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(Girard et al., 2000; Cassano et al., 2009), and microwave
heating (Robinson et al., 2009). Application of these tech-
nologies has been exploited on a limited scale for tangerine,
mandarin, and clementines as compared to some other trop-
ical and subtropical fruits such as banana, guava, mango,
and oranges. Most of the work done with tangerines and
mandarins have been on juice microfiltration and ultrafil-
tration (Chamchong and Noomhorm, 1991; Cassano et al.,
2009).
Lim et al. (2006) used a continuous, high-pressure CO 2
system to process mandarin juice, and the effects of temper-
ature, pressure, residence time and CO 2 :juice ratio (w/w)
were determined on total aerobic counts, pectinesterase ac-
tivity, cloudiness, Brix, color, pH, and titratable acidity
(TA). The results of this study showed that maximum log
reduction in microbial counts (3.47) was achieved after
treatment at 35 C and 41.1 MPa, with a 9 min residence
time and a CO 2 :juice ratio of 7%. Under these conditions,
cloudiness was enhanced by 38%, lightness and yellowness
increased, redness decreased, and Brix, pH, and TA were
unaffected.
Hayat et al. (2010) studied the effects of microwave treat-
ment on the phenolic compounds and antioxidant capacity
of citrus mandarin pomace. The content of total flavanol,
flavonone, and flavonol (FCs) increased with power but,
at longer irradiation time (15 min vs. 5 or 10 mi), it de-
clined, showing that some FCs might have been degraded
(Fig. 22.5). These results indicated that appropriate mi-
crowave treatment could be an efficient process to liberate
and activate the bound phenolic compounds and to en-
hance the antioxidant activity of citrus mandarin pomace.
Robinson et al. (2009) reported that the microwave heat-
ing presents an advantage since the internal temperature
distribution of a material subjected to conventional heating
depends on its thermal conductivity, whereas microwave
heating results in the heating of all the individual elements
of a material instantaneously. Consequently, heating time
using microwaves can be significantly reduced as compared
to conventional heating methods.
Chafer et al. (2001) reported that the beneficial nutri-
tional and health properties of citrus peel components, such
as pectins, flavonoids, carotenoids, and limonene, have led
to increased interest in the development of high-quality cit-
rus peel products. With the aim of preserving these compo-
nents, Chafer et al. (2001) investigated the osmotic drying
kinetics of orange and mandarin peels (0.45-0.5 cm thick-
ness) to identify optimal conditions for mild-temperature
processing of peel. Osmotic drying was carried out at 30 ,
40 , and 50 C under both atmospheric pressure and with
application of a vacuum pulse at the beginning of the pro-
cess. Results showed that application of a vacuum pulse
greatly affected mass transfer behavior of peels due to the
highly porous structure of the albedo and thus greatly accel-
erated changes in product composition in line with increas-
ing peel thickness. Chafer et al. (2001) recommended low-
viscosity osmotic solutions to promote both diffusional and
Figure 22.5. Effect of microwave treatment on flavanol, flavonone, and flavonol compounds of kinnow
(mandarin) pomace (source: Adapted from Hayat et al., 2010).
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