Protein alternatives to animal proteins traditionally obtained from the meat or milk of higher farm animals; can come from plant sources (e.g. pea protein), from microbial biomass (e.g. yeast) or from targeted microbial fermentation (precision fermentation). They can also come from protein-rich edible insects or from meat-like tissues cultivated in the laboratory ("clean meat"); the aim of producing alternative proteins is to avoid factory farming and the associated environmental destruction and to reduce CO2 emissions.
Animal-identical" alternative proteins are proteins of animal origin that are produced by microorganisms while retaining their biochemical structure and functionality. Examples include milk proteins, egg proteins or proteins for the production of meat substitutes. In the case of other proteins (e.g. enzymes, structural proteins), the protein structure is often deliberately and specifically modified in the bioprocess in order to improve properties for later use (e.g. enzyme activity) or to eliminate them (e.g. instability)