Influence of humectants in the ascorbic acid stability during storage of sweet aqueous model systems.

ROJAS A.M.L.; DÍAZ M. Y GERSCHENSON L.N.,

New Orleans, U.S.A.

Congreso; Institute of Food Technologists (IFT) Annual Meeting.; 1996

IFT Institute of Food Technologists.

The influence of different non-electrolytes (fructose, xylitol, glucose/mannitol mixture) and electrolytes (NaCl, KCl) on anaerobic L-ascorbic acid (AA) degradation in an aqueous model system (pH 3.5, aW 0.94) was studied to assess the effect on that reaction of substances commonly used to diminish the water activity of fruit or vegetable juices, as well as its relation with non-enzymatic browning (NEB) development, at processing (70, 80, 90ºC) and storage (24, 33, 45ºC) temperatures. AA degraded as a function of time with a behaviour that could be described by first-order kinetics at all temperatures studied, and activation energies could be calculated using the Arrhenius law. The presence of humectants enhanced AA destruction, with D-fructose promoting the fastest L-ascorbic acid destruction and browning development at processing temperatures. The influence of humectants on NEB seemed to determine differences between their influence on AA degradation. Water activity decrease by humectant addition produced higher AA stability in solution at storage temperatures. The differential effect of each humectant used to decrease the water activity seemed to be related to its influence on solvent structure.