Effects of Chemicals Used in Storing Maize on its Zein Content over a Duration of Time.
Abstract
Maize is the largest and most important agricultural commodity in the world. Zein is the storage protein in maize known as prolamine.
It is water insoluble and forms odorless, tasteless, clear edible films. The zein content of maize is 25% of the dry weight of maize seeds, it is resistant to hydrolysis by very dilute acids and contains the following amino acids:
glutamic acid and glutamine, leucine, proline, alanine, phenylanlanine, isoleucine, serine, tyrosine and asparagine but lacks lysine and trytophan. Stored maize is attacked by three major groups of pests namely fungi, insects and rodents.
Methods such as the use of natural materials like plants, minerals and oil are still in effective use, chemicals such as dichlorovous and calcium hydroxide are used for storage over a long period.
This study was aimed at investigating the effects of these chemicals used on zein content. Maize was stored for ninety days with dichlorovos and calcium hydroxide.
After 2 weeks interval, zein was extracted and tested for malondialdhyde level, total protein content and composition of amino acids present. MDA levels increased over the storage period from 2.629mg/100g+ 0.186 to 4.685mg/100g + 0.003.
The mean protein content of crude zein extract showed a significant decrease from 31.215% + 0.002 to 26.264%+ 0.004, the mean moisture content showed a decrease from 7.160% + 0.003 to 2.645% + 0.003, mean ash content Increased from 3.343% + 0.004 to 6.655% + 0.003.
Introduction
1.1 Background of Study
Maize is known in many English speaking countries as Corn. It is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times (Green,1999).
The leafy stalk produces ears which contain seeds called kernels, though technically a grain. The Olmee and Mayons cultivated it in numerous varieties throughout central southern Mexico between 1700 and 1750, the crop spread through America (Boyd et al.,2006).
The region developed a trade network based on surplus and varieties of maize crops. After the European contact with the America in the late 15th and early 16th centuries, explorers and traders carried maize back to Europe and introduced it to other countries.
Maize spread to the rest of the world due to its ability to grow in diverse climates (Piperno et al., 2009).The term “Maize” was derived from the Spanish form of the indigenous Taino word for the plant, Maiz.
It is known by other names around the world. The term “Maize” was used in the United Kingdom and Ireland, where it is now usually called “sweetcorn”, a common crop known to people there (Cudderford,1995).
Corn was originally the English term for any cereal crop. In North America, its meaning has been restricted since the 19th century to maize as it was shortened from “Indian corn”.
The term Indian corn now refers specifically to multi-coloured “field corn” (flint corn) cultivars (Herman and Larkins,1999).
In scientific and formal usage, “maize” is normally used in a global content. In English speaking countries, the word corn is often used in culinary contexts, particularly in naming products such as popcorn, cornflakes and baby corn.
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