206 Produce Degradation: Reaction Pathways and their Prevention
Several varieties of anthocyanin-pigmented rice have been developed through
genetic engineering. Hyun and Chung (2004) isolated two anthocyanidins from dark
purple grains of rice (Oryza sativa cv. Heugjinjubyeo). They identified these com-
pounds as cyanidin and malvidin and demonstrated that they inhibit growth of human
monocytic leukemia cells.
Black chokeberry (Aronia melanocarpa Elliot) fruit extract showed antioxidant
activity both in vitro and in vivo. Matsumoto et al. (2004) measured radical scavenging
activity of the extract using DPPH stable radicals. The red pigment fraction did scavenge
over 44% of DPPH radicals at a concentration of 25 μg/mL compared with a control
solution. The HPLC profile of the red pigment fraction gave three major peaks, the
largest one identified as cyanidin-3-glucoside. The black chokeberry extract adminis-
tered at 2 g/kg of body weight of rats showed significant antiulcerative properties.
Biosynthesis of radiolabeled anthocyanins, proanthocyanidins, and other fla-
vonoids using cell suspensions of two plant species, ohelo (Vaccinum pahalae) and
grape (Vitis hybrid, Bailey Alicant A), was reported by Yousef et al. (2004). Uni-
formly labeled (^14 C) sucrose was used in the medium. In the flavonoid-rich fractions
of ohelo and grape cultures, an average of 14 or 15% of the of the radioactivity was
recovered, respectively. HPLC-MS and NMR were used to characterize obtained
fractions. Proanthocyanidins ranging from monomers to dodecamers were deter-
mined from ohelo cell cultures. Small amounts of several anthocyanins were also
detected in these samples. Grape cell cultures contained more anthocyanins and
fewer proanthocyanidins. Peonidin 3-O-glucoside and cyaniding p-coumarylgluco-
side were dominant in grape fractions. Several other anthocyanins occurred in small
amounts. The reported biosynthesis allowed the researchers to obtain in a reproduc-
ible manner and in sufficient amounts uniquely labeled phytochemicals suitable for
in vivo experiments.
7.4.3 POSTHARVEST AND PROCESSING CHANGES OF ANTHOCYANINS
Retaining color in products containing anthocyanins is a paramount task for the food
industry. The factors affecting color stability of anthocyanins include nature of
compounds used, their concentration, pH, light, storage conditions, presence of
phenolic compounds, and other product constituents or additives. These topics are
covered in classic monographs, such as Stability of Anthocyanins in Foods by
Markakis (1982). The occurrence, properties, stability, and changes of anthocyanins
in various foods remain subjects of numerous current publications (Eiro and Hei-
nonen, 2002; Garzon and Wrolstad, 2002; Lopez-Da-Silva et al., 2002; Kahkonen
et al., 2003; Kirca and Bekir, 2003; Schwartz et al., 2003; Talcott et al., 2003).
Rein and Heinonen (2004) studied color enhancement and stability of four berry
juices: lingonberries (Vaccinium vitis-idaea L.), cranberries (Vaccinium oxycoccus
L.), strawberries (Fragaria ananasa), and raspberries (Rubus ideaeus L.). For co-
pigmentation, ferulic, sinapic, and rosmarinic acids were added in an amount 10
times greater than that of anthocyanins in juices. Grape skin and black carrot extracts
containing 3% anthocyanins and 97% carbohydrate carriers as well as non-antho-
cyanin extract of rosemary were also added at 2 g/L of juice. The juices were stored
in sealed tubes in daylight at room temperature for 103 d. The absorption spectra