Development, Optimization and Evaluation of Enriched Custard Powder from Selected Local Food Ingredients

: Custard powder is a breakfast cereals meal, primarily, made from corn starch; processed with added flavour and fortified with vitamins and minerals. The aim of this study is to formulate, characterize, and optimize enriched custard powder from bio-fortified cassava, pearl millet, soybeans, Africa locust beans fruit pulp, ginger, egg powder, and milk powder; using a seven-component constrained, D-optimal mixture experimental design, with thirty-eight randomized experimental runs. The formulation design constraints were: bio-fortified cassava (10% - 70%), pearl millet (10% - 70%), soybeans (10% - 60%), Africa locust beans fruit pulp (5% - 30%), ginger (1% - 2%), egg powder (0.5% - 1.5%)


Introduction
Custard powder is a breakfast cereals meal, primarily, made from corn starch; processed with added flavour and fortified with vitamins and minerals.It is a good source of digestible carbohydrate for a fast energy boost and dietary fibre.However, the prolonged consumption of most traditional custard can lead to protein-energy malnutrition and chronic malnutrition, which is common in most developing countries.There is need the to develop and optimize value added custard that combines nutritional and health benefits with good sensory properties from our locally available food ingredients.Food supplementation is the process of increasing in a food the level of specific nutrients previously identified as inadequate and their intake by the use of another food rich in that specific nutrient.This is usually done to prevent malnutrition in developing countries [1].The following issues have influenced the current research: i. High competition for maize which is the major ingredient for the traditional custard.ii.Vitamin and mineral imbalances in the traditional custard powder.iii.There is no or less fibre in the present marketed custard powder which increases the development of obesity in consumers.iv.Existing traditional custard powder has relatively low carotenoid.Thus, the supplementation of corn with high-quality product such as biofortified cassava, pearl millet, soybeans, Africa locust beans fruit pulp, ginger, egg powder, and milk powder, in the production of custard powder could improve its quality and quantity.
Biofortified cassava is a high-quality yellow cassava rich in vitamin A (provitamin A carotenoids), an essential nutrient responsible for the yellow, orange, and red color in many fruits and vegetables.Since one of the most common micronutrient deficiencies worldwide are those of vitamin A, supplementation of corn with biofortified cassava could help in reducing the effect of vitamin A deficiency.Millet is rich in dietary fiber, both soluble and insoluble.The outstanding nutrients in millets include protein, ash, minerals (Ca, Fe, K, Mg and Zn) and B vitamins (B6 and folic acid).Millets are non-glutinous and non-acid forming foods.They have many nutraceuticals and health promoting properties especially the high fibre content [2][3][4].Pearl millet has high-grade macro and micronutrients, making it excellent for enriched custard powder.Soybeans is rich in quality protein and digestible energy and are a rich source of various vitamins, minerals, and beneficial plant compounds, such as isoflavones [5,6].Soybeans and soy foods may reduce the risk of a range of health problems, including cardiovascular disease, stroke, coronary heart disease (CHD) and some cancers, as well as improving bone health.In Nigeria, African locust bean fruit pulp is underutilized.Bot (2011) discovered that the macro and micronutrient content of pulp fruit was abundant, making it appropriate for custard powder production [7].The fruit pulp of the African locust bean is sweet to the taste, which indicates the presence of natural sugars and thus a potential energy source.The attractive yellow colour indicates the presence of phyto-nutrients, possibly carotenoids, which are important precursors of retinol (vitamin A).It has a sour taste which indicates the presence of ascorbic acid [8].Ginger is loaded with antioxidants, compounds that prevent stress and damage to the body's DNA.They help our body to fight off chronic diseases like high blood pressure, heart disease, diseases of the lungs, and also promote healthy aging [9].
The aim of this study was to formulate, characterize, and optimize enriched custard powder from bio-fortified cassava, pearl millet, soybeans, Africa locust beans fruit pulp, ginger, egg powder, and milk powder; using a seven-component constrained, D-optimal mixture experimental design, with thirty-eight randomized experimental runs.

