Miscellaneous Food Products 207
SINGLE-CELL PROTEIN (SCP)
The cultivation of unicellular microorganisms as a direct source of human food was suggested in
the early 1900s. The expression single-cell protein (SCP) was coined at the Massachusetts Institute
of Technology around 1966 to depict the idea of microorganisms as food sources.
54 Although SCP
is a misnomer in that proteins are not the only food constituent represented by microbial cells, it
obviates the need to refer to each product generically as in “algal protein,” “yeast cell protein,”
and so on. Although SCP as a potential and real source of food for humans differs from the other
products covered in this chapter, with the exception of that from algal cells, it is produced in a similar
manner.
Rationale for SCP Production
It is imperative that new food sources should be found in order that future generations are adequately
fed. A food source that is nutritionally complete and requires a minimum of land, time, and cost to
produce is highly desirable. In addition to meeting these criteria, SCP can be produced on a variety of
waste materials. Among the overall advantages of SCP over plant and animal sources of proteins are
the following:
28
1) Microorganisms have a very short generation time and can thus provide a rapid mass increase.
2) Microorganisms can be easily modified genetically—to produce cells that bring about desirable
results.
3) The protein content is high.
4) The production of SCP can be based on raw materials readily available in large quantities.
5) SCP production can be carried out in continuous culture and thus be independent of climatic
changes.
The greater speed and efficiency of microbial protein production compared to plant and animal
sources may be illustrated as follows: a 1,000-lb steer produces about 1 lb of new protein per day;
soybeans (prorated over a growing season) produce about 80 lb, and yeasts produce about 50 tons.
Organisms and Fermentation Substrates
A large number of algae, yeasts, molds, and bacteria have been studied as SCP sources. Among the
most promising genera and species studied are the following:
1) Algae: Chlorella spp., and Scenedesmus spp.
2) Yeasts: Candida guilliermondii, C. utilis, C. lipolytica, and C. tropicalis; Debaryomyces kloeckeri; Candida famata, C. methanosorbosa; Pichia spp.; Kluyveromyces fragilis; Hansenula polymorpha; Rhodotorula spp.; and Saccharomyces spp.
3) Filamentous fungi: Agaricus spp.; Aspergillus spp.; Fusarium spp.; Penicillium spp.; Saccharomycopsis fibuligera; and Trichosporon cutaneum.
4) Bacteria: Bacillus spp.; Acinetobacter calcoaceticus; Cellulomonas spp.; Nocardia spp.; Methylomonas spp.; Aeromonas hydrophila; Alcaligenes eutrophus (Hydrogenomonas eutropha), Mycobacterium sp.; Spirulina maxima, and Rhodopseudomonas sp.
SINGLE-CELL PROTEIN (SCP)
The cultivation of unicellular microorganisms as a direct source of human food was suggested in
the early 1900s. The expression single-cell protein (SCP) was coined at the Massachusetts Institute
of Technology around 1966 to depict the idea of microorganisms as food sources.
54 Although SCP
is a misnomer in that proteins are not the only food constituent represented by microbial cells, it
obviates the need to refer to each product generically as in “algal protein,” “yeast cell protein,”
and so on. Although SCP as a potential and real source of food for humans differs from the other
products covered in this chapter, with the exception of that from algal cells, it is produced in a similar
manner.
Rationale for SCP Production
It is imperative that new food sources should be found in order that future generations are adequately
fed. A food source that is nutritionally complete and requires a minimum of land, time, and cost to
produce is highly desirable. In addition to meeting these criteria, SCP can be produced on a variety of
waste materials. Among the overall advantages of SCP over plant and animal sources of proteins are
the following:
28
1) Microorganisms have a very short generation time and can thus provide a rapid mass increase.
2) Microorganisms can be easily modified genetically—to produce cells that bring about desirable
results.
3) The protein content is high.
4) The production of SCP can be based on raw materials readily available in large quantities.
5) SCP production can be carried out in continuous culture and thus be independent of climatic
changes.
The greater speed and efficiency of microbial protein production compared to plant and animal
sources may be illustrated as follows: a 1,000-lb steer produces about 1 lb of new protein per day;
soybeans (prorated over a growing season) produce about 80 lb, and yeasts produce about 50 tons.
Organisms and Fermentation Substrates
A large number of algae, yeasts, molds, and bacteria have been studied as SCP sources. Among the
most promising genera and species studied are the following:
1) Algae: Chlorella spp., and Scenedesmus spp.
2) Yeasts: Candida guilliermondii, C. utilis, C. lipolytica, and C. tropicalis; Debaryomyces kloeckeri; Candida famata, C. methanosorbosa; Pichia spp.; Kluyveromyces fragilis; Hansenula polymorpha; Rhodotorula spp.; and Saccharomyces spp.
3) Filamentous fungi: Agaricus spp.; Aspergillus spp.; Fusarium spp.; Penicillium spp.; Saccharomycopsis fibuligera; and Trichosporon cutaneum.
4) Bacteria: Bacillus spp.; Acinetobacter calcoaceticus; Cellulomonas spp.; Nocardia spp.; Methylomonas spp.; Aeromonas hydrophila; Alcaligenes eutrophus (Hydrogenomonas eutropha), Mycobacterium sp.; Spirulina maxima, and Rhodopseudomonas sp.