Corn, Supply, And Protein

1301 WordsApr 9, 20176 Pages
Introduction Corn is one of the most dominate crops in the US and a major cereal grain though out the world. It can be processed to yield fiber, oil and protein. Corn is primarily processed in four main ways: dry milling, alkaline processing, wet milling and dry grinding. Wet milling is the most efficient commercial way to extract zein. Corn’s main storage protein is zein, which accounts for 40-50% of the total protein found in corn. Zein is primarily found in the endosperm where 75% of the total protein is found (Figure 1). It is part of the prolamines family, which consist of many cereal endosperm storage proteins. The cost of zein ranges from $10-40 per kg, depending on the purity. This limits the widespread utilization of zein…show more content…
These helixes are stabilized by intramolecular hydrogen bonding. The polar residues on the helixes are also able to form intermolecular hydrogen bonding with other zein molecules in the same plane. α-zein is similar to the commercially available zein. β-zein is only able to be extracted under reducing conditions and is soluble in 60% ethanol. The primary sequence of β-zein has no sequence similarity to α-zein and no repeated blocks of amino acids. β-zein consists of 160 residues, rich in methionine and cysteine. The secondary structure of β-zein primarily consists of β-sheets with minimal α-helixes. γ-zein is also extracted under reducing conditions and unlike the others type of zein, is water soluble. The primary sequence consists of 11 residues at the N-terminus and 156 residues at the C-terminus with a domain of 8 hexapepties with the sequence Pro-Pro-Pro-Val-His-Leu. In addition to γ-zein being rich in proline, it is also rich in cysteine. Depending of the procedure used, the secondary structure consists of 19-32% α-helixes and 11-34% β-sheets. Like β-zein and γ-zein, δ-zein is extracted under reducing conditions. δ-zein consists of 129 residues, rich in methionine. It has no repeat sequences or a clear domain structure. Applications Zein is very useful in the industrial world due to its tough, glossy, hydrophobic, greaseproof and antimicrobial properties. However, the high cost of zein
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