Production, acceptability, nutritional and pasting properties of orange-flesh sweet potato, cowpea and banana flour mix

Promoting the intake of foods rich in vitamin A is key to combating the increase in vitamin A deficiency. This research focused on the utilization of orange-fleshed sweet potatoes (a tuber-based food), cowpea (a pulse), and ripe bananas (a fruit) for the production of flour mix as a means to reduce Vitamin A deficiency in children. Different ratios of sweet potato-cowpea-banana (PCB) mix, resulting in 8 different blended samples, were optimized. The flour mix was evaluated for its overall acceptability, vitamin A content, beta-carotene, and other nutritional and functional properties. The panelists rated the sweet potato-cowpea banana blends labeled PCB8 (60% OFSP, 30% cowpea, 5% ripe banana flour, and 5% sugar) as most preferred and acceptable with average scores of 8.96 points for color, 8.75 points for flavor, 8.88 points for appearance, 8.33 points for taste, 8.07 points for texture, and 8.39 points for overall acceptability on a 9-point hedonic scale. The vitamin A and beta-carotene contents ranged 7.62 to 8.35 mg/100 g and 0.15–0.17 mg/100 g for all blends. A significant difference in the functional properties of the flour mix were observed with an increase in the ratio of sweet potato flour addition. Findings from this study show that the flour mix PCB4 (65% sweet potato, 30% cowpea, and 5% ripe banana flour) was acceptable (8.15) and is recommended based on its vitamin A content (8.35 mg/100 g), nutritional properties, and functional properties. The study showed that locally available food commodities have good nutritional value that will help reduce vitamin A deficiency in children.


Color properties of the formulated sweet potato-cowpea-banana (PCB) blends
The color evaluation of the PCB blends is shown in Fig. 1.There was some significance (P < 0.05) in the color parameters for the formulated blends.The lightness value (L) ranged from 42.14 to 67. 18. PCB 4 blend showed the highest L-value, while PCB 2 presented the lowest L-value.This is due to an increase in the OFSP content of the PCB 4 blend.The red-green value (a) was highest in the PCB 4 blend and lowest in the PCB 6 blend.This is also a result of the PCB 4 blend having the highest OFSP content.The yellow-blue value (b) ranged from 19.37 to 29.44.PCB 4 showed the highest b-value.The huge angle (HA) of the blends showed a small variation (1.33 to 1.47).The maximum HA was recorded for the PCB 6 blend, while the lowest HA was shown in PCB 3 , followed Table 3. Nutrient composition of the sweet potato-cowpea-banana (PCB) blends.Codes: PCB 1 : 50% OFSP, 30% cowpea, 20% ripe banana flour and 0% sugar; PCB 2 : 55% OFSP, 30% cowpea, 15% ripe banana flour and 0% sugar; PCB 3 : 60% OFSP, 30% cowpea, 10% ripe banana flour and 0% sugar; PCB 4 : 65% OFSP, 30% cowpea, 5% ripe banana flour and 0% sugar, PCB 5 : 60% OFSP, 40% cowpea, 0% ripe banana flour and 0% sugar; PCB 6 : 50% OFSP, 30% cowpea, 15% ripe banana flour and 5% sugar; PCB 7 : 55% OFSP, 30% cowpea, 15% ripe banana flour and 5% sugar; PCB 8 : 60% OFSP, 30% cowpea, 5% ripe banana flour and 5% sugar.a-h Values with different letters along a column for a given parameter are significantly different from each other at P≤ 0.05.The color intensity (CI) varied between 36 and 53.36 PCB 4 blend presented the lowest CI, while PCB 2 had the highest CI.Generally, the objective color evaluation of the blends showed that PCB 4 presented significantly (P < 0.05) higher lightness and chroma and the lowest CI and HA.The high lightness values in the study can be attributed to the quantity of OFSP used for the formulation of the blends.OFSP flour has been reported to be high in carotenoid which is rich in β-carotene pigments 30 .

