Besides microbiological safety, lipid oxidation is another
important concern for evaluation of chiffon cake shelf life. As can be
seen in Fig. 1, peroxide values of ordinary chiffon cakes and chiffon
cakes added with 3 g/kg CAP were 5.7 and 6.0 meq/kg respectively.
These values increased rapidly to 13.0 and 12.2 meq/kg during
storage in ambient conditions for 9 d. Although gamma irradiation
at 4 kGy accelerated peroxide values of chiffon cakes at the
beginning, a slow increase was observed during storage. Peroxide
values of chiffon cakes irradiated at 4 kGy (9.4 meq/kg), and chiffon
cakes added with 1.5 g/kg CAP and irradiated at 4 kGy (10.1 meq/kg)
slightly increased to 12.2 and 12.0 meq/kg during 45 d of storage.
Food products that have a peroxide value > 20 meq/kg are rancid
and unacceptable to the consumer (Pearson, 1970). Irradiated
chiffon cake had peroxide values less than 20 meq/kg when storing
for 75 d. However, these values had distinctly increased to 24.3 and
23.0 meq/kg at 90 d of storage.
During storage in the presence of oxygen, oil in the chiffon cake
underwent lipid oxidation and consequently, oxidative rancidity
was perceived. Polyunsaturated fatty acids are attacked by oxygen
and yield primary oxidation products as hydroperoxides. Oxidative
stability of bakery products considerably changes with storage
time. In cakes, Hafez (2012) confirmed an increase in the peroxide
values of cake from 13.7 to 16.3 meq/kg during 21 d of storage.
However, rancidity induction time differed among bakery products
which had varying total fat contents and types of major fatty acids.
Dissimilar findings were observed by Izzreen and Noriham (2011),
whose cakes had comparatively low peroxide values at the beginning
and remained at