Food & Nutrition

Arab Journal of Food & Nutrition
121. The Effect of AMURCA (OLIVE OIL LEES) on Lipid Peroxidation and
Oil Shelf Life (2010)
Fawzia Jamal Hammad\ Jordan University of Science & Technology
Supervisor: Dr. Sana Janakat
Amurca is known as olive oil lees in English and turtub in Jordan ‏;(طرطب)‏ one of olive
oil byproducts which is watery bitter tasting and dark colored sediment that settles at
the bottom of olive oil container after several months. In this study, the composition of
Jordanian amurca, total phenol content, antioxidant activity and liperoxidative (LPO)
inhibition activity of amurca was assessed, in addition to its effect on Jordanian olive
oil shelf life.
Gross composition of amurca was as follows; carbohydrates 0.91 0.411 %,
proteins 7.0 0.023 %, fats 50.03 1.08 %, moisture 47.1 0.474 % and ash 1.23
0.292 %. Phenol content was 289 mg GAE / 100 g of amurca and antioxidant activity
was 22.3 0.21 mg vitamin E equivalent / 100 g that caused 95.7 % LPO inhibition
and low peroxide value (1.78 0.03 meq O 2 / Kg amurca).
Total phenol content significantly decreased in olive oil over time from 31.6
0.37 mg GAE / 100 g oil at zero time to 6.7 0.19 mg GAE / 100 g in samples taken
after 12 months storage (p < 0.05). In contrast total phenol content of samples taken
after 12 months of storage from the bottom of container was 17.1 0.30 mg GAE /
100 g oil (p < 0.05).
Antioxidant activity significantly decreased after milling from 1.29 0.004 mg
vitamin E equivalent / 100 g oil to 0.39 0.003 mg vitamin E equivalent / 100 g oil in
samples taken after 12 months of storage, with linear positive correlation with phenol
content (r 2 = 0.8811). As expected olive oil samples taken over the period of 12
months possessed decreasing amounts of phenol content, anti – oxidant activity and
anti – lipoperoxidative activity, which lead to increased peroxide and acid values. In
contrast olive oil samples taken from the bottom of the container after 12 mnths
possessed high phenol content, antioxidant activity and anti – lipoperoxidative activity
and low acid and peroxide values.
These results show that sedimentation of amurca during storage decreases total
phenol content, antioxidant activity which decreases anti - lipoperoxidative activity of
olive oil and increase acid and peroxide values which will shorten the shelf life of
olive oil. Therefore, it is recommended not to completely separate amurca from olive
oil container and to vigorously shake the container from time to time to elongate the
shelf life of olive oil.
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Volume 11, No. 25, 2011