Influencia de la composición del sistema en la destrucción del ácido ascórbico en sistemas azucarados de actividad de agua reducida.

ROJAS A.M.L.; GERSCHENSON L.N. Y ALZAMORA S.M.

Capital Federal, Argentina.

Congreso; XIX Congreso Latinoamericano de Química, Buenos Aires, Argentina, noviembre. Organizó: Asociación Química Argentina.; 1992

Asociación Química Argentina.

The anaerobic destruction of L-ascorbic acid in sweet aqueous model systems (water activity=0.94) of pH 3.5 was studied. Ascorbic acid degraded as a function of time and temperature with a behaviour that, in general, could be described by first order kinetics. The influence of the humectants tested (glucose, sucrose and sorbitol) on nutrient destruction depended on the temperature studied: at lower temperatures (24, 33 and 45ºC), humectants protected L-ascorbic acid from destruction, sugars being the most effective due to the structure-forming effect they have; at higher temperatures characteristic of processing (70, 80 and 90ºC), humectants with active carbonyls (glucose and sucrose) promoted ascorbic acid destruction, non-enzymic browning reactions probably being responsible for these results. The effect of sodium bisulphite presence was only significant at the lower temperature range producing inhibition of destruction; at higher temperatures the prevalence of non-enzymatic browning seemed to nullify the effect of this additive. It is concluded that not only water activity or additive effect but also solute-solvent interaction and other reactions taking place must be considered when analysing the effect of humectants and additives on ascorbic acid degradation.