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Single Cell Protein - SCP |
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Single
Cell
Protein
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SCP - SCP is the name given to a variety of microbial products, that are produced by fermentation. When properly produced, this materials make satisfactory proteinaceous ingredients for animal feed or human food. The production of protein from hydrocarbon wastes of the petroleum industry is the most recent microbiological industry.
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Yeast, fungi, bacteria, and algae are grown on hydrocarbon wastes, and cells are harvested as sources of protein. It has been calculated that 100 lbs of yeast will produce 250 tons of proteins in 24 hours, whereas a 1000 lbs steer will synthesize only 1 lb of protein 24 hours and this after consuming 12 to 20 lbs of plant proteins. Similar, algae grown in ponds can produce 20 tons (dry weight) of protein, per acre, per year.
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This yield is 10 to 15 times higher than soybean and 25 to 50 times higher than corn. There are both advantages and disadvantages in using microorganisms for animal or human consumption. Bacteria are usually high in protein (50 to 80 percent) and have a rapid growth rate. The principal disadvantages are as follows:
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1. Bacterial cells have small size and low density, which makes harvesting from the fermented medium difficult and costly.
2. Bacterial cells have high nucleic acid content relative to yeast and fungi This can be detrimental to human beings, tending to increase the uric acid level in blood. This may cause uric acid poising or gout. To decrease the nucleic acid level additional processing step has to be introduced, and this increases the cost.
3. The general public thinking is that all bacteria are harmful and produce disease. An extensive education programme is1required to remove this misconception and to make the public accept bacterial protein.
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Yeasts have as advantages their larger size (easier to harvest), lower nucleic add content, high lysine content and ability to grow at acid pH. However the most important advantage is familiarity and acceptability because of the long history of its use in traditional fermentations. Disadvantages include lower growth rates, lower protein content (45 to 65 per cent), and lower methionine content than in bacteria.
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Filamentous fungi have advantages .in ease of harvesting, but have their limitations in lower growth rates, lower protein content, and acceptability. Algae have disadvantages of having cellulosic cell walls which are not digested by human beings. Secondly, they also concentrate heavy metals.
Single cell protein basically comprises proteins, fats carbohydrates, ash ingredients, water, and other elements such as phosphorus and Potassium. The composition depends upon the organism and the substrate which it grows. some typical compositions which are compared with soymeal and fish meal. If SCP is to be used successfully, there are five main criteria to be satisfied;
1. The SCP must be safe to eat.
2. The nutritional value dependent on the amino acid composition must be high.
3. It must be acceptable to the general public.
4. It must have the functionality, i.e. characteristics, which are found in common staple foods.
5. The economic viability of the SCP process is extremely complex and is yet to be demonstrated
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