OXIDATION OF METHYL LINOLEATE ENCAPSULATED IN AMORPHOUS LACTOSE-BASED FOOD MODEL

A food model containing methyl linoleate encapsulated in an amorphous lactose-gelatin matrix was used to study the effect of physical changes in the amorphous matrix on the rate of lipid oxidation. The glass transition temperature (T(g)) and crystallization behavior of the material were determined by using differential scanning calorimetry. The rate of oxidation was measured spectrophotometrically in samples incubated at various temperatures above T(g). The encapsulated oil was released as a consequence of crystallization of the amorphous lactose. The released oil underwent rapid oxidation, while encapsulated oil remained unoxidized. Oxidation of encapsulated fat in dried foods is related to physical changes in the amorphous matrix. The measurement of T(g) is important in predicting the onset of deteriorative reactions in foods and should be considered in accelerated shelf life tests.