1.   Introduction

Biscuits are baked products made from wheat flour, sugar, milk, fat, flavouring agents and other raising agents [1]. They are ready-to-eat, convenient and inexpensive food products [2] with appreciable quantities of fat and carbohydrate [3]. They represent a fast growing segment of food because of consumer demands for convenient and nutritious food products with improved taste, safety [3] and good shelf life at ambient temperature [4]. This has necessitated renewed interest and attempts to improve the nutritional quality and functionality of biscuits [5] by enriching, supplementing or substituting wheat flour with a wide variety of nutrient rich cereals, pulses, fruits, tubers [6, 7] such as African pear and orange flesh sweet potato.

 

African pear (Dacryodes edulis) is a fruit tree native to Africa, sometimes called Safou, atanga, ube [8], African bush pear or plum, nsafu, bush butter tree or butter fruit. It serves as food for direct consumption and raw material for food production if properly harnessed [9]. It has the ability to improve food nutrition and food security [9]. The seeds of African pear are rich in different proportions of carbohydrates, proteins, crude fiber, and appreciable amount of potassium, calcium, magnesium and phosphorus [10]. It is also rich in essential amino acids such as lysine, phenylalanine, leucine, and isoleucine [11]. It contains a considerable amount of fatty acids such as palmitic acids, oleic acids and linoleic acids [11]. An important natural product like gallic acids is found in significant quantity in the seed of African pear [12].

 

Orange-fleshed sweet potato (OFSP) is one of the sweet potato varieties being promoted in sub-Saharan Africa as a food-based measure to complement other efforts in reducing the occurrence of vitamin A deficiency (VAD) in this region [13]. Studies have proven that consumption of boiled roots improved the vitamin A marker in adults and children [14]. OFSP has been found to be a good flour substitute for wheat flour in composite flour formulation which is grown in many tropical and subtropical regions. Among the world’s major food crops, sweet potato produces the highest amount of edible energy per hectare per day [15]. Among the root and tuber crops, sweet potato is the only crop that has a positive per capita annual rate of increase in production in sub-Saharan Africa [16]. and it also has considerable potential to contribute to food-based approach to tackle the problem of vitamin A deficiency, a major public health concern of the poorer nations [13].

 

The conventional use of wheat flour in baking has been confronted with numerous challenges such as increasing cost of importation, non-conducive growing conditions in Nigeria, allergy to gluten-sensitive individuals and non-functional contribution to health. The adoption of composite flour intended to replace wheat flour totally or partially in bakery and pastry products has been recommended. This will save money for the country, promote high yielding native plant species, better supply of protein for human nutrition and overall use of domestic agriculture. Therefore, the objective of this study was to evaluate the quality of biscuits produced from African pear and orange flesh sweet potato composite flour.

 

2.   Materials and methods

2.1 Source of raw materials

Wheat flour (Nigeria Flour Mill Ltd), baking powder, eggs, sugar, margarine, salt (Dangote Nigeria Ltd) and African pears (D. e. var. edulis variety) were purchased from commercial stockers at Ubani main market, Umuahia, Abia state, Nigeria. Fresh orange flesh sweet potato tubers were purchased from National Root Crops Research Institute (NRCRI) Umudike, Ikwuano Local government area, Abia state in Nigeria. All reagents used in this study were of analytical grade and were sourced from the Laboratory Department of Biochemistry, National Root Crops Research Institute, Umudike, Abia State, Nigeria.

 

2.2 Processing of African pear (Dacryodes edulis) into flour

Fresh African pears were sorted to remove extraneous substances like stones, pebbles and spoilt fruits before washing with potable tap water. The fruits were washed, deseeded and diced (2 cm). The diced fruits were dried in a hot air oven (Model no.SX3-4.5-15: made in China) at 60°C for 24 hours to a moisture content of 10%. The dried diced fruits were milled into powder using a commercial hammer mill. The subsequent flour was sieved through a 500 µm mesh and stored in an air tight container under refrigeration temperature of 4^oC prior to use.

 

2.3 Processing of orange flesh sweet potato (OFSP) tubers into flour

OFSP tubers were sorted for wholesomeness, washed with portable water for dirt removal and peeled to remove the outer layers. The peeled tubers were washed again with portable water and subjected to size reduction by dicing for ease of drying. The diced OFSP were spread out on trays and dried in a hot air oven (Model no.SX3-4.5-15: made in China) at 55°C for 36 hours. The dried OFSP was milled using SFSP 56 x 40a hammer mill, sieved through a 500 µm mesh and stored in air tight containers under refrigeration condition of 4^oC prior to use.

 

2.4 Composite flour formulation

The composite flours were formulated as shown in Table 1. Biscuits produced from 100% wheat flour served as the reference sample.

 

Table 1. Formulation of composite flours.

Sample codes	African pear flour (AP) (%)	OFSP flour (%)
AP90	90	10
AP80	80	20
AP70	70	30
AP60	60	40
AP50	50	50

 

 

 

 

 

 

 

 

 

2.5 Determination of functional properties of composite flour

The bulk density, water absorption and oil absorption capacities, emulsion capacity, swelling index, and gelatinization temperature were determined using the method described by Onwuka [17].

 

2.6 Production of biscuit samples

Biscuits were produced using the rubbing in method as described by Ahmed et al. [18] with some modifications in the recipes. First, all the ingredients contained in the recipe as presented in Table 2 were accurately weighed or measured as the case may be. The dry ingredients (flour, sugar, salt and baking powder) were mixed manually in a bowl for about 3 minutes. Vegetable shortening (baking margarine) was added and mixed until uniform. Egg, milk and water were then added and the mixture kneaded. The batter was rolled and cut with a 20 mm diameter biscuit cutter. The biscuits were placed on greased baking trays, leaving 25 mm spaces in between and baked at 180°C for 10 minutes in the baking oven (Gallenkamp, Model OV 160, England). Following baking, the biscuits were cooled within 1 h in the open air to ambient temperature and then packed in an airtight high density plastic transparent containers before being stored at 23°C prior to subsequent analysis and sensory evaluation.

 

Table 2. Biscuits recipe with different levels (%) of African pear and orange flesh sweet potato flour blends.

