Food Science and Technology (Campinas)
On-line version ISSN 1678-457X
GABAS, Ana Lúcia; TELIS-ROMERO, Javier and MENEGALLI, Florencia Cecilia. Kinetic of ascorbic acid degradation in freeze-dried prunes. Ciênc. Tecnol. Aliment. [online]. 2003, vol.23, suppl., pp. 66-70. ISSN 1678-457X. http://dx.doi.org/10.1590/S0101-20612003000400013.
The degradation of vitamin C in prunes submitted to different conditions of temperature and moisture content was modeling by using the Bigelow equation. Firstly, plums were freeze-dried and conditioned in dessecators with different saturated salt solutions at 4ºC. After reaching the equilibrium, dessecators were submitted to a range of temperature between 40 to 80ºC. The vitamin C degradation was analyzed during 5 days, by applying the titration method with patronized solution of 2,6-dichlorophenolindophenol 0.01%. Samples presented the following moisture contents: 0.05; 0.11; 0.18; 0.38 and 1.40 g water/g dry solid. From the parameters of Bigelow equation, reducing decimal time (DT) and z-value, the results showed that the samples submitted to a temperature range of 40 - 60ºC, presented loss of vitamin C slower than at high temperatures (DT at the moisture content of 0.05 presented a range of 1672 - 275h and 110 e 47h, respectively). Parameters z-value and DT showed a linear and quadratic dependence with the moisture content of the samples, respectively. In general, at high moisture content, it occurs more pronounced ascorbic acid degradation, due to its high solubility.
Keywords : dehydration; modeling; fruits; vitamin C.