ABSTRACT

A morphological characteristic feature of one hundred Nigerian maize cultivars was established. This repository sought a baseline upon which Nigerian maize cultivars could be classified based on kernel morphology, germinating properties such as shoots length and percent of growth. Out of all the maize cultivars, forty eight were classified as Dent maize, five were found to be Pop maize, thirteen were Waxy maize and six were also classified as Sweet maize while fourteen were found to be Floury and Flint maize respectively. The information would serve as reference for the selection of appropriate Nigerian maize cultivars for specific use in food processing and allied industries.

Keywords:

Dent Maize; Pop Maize; Waxy maize; Floury and Flint maize

1. Introduction

Maize (Zea mays L.) belongs to the cereal family (Graminea). It originated in central and south America [1] . It is otherwise known as corn which literally means “that which sustains life” [2] . It is a versatile cereal crop growing across a range of agroecological zones. The plant is primarily a cross pollinating specie and this feature has contributed to its ability to grow well under the most varied condition unlike Barley, Wheat and Sorghum which are limited by climate [3] . It is the cereal with the highest yield potential and cheaper than other cereals hence corn ranks third following wheat and rice in the world production of cereal crop [1] . It is mostly cultivated for its edible fruit otherwise known as grains or kernels. The fruit is easy to process, readily digested and known to be the most important cereals crop in sub-Saharan Africa [4] . These grains are good source of dietary fiber, essential fatty acids, and other important nutrients [5] . The grains are known to have several major groups namely Floury corn, Popcorn, Waxy Corn, Pod Corn, Dent Maize, Flint Maize and Sweet Maize [6] [7] . In Western countries where maize for human food is industrially processed, these aforementioned features contribute to the extent of their exploitation to form different food and allied products [8] [9] . The knowledge of physical properties constitutes important data in the design of processes and potential utilization [10] [11] . The value of this basic information is important to food scientist, processors and other scientists who may want to exploit these properties and find new uses [12] . Hence there is a need for detailed information on the physical properties of these maize seeds within the kernel characteristics for processing. It is on this basis that this study was carried out so as to promote our local maize cultivar and bridge the gap of information on our locally cultivated maize as regards their exploration in the industry for the benefits of man. In course of the present study, a repository of the characteristic features of one hundred Nigerian maize cultivars after third day of germination was established. This repository established relevant germinative properties such as shoots length and percent of growth. The information would serve as reference for the selection of appropriate Nigerian maize cultivars for specific use in food and allied processing industries.

2. Material and Methods

2.1. Cultivar Collection

One hundred maize cultivars were obtained from the International Institute of Tropical Agriculture (IITA) Ibadan, Nigeria. The cultivars were handpicked to obtain uniform grains and exclude broken kernel and extraneous materials.

2.2. Physical characteristics Tests

The method of Rooney and Miller [13] was modified to carry out the physical features on the entire hundred maize cultivars. These include colour, kernel classification, number of grains per 100g dry weight of each cultivar, and endosperm-pericarp ratio. One hundred kernels were randomly selected from each of the cultivar and mass were recorded with a top loading weighing balance. The pericarp-endosperm ratio was determined after staining the longitudinal sectioned seed with iodine solution. The length of the starchy pericarp was recorded over the length of the endosperm which turns blue-black.

The modified method of Institute of Brewing [14] as reported by Awoyinka [15] was adopted to investigate the germinative properties of each of the cultivar. 250 grams of each grain was steeped to give a grain/water ratio 3:4 in a cycle comprising six hours wet and three hours dry for sixty-five hours. After the steeping regime the cereal was spread in germination boxes in the dark and made to grow for three days in an atmosphere of near water saturation at room temperature to encourage sprouting as described by Morral et al. [16] . Shoot length was taken with a graduated meter rule and manual counting of percentage growth of the respective maize cultivar.

2.3. Statistical Analysis

A total of nine readings collated from three successive replicated experiments at three separate periods but same laboratory conditions were analyzed for their means using Sigma Plot [17] .

3. Results and Discussion.

The selected physical characteristic on all the hundred maize cultivar is shown in the Table 1. Generally, the maize kernel color is in two major forms namely white and yellow. From the observations recorded a total number of fifty-nine of the cultivar were pure white while seven of the cultivar was found to have dull-white coloration. Twenty-three of all the maize cultivar obtained was of deep yellow coloration while the remaining eleven were light yellow. It is a known fact that colour of kernel may contributes significantly to the overall appearance after processing [18] . This may also be a factor by which a product made from maize could be appealing and accepted for consumption by an individual.

