Materials and Methods

Sources of Raw Materials

African yam bean (AYB) seeds, maize grains and firm ripeplantain were obtained from Anyigba Central Market, Kogi State,Nigeria.

Preparation of African Yam Bean (AYB) Flour

AYB flour was prepared following the method derscribed byYusufu, et al. [5]. AYB seeds were cleaned of dirts, parboiled (100 °Cfor 20 min) in an aluminum pot with lid. The parboiled seeds weredrained for 5 minutes, dehulled manually and washed with cleanwater. The seeds were oven dried and toasted at 150 °C for 1 hr. Thetoasted seeds were milled in a hammer mill and sieved through a500μm mesh. The flour was packaged in an air tight container.

Preparation of Maize Flour

Maize flour was processed using the method described by Enwere[3]. The grains were cleaned and washed. The cleaned grains wereboiled in water at 100 °C for 10 minutes and drained for 10 minutes.The grains were dried in an oven (uniscope 9053) at 70 °C for 1 hr andthe dried grains were dehulled by the use of hands and winnowed.The dehulled grains were milled and sieved (500μm) and packaged.

Preparation of Plantain Flour

The method described by Enwere was used to prepare theplantain flour [3]. Firm ripe plantain fruits were washed to removeadhering soil particles, peeled and sliced into thin thickness of about2mm. 5.25ml of 2.0% sodium metabisulphite was added to each 500gweighed chopped pulp and allowed to stand for 20 min and driedin the cabinet dryer at 50 °C for 24hr. The dried plantain slices weremilled into flour using a hammer mill and sieved through 500μmsieve. The flour was packaged and sealed in polyethylene bag.

Blend Formulation

Maize, AYB and plantain flour were blended in a proportion of70: 20: 10 (maize: AYB: Plantain) and coded sample B, 60: 20: 20 toproduce sample C and 50: 25: 25 to produce sample D. Cookies madefrom 100% wheat was coded sample A and served as control.

Proportions of Ingredients

The proportions of ingredients used in cookies productionwere as described by Chinma et al. with slight modification [1]. The ingredients consist of 100g flour, 53.0g of sugar, 26.5g of margarine,1.10g of sodium bicarbonate, 0.89g of sodium chloride, 7.5ml ofunsweetened evaporated liquid milk (peak) and 12.0ml of water.

Preparation of Cookies

The flour was mixed with other ingredients and blendedthoroughly to form dough. The dough was placed on a clean table,rolled and cut out into required shapes, baked in an oven at 180 °Cfor 30 minutes. The cookies were allowed to cool and packaged in lowdensity polyethylene bags of thickness 0.5mm and stored in air tightcontainers for further analysis.

Chemical Analysis

The moisture, crude protein, fat, crude fibre and ash contents weredetermined following the procedure outlined by AOAC [8], whilecarbohydrate was calculated by difference [9]. Energy was calculatedusing Atwater factors (9x fat, 4x protein and 4x carbohydrate).Beta carotene, Vitamin C, potassium and calcium contents weredetermined following the methods described by Onwuka [9].

Sensory Evaluation

Sensory evaluation was conducted mid-afternoon (1.00-2.00p.m.) in a sensory evaluation room. A-20 member Panel was trainedon sensory attributes for the evaluation. The scores were based onthe intensity of organoleptic quality attributes of taste, crust color,flavor, texture and overall acceptability. Each sensory attribute wasrated on a-9 point Hedonic Scale (1= disliked extremely while 9=liked extremely).

Microbiological Analysis

Microbiological analyses were carried out according to the methoddescribed by Jideani [10]. One gram of sample was homogenized in10ml of 1/4 Strength Ringer’s Solution. Dilutions were made by mixing1.0ml of the homogenate in 9.0ml of the sterile diluent to obtain10-1 dilution. The dilution was then made up to 10-2, 10-3 and 10-4.Total viable counts of bacteria were determined by enumerating thecolony forming units (cfu) by pour plating on nutrient agar plates andcultured at 37 °C for 48hrs. The number of colony forming units oneach plate was counted using colony counter and expressed as cfu/g.

Total fungal counts were determined by pour plating on potatodextrose agar plates supplemented with 1.0% tartaric acid to inhibitbacterial growth and incubated at room temperature (30±2 °C) for4-6 days. The number of colonies were expressed as cfu/g. All theanalyses were carried out in triplicates.

Statistical Analysis

Data were subjected to analysis of variance as described byEgbekun and Akubor [11]. Least significance difference (LSD) testwas used to separate means where significant. Significance wasaccepted at (p≤0.05).

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Results and Discussion

Chemical Composition of the Cookies

The chemical composition of cookies is shown in Table 1. Therewas significant difference (p≤0.05) between cookies made fromcontrol (100% wheat) and composite flours in terms of protein,moisture, ash and carbohydrate. A gradual decrease in carbohydratewith increasing level of AYB flour inclusion was observed while thereverse was the case with protein content. This is in agreement withYusufu et al. [12] who reported a decrease in carbohydrate contentof cookies when green bean flour was blended with wheat to producecookies. Sample D had the highest level of protein (18.71%). Thehealth benefits of proteins are well documented. The energy valueranged from 408Kcal in sample D to 417 Kcal in sample A with nosignificant ((p≥0.05) difference among the samples.

World Health Organization (WHO) recommended 1790Kcal to2500 Kcal/day of energy for children aged between 5 and 19 years[4]. This suggests that biscuits prepared from flour blends comprisingof maize, AYB and plantain could be included in school feedingprogrammes for children. Beta carotene and Vitamin C increasedsignificantly (p≤0.05) with increased level of plantain flour. Betacarotene is a pro-vitamin A. Vitamin A is a powerful natural antioxidantand required by the body for maintaining the integrity ofskin and mucus membranes. It is an essential vitamin for good visualsight. Vitamin C is vital in iron metabolism and subsequent fightagainst iron deficiency anaemia Akubor [13].

The composite cookies were higher in all the minerals (Ca, K andFe) than the control. This could be attributed to the relatively highermineral content of AYB and plantain. From the results of the mineralcomposition of cookies shown in Table 1, it is evident that cookiesprepared from the composite flour of maize, AYB and plantain aremore nutritious than 100% wheat flour cookies. This study is inagreement with the values reported by Chinma et al. for tiger nut andpigeon pear flour cookies [1].

Table 1: Chemical Composition of Cookies Produced from Maize, AYB and Plantain Composite Flour.

The sensory characteristics of cookies are shown in Table 2.The statistical analysis showed that there was significant difference((p≤0.05) among the cookie samples in crust color. Control sample(A) had the highest score while sample D had the least score. Therewas no significant (p≥0.05) difference in texture. The panelistsshowed preference for sample A in terms of flavor. The inherentbeany flavor of the composite cookies may have accounted for thelower rating by the panelists. All the samples were scored high in terms of crunchiness. For the general acceptability, cookies preparedfrom 70% maize, 20% AYB and 10% plantain composite flour had thehighest score next to control sample. Sample B therefore, competedfavorably with 100% wheat cookies.

Table 2: Means Sensory Scores of Cookies Produced from Maize, AYB andPlantain Composite Flour.

Acknowledgement

The authors highly acknowledge the Management of KogiState University and the Department of Food, Nutrition and HomeSciences in particular for making the Laboratory available for thiswork. We are grateful.