Functional and pasting properties of the formulated sweet potato-cowpea-banana (PCB) blends
The result of the functional and pasting properties of the blends is represented in Table 4 and Fig. 2.There was a significant difference (P < 0.05) in the functional and pasting properties of the blends.The water absorption capacity (WAC) of the blends ranged from 189.73% to 226.54%.PCB 4 blend showed the highest WAC, while PCB 6 had the lowest WAC.WAC of flour is usually enhanced by some major chemical composition like protein and carbohydrate.The higher WAC of the PCB 4 blend is due to its high starch composition and also depends on the availability of hydrophilic groups that hold water molecules and, on the gel, the forming ability of macromolecules 31 .Though the low water absorption capacity of the flour blend is desirable for producing a less bulky, thinner gruel with a high caloric density per unit value 31,32 .
The trough viscosity (TV) varied between 528 and 2588 cP.PCB 2 and PCB 4 had the highest TV, while PCB 6 showed the lowest TV, followed by PCB 8 .High TV shows the stability characteristics of the blend during heating and cooling.This is as a result of the increased inclusion of the OFSP (i.e., a carbohydrate source).The breakdown viscosity (BDV) of the blends ranged from 33.33 to 829.67 cP.The least BDV was for the PCB 6 blend, while the highest was for the PCB 4 blend, followed by PCB 3 (771.33cP) and PCB 2 (637.67 cP).The breakdown viscosity is the measure of the degree of paste strength or starch granule fragmentation during heating 33 .Therefore, the weaning mix with the high breakdown viscosity will have a more stable paste during heating than others with a low breakdown viscosity 34 .The final viscosity (FV) of the blends varied between 892.33 and 3621.33 cP.PCB 2 blend had the highest FV; it was closely followed by PCB 4 blend (3060 cP), while PCB 6 blend presented the lowest FV.High FV represents a higher ability of the blend to paste during heating, low viscosity connotes thinner gruel which is a desirable quality because the viscosity of weaning or complementary food plays a significant role in its acceptability as well as an infant's energy intake 34 .The final viscosity is often regarded as an indicator of the stability of the cooked paste when prepared 31 ; the setback viscosities (SBV) of the blends ranged from 136.33 to 1190 cP.PCB 4 showed the highest SBV, while PCB 1 presented the lowest SBV.A higher SBV shows the ability of the cooked blend to retrograde during cooling.PCB 6 and PCB 8 had the lowest SBV values (360.67 and 333.33), which indicate low starch retrogradation and syneresis 33 .Peak time (PT) varied between 4.67 and 7.17 min.Higher PT was shown for the PCB 6 blend, while lower PT was recorded for the PCB 8 (4.67 min), PCB 5 (4.73 min), and PCB 4 (5.6 min).The higher PT reflects that more time is required for complete gelatinization of the starchy blends.The pasting temperature (PAT) ranged from 78.21 to 92.14 °C and the variances in the pasting temperatures of the blends of weaning food show that they all have different gelatinization temperatures.It also suggests the minimum temperature required to cook a given sample, which could also have effects on energy usage 35 .PCB 4 blend showed a lower PAT, while PCB 1 blend had a higher PAT, though a lower PAT is still desirable.Generally, the functional and pasting evaluation showed that PCB 4 (65 g of OFSP, 30 g of cowpea, and 5 g of ripe banana flour) showed significantly higher water absorption capacity, peak viscosity, trough viscosity, breakdown viscosity, final viscosity, setback viscosity, and lower peak time and pasting temperature.Functional properties of the formulated blends in the study showed reduction in water absorption capacity, and pasting properties which is advantageous as this would assist in the preparation of gruels with low viscosity and high calorie density per unit volume that can be easily swallowed by babies 21 .
Vol:.( 1234567890 and CI (− 0.99**).Similar trend was noticed for a and b-value.This study's correlation between colour parameters and some nutritional components, notably lycopene, beta-carotene, and vitamin A, supported earlier researches suggesting that colour has a significant role in drawing children's attention to food while preserving the flour mix's optimal nutritional value 8,9,18,20 .

Relationship between proximate and pasting properties of the formulated sweet potato-cowpea-banana (PCB) blends
The Pearson correlation between proximate and pasting properties is shown in Table 6.The ash content of the blends significantly correlated (P < 0.05) with fiber (− 0.61**), fat (− 0.41*), carbohydrate (− 0.61**), calorific value (− 0.67**), BDV (0.52**), FV (0.45*), SBV (0.67**), and PAT (− 0.52**).This signifies that increasing the raw materials with high ash content will decrease the fiber, fat, carbohydrate, calorific value, and PAT and increase the BDV, FV, and SBV.Fiber content only correlated well with protein (0.61**).Fat content of the blends showed a positive correlation with protein (0.49*) and PT (0.47*), showing that an increase in the raw material with a high fat content will increase the time required for complete gelatinization of the blend.Protein content showed a strong and significant correlation with SBV (− 0.52**) and PAT (0.72**), showing that an increase in protein source will decrease the tendency of the cooked blend to retrograde during cooling and increase the gelatinization temperature.Carbohydrate correlated well with energy content (0.98**), WAC (− 0.44*), BDV (− 0.62**), and SBV (− 0.53**), indicating that an increase in the carbohydrate source will increase the energy content dissipated by the blend, decrease its WAC, and increase the ability of the starch to disintegrate during heating and syneresis.Amongst the pasting parameters there were significant correlation coefficients.In order to improve the health, mineral content, and nutritional values of the developed flour mix as complementary food, it is important to www.nature.com/scientificreports/consider the relationship between proximate and pasting properties.Specifically, an increase in protein source will decrease the cooked blend's tendency to retrograde this is agreement with findings of previous researches 2,4,9 .

