RHEOLOGICAL PROPERTIES OF MUSTARD MUCILAGE ISOLATED FROM RAW AND FROMPROCESSED MUSTARD

Mucilage of yellow mustard (Sinapis alba L.) exhibits completely diffe rent rheological behaviour, depending on where it has been extracted f rom. Whereas mucilage isolated from intact mustard seeds or from separ ated brans acts like many hydrocolloids (e. g. increasing viscosity si gnificantly at low concentrations) these and related properties (i. e. shear thinning behaviour) are lost, once mustard seeds are processed. Mucilage extracted from processed mustard only raises viscosity sligh tly. Although the supernatant of processed mustard consists of 3-5 % m ucilage (dry matter), it exhibits Newtonian flow. Changes of rheologic al properties of mustard mucilage were attributed to a change of molec ular shape from an extended to a globular state due to processing. Che mical analysis has shown a significant raise of nitrogen content of mu cilage after processing and during storage, indicating some chemical r eaction taking place, possibly involving proteins.