EFFECT OF USING SOME RICE BY-PRODUCT ON THE PHYSICOCHEMICAL PROPERTIES OF HEATED SUNFLOWER OIL DURING DEEP FRYING

Rice hulls are inexpensive sfica-ricn by-product of the cereal industry. They
are capable of binding lutein from soybean oil in hexane at room temperature. The
objective of this study was to use rice hulls (RH) and rice straw (RS) as adsorbents for
improving the physicochemical properties of heated sunflower oil for 36 h during deep
fat frying of potato chips at 180· C. Results revealed that physicocnemicat parameters
of the heated oil were markedly improved due to the use of RH and RS. Color was
improved by 11.43,56.94,61.81 and 41.72& with RHB while improved by 9.35, 50.99,
53.21. 48.92 and 33.65% with RS8 at the same heating time of 8. 16, 24, 32 and 36
h, respectively. The free fatty acids improved by 42.79, 49.21, 64.18, 47.19 and 40.59
with RH8 and improved by 37.83, 42.45, 51.31.40.16 and 32.09% with RS8. The
peroxide value improved by 46.15. 63.64, 69.29, 46.29 and 14.11 with RH8, and also
improved by 30.77, 56.82, 56.14, 31.48 and 14.04% with RSB. Total polar compounds
of heated sunflower oil improved by 4.97,61.79,72.91,59.72 and 23.84% with RHB
and improved by 3.58, 55.39, 69.31, 49.39 and 14.74% with RSBat the same heated
time of 8. 16, 24, 32 and 36 h, respectively. The results obtained indicated that
treatments with RHB and RSB could improve oil quality as measured by changes in
color, FFAs, PV and TPC. Both adsorbent materials were most effective when used in
the early stages of deterioration. Results also revealed that while the initial treatments
with RHB and RSB improved the oil quality up to 24 h, subsequent frying showed that
useful life of the oil was not markedly extended.