As shown in the Table 1 the pericarp-endosperm ratio for both Dent and Floury maize on the average ranged between 0.3/0.6 cm and 0.3/0.7 cm respectively. Except for waxy maize that has its pericarp-endosperm ratio at 0.3/0.6 cm the pericarp-endosperm ratio for both Flint and Sweet maize was found to be between 0.2/0.5 cm and 0.3/0.6 cm respectively. The pericarp-endosperm ratio is an estimation of the amount of starch present in a kernel [19] .

^*values are means of replicated experimental readings.

In this study Dent maize cultivar Ev8766sfbc₆ qpm was found to have the highest number of grains with 476 per 100 g weight closely followed was Flint Tzbreld₁c₄ with 468 per 100 g weight while Br922dmrsf₂ has the least number with 178 per 100 g of the grains. At third day germination the cultivar with highest shoot length was Tzeewsrbc₅ with the value 3.9 cm (Figure 1), while Samaru inb-y-strhave the least shoot length with the value 0.1 cm (figure 2). The determination of sprouting rates as a function of amylase content is important for an analytical prediction of diastatic power otherwise known as combined effect of α and β amylases [20] [21] . The high amylase content of barley compare to other cereal like maize confer on it high diastatic power which has made the grain the choice cereal in brewing [22] .

Observation made on the type of maize in this study in terms of the type of kernel indicates that forty-eight of the cultivar was Dent. The kernels contain a hard form of starch at the sides and a soft type in the centre. The crown of the kernel consists of soft starch hence moisture loss form this area as the kernel ripens causes a slight collapse in volume resulting in a characteristics dent and generally higher yielding than other maize types. Most of the cultivated Dent maize is either white grain which is preferred as human food or yellow grain which is largely used for animal feed [3] . Fourteen percent of the cultivar was Floury their endosperm is composed entirely of soft starch which can easily be scratched with a thumbnail. Floury maize is known to be industrially processed into starch of which a considerable proportion is used for high fructose corn syrup. However, other by-products from Floury maize, such as fodder protein and vegetable oil, also have a good market [5] [23] . A total number of fourteen of the cultivar was also found to be Flint. Characteristically the kernels are round, hard and smooth with only some starch in the very centre of the grain. It is known that Flint maize is most preferred for human fermented food [24] . Five of the entire cultivars used in this study were Pop maize. Pop Corn is an extreme form of Flint maize with a hard endosperm occupying most of the kernel and a small amount of starch in the basal part of the grain. The kernels are small with thick pericarp that varies in shape from round to oblong. The crop is grown primarily for human consumption as freshly popped corn and is the basis of popcorn confections [7] . The moisture trapped in the flour starch expands upon heating and burst through the hard kernel. The ability to pop seems to be conditioned by the unique quality of the endosperm which resists the steam pressure when heated to about 170˚C [22] .

A total number of thirteen cultivars showed a characteristic feature of waxy maize. Waxy maize otherwise known as ornamental maize is currently grown in the tropics in a small area in pockets where natives prefer it as a food crop. The endosperm has a dull wax-like appearance. The starch of these maize types differs chemically from common corn starch in that it lacks amylase and is made up of amylopectin [25] . The starch of waxy corn is used for food or for making adhesives such as the gums applied to stamps, envelopes, gummed tape, corrugated paper boxes, and plywood [5] [8] . However, six percent of the cultivars in this study possess the feature of Sweet maize. The grains are high in sugar content and Sweet in taste while fresh. It is also characterized by translucent, horny appearance when immature and a wrinkled condition when dry. This type of maize is known to have high cash value as a processed vegetable in industrial economies [26] .

4. Conclusion

The empirical data from this study have practical applications in food and allied industries in which any of the maize cultivar could be preferentially exploited to useful products for human consumptions.

Cite this paper

Awoyinka Olayinka Anthony, (2014) Physical Features of Some Selected Nigerian Maize Cultivars. American Journal of Plant Sciences,05,1352-1358. doi: 10.4236/ajps.2014.59149

References