Acceptability of the formulated sweet potato-cowpea-banana (PCB) blends
Sensory responses to the taste, smell, and texture of foods assist in determining food preferences and eating habits.Color is a strong indicator of whether the developed product will be acceptable.The color of the sweet potato-cowpea banana blends presented to panelists in porridge form ranged from 8.96 to 7.68 as assessed based on a 9-point hedonic scale (Fig. 3), and they were generally acceptable, with the highest average score of 8.96 recorded for PCB 8 blends (60:30:5:5 of OFSP, cowpea, ripe banana, and sugar, respectively) and the least (7.68) for PCB1 blends (50:30:20:0 of OFSP, cowpea, ripe banana, and sugar, respectively).Flavor is also a significant element in the acceptance of foods as it's a combination of the senses of taste, aroma, and mouth feel.There was a significant difference in the flavor of the blends, with PCB 8 (8.75) being most preferred, followed by PCB 7 (8.57),PCB 5 (7.93),PCB 3 (7.75),PCB 6 (7.71), PCB 4 (7.64),PCB 1 (7.46), and PCB 2 (6.79) in descending order.The panelists rated the appearance (8.88-7.21) in a similar order, except that PCB 6 and PCB 7 have the same score (7.89); besides that, there is no significant difference between PCB 5 (7.39),PCB 3 (7.24),and PCB 2 (7.21), respectively.There were no significant differences texture and the tastes of all the sweet potato-cowpea-banana (PCB) blends assessed as were all acceptable range with PCB 8 most preferred.Overall acceptability of the blend was highly acceptable with the lowest been 6.36 and highest been 7.95.There is no negative report with all sample.Addition of banana and cowpea to OFSP up to 40 and 20% reveal no undesirable descriptions in the developed products.The general observation that PCB8 is more preferred compared to PCB 1 agrees with Biernacka et al. 20 , who reported that overripe banana flour's natural sweetness with little sugar increases the overall acceptability of muffins.Products such as pasta, biscuits, and porridge from OFSP have been reported to be acceptable in terms of color, texture, taste, flavor, and texture 8,30 .
In conclusion, the nutritional compositions of the formulated blends show that they can be used in the management of protein-energy malnutrition.The formulated blends showed advantages over other blends recorded in the literature as they had good water absorption capacity.PCB 4 in particular was noted to be the best in terms of its vitamin A value, functional properties, and pasting properties, as it had higher WAC, PV, TV, BV, FV, and SV.This study is showcasing locally obtained food items for innovative combination of tubers-pulses and banana for production of a nutritionally enriched flour mix with potential of combating vitamin A deficiency (VAD) in the country.

Materials
Freshly harvested OFSP (Ipomoea batatas) and bunches of ripe sweet bananas (Musa acuminate) were transported to the food processing laboratory in sacks and Ife brown variety cowpea (Vigna unguiculata) were procured from a local vendor in Omu-Aran, Nigeria.Table 1 shows the proximate analysis of the raw materials used for production of sweet potato-cowpea-banana blends.

Production of sweet potato-cowpea-banana blends
Sorted cowpea seeds were weighed (5 kg) and soaked in 10 L of potable water for 6 h.The soaked seeds were drained, manually dehulled, and washed under running water.Four (4) kg of cleaned dehulled cowpea was steamed in 2 L of boiling water for 15 min, allowed to cool and dried in a hot air oven for 12 h at 60 °C, and kept for further processing.Washed and peeled OFSP tubers were diced (3 mm) and dried on stainless steel trays at 60 °C for 12 h 2 .The modified method of (36) was used for the preparation of dried banana chips.Ripe bananas were peeled, sliced into thin sheets (2 mm) using a slicer; 0.5% (v/w) of fresh lime juice were added to reduce browning of the chips during drying and dried at 60 0 C for 24 h.Eight (8) different formulations of the sweet potato-cowpea-banana (PCB) blends were carried out as shown in Table 2 and properly labeled samples were packaged and sealed in 100 g sachets in triplicates for further analysis.All methods were carried out in accordance with relevant guidelines and regulations.In addition, all experimental protocols were approved by Landmark University ethical committee (LUAC/FSN/SCI/0001).

