An increment of the drying temperature increases the
dehydration rate, but also increases the rate of ascorbic acid
degradation.Whenthemoisturecontentdescendsnextto50%
and 30% of initial moisture, the l-ascorbic acid retention and
therequireddryingtime,ateverydryingtemperature,arepresented in Table 1. The l-ascorbic acid retention is expressed
as a percentage of its content in the fresh fruit. Standard
deviation is a widely used measure of the variability or dispersion; obtained values in this work are shown in Table 1.
The time needed to reach a certain value of W/W0 is smaller
at 75◦
Cthanat 45◦
C,nevertheless greater ascorbic acidretention was observed at 45◦
C than at 75◦
C. This fact is showing
thatthetemperatureeffectwasmoreimportantthanthetime
effect on the l-ascorbic acid degradation during drying process.Theseobservationsareinagreementwiththatexpressed
by Santos and Silva (2009). They studied kinetics of l-ascorbic
acid degradation during pineapple drying at 40 and 60◦
C andtwo air velocities: 0.42 or 0.84m/s. In those conditions, the lascorbic acid retention was smaller than which was found
in our present study. These discrepancies can be due to the
difference in air velocity values that causes, consequently, a
remarkable difference in drying time.
For a given value of moisture content, similar AA content
was measured at 60 and 75◦
C;but at 45◦
C the AA retention
was higher.