Materials
Bio-fortified cassava (TMS 593), pearl millet, soybeans, Africa locust beans fruit pulp, ginger, egg powder, milk powder, sodium metabisulphite, hydrogen peroxide, and sodium bicarbonate were among the items used for the study.Bio-fortified cassava (TMS 593) was gotten from Moniya market in Ibadan, Oyo state, Nigeria.Soybean, pearl millet, fresh ginger stem, fresh poultry egg, and powder milk were purchased from Kure market, Minna, Niger State.The fresh African locust bean fruit's pulp with the pod was sourced from Zugurma, Niger State's Mashegu Local Government Area.

Equipment
Gas cookers, a weigh scale, an oven drier, an electric kettle, a plastic container with a lid, a stainless-steel knife, a stainless tray, and a spatula were all employed in the conduct of the experiments.Plastic bucket, hammer milling machine and mixing machine were also part of the items used.

Custard Powder Ingredients Processing
The fresh bio-fortified cassava (pro-vitamin A cassava) root starch was produced using the method adopted by Akinwale et al. (2017) [10], with little modifications.Millet starch was obtained using the standard wet milling and starch extraction technique reported by Ajanaku et al. (2012) [11], with minor modifications.The soybean flour was prepared as stipulated by Amankwah et al. (2009) [12], with minor modification.The method by Gernah et al. (2007) [8], was employed for locust bean fruit powder processing.The method employed by Akinwale et al. (2017) [10], was used for ginger powder processing.Preparation of whole egg powder was done using the method employed by Ndife et al. (2010) [13].

Statistical Analysis of Experimental Data
The experimental data were analyzed and appropriate Scheffe canonical models relating the quality indices with the mixture component proportions were fitted to the mean quality and sensory properties (experimental data).The statistical significance of the terms in the Scheffe canonical regression models were tested using analysis of variance (ANOVA) for each response, and the adequacy of the models were evaluated by coefficient of determination, F-value, and model p-values at the 5% level of significance.The models were also subjected to lack-of-fit and adequacy tests.The fitted models for each of the response was used to generate 3-D response surface as well as the contour plots for the proximate properties using the DESIGN EXPERT 13.0.0statistical software package.Optimal production conditions were obtained, based on set optimization goals and individual quality desirability indices; using numerical optimization, via desirability function [17][18][19][20].

Experimental Data
The results of quality analyses and sensory evaluations of the formulated custard were presented in Tables 2 -6.

Results of Statistical Analyses of Experimental Data
The summary statistics of the regression analyses (indicating only the significant terms) of the enriched custard's proximate properties, functional properties, vitamin contents, mineral contents, anti-nutritional contents, and sensory properties were presented in Table 7. P-values less than 0.05 indicate models and model terms that are significant.A negative Predicted R² implies that the overall mean may be better predictors of the response than the fitted model.Adequacy of Precision measures the signal to noise ratio.A ratio greater than 4 indicates an adequate signal.For such, the models can be used to navigate the design space and to make predictions about the responses for given levels of the factors (ingredient proportions).The models are useful for identifying the relative impact of the ingredient proportions on the quality parameters by comparing the model's regression coefficients.

Conclusion
In this study, using composite products technology, enriched custard powder was developed, characterized and optimized, via a seven-component constrained, D-optimal mixture experimental design, from blends of bio-fortified cassava, pearl millet, soybeans, Africa locust beans fruit pulp, ginger, egg powder, and milk powder.The development of enriched custard powder from indigenous local food ingredients offers end users with novel choices to the traditional custard which are produced from mono-cereals.
Composite novel food products technology has many advantages.It plays a vital role in complementing the deficiency of essential nutrients; it is suitable for enhancing and solving the problems of malnutrition, especially in the African continent, it promotes the use of locally available food ingredient.However, this study encouraged exploitation of more underutilized local food resources in the production of value-added custard powder.There is the need for research on formulating custard powder from blends of different unique local food ingredients.

Table 1 .
Design matrix for the custard formulation experiments.

Table 2 .
Proximate Properties of Custard Powder.

Table 3 .
Functional and Operational Parameter of Custard Powder.

Table 4 .
Vitamin Contents and Anti-nutritional Properties of Custard Powder.

Table 5 .
Mineral Composition of Custard Powder.

Table 6 .
Sensory Characteristics of Custard Powder.

Table 7 .
Summary Statistics of the Regression Analyses of enriched custard's proximate properties, functional properties, vitamin contents, mineral contents, anti-nutritional contents, and sensory properties. .