Produce Color and Appearance 197
capability of the fruits was observed. During the following 48 h a sharp increase in
carotenoids took place. Since the final high content of carotenoids is an important
quality requirement, the authors concluded that a careful control of temperature and
humidity may improve carotenoid retention.
Among several groups of compounds possessing antioxidant activity (Kaur and
Kapoor, 2001) carotenoids are an important category. In a recent study Matsufuji et
al. (2004) examined the antioxidant effects of paprika pigments on oxidation of
linoleic acid at 37°C in darkness or exposed to fluorescent light. The addition of
paprika pigments significantly suppressed the oxidation of linoleic acid in darkness
and only slightly under light. The antioxidant effect was higher with increased
concentration of pigments from 0.02 to 2%. The authors suggested that discoloration
of paprika pigments may be used as a visual indicator of the oxidative deterioration
of oils. It is worth mentioning that the author of this chapter used, many years ago,
discoloration of paprika pigments to estimate the progress of oxidation of rapeseed
oil with and without antioxidants from wood smoke.
7.2.4 PROGRESS IN ANALYTICAL METHODOLOGY
An excellent and comprehensive description of analytical aspects of carotenoids may
be found in Advances in HPLC and HPLC-MS of Carotenoids by Taylor et al. (1990),
Isolation and Analysis by Schiedt and Liaaen-Jensen (1995), Mass Spectrometry by
Enzell and Back (1995), and chapters of Carotenoids, Volumes 1A (Isolation and
Analysis) and 1B (Spectroscopy) edited by Britton et al., and in other related
monographs. Only selected publications after 1995 will be mentioned here.
Bhosale et al. (2004) used resonance Raman spectroscopy for a rapid, nondestruc-
tive estimation of carotenoids in selected fruits and vegetables. The results were com-
pared with data obtained by extraction and HPLC. A strong correlation was observed
in the case of fruit juices and tomatoes at the same stage of ripening. Spinach leaves
showed very high Raman counts despite lower carotenoid content. The method dem-
onstrates potential value in some instances but also presents important limitations.
Cortes et al. (2004) described a method for identification and quantification of
carotenoids, including isomers, in fruit and vegetable juices. The authors used HPLC
with an ultraviolet-diode array detector. Seventeen different cis- and trans-caro-
tenoids were identified in orange juice and a mixture of orange and carrot juice. For
identification, spectral and retention time data from standards and literature values
were utilized. The authors claimed that their proposed method is fast, sensitive,
reliable, accurate, and reproducible for determination of cis- and trans-carotenoids
in produce juices.
Felicissimo et al. (2004) applied ToF-SIMS (time-of-flight secondary ion mass
spectrometry) and XPS (x-ray photoelectron spectroscopy) to analyze annatto in
seeds and seed extracts. The analysis of seeds without any sample treatment showed
the presence of bixin and its characteristic fragments. When an extract of seeds was
analyzed, the results revealed the same components. Internal parts of seeds did not
show the presence of the colorant. A prolonged exposure to light led to significant
degradation of bixin. Several minor constituents and products of bixin degradation
were observed, but their precise assignment requires further analysis.