KINETICS FOR ISOBARIC-ISOTHERMAL DEGRADATION OF L-ASCORBIC-ACID

A study of the thermal degradation of L-ascorbic acid in different buf fer systems (pH 4, 7, and 8) and in real products (juice from squeezed oranges and tomatoes) revealed that L-ascorbic acid is most thermosen sitive in real products. These products were selected to investigate i n detail the degradation kinetics of L-ascorbic acid by heat (120-150 degrees C) as well as by combined pressure-temperature treatment (8.5 kbar and 65-80 degrees C). In both cases the L-ascorbic acid degradati on was confirmed to be a first-order reaction. The z values of thermal destruction of L-ascorbic acid in squeezed oranges and tomatoes were respectively 27.15 and 30.15 degrees C and were shown to be similar fo r pressure-temperature degradation.