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Questions and Answers
How is the starch milk dewatered in the starch dewatering and drying stage?
What is the purpose of the primary separator in the protein separation and starch washing stage?
What is the desired moisture level in the final dry starch product?
What is the purpose of the bundle dryer in the germ washing, dewatering, drying, extraction oil, and oil refinery stage?
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What is the final product of the gluten concentration, dewatering, and drying stage?
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What is the purpose of the evaporator in the processing water recovery and steeping liquid evaporation stage?
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What is done to the process water from the concentrator and dewater machine?
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What is the purpose of the air flow dryer in the starch dewatering and drying stage?
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What is done to the corn steeping liquid in the processing water recovery and steeping liquid evaporation stage?
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What is the purpose of the gravity arc screen in the germ washing, dewatering, drying, extraction oil, and oil refinery stage?
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Study Notes
Corn Structure and Types
- Corn kernels are the fruit of maize (Zea mays L.) and contain approximately 800 kernels in 16 rows.
- Each kernel is called a caryopsis.
- Maize is deficient in two essential amino acids: lysine and tryptophan, making it a poor protein food.
Types of Corn
- Sweet corn: contains a sugary gene that retards conversion of sugar into starch, used as a vegetable when young.
- Dent corn: usually has yellow endosperm, contains phenolic compounds with antioxidant properties, and is used to make most products.
- Waxy corn: contains 100% amylopectin, used as a stabilizer in paper or as an adhesive.
- Popcorn: has a hard endosperm that surrounds a small amount of starch, which expands 30-40 times its volume when heated.
- Flour corn: has an endosperm made up of soft starch with a thin pericarp.
Corn Composition
- High starch content (around 65%).
- 4% oil content.
- Protein in maize consists of zein and glutelin, present in the endosperm and germ, respectively.
- Zein is the major seed storage protein, constituting approximately 50-70% of kernel endosperm.
Corn Products
- Corn starch
- Dextrose
- Corn oil
- Corn syrup
- Sorbitol
- Ethanol
- Corn flakes
Nutritional Value of Corn
- 1 ear of fresh corn (90g) contains:
- 80 calories
- 3g of sugar
- 17g of carbohydrate
- 1g of fat
- 2g of dietary fiber
- 3g of protein
Corn Starch Processing
- Purifying: removes foreign substances and separates germ cake.
- Steeping: makes corn soft using acid and counter current steeping principle.
- Sulfurous acid making: burns sulfur to create SO2 gas, which is mixed with water to create sulfurous acid.
- Corn crushing and germ separation: separates germ and crushes corn into smaller pieces.
- Fine milling and fiber wash, dewatering, drying: removes fiber and washes starch.
- Protein separation and starch washing: separates gluten and washes starch.
- Starch dewatering and drying: dewatered starch is dried to a moisture level below 14%.
- Germ washing, dewatering, drying, extraction oil and oil refinery: processes germ to extract oil.
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Description
Explore the world of corn kernels in Cereal Science, from the anatomy of corn ears to the significance of maize in American Indian culture. Learn about the characteristics of sweet corn, its sugary gene, and the conversion of sugar into starch after harvest.
