and sausages for the consumption of cereals pressed into cakes and preserved for later use or used in the preparation of some indigenous drinks (Muller, 2008). Literature reveals that the fruit pulp is used in rural Africa during emergencies, when the grain stores are empty, which is an indication of its edibility and non-toxicity (Akoma et al. 2001).
High cost of animal protein has directed interest towards several leguminous potential sources of vegetable protein for human (Esenwah and Ikenebomeh, 2008). Among plant species, grain legumes are considered as major source of dietary proteins. African locust bean seeds are rich in protein and are usually fermented to a tasty food condiment called dawadawa which is used as a flavour intensifier for soups and stews and also adds protein to protein-poor diets (Ikenebomeh and Kok, 2004; Odunfa, 2006; Dike and Odunfa, 2003).
Locust bean tree plays a vital role in stabilizing the soils in farming areas and cycling nutrients from deeper soil layers, as well as by providing shade (Campell-Platt, 2000). As a leguminous plant of sub-family Mimosoideae, it also fixes atmospheric Nitrogen (Cobley and Steele, 2006).
African locust bean tree has a high nutritional economic, industrial and medicinal value (Adewumi, 1997). The most important use of African locust bean tree is found in its seed which is a grain legume. The husks and pods have been reported as good food for livestock (Obiazoba, 1998). The pod shell traditionally is used to extract a substance that helps to harden beaten natively made house floors and is an important source of tannin for leather industry. The yellow powdery pulp is rich in carbohydrate (Oladele et al., 2005) and rich in oil suitable for the manufacture of soap and is used in the production of a native gruel (Kunnu) (Musa, 2001).
The presence of fibres in the husk, together with tannins makes it a good raw material for production of particle board (Owoyale et al., 2006). The leaves are rich in Nitrogen and used as feed for livestock and manure (Adewumi, 1997). The bean coat is used with indigo dye to improve the lustre of fabric, while the tree bark yields red tannin for dying leather. Carbon gum is extracted from the bean and added to foods and cosmetics as thickeners and emulsifiers (Yudkin, 2005). The dried pods could be used as fuel.
MATERIALS AND METHODS
Parkia biglobosa seeds used were purchased from local market in Owo, Ondo State. All the chemicals and wares used were of analytical grade obtain from Chemistry and Microbiology Laboratory of Food Science and Technology, the processing of the Parkia biglobosa seeds was processed in processing laboratory of Food Science and Technology. The starter culture used was prepared in Rufus Giwa Polytechnic Microbiology laboratory, Owo, Ondo State, Nigeria.
Processing of African locust bean seed
The raw locust bean (Parkia biglobosa) was first poured in a big pot filled with water and cooked for about 8 hours (Sample A) and 10 hours for Sample B. After which it was poured inside a bowl filled clean water in order to cool, after cooling dehulled, and fermented for 48 hours. Sample A was sundried for 3 days (72 hours) while Sample B oven dried for 3 days (72 hours). After drying it was then milled to powder using attrition mill.
RESULTS AND DISCUSSION
Table 4.1: Proximate composition of locust bean
CONCLUSION AND RECOMMENDATION
From the findings of the research work, it is observed that sundried locust bean flour sample has better nutrient in terms fat and carbohydrate content compared to ovendried locust bean sample. The moisture content of ovendried locust bean is lower compared to sundried locust bean indicating longer shelf life of OLB. It was also observed that nutrient retain after drying for OLB is higher than SLB in terms of fibre, protein and ash content. From the microbial analysis for both samples SLB has higher microbial growth compared to OLB, this can be due to higher moisture content of SLB. In conclusion, ovendried method of drying is better than sundried method since it helps retain higher nutrient than sundried method.
Based on the research findings above, it is therefore recommended that Oven dried methods should be adopted when processing locust bean.
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