Effects of chemicals used in storing maize on it s zein content over a duration of time

Thesis 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, mean fat content increased from 3.373% + 0.003 to 3.385% + 0.003, mean fiber content increased from 1.3097% + 0.002 to 1.432% + 0.003, mean carbohydrate content increased from 53.605% + 0.011 to 59.41% + 0.005. Amino acid content of the zein samples decreased over the duration of storage. The chemicals used in storage increased the MDA levels, reduced the amino acid content and had no negative impact on the moisture, ash, fiber, fat and carbohydrate contents of the zein samples.