Degradation kinetics of monacolin K in red yeast rice powder using multiresponse modeling approach

The effects of storage temperature (4, 20, 30, 40, 50 °C) and atmospheric conditions in packages (vacuum, atmospheric) on degradation kinetics of monacolin K, an antihypercholesterolemic agent, in red yeast rice powder were investigated using multiresponse modeling approach. Storage of red yeast rice powder at 4 °C under vacuum package was found to enhance retention of monacolin K. Multiresponse modeling revealed degradation path of monacolin K acid form into their dehydromonacolin K and unknown product under vacuum package, while oxidized product was also formed under atmospheric package. Monacolin K lactone form and precursor were degraded into dehydromonacolin K lactone form, while degradation of dehydromonacolin K lactone form to unknown was more pronounced at temperature higher than 30 °C. Oxidized product was also generated from monacolin K lactone form in atmospheric package. High activation energy of monacolin K degradation in acid form indicated that degradation of monacolin K to their dehydromonacolin K was more susceptible to temperature change as compared to lactone form.

► This work gave an insight on degradation pathway of monacolin K during storage.
► Monacolin K acid form was degraded to their dehydromonacolin K and unknown.
► Monacolin K lactone form and precursor was degraded to dehydromonacolin K.
► Dehydromonacolin K lactone form was then converted to unknown in vacuum package.
► The formation rate of oxidized product in lactone form was lower than acid form.