Grasas y Aceites (Dec 2007)

Assessment of oxidative deterioration of soybean oil at ambient and sunlight storage

  • Farooq Anwar,
  • Shahzad Ali Shahid Chatha,
  • Abdullah Ijaz Hussain

DOI
https://doi.org/10.3989/gya.2007.v58.i4.451
Journal volume & issue
Vol. 58, no. 4
pp. 390 – 395

Abstract

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This study was carried out in order to probe the extent of oxidative alterations in soybean oil (SBO), subjected to ambient and sunlight storage, over a period of 180 days. The magnitude of oxidative changes was monitored by the periodical measurement of peroxide value (PV), color, free fatty acid (FFA) contents, refractive index (RI), p-anisidine-, conjugated dienes-, conjugated trienes-, and iodine- values. At the end of storage period (180 days), the initial contents of FFA (0.02 % as oleic acid) and PV (0.02 meq/kg of oil) of the SBO samples subjected to ambient and sunlight storage reached the level of 1.77, 2.90 % and 20.52, 41.89 meq/kg of oil, respectively. The initial values of RI (40°C) (1.4630), panisidine (1.10), conjugated dienes (0.08) and conjugated trienes (0.04) rose to the point of 1.4647, 1.4659; 36.13, 50.40; 23.97, 41.49 and 13.81, 19.35, respectively. Whereas, the iodine value (g of I /100 g of oil) decreased from 138.00 to 126.18 and 118.04, respectively. At the end of storage period, the overall order, indicative of the oxidative changes in RI, FFA, IV, color (red + yellow), PV, P-anisidine, conjugated dienes and conjugated trienes of the SBO subjected to ambient and sunlight storage was as follows: 1.001:1.002, 1.00:1.65, 0.91:0.86, 0.80:0.60 + 0.75:0.50, 1.00:2.04, 1.00:1.39, 1.00:1.73 and 1.00:1.40, respectively. The results of various parameters investigated in the present study demonstrated the magnitude of oxidative deterioration of the SBO samples exposed to sunlight to be significantly (P < 0.05) pronounced as compared with that of ambient.

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