S-Adenosyl-L-methionine (SAM) production from Saccharomyces cerevisiae K-9 was comparatively stable under slightly acidic conditions (pH 3.0-5.0) and at low temperature (20-25°C). The kinetics of SAM degradation and 5'-methylthioadenosine (MTA) formation in yeast solution at high temperature (40-60°C) were described by zero-order reactions and the activation energy levels were 104 and 102 kJ/mol, respectively. The optimum retention of SAM after spray drying was obtained at 120°C inlet air temperature. The water content of the powder has a significant effect on the stability of SAM. The SAM yeast powder with trehalose and maltodextrin (dextrose equivalent, DE = 25), used as carrier solids, exhibited higher stability. [ABSTRACT FROM AUTHOR]