 

Ingredients	AP0	AP90	AP80	AP70	AP60	AP50
Wheat flour (g)	500	0	0	0	0	0
African pear (g)	0	450	400	350	300	250
OFSP (g)	0	50	100	150	200	250
Margarine (g)	100	100	100	100	100	0
Sugar (g)	250	250	250	250	250	250
Baking powder (g)	7.5	7.5	7.5	7.5	7.5	7.5
Salt (g)	2	2	2	2	2	2
Egg (g)	60	60	60	60	60	60
Milk  (ml)	75	75	75	75	75	75
Water (ml)	75	75	75	75	75	75
AP0 = 100% wheat flour, AP90 = 90% African pear flour: 10% orange flesh sweet potato flour, AP80 = 80% African pear flour: 20% orange flesh sweet potato flour, AP70= 70% African pear flour: 30% orange flesh sweet potato flour, AP60= 60% African pear flour: 40% orange flesh sweet potato flour, AP50= 50% African pear flour: 50% orange flesh sweet potato flour.

 

2.7 Proximate determination of biscuit samples

The moisture, ash, crude protein, crude fibre and crude fat were determined according to AOAC [19]. A protein conversion factor of 6.25 was used to convert N content to crude protein, while carbohydrate was estimated by difference [i.e. 100% – protein (%) + fat (%) + crude fibre (%) +Ash (%)].

 

2.8 Mineral content determination

Mineral content of the test samples was determined by the dry ash extraction method followed by the determination of specific mineral content. Two (2) grams of each sample was dried and burnt to ash on a digital muffle furnace (model no: Sx2 -2.5-12; made in China). The resulting ash was dissolved in 100 ml of dilute hydrochloric acid (2M HCL), heated for 30 min and made up to 100 ml with distilled water. The digest obtained was used for the analysis of the various minerals. Calcium (Ca) and magnesium (Mg) contents were determined by the EDTA versanate complexometric titration method; potassium (K) and sodium (Na) contents by the flame photometer with appropriate standards while phosphorus (P) was determined by the vanado-molybdate yellow method using spectrophotometer [19].

 

2.9 Vitamin content determination

Ascorbic acid (vitamin C), thiamin (B₁), riboflavin (B₂), and niacin (B₃) contents of the biscuit were determined following the method of AOAC [19] while vitamin A content was determined following the method described by Onwuka [17].

 

2.10 Sensory Evaluation

A 25-member semi trained panelists conducted a descriptive sensory evaluation on the biscuit samples from different combinations. The panelists were trained using ISO 8586-1 [20] and Iwe [21] with some modifications. Each sample was placed on white saucer, coded with random 3 or 4-digit numbers as the case may be and presented to the panelists for analysis. The biscuits were analysed for appearance, texture, aroma, taste, mouth-feel and over-all acceptability, using 9-point hedonic scale with 1 for disliked extremely and 9 for liked extremely. Panelists were provided with distilled water to rinse mouths between tasting to avoid carrying over taste. Biscuit samples that scored 5 and above (neither liked nor disliked to extremely liked) for over-all acceptability were considered acceptable.

 

2.11 Experimental Design

This was a completely randomised design (CRD) with all the components given equal treatment.

 

2.12      Statistical Analysis

Data obtained were subjected to descriptive statistics and means of one-way analysis of variance (ANOVA). Means, where significantly different at p < 0.05 were separated using Duncan’s Multiple Range Test (DMRT) with Statistical Package for the Social Science Version 21.0.

 

3.   Results and discussion

3.1 Functional properties of composite flours

Table 3 shows that formulation of composite flour with different levels of African pear flour and orange flesh sweet potato flour blends significantly (p<0.05) affected the functional properties of the composite flour. The control sample (100% wheat flour), had a relatively higher water absorption capacity (1.93 g/ml) and oil absorption capacity (1.47 g/ml) than composite flours. Decreased proportion of African pear flour from 90% to 50% with the concurrent increase in orange flesh sweet potato flour from 10% to 50% resulted to a corresponding increase in the swelling index and gelatinization temperature while the water absorption capacity, oil absorption capacity and emulsion capacity decreased. The bulk density of the composite flours was significantly (p< 0.05) not affected.

 

Bulk density (BD) is influenced by the structure of the starch polymers [17]. The values obtained in this study ranged from (0.64 to 0.67 g/ml) and were lower than 0.72 to 0.85 g/ml reported by Florence et al. [22] and 0.65-1.07 g/mL reported by Oppong et al. [23], but higher than 0.50 to 0.55 g/ml reported by Olosunde et al. [24] and 0.55 - 0.57 g/mL reported by Siddiq et al. [25]. There was no significant (p< 0.05) difference in the values of bulk density obtained in this study which suggests that the composite flours and the control flour sample may possess similar starch structures. The values obtained were below 1.00 g/ml, suggesting loose structure of starch polymers [25]. This is ideal for good biscuit quality with high specific volume [26], and may encourage bulk packing of the flour samples using compact packaging material [27]. Water absorption capacity (WAC) is an important property in food. The ability of protein in flour to bind water is a result of its water absorption capacity [28]. Decreasing WAC in the composite flours may be attributed to decreasing amount and nature of hydrophilic constituents [29] as the proportion of African pear decreased. Butt and Batool [30] reported that increased concentration of protein, degree of association and conformational characteristics positively influence the WAC of flours. Consequently, increasing the proportion of orange flesh sweet potato flour affected the concentration of protein content negatively. Water absorption capacity suggests a good baking quality [31]. WAC obtained in this study were below 2.40 to 2.67 g/ml reported by Olosunde et al. [24], lower than 7.6 mL/100 g reported by Siddiq et al. [25], but higher than 1.00 to 1.47 g/ml reported by Florence et al. [22]. A water absorption capacity of 1.25 g/g (125 mL/100 g) and above is an indication of good bakery properties that required high water imbibition[25].

 

Oil absorption capacity (OAC) and emulsifying capacity (EC) is an important parameter of flour used in baking [32] since it is an important property in food formulation. Ability of flour to absorb oil improves the mouth feel and flavour retention [33]. The emulsion capacity is the extent to which the dietary protein will mix with oil [34]. Decreasing oil absorption and emulsifying capacities of the composite flours may be influenced by the decreasing Lipophilic nature associated with decreasing proportion of African pear flour. Composite flour with high African pear flour concentration had higher OAC and indicates desirable flavour retention ability and palatability [35]. The oil absorption capacity (OAC) of this study was higher than 0.27 to 0.82 g/ml reported by Kwaghsende et al. [4] but is in agreement with 1.39 to 1.57 g/ml reported by Olosunde et al. [24]. Also, the oil absorption capacities of this study were below 26.91 mL/g and 21.94 mL/g respectively for pigeon pea flour reported by Oppong et al. [23].

