Solid state fermentation (SSF) has become a very attractive alternative to submerged fermentation (SmF) for specific applications due to the recent improvements in reactor designs. This paper reviews the application of SSF to the production of several metabolites relevant for the food processing industry, centred on flavours, enzymes (alpha-amylase, fructosyl transferase, lipase, pectinase), organic acids (lactic acid, citric acid) and xanthan gum. In addition, different types of biorreactor for SSF processes have been described. (c) 2005 Elsevier Ltd. All rights reserved.