Food Science and Technology Project Topics

Effect of Processing Methods on the Physicochemical, Microbiological and Sensory Properties of Enriched Maize Snacks (Ipekere Agbado)

Effect of Processing Methods on the Physicochemical, Microbiological and Sensory Properties of Enriched Maize Snacks (Ipekere Agbado)

Effect of Processing Methods on the Physicochemical, Microbiological and Sensory Properties of Enriched Maize Snacks (Ipekere Agbado)

Chapter One

Objective of the Study

            The objective of the study is to examine the effect of cowpea enrichment on the proximate, microbiological, and sensory properties of maize snacks (Ipekere-agbado).



Maize (Zea May L.)

Maize is a domesticated grass that originated approximately 7000 years ago in what is now Mexico. It is also referred to as corn, and both words are used as synonyms in this review, depending on the source of data or references consulted. Maize was spread across the world shortly after the European discovery of the Americas. Regardless of origin, corn has proven to be one of the most adaptable crops. Its evolution apparently occurred mainly under domestication and resulted in biotypes with adaptation ranging from the tropics to the north temperate zone, from sea level to 12,000 feet altitude, and growing periods (planting to maturity) extending from6weeks to13months (Brown and Darrah, 2005; Vollbrecht and Sigmon, 2005).

Currently, the United States, Brazil, Mexico, Argentina, India, France, Indonesia, South Africa, and Italy produce 79% of the world’s maize production (FAO, 2009). Between 2000 and 2011, the number of millions of maize hectares harvested ranged from 129.1 to 163.9. During the same period the production of maize in metric tons per hectare increased from 3.7 to 5.1, and total maize production increased from 482.0 to 832.11 million metric tons. Worldwide, 60–70% of maize production is used domestically as livestock feed, and the remaining 30–40% is used for production of items for human consumption (FAO, 2006).

Corn is the main cereal grain as measured by production but ranks third as a staple food, after wheat and rice. The reasons for this fact are varied, but some of them are related to cultural or social preferences and also because in some countries, corn is cultivated as live-stock feed. More recently, the use of corn as a bio-fuel has generated great concern about rises in the market price of corn for consumption, the need to increase cultivable areas, as well as water quality and other ecological damages. Some predictive models project that large-scale corn ethanol production could lead to decreases in food exports, higher prices and a greater global deforestation (Secchi et al., 2011; Wallington et al., 2012).

Maize Anatomy

The maize kernel is composed of four primary structures from a processing perspective. They are endosperm, germ, pericarp, and tip cap, making up 83%, 11%, 5%, and 1% of the maize kernel, respectively. The endosperm is primarily starch surrounded by a protein matrix. Two main types of starch include hard or vitreous, and soft or opaque. Vitreous endosperm is negatively related to starch degradability and in vivo starch digestibility in ruminants (FAO, 2002; FAO, 2006).

The germ or embryo of the maize kernel is high in fat (33.3%) in addition to enzymes and nutrients for new maize plant growth and development. The germ also contains vitamins from B complex and antioxidants such as vitamin E. Maize germ oil is particularly high in polyunsaturated fatty acids (54.7%), which are subject to oxidative and other forms of rancidity resulting in off or objectionable flavors from full-fat maize products. Pericarp is a high-fiber (8.8% crude) semi permeable barrier surrounding the endosperm and germ, covering all but the tip cap. The tip cap is the structure through which all moisture and nutrients pass through during development and kernel dry down. The black or hilar layer on the tip cap acts as a seal (Eckhoff, 2010). The term bran is also used to refer to the fiber-rich outer layer (pericarp) that contains B vitamins and minerals and the tip cap.

Corn variations may be artificially defined according to kernel type as follows: dent, flint, waxy, flour, sweet, pop, Indian, and pod corn. Except for pod corn, these divisions are based on the quality, quantity, and pattern of endosperm composition, which defines the size of the kernel, and are not indicative of natural relationships. Endosperm composition may be changed by a single gene difference, as in the case of floury (fl) versus flint (FI), sugary (su) versus starchy (Su), waxy (wx) versus on-waxy (Wx), and other single recessive gene modifiers that have been used in breeding special-purpose types of corn (Brown and Darrah, 2005; Doebley, 2004).

Cultivation of Maize

Maize improvement work started in the forest zones but yield trials were soon conducted in both forest and savanna locations (Van Eijnatten, 2005). The evaluation zones were:

  1. Wet rainforest, covering most of Eastern States of Nigeria and the South-Western part.
  2. Derived Savanna, fringing the forests and forming the transition to the southern Guinea Savanna.
  3. Southern Guinea Savanna.

Because of the differences in yield potential of the ecological zones, testing of new maize varieties across the country became an established practice in maize breeding. These trials were called cooperative maize yield trials (Chinwuba, 2002). With time, the name has gone through several changes, including zonal Trials, Uniform maize, variety trials and now, Nationally Coordinated Maize Variety Trials (NCMVT).





Dried yellow maize (Zea mays), cowpea (Vigna unguiculata) and other ingredients (onion, fresh pepper, palm oil) used for this research were sourced from Obada market in Emure-ile, Owo Local Government Area of Ondo State, Nigeria. The equipment used for this research were from the Food Chemistry Laboratory of the Department of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo State. All chemicals used for the analyses were of analytical grade.


Production of Maize Flour

Maize flour was produced following the procedure adopted by Barber et al. (2010) with slight modification. The maize grains were sorted to remove extraneous matter, then washed with potable water and boiled for 1 h in a pressure pot. The drying was achieved with the aid of hot air oven (Memmert 854, Gallenkamp, UK) at 65oC for 8 h. The dried maize was milled into flour using attrition mill and was stored in air tight container until needed for further analysis as shown in figure 1 below.




Table 4.1: Proximate composition of Ipekere samples produced from maize and cowpea flour





Variety and nutrient adequacy are factors of importance in the formulation of food for the benefit of people. Ipekere is an indigenous snacks consumed by adverse and immense number of people. The nutritional content and acceptability of the snacks can be improved if cowpea is incorporated with maize in the ratio 50:50. Ipekere produced from cowpea and maize is highly nutritious, it has a better protein and crude fibre content. The addition of cowpea to maize in the production of Ipekere proved to be more nutritious although MP (control sample) was accepted in terms of consumer acceptability. It should therefore be incorporated into complementing mixes up to 70:30 (MP5Y).


The following points can be recommended based on this research

  • The local producers of Ipekere should fortify the maize with cowpea to yield high percentage of good nutrient.
  • Enlightenment programme (food fortification programme) should be made to the general public to mesmerize the populace on the nutritional benefits of cowpea. This will also enable the developing countries that suffer from food and nutrient inadequacies to fortify cowpea with maize to improve their nutrient status.


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