 

The swelling index is a measure of hydration capacity which defines the wettability of flour samples [36]. The higher the swelling index, the lower the wetting time [36]. As orange flesh sweet potato flour substitution increased from 10 - 50%, swelling index of the composite flours increased which may be due to increased hydrophilic sites. Swelling index values for this study were lower than 3.00 to 9.40% reported by [4] but higher than 0.53 to 0.71% recommended for wheat flour [38]. Gelatinization temperature (GT) increases as African pear flour substitution increases and vice versa. Control sample gelatinized at a lower temperature. The high gelatinization temperature of composite flours suggests starch dilution [39], hence, requiring higher temperature to gelatinize. 

Table 3. Functional properties of African pear-orange flesh sweet potato flour blends.

 

Samples	Bulk density (g/ml)	Swelling index (%)	Water absorption capacity (g/ml)	Oil absorption capacity (g/ml)	Gelatinization temperature (°C)	Emulsion capacity (%)
AP0 AP90 AP80 AP70 AP60 AP50	0.66a±0.003 0.66a±0.001 0.64a±3.382 0.66a±0.001 0.66a±0.001 0.67a±0.001	1.19c±0.03 1.32bc±0.03 1.35bc±0.01 1.27c ±0.23 1.50b ±0.62 1.71a±0.02	1.93a±0.12 1.60b±0.10 1.53bc±0.16 1.43bc±0.06 1.40c ±0.10 1.13d ±0.16	1.47a±0.06 1.37b±0.06 1.27c±0.06 1.10d±0.00 1.03d±0.06 0.93e±0.06	89.0d±1.73 95.66a±0.58 93.67b±0.58 91.67c ±0.58 90.67cd ±1.15 90.33cd ±0.58	55.97c±0.12 61.69a±0.43 59.76b±0.39 55.72c±0.74 52.08d±0.84 47.44e±0.63
a-d: Values are means ± s.d of duplicate determination. Mean value in the same column but with different superscript are significantly different (P<0.05). AP0 = 100% wheat flour. AP90 = 90% African pear flour: 10% orange flesh sweet potato flour. AP80 = 80% African pear flour: 20% orange flesh sweet potato flour. AP70= 70% African pear flour: 30% orange flesh sweet potato flour. AP60= 60% African pear flour: 40% orange flesh sweet potato flour. AP50= 50% African pear flour: 50% orange flesh sweet potato flour.

3.2 Proximate composition of biscuit samples

Table 4 shows the proximate composition of the biscuit samples. Crude protein, fat, crude fibre and ash contents of the biscuit samples increased progressively with increasing proportion of African pear flour from 50% to 90% while moisture and carbohydrate contents decreased concurrently. Control samples had higher moisture and ash contents than the composite samples. Orange flesh sweet potato (OFSP) contains higher moisture [40] compared to African pear. Higher moisture content in biscuit samples containing higher proportion of orange flesh sweet potato flour can be attributed to the high moisture content present in orange flesh sweet potato tuber, which consequently influences the moisture rise, suggesting lower shelf stability, since baked foods with high moisture content encourage bacterial, yeast and mould growth that could lead to spoilage [41]. The moisture content obtained in this study (4.99-8.54%) was lower than 11.09-15.10% reported by Ezeocha and Onwuneme [42], 19.57-21.03% reported by Angela et al. [43], 13.80-14.70% reported by Ade-Omowaye et al. [44] and 23.49-28.62% reported by Adeyeye et al. [45]. Increased ash content implies increased mineral contents [46] with increased proportion of African pear flour. Ash content is the fraction of biomass that is composed of incombustible mineral material, which is a representation of mineral availability in food [47]. It is a measure of mineral content or inorganic residue remaining after water and organic matter have been removed by open air incineration [48]. The higher ash content present in the composite samples suggests possible improvement in the mineral contents compared to the control sample. African pear has been reported to be high in useful minerals such as iron and calcium [49], which may have contributed to the increase. The ash content of this study (4.59-5.02%) was higher than the 1.61 -1.85% reported by Ezeocha and Onwuneme [42], 0.45-1.60% reported by Ade-Omowaye et al. [44], 0.83-1.39% reported by Adeyeye et al. [45] but lower than 5.65-8.00% reported by Angela et al. [43]. These variations may be attributed to compositional variations, processing methods, and raw material differences among others.

 

Proteins are the building blocks of life. About 23-56 g of protein was recommended by [50] to meet the protein needs of the human body and combat protein deficiency. The higher protein content of composite biscuits as the proportion of African pear flour increased suggests valuable contribution in combating protein energy malnutrition, especially for low income earners. However, the values obtained (7.35 – 8.09%) in this study were below the recommended intake value (23-56 g) as well as the value (9.45-15.10%) reported by Ade-Omowaye et al. [44], 7.69-10.64% reported by Adeyeye et al. [45] and 10.79-15.30% reported by Angela et al. [43] but higher than 3.50-6.97% reported by Ezeocha and Onwuneme [42]. Composite biscuits had significantly higher fibre contents than the control sample. Composite biscuits containing higher proportion of African pear flour had higher fibre content. OFSP has low crude fiber content [51]. In the present study, a fibre content of 3.01-3.18% was recorded which was higher than 2.29-2.80% reported by Ezeocha and Onwuneme [42], 0.56-1.80% reported by Angela et al. [43], 0.30-3.20% reported by Ade-Omowaye et al. [44] and 0.78-1.31% reported by Adeyeye et al. [45]. Fibre offers a variety of health benefits. It is essential in reducing the risk of chronic diseases such as diabetes, obesity, cardiovascular diseases and diverticulitis, helping in bowel movement, lowering blood cholesterol, and reducing the risk of colon cancer [52]. Higher fat content in composite biscuits containing at least 60% African pear flour suggests the possible presence of a higher amount of fat-soluble vitamins (A, D, E and K). African pear contains about 18 to 70% of oil and there was a notable increase (p<0.05) in fat content as the African pear quantity increased. According to the reported data of Ariyo et al. [53], lipids play very important roles in the human body such as in brain function, joint mobilization, and energy production and helps the body to absorb fat-soluble vitamins A, D, E, and K which keep the body healthy. Dietary fat increases the palatability of food by absorbing and retaining flavor although excess fat is also implicated in certain cardiovascular diseases [4]. Findings from this study suggest that OFSP has a low fat content and may signify that flour blends with OFSP may likely not undergo rapid oxidative rancidity during storage if suitably packaged [54]. The fat content obtained in this study (13.35-21.05%) was higher than 1.30-17.30% reported by Ade-Omowaye et al. [44], 1.38-1.74% reported by Adeyeye et al. [45], 1.64-3.15% reported by Eweocha and Onwuneme [42] and 6.76-7.97% reported by Angela et al. [43]. Reduced carbohydrate contents in the composite samples with increasing proportion of African pear flour may be due to starch reduction with the concurrent increase in ash, fat and protein. However, the carbohydrate contents in the biscuits are considerably high and may be good source of energy for the body. Findings from this study relative to carbohydrate content (57.39-60.48%) were lower than 73.47-79/2% reported by Ezeocha and Onwuneme [42], higher than 45.91-56.71% reported by Angela et al. [43] but in agreement with 54.70-68.70% and 57.78-64.38% reported by Ade-Omowaye et al. [44] and Adeyeye et al. [45] respectively.

