EFFECT OF SAGE (Sa/via officinalis) EXTRACTS ON THE STABILITY OF CORN OIL AND ITS TOCOPHEROLS CONTENT DURING HEATING PROCESS.

The activity of hexane- extract (H.E) and ethanol extract {E. E) of sage leaves
as a natural antioxidant, in a comparison with butylated hdroxytoluene (BHT), as a
synthetic one in reducing the oxidative changes during intermittent heating of corn pil
was studied. Changes in some constants. oxidized products, the fatty acids and
tocopherols contents of corn oil free or containing hexane (H.E) and ethanol extract
(E.E) of sage leaves and (BHT) as antioxidants were tested. Refractive index, acid
value, peroxide value, total carbonyls and absorbance at 234. 270. 400 and 450 m
increased progressively during the Intermittent heating process, while iodine value
decreased. Addition of 0.1% of (E.E) and 0.05% (BHT) showed clear eHect in
reducing these changes, whereas (H.E) was less effective. The addition of (E.E) and
(BHT) reduced mao:edly the loss of linoleic acid after 10 hr of intermittent heating. y •
tocopherol represented the major tocopherol fraction in corn oil, while 13- tocopherol
was not detected. The losses of 0-, y-.'6- and total tocopherols were 70.9%, 50.6°(0.
20.3% and 53.9% respectively after 4 hr of intermittent heating of com oil without
additiVes. (E.E) reduced lhese losses to 17.7%,4.5%.5.5% and 7.2% respectively for
the same tocopherols mentioned above and under the same conditions comparing
with BHT. which decreased lhese losses to 19.0%. 5.0%. 7.7% and 80%
respectively, while H.E had less effect. So. (E. E) had nearly 50% of lhe efficiency f
BHT as antioxidant.