African oil bean seed slices (Pentaclethra macrophylla Benth) were prepared by two traditional methods, packaged in sterilized plastic containers and fermented at two different temperatures (ambient (28 ± 2 oC) and 37.5 oC temperature) for 96 hours to produce Ugba (a Nigerian indigenous protein rich food). Proximate analysis (moisture, ash, protein, fat, carbohydrate and fibre content), physicochemical analysis (peroxide, saponification, iodine, pH value), protein solubility and microbial analysis were carried out.These Analyses were carried out at 24 hours interval for 96 hours. The result showed an increase in protein, fat, crude fibre and ash contents of the samples after 96 hours of fermentation with an increase in pH value and a decrease in carbohydrate content for all samples after 96 hours fermentation. The peroxide values, iodine values, and saponification values of the oils decreased while the protein solubility content increased with fermentation time. The result of the total viable counts were 2.74×1017 Cfu/g, 2.34×1017 Cfu/g, 2.18×1017 Cfu/g, 2.9×1017 Cfu/g, for sample A1 (boiled twice and fermented at 28 ± 2 oC ambient temperature), A2 (boiled twice and fermented at 37.5 oC), B1 (boiled once and fermented at 28 ± 2 oC ambient temperature), B2 (boiled once and fermented at 37.5 oC), respectively after 96 hours fermentation. No mould growth was found in the unfermented and fermented Ugba slices for all the products. At the end 96 hours fermentation, sensory evaluation showed that samples B1 and B2 were the least accepted in terms of aroma, taste and overall acceptability while, while in terms of texture, taste and overall acceptability sample A1 (control sample) and A2 were most preferred.
1.1 Background of study
Ugba is the Igbo name for sliced fermented African oil bean seed (Pentaclethra macrophylla Benth).The African oil bean seed is called several names in Nigeria, such as “Apara” by the Yoruba, “Ugba” or ” Ukpaka” by the Igbo’s (Enujiugha and Akanbi, 2005). It is consumed mostly in the eastern states of Nigeria as a local delicacy popularly known as “African salad” prepared with oil, pepper, fish and salt and also prepared with tapioca, stockfish and garden eggs. It can be eaten with boiled or roasted yam and cocoyam (Okafor et al., 1991; Mbajunwa et al., 1998). Ugba is a traditional food generally prepared in homes as a small family business. Its method of preparation varies from one place to another resulting in a non-uniform product (Njoku and Okemadu, 1989). According to Enujiugha (2000), “Ugba” is produced traditionally by boiling the seeds overnight for easy removal of the seed coat. The cotyledons are sliced and cooked until they are soft with reduced bitter taste. The sliced “Ugba” is washed about 5 times or more and fermented for 3 days (Enujiugha, 2000).
According to Enujiugha (2003), the cooked, processed and fermented seed “Ugba” is used to prepare some delicious African soup and sausages for eating different staples. Enujiugha (2003) also noted that it is a rich source of vitamins and minerals, having a high demand for local and export consumption. Previous research showed that fermentation gives a better nutritional product than the raw seed (Achinewhu, 1986; Enujiugha and Olagundoye, 2001). According to Siggel and Faucet (1976), fermentation is the oldest method of processing legumes. Other workers discovered that less fermented foods are produced and consumed in Nigeria and only few studies have been carried out on them. Onwuliri et al. (1986) and Onwuliri and Ekepenyong (1994) reported the chemical composition of Pito and Burukutu a known Nigerian traditional brand of alcoholic beverage brewed from sorghum and millet, while another worker studied the fermentation of cassava. Enujiugha and Akanbi (2002) reported that fermentation of African oil bean seeds to produce “Ugba” softens the cotyledon, improves its digestibility and nutrients availability. Obeta (1983) showed that “Ugba” is a cheap and important source of protein especially for people whose staple foods are deficient of proteins. The consumption of the Ugba could pose as a means of addressing the prevailing protein energy malnutrition (PEM) in developing countries (Enujiugha and Akanbi, 2008). It is a cheap and available source of plant protein in developing countries of the world. Its protein contains 20 amino acids and 80 % of its fatty acids are also essential (Enujiugha and Agbede, 2000; Ikediobi, 1981). “Ugba” is a low acid food and a product of alkaline fermentation (Enujiugha and Akanbi, 2005). The rise in pH into the alkaline region has been attributed by Njoku and Okemadu (1989) to activities of various hydrolytic enzymes.
In many Eastern communities in Nigeria, “Ugba” is consumed as a meat analogue due to its high protein content, the locally prepared” Ugba” is done through a mixed wild bacteria fermentation of the sliced, boiled and soaked African Oil bean seeds. Its raw seeds are bitter and contain antinutritional factors like paucine, cyanide, oxalate, saponin, phytate and tannins (Achinewhu, 1983; Enujiugha and Akanbi, 2005; Onwuliri et al., 2004). Thermal treatment of the seeds increases the nutrient bioavailability and the digestability and drastically reduces the level of antinutritional compounds while increasing iron, calcium, potassium, thiamine and riboflavin levels (Enujiugha and Ayodele-oni, 2003). Obeta (1983) and Odunfa and Oyeyiola (1985) Observed that the source of micro-organisms in fermenting seeds comes from handling processing, utensils used in processing and the leaves used in packaging. The result of this uncontrolled fermentation of “ugba” is a very short shelf- life product that lasts for 3-4 days, thereby, limiting the availability of “Ugba”. This is due to the activities of micro-organisms involved in the fermenting process that remains viable till the product is consumed or continues fermentation till the product becomes unacceptable. The product deterioration or spoilage is evidenced by organoleptic changes in colour, texture, odour and taste (Mbata and Orji, 2008). In this research work, a detailed study will be carried out on improving nutritional quality, freshness and general acceptability of “Ugba”. The chemical composition of hygienically processed “Ugba” fermented at different temperatures will also be evaluated.
1.2 Statement of Problem
The growing profile of “Ugba” has made it an important snack food among the low and middle income earners. It is also seen as food for the elderly in the south eastern part of the country, especially during festivities. The increased acceptance and consumption of “Ugba” has led to its high demand. However, due to its long fermentation time of about 3-4 days for an unreasonable quantity and its short shelf life,” Ugba” processors have encountered daunting tasks in keeping up to the demands and maximizing gain as a result of loss of quality due to its continued fermentation, even days after the desired texture has been attained. The lack of uniformity in texture of fermented Ugba is also a major worry. Nevertheless, good processing and storage techniques that can impact improvements in nutrient availability and digestibility are very essential to producing quality Ugba while at the same time ensuring the elongation of its shelf-life and maintaining quality.
1.3 Research Objectives
The main objective is to compare the quality of Ugba produced from two traditional methods. The specific objectives are:
- To evaluate the physico-chemical characteristics of Ugba at different fermentation temperatures.
- To monitor the microbial population of Ugba fermented at different temperatures.
- To determine the general acceptability of Ugba produced under different fermentation temperatures.
- Significance of study
Ugba has the potential of achieving prominence and featuring regularly in the food menu as one of the traditional dishes. Its roles in providing the needed protein requirements of the body among the low and middle income earners and the aged people in most rural villages in eastern Nigeria ,coupled with providing employment for the processors are being limited by all the problems stated above. This work therefore, attempts to find out the best processing (fermentation temperature) conditions of Ugba in order to help Ugba achieve its nutritional and industrial potentials.