 Table 4. Proximate composition of composite biscuits samples (%).

Samples	Moisture content	Protein content	Fat content	Fibre content	Ash content	Carbohydrate content
AP0	8.54a±0.12	7.58bc±0.20	18.45a±0.19	3.01b±0.09	5.02a±0.03	57.39d±0.47
AP50	5.21 b±0.02	7.35 c±0.26	13.35a±9.88	3.07 b±0.30	4.87ab±0.01	60.48a±0.22
AP60	5.19b±0.03	7.25 c±0.38	19.00a±0.08	3.08ab±0.03	4.59 b±0.51	60.26a±0.41
AP70	5.09bc±0.01	7.67abc±0.03	19.99 a ±0.28	3.11ab±0.01	4.93ab±0.01	59.21c±0.25
AP80	4.95c ±0.03	7.82ab ±0.10	20.60a ±0.10	3.11ab±0.01	4.95ab±0.01	58.57c±0.03
AP90	4.99c ±0.12	8.09a ±0.24	21.05a ±0.23	3.18a ±0.07	4.98ab±0.02	57.71d±0.21
a-d:Values are mean standard deviation for duplicate determination. Values with different superscripts within the same column are significantly different (p<0.05). AP0 = 100% wheat flour. AP90 = 90% African pear flour: 10% orange flesh sweet potato flour. AP80 = 80% African pear flour: 20% orange flesh sweet potato flour. AP70= 70% African pear flour: 30% orange flesh sweet potato flour. AP60= 60% African pear flour: 40% orange flesh sweet potato flour. AP50= 50% African pear flour: 50% orange flesh sweet potato flour.

 

3.3 Mineral content of biscuit samples

The result of the mineral content of biscuit samples is presented in Table 5. Development of biscuits from blends of African pear and orange flesh sweet potato flours progressively and significantly (p<0.05) improved the calcium, potassium, sodium and phosphorous contents of the samples. The control sample had higher magnesium contents than the composite samples. Increasing the proportion of African pear flour with concurrent reduction of orange flesh sweet potato flour resulted in increased calcium, potassium, sodium and phosphorous owing to the rich source of these minerals in African pear fruit [55, 56], while magnesium decreased progressively. OFSP has higher magnesium content [57], hence, its reduction in proportion resulted to decrease in magnesium in the final product. Mineral content obtained in this study was lower than 117.50 to 130.50 mg/100 g for calcium, 218 to 343.00 mg/100 g for phosphorous but higher than 114 to 126.50 mg/100 g for potassium reported by [4]. [22] reported lower values for potassium (61.90 – 92.84 mg/100 g), calcium (3.28-8.25 mg/100 g) and magnesium (1.98 – 4.56 mg/100 g) contents but higher values for sodium (123.90-184.86 mg/100 g) content. The values obtained for calcium are below the FAO/WHO recommended daily intake for calcium of different target consumers such as infants and children of 0 to 9 years (300 to 700 mg/day), adolescents of 10 to 18 years (1300 mg/day), adults of 19+ years (1000 to 1300 mg/day), pregnant women (1200 mg/day) and lactating women (1000 mg/day) [58]. Increase of African pear flour in composite biscuits, although, below the FAO/WHO recommended daily intake might contribute to the calcium needs of the body. Also, the magnesium content of the biscuit samples is below the recommended intake for infants and children (26 to 100 mg/day), adolescents (230 mg/day for females and 220 mg/day for males) and adults (220 mg/day for females and 260 mg/day for males) [58]. Consequently, the magnesium content of the samples may not be adequate to meet the needs of magnesium in the body.

Potassium content was many times higher than sodium contents in the biscuit samples and suggests safe and low incidence of hypertension from consuming such biscuits. Calcium is necessary for growth and helps in the calcification of strong bones for optimal growth and development [59]. Sodium is an important electrolyte in every living cell, essential in balancing fluid and muscle contraction in the body. However, excess sodium in the cell induces hypertensive condition in the cells [60]. Fortunately, the high relative potassium to sodium content in these biscuit samples is of high health benefit to consumers since both are involved in sodium-potassium ATPase in the cell system. Increased magnesium contents when orange flesh sweet potato flour was increased is of health benefit since magnesium is an essential component of all cells and is necessary for the functioning of enzymes involved in energy utilization and it is present in the bone [61]. Increased phosphorous content as the level of African pear flour substitution increases from 50 to 90% will also be beneficial in bone health. Phosphorus works closely with calcium to build strong bones and teeth. These two minerals combine to form calcium phosphate, the predominant mineral of bone. Most of the phosphorus in the body is found in the bones and teeth [62].

 

Table 5. Mineral content (mg/100 g) of composite biscuit samples

Samples	Calcium	Magnesium	Potassium	Sodium	Phosphorous
AP0	26.72d±2.31	25.50 a ±1.31	179.67d±6.64	10.82a ±0.57	46.16c±1.10
AP50	33.40bcd±2.32	22.40 b±1.39	194.93c ±1.40	8.80bc ±0.27	72.73c ±3.30
AP60	30.74cd ±9.23	20.800bc±1.39	200.40bc±1.56	8.32c ±1.05	89.77bc±1.32
AP70	38.74abc±2.31	20.00bcd±1.39	203.50b ±1.91	9.11bc±0.02	76.57bc ±56.26
AP80	41.42ab ±2.31	18.43cd ±1.42	205.87b ±1.10	9.08bc ±0.09	118.47ab ±5.08
AP90	42.75a ±2.31	17.60d ±1.39	212.50a ±2.60	9.48b ±0.32	138.80a ±2.61
a-d:Values are mean standard deviation for duplicate determination. Values with different superscripts within the same column are significantly different (p< 0.05). AP0 = 100% wheat flour. AP90 = 90% African pear flour: 10% orange flesh sweet potato flour. AP80 = 80% African pear flour: 20% orange flesh sweet potato flour. AP70= 70% African pear flour: 30% orange flesh sweet potato flour. AP60= 60% African pear flour: 40% orange flesh sweet potato flour. AP50= 50% African pear flour: 50% orange flesh sweet potato flour.

