APPLICATION OF CHEMOMETRICS TECHNIQUE TO NUTRITIONAL QUALITY EVALUATION OF SELECTED UNPROCESSEDAND PROCESSED WHEAT PRODUCTS IN MINNA, NIGER STATE

ABSTRACT

The  study focused  on  the  application  of  chemometric  technique  to  nutritional  quality evaluation of selected processed and unprocessed wheat products in Minna, Niger state. Fourteen wheat samples were collected from three markets in Minna. Proximate compositions of the samples were determined using standard methods. The samples were first wet ashed using H2SO4, H2O2 and deionized water before instrumental analysis using FES for (Na, K, Mg and Ca), colorimetry (P) and AAS for (Fe and Zn). The proximate compositions indicated moisture contents range between 8.83-13.74% and 7.7-11.00% for the processed and unprocessed samples respectively. The unprocessed samples had more ash, carbohydrate, fat, fibre and energy values of 1.44-1.89, 66.39-70.84, 5.59-6.92, 1.16-1.01% and 369.71-383.95 kCal/100 g respectively. The protein contents ranged from 12.25-16.61% for all the samples. The mineral contents (mg/100g) were: Na (5.91-6.82 and 3.20-4.61), K (506.33-558.35 and 161.57-482.50), Ca (50.24-56.20 and 27.43-54.40), Mg (68.64-92.23 and 46.17-66.30), P (156.12-278.32 and 128.23-268.30), Fe (4.22-5.18 and 2.87-6.58) and Zn (5.19-6.43 and 2.57-5.24) for the unprocessed and processed samples respectively. The unprocessed samples had more amounts of K, Zn, Na, Ca and Mg while the processed samples had more Fe and P contents. Physical tests (farinography and sedimentation analysis) suggested that the processed samples had better physical properties such as rheological and baking properties and better gluten contents. PCA and HCA revealed that substitutability is peculiar to either the processed or unprocessed samples. Correlation matrix further revealed that there was loss of identity due to processing as the correlation observed in the unprocessed samples could not correlate with the processed samples. This study shows that the unprocessed samples are richer in both micro and macro nutrients and therefore, could be suggested for more consumption than the processed.

CHAPTER ONE

1.0      INTRODUCTION

1.1       Background to the Study

Food is the most essential of all the basic needs of every living thing. It provides nutritional support when consumed (through eating or drinking) and thus, help to maintain life and growth. It is commonly obtained from plant (crops, and herbs) and animals (meat, fish, milk) (Ward et al., 2008). Usually, food is known to constitute important nutrients such as fats and oils, proteins, carbohydrates, minerals and vitamins which when consumed, is absorbed by the body cells to give energy and maintain or promote growth (Gupta et al., 2010).

Food rich in protein such as meat, egg and milk help to build, repair and maintain muscles, blood, skin, bones and other tissues in the body. Fats serve as body’s secondary source of energy than other nutrients, though they are difficult to burn. Carbohydrates can be subdivided into starch and sugar thus, serves as the body’s main source of energy. Starch-rich foods are wheat, maize, potatoes while sugar-rich foods are fruits, honey, and other sweetened foods (Brody, 2014).

Vitamins and minerals are required in minute quantities and hence are referred to as micro nutrients. They are essential for good health as they regulate or control many metabolic processes (vitamins). Minerals are essential chemical elements present in food. They are required to aid proper functioning of the body metabolic activities and also build or repair body tissues such as bones. The major mineral elements are sodium, potassium, calcium, phosphorus and magnesium (Vasfiye et al., 2015).

Wheat (Triticum) which are cereal-based foods like rice, millet and guinea corn are cultivated because of the edible component of their grains. Wheat is made up of germ, bran and endosperm. Wheat is highly nutritious and it is a rich source of carbohydrates, minerals, fats, vitamins and proteins (macronutrients). Wheat is also known to be rich in mineral elements such as potassium, phosphorus and zinc (Ward et al., 2008).

Wheat is one of the major cereal crops grown in Nigeria, about 60,000 tonnes is harvested annually (Oladumoye et al., 2010). All over the country, natural wheat (whole-wheat meal) and commercial products are being consumed unavoidably on daily basis in the form if bread, cake, biscuit, wheat-meal and so on. This conferred on it an important position in the nutritional ranking as it is known to contain high starch, rich dietary fibre, nutritious protein and lipids and also rich in important fatty acids (Saka and Lawal, 2009).

It is also a good source of micro nutrients such as vitamins. It has high yield of gluten fraction (a polymer which improves the rheological properties of wheat flours), thereby enhancing its visco-elastic properties (the viscous and elastic property of a material when undergoing deformation) and thus, allows it`s dough to be processed into bread, pasta, noodles and other food products for both human and livestock feeds (Shewry, 2009).

Nutritional parameters on wheat include farinography, sedimentation, proximate composition as well as parameters such as vitamin A, maltose, minerals and protein. Thus, its nutritional compositions are evaluated and ascertained to be in conformity with the required standard. Having known the nutritional quality of product(s), quality control and assurance practice help consumers of such product(s) to make knowledgeable choices as manufacturers are required to adhere to the specified standards established by standard organizations (Udeme et al., 2014).

