Production of Fungal Biomass, the Mycoprotein (other than Mushrooms)

During the World War II, attempts were made to use the cultures of Fusarium and Rhizopus grown in fermentation as protein food. The inoculum of Aspergillus oryzae or Rhizopus arrhizus is chosen because of their non-toxic nature (Riviere, 1977). Saprophytic fungi grow on complex organic compounds and render them into simple forms. As a result of growth, high amount of fungal biomass is produced. Mycelial yield vary widely depending upon organisms and substrates. Strains of some species of moulds, for example, Aspergillus niger, A. fumigatus, Fusarium graminearum are very hazardous to human, therefore, use of such fungi should be avoided or toxicological evaluations should be done before recommending to use as SCP. Protein contents of moulds are given in Table 18.1. Chahal (1982) has described the increasing popularity of myco-protein because of the following reasons: (i) some of the filamentous fungi grow as fast as most of the single celled organism; (ii) the finished product of filamentous fungi is fibrous in nature and can be easily converted into various textured foods. In comparison, protein is extracted from single celled organisms and spun into fibrous form; (iii) filamentous fungi have a greater retention time in the digestive system than single celled organisms; (iv) protein content can be as high as 35-50 per cent with comparatively less nucleic acid than single celled organism;
(v) digestibility and net protein utilization without any pretreatment is higher than single celled organisms; (vi) the overall cost of protein production from filamentous fungi is more economical as compared to that of single celled organism; (vii) filamentous fungi have greater penetrating power into insoluble substrates and are therefore, more suitable for solid state fermentation of lignocellulosic materials; (viii) most of filamentous fungi have a faint mushroom like odor and taste which may be more readily acceptable as a new source of food than the yeast odor and green color associated with yeasts and algae respectively; (ix) the biomass produced by filamentous fungi can be used as such without any further processing because it provides carbohydrates, lipids, minerals, vitamins and proteins. In addition, nucleic acid contents of fungal protein is lower than that of yeast and bacteria.