3.4 Vitamin content of biscuit samples

Table 6 shows the vitamin composition of the biscuit samples. The studied vitamins were significantly (p<0.05) different among the samples as wheat flour was completely substituted with African pear and orange flesh sweet potato flour blends. The control sample had the lowest vitamin content in all samples. By increasing the proportion of African pear flour, there was notably increase in the vitamin C content of the biscuit samples while vitamin A reduced progressively. African pear fruit contains a good proportion of vitamin C [63] while orange fleshed sweet potato has been reported to be highly rich in beta-carotene [64], hence, the reported increase in vitamin A as the proportion of orange flesh sweet potato flour increases. Ascorbic acid and vitamin A were relatively higher in comparison to the B-complex vitamins. Akujobi [65] reported lower vitamin A (2.46 to 3.17 mg/100 g) but higher vitamin C (4.70 to 5.40 mg/100 g) contents than the values obtained in this study.

Vitamin A improves growth, promotes resistance to disease, delays ageing and promotes healthy eyes, skin, nails and hair [66, 67]. It also acts as an antioxidant and as free radical scavenger. Ascorbic acid helps in healthy lungs and bronchia, strong teeth and gum formation; and reduces several inflammatory disorders [68]. Both thiamine (B₁) and riboflavin (B₂) are involved in release of energy in the cells, help to keep the eyes, skins around mouth and nose smooth and healthy. Deficiency in riboflavin causes glossitis in men. Vitamin B₃ aids in cholesterol production and conversion of food carbohydrates into energy, digestion and nervous system functioning [69]. It aids in absorption of iron from the intestines, healing of wounds and in teeth and bone formation.  However, the vitamins B₁, B₂ and B₃ obtained in this study are too low to significantly contribute to human health.

 

Table 6. Vitamin contents of composite biscuit samples 

 

Samples	Vitamin A (ug/g)	Vitamin B1 (mg/100g)	Vitamin B2 (mg/100g)	Vitamin B3 (mg/100g)	Vitamin C (mg/100g)
AP0	562.00e±4.00	0.01a ±0.00	0.00 a±0.00	0.07d ±0.01	1.70f±0.04
AP50	1117.66a±19.09	0.01a ±0.01	0.00a ±0.00	0.13a ±0.01	3.92e±0.06
AP60	1040.00b±12.12	0.31a ±0.51	0.01a ±0.00	0.13ab ±0.01	4.01d±0.10
AP70	1009.00c ±9.54	0.02a ±0.01	0.01a ±0.00	0.12ab ±0.01	4.12c±0.01
AP80	988.33d ±2.52	0.03a ±0.01	0.01a ±0.00	0.12b ±0.01	4.23b±0.02
AP90	888.67 a±4.62	0.03a ±0.01	0.87 c±1.50	0.10b ±0.01	4.30a±0.11
a-f:Values are mean standard deviation for duplicate determination. Values with different superscripts within the same column are significantly different (p< 0.05). AP0 = 100% wheat flour. AP90 = 90% African pear flour: 10% orange flesh sweet potato flour. AP80 = 80% African pear flour: 20% orange flesh sweet potato flour. AP70= 70% African pear flour: 30% orange flesh sweet potato flour. AP60= 60% African pear flour: 40% orange flesh sweet potato flour. AP50= 50% African pear flour: 50% orange flesh sweet potato flour.

 

3.5 Sensory characteristics of biscuit samples

Table 7 shows the sensory scores of the biscuit samples by the panelists. The 25-member semi-trained panelists assessed the biscuit samples on appearance, texture, aroma, taste, mouthfeel and overall acceptability. Appearance is an important sensory feature of any food product as it influences acceptability. Consumers use the appearance to predict the quality of food products like biscuits. Taste is the sensation of flavour perceived in the mouth and throat on contact with a substance, food or non-food [70]. Aroma is a distinctive, typically pleasant smell perceived by the olfactory sense while mouthfeel refers to the rheological perception of food material [70]. It is one of the vital organoleptic properties of food products.

Increasing proportion of African pear flour from 50% to 90% significantly increased the scores for taste and aroma while the appearance, texture, mouthfeel and general acceptability scores increased with increasing proportion of orange flesh sweet potato flour. All the experimental biscuits had sensory scores significantly (p<0.05) lower than the control sample.  The scores of the control sample for appearance, texture, aroma, taste and mouthfeel include 7.87, 7.87, 7.83, 7.87, and 7.70, respectively. The sensory score for each parameter decreased progressively as the level of substitution increased which is similar to the observation of [71]. Biscuits containing increasing proportion of African pear flour had lower sensory scores, indicating poor sensory preference.

 

Generally, in terms of the assessed sensory parameters, AP0 was most acceptable, followed by AP50 and AP60, then other experimental samples in their order of increasing African pear flour substitution. Hence, among the composite biscuit samples, biscuit samples produced from 50% African pear flour:50% orange flesh sweet potato flour and 60% African pear flour:40% orange flesh sweet potato flour were rated highest (6.39) among the samples with respect to general acceptability and was liked slightly while the control sample with a rating of 7.73 was liked very much.

 

Table 7. Sensory characteristics of composite biscuit samples

Samples	Appearance	Texture	Taste	Aroma	Mouth feel		General acceptability
AP0	7.87 a±1.01	7.87a±0.97	7.87a ±0.97	7.83a±0.94		7.70a ±1.06	7.73a ±0.96
AP50	6.61b±0.99	6.39bc±1.03	5.43d±1.56	5.96b±1.38		6.52bc ±1.27	6.39a ±1.78
AP60	6.48b ±1.27	5.78bc±0.99	5.61cd±1.62	5.96b±1.32		6.34c ±1.87	6.39a ±1.70
AP70	4.87c ±1.84	5.39bc±1.08	6.00cd±1.28	6.00b±1.17		6.17bc ±1.24	5.70a ±9.96
AP80	4.57b ±1.93	4.87b ±1.18	6.96b ±1.52	6.13b±1.58		5.30b ±1.69	5.43a ±1.20
AP90	4.17b ±1.77	4.52c ±1.95	6.52bc±1.95	6.41b±1.67		5.00bc ±1.88	5.09a ±1.93
a-d: Values are mean standard deviation for duplicate determination. Values with different superscripts within the same column are significantly different (p< 0.05). AP0 = 100% wheat flour. AP90 = 90% African pear flour: 10% orange flesh sweet potato flour. AP80 = 80% African pear flour: 20% orange flesh sweet potato flour. AP70= 70% African pear flour: 30% orange flesh sweet potato flour. AP60= 60% African pear flour: 40% orange flesh sweet potato flour. AP50= 50% African pear flour: 50% orange flesh sweet potato flour.