Also, nutritional information about these products enhances fair competition between manufacturers and help in ensuring that manufacturers keep to the standard specified by the government and other relevant authorities thereby minimizing economic fraud (Asamudo et al., 2017).

Quality can be defined as fitness for purpose, it determines the ability of a product to possess properties that can make it suitable to meet the expressed or potential needs of its users. Authenticity deals with moves made at ascertaining the quality of nutrients or compositions said to make up a food substance according to its nutritional label. Thus, enabling quality assurance of such food product and discouraging economic fraud (Lia et al., 2010). Chemometrics is a statistical analytical technique used to derive information from results obtained or measurement(s) made on chemical systems. It is a scientific approach which enables the analysis of multidimensional data using mathematical statistics, probability theory and information technology (Yu, 1992; Mike, 2016).

Unlike traditional statistical methods which are often inadequate for a more accurate and deeper interpretation of results as it allows valuable information to be obtained from a wide range of complex data sets and facilitates the detection of hidden relationships between variables. (Kamal and Karoui, 2015). Examples of these techniques are; principal component analysis (PCA), hierarchical cluster analysis (HCA), cluster analysis (CA), linear discriminant analysis (LDA) and Fischer-Routy discriminant analysis (FDA). The principal component analysis (PCA) is commonly employed in exploratory data analysis as it shows the original measurement by discovering the dominant factors and keeping the interference factors at minimum significance (Liang et al., 2020). Hierarchical cluster analysis (HCA), this is most advantageous in its flexibility to alter the similarity measurement criteria and the applied linkage method to suit different uses. Cluster Analysis (CA), this is employed for easy classification of objects based on their quantitative characteristics (Huang et al., 2014). Linear Discriminant Analysis (LDA) and Fisher-Routy discriminant analysis (FDA) are both discriminant analytical technique that assign samples to specific classes. It shows linear classification or aids dimensionality reduction and are used to set up a discriminate function (Chen et al., 2012).

Balanced diet is vital in maintaining good health. Thus, the nutritional quality of foods is an important aspect that should be vigorously considered especially with respect to metal intake such as iron, calcium, magnesium, potassium, sodium, selenium, manganese, copper, chromium and zinc (Ward et al., 2008). Minerals are inorganic elements, usually required in trace amounts from less than 1 to 2500 mg per day, depending on the mineral. They are present in body tissues and fluids for the maintenance, repair and proper functioning of certain physicochemical processes which are important to life. Minerals are classified into two groups Essential and Trace minerals, depending on the quantity required and found in the body, essential minerals are present in the largest amounts, they are the macro elements which include calcium, magnesium, potassium and sodium (Udeme, 2014).

Wheat is generally not classified by variety. Instead, it is classified based on the time of year the wheat is grown and the milling and baking quality of the flour produced. Within each class there is a group of different varieties of wheat with similar characteristics. Most of the wheat produced is used for human consumption and a large range of ingredients and foods are produced from it because of its unique properties (Ward et al., 2008).

Atomic absorption spectrometry (AAS) is an analytical technique that measures the concentrations of elements. Atomic absorption spectrophotometer is so sensitive that it can measure down to parts per million of a gram in a sample. The technique makes use of the wavelengths of light specifically absorbed by an element. They correspond to the energies needed to promote electrons from one energy level to another (higher energy level). Atomic absorption spectrometry has many uses in different areas of chemistry such as clinical analysis,  environmental  analysis, pharmaceuticals, industries and mining (Wiley et al., 2015).

The technique makes use of absorption spectroscopy to assess the concentration of an analyte in a sample. It requires standards with known analyte content to establish the relation between the measured absorbance and the analyte concentration (Adebiyi et al., 2017).

1.2       Statement of the Research Problem

Lack of detailed nutritional information on wheat products had made some consumers victims of economic and food fraud as some wheat flour and product may fall below the standard quality composition contrary to their nutritional labeling. Thus, hindering the consumers from making informed choices. Several conventional statistical analytical techniques, have proven inefficient in the proper interpretation of analytical data as they are unable to give detailed information on principal components, clustering, similarities and hidden relationships existing amidst the chemical data set.

1.3 Justification of the Study

Quality evaluation of nutritional parameters of selected unprocessed and processed wheat products will give better information of the nutritional composition of the wheat products. The application of chemometric technique on the data obtained from proximate composition, mineral content and physical tests (farinography and sedimentation analysis) will reveal more information about the wheat products.

1.4 Aim and Objectives of the Study

The aim of this research was to apply chemometric technique to interpret the nutritional parameters of selected unprocessed and processed wheat products in Minna, Niger State. The above aim shall be achieved by the following specific objectives;

i. Determination of the proximate composition of unprocessed and processed wheat products using standard methods.

ii. Quantification of the mineral content (Na, K, P, Ca, Fe, Mg and Zn) of the unprocessed and processed wheat products using atomic absorption spectrophotometry, flame photometry and colorimetry.

iii. Evaluation of the physical properties through farinography and sedimentation analysis. iv. Performance of  principal component, correlation and hierarchical cluster analysis on the chemical data for pattern recognition and characterization.

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