Antioxidant efficacy of water washed gums as a function of relative humidity in peanut oil.

The stability of raw peanut oil to autoxidation at 40 C increased
with ambient relative humidity, reaching a maximum stability at
90.5% RH (KM x 10-3 2.54, 1.83, 0.50 meq O2/kg/hr at RH of 2,
47.5, 90.5%, respectively). Degumming with water or with phosphoric
acid accelerated autoxidation at all test humidities. The trend
in the rate of autoxidation was opposite that of the raw oil, increasing
with relative humidity. It reached its maximum at 90.5% RH
(KM X 10-3 of 3.93, 3.16, 6.65 meq O2/kg/hr at RH of 2, 47.5,
90.5% respectively for phosphoric acid degummed oil). Adding back
the water washed gums removed during degumming to the water degummed
peanut oil substantially restored the stability of the oil to
autoxidation. These studies indicate that water washed gums retain
most of their native state antioxidant activity. Hence, the gums removed
during processing of oils could be added back to the oil after
final processing to impart increased stability to the oil in some applications.
The antioxidant efficacy of water washed gums was as good
is that of synthetic antioxidants. These have an advantage over synthetic
antioxidants in that they are natural components of most oils
and fats.