 

4.   Conclusions

Substitution of wheat flour with blends of African pear flour and orange flesh sweet potato flour in biscuit production improved the nutrient composition. Proximate composition of composite biscuits improved over biscuits baked with 100% wheat flour. Micronutrients such as calcium, potassium, phosphorous, vitamin A and vitamin C were significantly improved in the composite samples with an appreciable reduction of detrimental sodium. The sensory properties and the overall acceptability of composite biscuits were acceptable to the panelist with a general acceptability score of not less than 5.0. African pear fruit and orange flesh sweet potato tuber should be valued as a dietary source to enrich bakery products  like biscuits in the country with the intent of developing healthier products. Substantially, the industrial value of the product is high and economically feasible due to the availability of its raw materials locally, thereby saving importation costs and generating more revenue for farmers and producers.

Authors’ contributions

Onwuzuruike Uzochukwu Anselm designed the study, conducted the statistical analysis and proofread the final copy of the manuscript.  Onuoha Nnamdi Dixon procured the raw material, and processed them into composite flour. and Uzochukwu Ugochi Comfort produced the gluten free biscuit samples and wrote the first draft of the manuscript.

Acknowledgements

The authors hereby acknowledge the efforts of the Laboratory staff of National root Crop

Research Institute, Umudike, Umuahia, Abia State, Nigeria.

 

Funding

This research was self-funded by the authors and did not receive funding from any source.

 

Availability of data and materials

All data will be made available on request according to the journal policy.

Conflicts of interest

The authors declare no conflict of interest

References

1.         Ayo, J.A.; Gidado, F.E. Physicochemical, phytochemical and sensory evaluation of acha-carrot flours blend biscuit. Curr. J. Appl. Sci. Techn. 2017, 25(5),1-15.

2.         Kawai, K.; Matsusaki, K.; Hando, K.; Hagura, Y. Temperature dependent quality characteristics of pre-dehydrated cookies: Structure, browning, texture, in vitro starch digestibility, and the effect on blood glucose levels in mice. Food. Chem. 2013, 141(1), 223–228.

3.         Nermin, B.L. Improvement of nutritional properties of cake with wheat germ and resistance starch. J. Food. Nutr. Res. 2013, 52(4), 210-218.

4.         Kwaghsende, G.S.; Ikala, G.U.; Ochelle, P.O. Quality evaluation of biscuit from wheat-tiger nut composite flour. Int. J. Agric. Plant Sci. 2019, 1(3), 25-30.

5.         Kumar, S.; Rekha-Sinha, L.K. Evaluation of quality characteristics of soy based millet biscuits, Adv. Appl. Sci. Res. 2010, 1, 187-196.

6.         Ayo, J.A.; Kajo, N. Effect of soybean hulls supplementation on the quality of acha based biscuits. Am. J. Food. Nutr. 2016, 6(2), 49-56.

7.         Akubor, P.I.; Ishiwu, C. Chemical composition, physical and sensory properties of cakes supplemented with plantain peel flour. Int. J. Agric. Pol. Res. 2013, 1(4), 087-092.

8.         Sueli, R.; Ebenezar, S. ; de Olivera S. Safou–Dacryodes edulis, cultivar origin and botanic aspect. http://www.sciencedirect.com/topics/agricultural-and-bological-sciences/dacryodes-edulis 2018. Accessed 23 September, 2022.

9.         Duru, M.; Amadi, C.; Ugbogu, A.; Eze, A.; Amadi, B. Phytochemical, vitamin and proximate composition of Dacryodes edulis fruit at different stages of maturation. Asian J. Plant Sci. Res. 2012, 2(4),  437-441.

10.     Poligui, R.N.; Mouaragadja, I.; Haubruge, E.; Francis, F. The culturation of safoutier (Dacryodes edulis (G. Don) H.J. Lam (Burseraceae)): Challenges and perspective valorisation in Gabon (syntheses bibliographie). Biotech. Agrom. Soc. Env. 2013, 17(1), 131-147.

11.     Ondo-Azi, A.; Ella, M.M.; Silou, T. Chalchat, J. Variation in physicochemical characteristics of safou (Dacryodes edulis (G. Don) H.J. Lam) fruits. International conference, nutrition and food production, in the Congo basin. Brussels Belgium. 30 September-1 October. 22–25, 2013.

12.     Anyam, I. A.; Oderinde, R.A.; Kajogbola, D.O. Uponi, J.I. Varietal delimitation in Dacryodes edulis (G. Don) H.J. lam (Burseraceae). Int. Tree Crops J. 2016, 2, 255-265.

13.     Kurabachew, G. Orange-fleshed sweet potato. At the nutritional forefront of the battle against hidden hunger in sub-Saharan Africa region. Int. Potato Center. 2015, 1, 14-15.

14.     Hotz, C.; Loechi, C.; Brauw, A.; De, P.; Ezeonou, D.; Gilligan, M.; Meenakshi, J.V.A large scale intervention to introduce orange sweet potato in rural Mozambique increases vitamin A intake among children and women. British J. Nutr. 2012, 108(1), 163-176.

15.     Solomon, W.F. Review on nutritional composition of orange-fleshed sweet potato and its role in management of vitamin A deficiency. Food. Sci. Nutr. 7(6), 13-19. Onlinelibray.wiley.com. 2019, http://doi/full/10.1002/fsn3.1063.

16.     Mitra, S. Nutritional status of orange-fleshed sweet potatoes in alleviating vitamin a malnutrition through a food-based approached. J. Nutr. Food. Sci. 2012, 2, 160. Doi:10.4172/2155-9600.1000160. 152 -166.

17.     Onwuka, G.I. Food analysis and instrumentation theory and practices Naptali prints. Lagos, Nigeria, 2018.

18.     Ahmed, S.Z.; Hussein, M.S. Exploring the suitability of incorporating tiger nut flour as novel ingredients in gluten free biscuit. Polish J. Food. Nutr. Sci. 2014, 64(2), 27-33.

