EFFECT OF SUCROSE ON THE STRUCTURE, MECHANICAL STRENGTH AND THERMAL-PROPERTIES OF CORN EXTRUDATES

The effects of sucrose on extrusion process parameters and the structural, mechanical and thermal characteristics of the resultant extrudates have been investigated. To this end, sucrose in concentrations between 0 and 10% by weight was added to corn meal prior to extrusion at two levels of moisture (15 and 20%). The resulting data revealed the following significant features. (i) At the higher moisture level, sucrose progressively reduced the specific mechanical energy, while exhibiting little effect at the lower moisture level. (ii) At both moisture levels, sucrose increased the bulk density and reduced the cell size; this effect was progressive for high extrusion moisture samples and evident only at high sucrose contents for low extrusion moisture samples. (iii) In extrudate samples equilibrated to moisture contents between 12 and 17% wt, sucrose progressively plasticized the structures, as assessed by compression, dynamic mechanical spectrometry, and differential scanning calorimetry. In the aggregate, these results showed that the addition of sucrose requires a modification of the extrusion operating conditions to produce extrudates with optimal textural and storage properties.