Formulation, Optimization and Characterization of Dietary Cookies from Blends of Corn, Peanut, Sweet Potato and Soybean

: Traditionally wheat is used for cookies production but the harsh climatic conditions in the tropical regions is not conducive for the growth of wheat. There are locally grown crops that can be used to produce high quality cookies that meet consumer’s dietary requirements. The aim of this study was to develop, characterize


Introduction
Cookies are widely consumed all over the world by adults and children alike and they represent the largest, most popular category of snack foods in most parts of the world.They are convenient, easy and light to carry around, ready-to-eat and tasty, easy to be consumed, have long shelf life, wide acceptance by consumers of all ages, and their costs is reasonable) [1][2][3][4], Traditionally, the key ingredients generally used in the manufacture of cookies are flour, sugar and fat.However, wheat does not grow well in the tropics and has to be imported by countries in these regions.Incessant increases in the cost of wheat have in turn led to constant increases in the price of these products.This had led to the need to develop alternatives to the use of wheat flour in the production of baked goods [5][6][7][8][9][10][11][12][13][14][15].Beside these, traditional biscuits and cookies are deficient in nutrients, phytonutrients and fiber; they are high in carbohydrates, fat, and calorie, but low in fiber, vitamin, and mineral which made their consumption unhealthy.Generally, biscuits are characterized not only by low content of protein, vitamins, dietary fiber and minerals but also contain high amount of sugar and fat; making them not so healthy option for consumers.The association of wheat consumption with such health problems as celiac disease makes it pertinent to utilize composite flour in cookies manufacture [14,16]..This situation has created the need for the development of gluten free baked food products.This has led to the composite flour concept in which flours with high nutritional and sensory properties are derived from cereals, roots and tubers, legumes etc. with or without the addition of wheat flour [5,8,17,18,19,20].
A current trend in nutrition is the consumption of foods that not only supply basic nutrients but also help to prevent disease, advocated by world nutrition bodies due to different health problem related with wheat consumption such as celiac disease, diabetes and coronary heat diseases (WHO/ FAO, 2003).This situation has created the need for the development of gluten free baked food products.Composite flour formulation can enhance the nutritional, functional as well as sensory quality of cookies.Composite flour formulation/bakery products have many functional forms, (providing protein and energy), enriched with minerals and vitamins, nutritious (providing protein and energy), gluten-free, and can serve as good vehicle for carrying the added proteins to target populations for use in combating the protein malnutrition prevalent in many parts of the world.Composite flour cookies can be formulated to meet the dietary needs of different categories of consumers.They are considered as an essential source of energy by the majority of the population.[22,[24][25][26]).There are many flours which can be used as base materials for the formulation of composite flours.Products made from non-wheat flour or from composite flour are latest trend in producing baked goods.Currently, composite flour formulation or additive food manufacturing has evolved to enhancing nutritional quality of cookies [9, 13, 14, 27 -30].The increasing consumer demand for foods that combine additional benefits in addition to common nutrients imposes on the food industry a need for advances in ingredients and formulations [11,25].
Today foods are not intended to only satisfy hunger and to provide necessary nutrients for humans but also to prevent nutrition-related diseases and improve physical and mental well-being.Now a day's cookies are being considered to be most efficacious means of delivering supplementary nutritional on to weaker and vulnerable sections suffering from calories malnutrition.Development of diabetic friendly cookies and biscuits (especially designed for diabetes patients) prepared by incorporation of multigrain is becoming popular in the developed countries.Efforts have been made to promote the use of composite flour in in cookie productions, thereby decreasing the demand for imported wheat, improving the nutritional content of cookies, and also enhancing indigenous crop utilization.Protein-rich cookies are gaining popularity in countries where protein energy malnutrition is prevalent.Cookies are looked upon as carriers of nutrition and provide a good source of energy [1,3,4,11,20,[31][32][33][34][35][36].The aim of this study was to develop, characterize, and optimize the formulation and some production processes of dietary cookies from blends of corn, peanut, sweet potato and soybean.

Materials
The materials used in this study were roasted corn flour, defatted peanut meal, blanched soybean and sweet potato extract/gel.These were obtained locally from Kure market, Minna Nigeria.

Statistical Analysis of Experimental Data
The experimental data were analyzed and appropriate Scheffe canonical models, relating the quality indices with the mixture component proportions and process parameters, were fitted to the quality and sensory properties.The statistical significance of the terms in the Scheffe canonical 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 contour, mix-process, as well as the 3-D response surface for the quality properties using the DESIGN EXPERT 13.0.0statistical software package.A Numerical optimization approach, exploiting the desirability function technique, was utilized to generate the optimal formulation with the anticipated responses.Numerical optimization maximizes, minimizes, or targets desired response based on set criteria for all variables, including components proportions.Optimization goals are assigned to parameters and these goals were used to construct desirability indices (di).A goal may be to maximize, minimize, or target specific quality parameter to satisfy the dietary needs of the consumers of the formulated food product.Components can be allowed to range within their pre-established constraints in the design or they can be set to desired goals.Also, components can be set equal to specified levels.Desirabilities range from zero to one for any given response and individual desirability for all the responses, in the case of multi-response optimization, are combined into a single number known as overall desirability index.A value of one represents the case where all goals are met perfectly.A zero indicates that one or more responses fall outside desirable limits.
Numerical optimization solutions are given as a list in their order of desirability, detailing the components proportions and process variables values that satisfies the set criteria and the overall desirability.The numerical solution can also be presented in the form of bar graph, desirability contour and desirability mix-process graphs.Furthermore, optimization can also be achieved through graphical method.Graphical optimization yields the overlay contour and the overlay mix-process plots (Wendell, 2005;ReliaSoft, 2015;Raymond et al., 2016;Dharmaraja et al., 2018).A contour graph of overall desirability indicates the desirable formulation.Overlay plots of the responses indicates regions that meet specifications.The formulated dietary cookies were analyzed and evaluated for the proximate properties, minerals, some physical properties, physicochemical properties, and sensory characteristics (Tables 2 -4); using standard procedures.

