GATE (TF) Textile 2012 Question Paper Solution | GATE/2012/TF/08

The seed coat in cotton refers to the outer layer of the cottonseed, which is the small, brownish seed that is left after the cotton fibers are removed from the cotton boll during ginning. The seed coat, also known as the testa, is a thin, protective layer that covers the seed and helps to regulate moisture and gas exchange.
The cottonseed itself is composed of three main parts: the seed coat, the embryo, and the cotyledon. The embryo is the small, white part of the seed that will eventually grow into a new cotton plant, while the cotyledon is the larger, fleshy part of the seed that provides nutrients to the developing embryo.
The seed coat in cotton has several important uses beyond its role in protecting the seed. It is high in oil content, and the oil can be extracted and used for a variety of purposes, such as cooking and soap making. Additionally, the seed coat can be ground up and used as animal feed, or as a source of fiber for paper production. The seed coat also contains various compounds that have potential medical applications, such as antioxidants and anti-inflammatory agents.

The process of removing seeds from cotton is called ginning. There are two main methods of ginning: mechanical ginning and hand ginning.
Mechanical ginning involves the use of machines called cotton gins, which use a combination of mechanical and pneumatic actions to separate the cotton fibers from the seeds. In a modern cotton gin, the cotton is first fed into a series of saws or rotary knives, which cut the cotton fibers away from the seeds. The cotton fibers are then passed through a series of cleaning machines that remove any remaining debris or impurities. The seeds, which are too large to pass through the cleaning machines, are separated from the cotton fibers by a series of air blasts and screens. The cleaned cotton fibers are then compressed into bales for transport and processing.
Hand ginning, on the other hand, involves the use of hand-held tools such as handheld rollers or combs. The cotton fibers are manually pulled away from the seeds using the rollers or combs. While this method is still used in some parts of the world, it is much less efficient than mechanical ginning and is typically only used for small-scale operations.
Overall, mechanical ginning is the most common method of removing seeds from cotton due to its efficiency and speed.