EFFECT of STORAGE CONDITIONS AND PACKAGING MATERIALS ON THE PHYSICOCHEMICAL, MICROBIOLOGICAL AND SENSORY PROPERTIES OF CORN DRY MASA FLOUR

Abstract

Dry masa (corn dough) flour was stored for 6 months in paper and polyethylene bags at ambient conditions (average of 36°C and 29% R.H.) and under different controlled conditions of temperature (25 and 40°C; 60% R.H.). the physicochemical, microbiological and sensory properties of the dry masa flours were evaluated throughout storage. Polyethylene bags had more resistance to tearing and a lower rate of water vapor transmission than paper bags. Therefore, dry masa flours stored in paper bags deteriorated faster than counterparts stored in polyethylene bags. For each packaging system, masa flours deteriorated at the lowest rate when stored at ambient conditions. Within the controlled conditions, dry masa flour stored in polyethylene bags at 25°C and 60% R.H. retained its properties for a longer time than counterparts stored at 40°C in polyethylene bags or flours stored in paper bags. the dry masa flour water absorption index and amylograph peak viscosity decreased as the level of deterioration increased. Fat acidity and sensory evaluations were closely related to changes in dry masa flour quality. the adsorption isotherm of the dry masa flour indicated that the corresponding moisture content for an Aw of 0.8 was 15.3%. the most common fungi found in the deteriorated flours were Aspergillus terrus, Aspergillus flavus and Aspergillus ornatus.