Antiplasticization by water in reduced-moisture food systems

Antiplasticization of synthetic glassy polymers by low-molecular weight dil uents at low concentrations is a well-known phenomenon which leads to incre ased rigidity rather than flexibility of the polymer-diluent blends. Based on the food polymer science approach, we hypothesized that increases (rathe r than decreases) in modulus and brittleness, commonly observed when certai n solid food systems are humidified from the dry state, are synonymous with antiplasticization by water. Sugars and polyols, important components of f oods, behave in much the same manner as water in acting as either antiplast icizers or plasticizers of food polymer systems. Several mechanisms may be involved in antiplasticization by low-molecular mass diluents, Simultaneous changes in various physical properties, resulting from antiplasticization or plasticization by water and other diluents, may profoundly influence the quality and acceptability of food products.