VMD carrot slices was softer than that of AD samples
but harder than that of FD samples.
Carrot slices that were processed by the three drying
methods were distinguishable based on both visual and
instrumental assessment of color. Instrumentally, carrot
slices that were AD were darker, with less red and yellow hues than the FD and VMD samples (Table 1). FD
samples had the highest degree of lightness, with a
slightly lower yellow hue than that of VMD samples.
The darker appearance of the AD and VMD carrot slices compared to the FD samples may be due to the
exposure to heat during drying. According to Howard
et al.(1996), the lightness of carrot is aected by processing temperatures, with higher temperatures causing
darker color. A similar observation was also reported
by Abbatemarco and Ramaswamy (1995). It might also
be expected that the AD and VMD carrots would
appear darker since the density of these slices was
greater than FD product, yielding a higher concentration of pigment per volume of tissue.
The yellow and red color of carrot slices is attributed
to the presence of carotenes (Wagner and Warthesen,
1995). The decrease inavalues or red color in the AD
and VMD carrot slices compared to FD slices correlates
with the loss of-and-carotenes (Fig. 5). However,
this loss of pigment is not correlated with the bvalues
recorded. There may be an interaction between carotenoid degradation and structural changes in the carrot tissue that occur during heating and drying. Work
by Purcellet al.(1969) indicated that the bathochromic
shift from red to yellow hues observed after heating
high carotenoid containing vegetables was associated
with the degradation of the chromoplasts and solubilization of carotenoids in other cellular lipids.
When reconstituted, the dierences in color (Hunter
L, a, and bvalues) among the AD, FD, and VMD carrot slices were smaller. All the samples appeared darker,
with the largest decrease in the lightness noted for the
FD samples. There was a large increase in the red hue of
AD sample, and relatively minor changes in the othera
andbvalues.