Produce Degradation Pathways and Prevention

214 Produce Degradation: Reaction Pathways and their Prevention

(Cohen and Saguy, 1983). Degradation of betanin is influenced by oxygen in the
air. Betanin solutions exposed to air for 6 d at 15°C degraded 15% more than samples
under nitrogen (vonElbe et al., 1974). All the above-mentioned factors related to
betalains’ stability as well as potential off-flavor formation and economic feasibility
must be taken into account when red beet and other preparations are used commer-
cially as food colorants.
Jiratanan and Liu (2004) investigated antioxidant activity of processed table
beets (Beta vulgaris var. conditiva) and green beans (Phaseolus vulgaris L.). Sliced
beets were mixed to obtain a homogeneous sample, packaged in 8.8- × 6.2-cm cans,
sealed, and heat-treated for 15, 30, and 45 min at 105, 115, and 125°C. The com-
mercial condition for canning beets is 30 min at 115°C. The antioxidant activity of
beets processed under commercial conditions remained constant despite an 8% loss
of vitamin C and 60% loss of color. Changes of betacyanin and betaxanthin after
thermal processing were measured by spectrophotometry. After 115°C thermal treat-
ment for 15 min there was an approximate 50% loss of betacyanin. During the 115°C
heating, the half-lives of betacyanin and betaxanthin were 22 and 26 min, respec-
tively. The half-lives of pure pigments reported in the literature are approximately
50% of the half-lives reported by the authors for beet puree. The authors concluded
that the antioxidants in beets may help to preserve the pigments.
Swiss chard is a potential edible, betalain-containing source of food colorant prep-
arations. Kugler et al. (2004) investigated the betacyanin and betaxanthin composition

FIGURE 7.9Vulgaxanthin-I, R = NH2; vulgaxanthin-II, R = OH.

O

R

CH 2 CH 2 C

H CHCOO

N

HOOC COOH

H

N

acid-Glucose

(c)Amaranthin,R=2’-Glucuronic

(b)Betanin,R=-Glucose

GENERALFORMULA (a)Betanidin,R=-OH