ABSTRACT
The use of isolated components from microbial cultures in foods also has a long history. These range from vinegar (i.e., acetic acid, which is, of course, a product again almost as old as civilization) to citric acid, numerous amino acids, and polysaccharide gums. Of more recent appearance has been the advent of microbial proteins in which the whole organism (or almost so) is the object of consumption. The first uses of this technology came in the development of food yeast (the Torula process), which was devised as a means of converting surplus sugar and molasses in the West Indies in the 1940s and 1950s to a biomass that could be used as an animal feed supplement. (The nutritional value added to the biomass was derived by the yeast converting the sugar and ammonia, supplied as the sole nitrogen source, into proteins, which then were eaten by the animals.) Of major significance in the use of microorganisms for food was the advent of various Single Cell Protein (SCP) processes that further developed the original concept of the Torula process for use with other microorganisms and other substrates. In particular, alkanes were (and are) produced by the petroleum industry in vast amounts almost as a waste material during the refinement of crude petroleum oil. This led to major advances in the technology of large scale microbial cultivations with, eventually, fermentors up to 1500 m3 being built to produce large amounts of SCP. Such fermentation plants could easily generate upward of 5000 tons (dry weight) of biomass per year on a site about the size of three or four football fields. With the use of such large scale production facilities came economies of scale: yeast biomass derived from alkanes could be produced for as little as $150-200 per ton in the 1970s.