19.     AOAC, Official Methods of Analysis (13^th Edn.). Association of Official Analytical Chemists, Washington DC, 2010.

20.     ISO, Sensory analysis. General guidance for the selection, training and monitoring of assessors. Part 1: Selected Assessors (ISO 8586). Geneva (Switzerland): International Organization for standardization.1993, pp.19-33.

21.     Iwe, M.O. Some Sensory Methods and Data Analysis. In: Handbook of Sensory Methods and Analysis. Enugu, Nigeria: Rojoint Communication Services LTD, 2nd ed. 2010 pp. 80–85.

22.     Florence, A.B.; Etoro-Obong, E.A.; Victor, E.N. Development and quality characteristics of cookies from sprouted Sorghum, Pigeon Pea and Orange Fleshed Sweet Potato Flour Blends. Eur. J. Nutr. Food. Safety. 2020, 12(2), 11-21.

23.     Oppong, D.; Arthur, E.; Kwadwo, S. O.; Badu, E. and Sakyi, P. Proximate composition and some functional properties of soft wheat flour. Int. J. Innov. Res. Sci. Eng. Technol. 2015, 4(2), 753-758.

24.     Olosunde, O. O.; Adedeji, T. O.; Amanyunose, A. A.; Oluoti, O. J. Development and quality evaluation of a typical flour blend from Orange–fleshed Sweet potato (Ipomea batatas) and Soy-bean (Glycine max L). J. Nutr. Health Food. Eng. 2020, 10(1), 23-29.

25.     Siddiq, M.; Ravi, R.; Harte, J.B.; Dolan, K.D. Physical and functional characteristics of selected dry bean (Phaseolus vulgaricus (L.) flours. LWT-J Food Science and Technology. 2010, 43, 232-237.

26.     Malomo, F.D.; Adebowale, Y.A.; Adeyemi, I.A. A.A. Oshodi, Functional and physicochemical properties of flour of six Mucuna sp. Afr. J. Biotechnol. 2012, 4(12), 1461-1468.

27.     Rózyło, R.; Laskowski, J. Predicting bread quality (bread loaf volume and crumb texture). Polish J. Food. Nutri. Sci. 2011, 61 (1), 61-67.

28.     Ezeocha, V.C; Onwuka, G.I. Effect of processing methods on the Physicochemical and nutritional quality of maize and soybean based complimentary blends. Nigerian. Food. J. 2010, 28 (2): 210-216.

29.     Ikpeme-Emmanuel, C.A.; Osuchukwu, N.C.;  Oshiele, L. Functional and sensory properties of wheat (Aestium triticium) and taro flour (Colocasia esculenta) composite bread. Afr. J. Food. Sci. 2010, 4, 248-253.

30.     Seena, S.; Sridhar, K.R. Physicochemical, functional and cooking properties of under explored legumes, Canavalia of the southwest coast of India. Food. Res. Int. 2015, 38, 803-814.

31.     Butt, M.S.; Batool, R. Nutritional and functional properties of some promising legumes proteins isolates. Pak. J. Nutr. 2010, 9(4), 373–379. doi: 10.3923/pjn.2010.373.379.

32.     Ominawo, T.; Egbekun, L. Nutraceutical potential and sensory acceptability of composite flour blends. Food. Sci. Quality Manag. 2018, 39, 84-97.

33.     Harahap, E.S.; Juliani, E.; Sinaja, H. Utilization of orange fleshed sweet potato flour, starch and residual flour in biscuit baking. IOP conference series; earth and environmental science: 2020, DOI: 1088/1755-1315/454/1/012120.

34.     Khuhadzo, N.; Mpho, E. Henry, S. Physiochemical and functional properties of chemically pretreated Ndou sweet potato flour. Int. J. Food. Sci. 2019, article ID 4158213. https://doi.org/10.1155/2019/4158213.

35.     Bebre, Z. F.; Pamalavir, A.C. Improving protein content and composition of cereal grain. J. Cereal Sci. 2012, 46, 239-250.

36.     Arinola, S.O.; Ogunbusola, E.M.; Adebayo, S.F. Effect of drying methods on the chemical, pasting and functional properties of unripe Plantain (Musa Paradisiaca) Flour. British J. Appl. Sci. Technol. 2016, 14 (3), 1-7.

37.     Suresh, C.;  Samsher, P. Assessment of functional properties of different flours. Afr. J. Agric. Res. 2013, 8(38), 4849-4852.

38.     EAS (Eastern African Standard). Wheat flour specification. East African Community. Second Edition. 2011, 125-129.

39.     Akintayo, H.; Osagie, A.U.  Eka, O.U. Nutritional quality of plant foods. Post-harvest research unit, University of Benin press, Benin city. 2011, pp.1-31.

40.     Joshua, O.O.; George, O.A.; Michael, W.O. Production, utilization and nutritional benefits of OFSP puree bread. ISSN 2347 – 467x. www.foodandnutritionjournal.org. online ISSN, 2018, 2322–0007.

41.     Oluwatooyin, F.O.; Kudirat, T.; Olubukola, V. Potential of African pear as an ingredient in plantain based composite cookies. Nut. Food. Sci. J. ISSN: 00346659. 2010, 40(1):39–48.

42.     Ezeocha, C.V.; Onwuneme, N.A. 2016. Evaluation of suitability of substituting wheat flour with sweet potato and tiger nut flours in bread making. Open Agric. 1, 173–178.

43.     Angela, N.S.; Samuel, A.A.; Israel, O.A. 2019. Effect of addition of Tigernut and defatted sesame flours on the nutritional composition and sensory quality of the wheat based bread. Annals Food. Sci. Technol. 20(1), 15-23.

44.     Ade-Omowaye, B.I.O.; Akinwande, B.A.; Bolarinwa, I.F.; Adebiyi, A.O. Evaluation of tigernut (Cyperus esculentus)–wheat composite flour and bread. Afr. J. Food. Sci. 2008, 2, 087-091.

45.     Adeyeye, A.O.; Bolaji, O.T.; Abegunde, T.A.; Adebayo-Oyetoro, A.O.; Tiamiyu, H.K.; Idowu-Adebayo, F. Quality characteristics and consumer acceptance of bread from wheat and rice composite flour. Curr. Res. Nutr. Food. Sci. 2019, 7(2), 488-495.

