Plasticizing and Antiplasticizing Effects of Water and Polyols on a Meat-Starch Extruded Matri

ABSTRACT: The effects of plasticizers on the mechanical properties and glass transitions of a meat-starch extruded system were studied. Mixtures of meat and potato granules (1.48:1) and up to 4% glycerol and propylene glycol, respectively, were extruded and equilibrated at different relative humidities. Storage moduli and glass transitions were determined by mechanical spectroscopy. Water was the major plasticizer of the system, decreasing its mechanical properties and glass transition temperatures. At low-moisture content, the addition of water determined an increase in mechanical properties, interpreted as antiplasticization. Glycerol and propylene glycol had a softening effect on the matrix at a_w> 0.67. Propylene glycol also determined a significant decrease of the starch phase Tg.