Single Cell Protein (SCP) Production

Single-cell proteins (SCP) are the dried cells of microorganisms, used as a protein supplement in either human food or animal feed; the appeal of microorganisms as a protein source is that they synthesise protein far faster than higher plants or animals can. Algae, fungi, yeast and bacteria are all used to produce SCP, and this section works through small-scale biomass production of one alga in particular, Spirulina, as a home/small-scale process. The method needs only a roughly 30-litre aquarium, an air pump, nutrients and a Spirulina mother culture: the aquarium is filled about half-way with water first checked for heavy-metal, fluorine or calcium-carbonate contamination, then filled and dosed with nutrients — preferably Zarrouk medium — added in two halves rather than all at once, after which a (non-centrifugal) air pump is fitted to aerate the culture. The mother culture is added at a rate of about 4 g per litre of water, and the culture is kept in sunlight for 10-12 hours a day; after roughly a week it is checked and topped up with more water for a further week, until the biomass turns a dark green, at which point the algae are harvested through a very fine cloth, the water is reused, and the harvested algae is dried for storage. SCP's high nutritive value — protein, vitamins, essential amino acids and lipids — makes …