Gv. Arambula et al., EFFECTS OF STARCH GELATINIZATION ON THE THERMAL, DIELECTRIC AND RHEOLOGICAL PROPERTIES OF EXTRUDED CORN MASA, Journal of cereal science, 27(2), 1998, pp. 147-155
The effects of processing on starch gelatinisation of corn masa prepar
ed by extrusion were monitored by observing the changes in thermal dif
fusivity, starch crystallinity, peak viscosity and the differential di
ssipation factor (DDF). The results show that there is a threshold pro
cessing temperature (Tc), about 80 degrees C, above and below which di
fferent behaviour patterns for the measured properties are observed. T
he thermal diffusivity, starch crystallinity and the position of a pea
k in the DDF have a maximum at approximately Tc=80 degrees C. The peak
viscosity decreases monotonically for Tc up to 80 degrees C and then
remains constant. On the bases of textural characteristics of masa and
tortilla, this work indicates that the degree of starch gelatinisatio
n in the extruded masa is optimum at temperatures at approximately 80
degrees C where the room temperature thermal diffusivity and different
ial dissipation factors have maximum values. Textural analysis made in
tortillas with masas prepared at various temperatures support the abo
ve conclusions. (C) 1998 Academic Press Limited.