Shelf life stability
Although the initial value of quality parameters (FFA and COLOR) of
zero-TFA deodorized oils were a modestly higher than conventional
deodorized oils, there were no significant differences in the shelf life
stability between the oils processed by these two technologies. Soybean
oil is shown as an example in Fig.9. Changes during the 18-month shelf
life of important quality parameters (AV, PV, COLOR) for conventional
refined oils and “zero TFA” oils are illustrated. The AV of both
soybean oils increased slightly during the whole shelf life and well met
the national standard for 1st-grade soybean oil (≤0.5
mgKOH/g), which means that there was no significant difference in AV
change trends between the different processed oils. The PV is an
important indicator for the degree of primary oxidation of fats and
oils. Hydroperoxides can be decomposed to volatile and non-volatile
lower molecular weight components such as aldehyde and ketone at
temperatures above 100°C (Tsiadi et al., 2001) used during the
deodorization and therefore the PV value of freshly finished oils were
all zero. During the whole shelf life, it was found that both soybean
oils had a rising trend in PV, and most of the time conventional
rerfined soybean oil showed higher PV than zero-TFA soybean oil. The
color (R-value) of these two soybean oils both rose to a certain extent
(Fig.9), but at end of the 18-month-shelf live there was no differences
between the two oils. Besides, the flavor of them did not show
significant differences in changes during the shelf-life either (data
not shown). Not only soybean oil, but also rapeseed oil, maize oil and
sunflower seed oil showed similar trends in these quality parameters
during the shelf-life test obtained by the two different deodorization
methods (data not shown). In conclusion, DCDT and conventional
deodorization of several kind of oils had similar overall shelf-life
stability without significant differences, which is critically important
for industrial vegetable oil production and sales.