46.     Cho, I.H.; Peterson, D.G. Chemistry of bread aroma: a review. Food. Sci. Biotech. 2012, 19, 575–82.

47.     Mamiro, P.S.; Mbwaga, A.M.; Mamiro D.P.; Mwanri A.W.; Kinabo, J.L. Nutritional quality and utilization of local and improved cowpea varieties in some regions in Tanzania. Afr. J. Food. Agric. Nutr. Dev. 2011, 11(5), 4490-4506.

48.     Dabels, N.; Igbabu, B.D.; Amove, J.; Iorlam, B. Nutritional composition, physical and sensory properties of cookies from wheat, acha and mung bean composite flours. Int. J. Nutr. Food Sci. 2016, 5(6), 52-78.

49.     Onuegbu, N.C.; Nwuka, M.U.; Ojukwu, M.; Kabu, N.O. Nutritional properties of African pear seed and performance of defatted cake in poultry feed formulation. J. Anmal. Res. Nutr. 2016, 29(1), 1.

50.     FAO/WHO-UNU. Energy and Protein Requirements: Report of a Joint FAO/WHO/UNU Expert Consultation, WHO Technical Report Series no.724, Geneva: WHO. 1994.

51.     Peter, I.A.; Okafor, D.C.; Kabuo, N.O; Alagbaoso, S.O.; Njideka, N.E.; Mbah, R.N. Production and evaluation of cookies from whole wheat and date palm pulp as sugar substitute. Int. J. Adv. Eng. Technol. Mgt. 2017, 5-10.

52.     Ojo, A.; Abiodun, O. A.; Odedeji, J. O.; Akintoyese, O.A. Effects of drying methods on proximate and physico-chemical properties of fufu flour fortified with   soybean. Brit. J. Appl. Sci. Technol. 2014, 4(14), 2079-2089.

53.     Ariyo, O.; Adetutu, O.; Keshinro, O. Nutritional composition, microbial load and consumer acceptability of Tigernut (Cyperus esculentus), Date (Phoenix dactylifera L.) and Ginger (Zingber officinale Roscoe) blended beverage. Agro-Sci. 2021, 20(1), 72-99.

54.     Akubor, P.I.; Badifu, G.I.O. Chemical composition, functional properties and baking potential of African pear (Dacroydes edulis) flour. Res J. Med. Plants. 2014, 4, 30-39.

55.     Cadet, C.; Coste, P.; Kerloch, I.; Lequesne, L.; Maheu, E.; Moyse, D.; Ramdomised, controlled trial of Avocado-Soybean unsaponifiable effect on structure modification in hip osteoarthritis. Ann. Rheumatic Dis. 2014, 2(73), 376-384.

56.     Bibiana, I.; Grace, N.; Julius, A. Quality evaluation of composite bread Produced from wheat, maize and orange-fleshed sweet potato flours. Am. J. Food. Sci. Technol. 2014, 2(4), 109-115.

57.     Osundahusi, T.F.; Fagbemi, T.N.; Kesselman, E.; Shimoni, E. Comparison of physiochemical properties and pasting characteristics of flour and starch from red and white sweet potato cultivars. J. Agric. Food. Chem. 2016, 51(www.mdpi.com/journal/foods). 2018, 6(3), 33-39.

58.     FAO/WHO. Vitamin and mineral requirements in human nutrition: report of a FAO/WHO xpert consultation Bangkok, Thailand. 2^nd Edition. 1-362. ISBN 92 4154612 3. 1998

59.     Parr, R.M.; Crawley, H.; Abdulla, M.; Iyengar, G.V.; lainan, J. Human dietary intakes of trace elements. A global literature survey mainly for the period 1970-1991. Report NAHRES. Vienna. International Atomic Energy Agency. 2012, 125-143.

60.     Charles, H.D.; Eboh, L.; Nwaojigwa, S.U. Chemical composition, functional and baking properties of wheat-plantain composite flours. Afr. J. Food Agric. Nutr. Dev. 2015, 7(1), 1-22.

61.     Ayuk, E.T.; Duguma, B.;  Kengue, J.; Tiki–managa, T.; Zekkeng, P. Uses, management and economic potential of African pear (Dacroydes edulis) in human low-land Cameroon. Econ. Bot. 2019, 53 (3), 292-300.

62.     Ayo, J.A.; Ojo, M.O.; Popoola, C.A.; Ayo1, V.A.; Okpasu, A. Production and quality evaluation of acha-tigernut composite flour and biscuits. Asian Food Sci. J. 2018, 1(3), 1-12.

63.     Maitera, O.N.; Osemeahon, S.A. Barnabas, H.L. Proximate and elemental analysis of avocado fruit obtained from Taraba State, Nigeria. Ind. J. Sci. Res. Technol. 2014. 2(2), 67-73.

64.     Mohammed, K.A.; Ziani, H.; Sheikh, N. Comparison of the proximate composition, total carotenoids and total polyphenol content of nine orange fleshed sweet potato varieties grown in Bangladesh. 2016. www.mdpi.com/journal/foods.

65.     Akujobi, I.C. Nutrient composition and sensory evaluation of cookies produced from Cocoyam (Xanthosoma sagittifolium) and Tiger Nut (Cyperus esculentus) flour blends. Int. J. Innov. Food, Nutr.   Sus. Agric. 2018, 6(3), 33-39.

66.     FAO/WHO. Human Vitamin and Mineral Requirements. Report of joint FAO/WHO expert consultation: Bangkok Fd. Nutr. Division FAO, Thailand, Rome. 2002, pp.87–107.

67.     International Potato Center (2013). Potato Facts and Figures. Retrieved August, 2022.

68.     Goben, J.H.; Kristal, A.R.; Standford, J.L. Fruits and vegetables intakes and postrate cancer risk. J. Nat. Cancer Inst. 2000, 92(1); 61-68.

69.     Okaka, J.C. Foods. composition, spoilage, shelf-life extension second edition. OJC Academic Publishers, Enugu, Nigeria. 2010, Pp 201-220.

70.     Ogundele, G.F.; Ojubanire, B.A.; Bamidele, O.P.  Proximate composition and organoleptic evaluation of cowpea (Vignaugu culata) and soybean (Glycine max) blends for the production of Moi-moi and Ekuru (Steamed cowpea paste). J. Experimen. Biol. Agric. Sci. 2015, 3(2), 207.

71.     Adie, P.A.; Enenche, D.E.; Atsen, T.M.; Ikese, C.O. Physicochemical and sensory evaluation of cookies produced by partial substitution of margarine with Avocado (Persia americana) Pulp. Asian Food. Sci. J. 2020, 18(2), 41-47.