Results of Statistical Analyses of Experimental Data
The summary statistics of the regression analyses (indicating only the significant terms) of the formulated cookies quality and sensory properties were presented in Table 5. 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.
The fitted models in terms of L-pseudo components for the quality parameters of the formulated dietary cookies are presented as equations 1 -16.The equation in terms of coded factors can be used to make predictions about the quality parameters for given levels of each ingredient proportion and process factor.The coded equations are useful for identifying the relative impact of the factors by comparing the factor coefficients.
The quality parameters contour plots, mix-process plots, 3-D surface plots, and 3-D surface mix-process plots; for the formulated dietary cookies are presented in Figures 1 -4, respectively.

Optimization Constraints/Settings
The summary of the optimization constraints employed for the formulated dietary cookies are presented in Table 6.

Results of Numerical Optimization of the Formulated Cookies
Optimal production conditions were obtained, based on set optimization goals and individual quality desirability indices; using numerical optimization, via desirability function technique [17][18][19][20].Thirty-seven desirability optimal formulation conditions (component proportions) were found and summarized in Table 7, with the quality properties of the optimal formulation for the formulated cookies presented in Tables 8-10.The numerical solution desirability bar graph and desirability contour plot for the optimal formulated dietary cookies are presented in Figure 5.The numerical solution desirability mix-process and 3-D surface plots are presented in Figure 6.The graphical optimization contour and mix-process overlay plots are presented in Figure 7.

Conclusion
In this study, using composite products technology, dietary cookies were developed, characterized and optimized, via a four-components, constrained, randomized, combined, D-optimal mixture-process experimental design; from blends of roasted corn, defatted peanut, blanched soybean, sweet potato extract/gel.The development of dietary cookies from indigenous local food ingredients aimed at meeting the dietary needs of different consumers.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 dietary-based cookies.There is the need for research on formulating dietary-based snacks from blends of different unique local food ingredients.

Recommendations
Most of the developing countries are seasonally blessed with varieties of agricultural resources (tubers, roots, grains, legumes, cereals, pulses, fruits, vegetable, nuts, herbs, and other rich sources of protein, micronutrients, essential amino and fatty acids, minerals, vitamins, and lots more); but a high percentage of these are lost while malnutrition/nutrition insecurity, micronutrient deficiencies dietary deficit, and concurrent diseases are a persistent problem, particularly in rural areas.
This research has shown that locally available food resources can be blended to produce high quality cookies that meets the populace's nutrition needs and of acceptable sensory properties.The research has shown that additive food manufacturing and/or composite food formulation is an excellent way to achieve nutrition revolution; the road to healthier diets and optimal nutrition in the developing nations.Therefore, this study recommends exploitation of more local food resources in the production of high-quality cookies to improve the nutritional status and tackle the lingering problems of malnutrition/nutrition insecurity, micronutrient deficiencies dietary deficit, and concurrent diseases that are ravaging our developing countries.There is the need for concerted researches on formulating cookies from blends of different local food ingredients.

Figure 1 .
Figure 1.The Quality Parameters Contour Plots for the Formulated Dietary Cookies.

Figure 2 .
Figure 2. The Quality Parameters Mix-Process Plots for the Formulated Dietary Cookies.

Figure 3 .
Figure 3.The Quality Parameters 3-D Surface Plots for the Formulated Dietary Cookies.

Figure 4 .
Figure 4.The Quality Parameters 3-D Surface Mix-Process Plots for the Formulated Dietary Cookies.

Figures 6 .
Figures 6.The numerical solution desirability mix-process and 3-D surface plots for the optimal formulated dietary cookies.

Figure 7 .
Figure 7.The graphical optimization contour and mix-process overlay plots for the optimal formulated dietary cookies.

Table 1 .
Design matrix for the cookies formulation experiments.

Table 2 .
Proximate Properties and energy values of the formulated cookies.

Table 4 .
Sensory Characteristics of the formulated cookies.

Table 5 .
The summary statistics of the regression analyses of the formulated cookies quality and sensory properties.

Table 6 .
Optimization constraints for the formulated dietary cookies".

Table 7 .
Optimal formulation conditions for the formulated dietary cookies.

Table 10 .
The quality properties of the optimal formulated dietary cookies continue.