Acceptability assessment of sweet potato-cowpea-banana blends
Eight sweet potato-cowpea-banana blends flour samples were prepared into porrigde.The porrigde samples were prepared Blended sweet potato, cowpea, and banana Reconstituted porridge was made by mixing 50 g of flour with 250 mL of portable water, then adding boiling water and stirring constantly until gelatinization took place.and 50 ml randomly served in a labelled cups to 60 members of a panel conversant (nursing mothers) with commercial complementary food in coded plates, for evaluation using a 9 point structured Hedonic scale with 9 synonymous to like extremely and 1 dislike extremely.The colour, appearance, aroma, smoothness, and overall acceptability were assessed and scored.Inclusion criteria requires the recruited panelist must be a nursing mother or mothers with toddlers within the ages 6 months to 5 year.The participation is voluntary coupled with willingness to participate, availability and freedom from food allergies.Panelist must be familiar with the raw materials used for production and the final product.Those who participated in sensory tests are willing to use product as potential consumers based on their acceptability.While those who did not meet the inclusion criteria were excluded as well as those subjects who have prior technical knowledge of products or projects were not allowed to participate in sensory testing 31 .
Differences of L*, a* and b* were used to calculate the changes in different color attributes of samples.
where L, a, b is color component values of control.The following values were used to determine if the total color difference was visually obvious 36 .∆E* < 1 = color differences are not obvious for the human eye. 1 < ∆E* < 3 = color differences are not appreciative by the human eye.

Sweet potato-cowpea-banana (PCB) blends proximate composition determination
Sweet potato-cowpea-banana (PCB) blends proximate composition was determined using the procedure of AOAC, (2019) for crude fat, protein, fiber, ash, and moisture contents.Total carbohydrate was calculated by difference and calorific value were calculated and documented in kJ/100 g.

β-Carotene and lycopene estimation in sweet potato-cowpea-banana blends
Beta-carotene and Lycopene of sweet potato-cowpea-banana (PCB) blends were determined using dried methanolic extract Olaniran et al. 37 .100 mg of extract was mixed with 10 ml of an acetone-hexane mixture (4:6) for 1 min and filtered.The absorbance was recorded at three different wavelengths 453, 505, and 663 nm respectively, and calculated using the formula: where A = absorbance.

Sweet potato-cowpea-banana (PCB) blends Vitamin A quantification
One (1) gram of sweet potato-cowpea-banana (PCB) blends samples were homogenized and saponified with 5 ml of 12% alcoholic potassium hydroxide in a water bath for 30 min at 60 °C.The saponified extract was transferred into a separating funnel and thoroughly mixed with 15 ml of petroleum ether.The lower aqueous layer was transferred to a new separating funnel followed by a collection of the upper petroleum ether layer containing the carotenoids.Extraction was repeatedly done till the aqueous layer became colorless.Anhydrous sodium sulphate was added to the petroleum ether extract to remove excess moisture.The absorbance of the yellow color was read in a spectrophotometer at 460 nm using petroleum ether as blank.The quantity of Vitamin A (betacarotene equivalent) was calculated as 1 IU Vitamin A = 0.6 μg β-carotene, 1 IU Vitamin A = 0.3 μg vitamin A 38 .

Pasting properties of sweet potato-cowpea-banana blends
Pasting properties were determined using Rapid Visco Analyzer (RVA).Three (3) grams of sweet potato-cowpeabanana (PCB) blends were weighed into a test canister and distilled water (5 ml) added.The paddle placed in the canister and the slurry was vigorously jogged using a blade as the analysis proceeds and terminated automatically.The heated slurry from 50 to 95 °C was allowed to cool to 50 °C by the thorough continuous stirring of the content using a plastic paddle within 12 min rotating the can at 160 rpm.Peak viscosity, setback viscosity, final viscosity, pasting temperature, pasting time, trough, and breakdown value were estimated 39 .

Water absorption capacity of sweet potato-cowpea-banana-blends
Water absorption capacity (WAC) of the sweet potato-cowpea-banana (PCB) blends sample was determined by weighing 0.5 g of the sample dissolved in 10 ml of distilled water in centrifuge tubes and vortexed for 30 s.The dispersions were allowed to stand at room temperature for 30 min, centrifuged at 3000 rpm for 25 min.Fitration of resultant supernatant through filter paper (Whatman No 1) was carried out and volume recovered was correctly measured.Calculation of differences between initial volumes of distilled water added to the sample and the volume obtained after filtration was recorded.The results were reported as mL of water absorbed per gram of sample (ml/g) 31 .

Statistical analysis
Analyses of the samples were conducted in triplicates.Analysis of variance (ANOVA) and Duncan's multiple range tests (P < 0.05) were conducted using IBM SPSS Statistics 22.

Informed consent
Informed consent was obtained from all participants for this study.

Table 1 .
Proximate composition of the raw materials used for production sweet potato-cowpea-banana blends.n = 3 (analysis done in triplicates).

Table 5 .
Relationship between nutritional and colour properties of the potato-cowpea-banana (PCB) blends.*moderate positive relationship, **fairly strong positive relationship, ***very strong positive relationship