• What is rapeseed oil refining process?
  • Towards this, the crude rapeseed oil needs refining treatments to remove undesirable ingredients and produce higher quality oils [ 5 ¨C 7 ]. Traditional rapeseed oil refining processes generally involve four successive operations: neutralization, degumming, bleaching and deodorization.
  • What are rapeseed oil tocopherols?
  • They (¦Á, ¦Ã, and ¦Ä) are potent natural antioxidants that can inhibit the deterioration of oils during storage and prolong the shelf life of edible oils [ 29 ]. Fig 5 showed total and individual tocopherol contents of different rapeseed oil varieties at each step of refining process.
  • How much tocopherol is lost in rapeseed oil?
  • Previous study reported the greatest losses of total tocopherol content in oils could be induced by physical refining (deodorization), amounting approximately to 20.2¨C27.1% [ 32 ], and the deodorization step would cause 7¨C90% losses of tocopherols in rapeseed oils [ 33 ].
  • Why did rapeseed oil decrease -tocopherol?
  • The decrease of ¦Á-tocopherol, ¦Ã-tocopherol, ¦Ä-tocopherol and total tocopherols in different rapeseed oil varieties during the neutralization were from 6.21 to 10.01%, 8.71 to 14.52%, 13.70 to 29.12%, and 9.31 to 12.94%, respectively. The reduction might be due to the instability of tocols in the presence of air and alkali.
  • Is rapeseed oil a polyunsaturated fatty acid?
  • Rapeseed oil contains around 1.5¨C6% palmitic acid, around 0.5¨C3.1% stearic acid, around 28% oleic acid, around 11¨C23% linoleic acid, and around 5¨C13% linolenic acid. It is characterized by the ideal content of polyunsaturated fatty acid due to the ratio (2:1) of linoleic acid (n-6) and linolenic acid (n-3) fatty acid.
  • Does rapeseed oil differ after refining?
  • Differences were considered statistically significant at P< 0.05. The AV, PV, p -AV of the rapeseed oil in varieties after each refining process are shown in Fig 1. The AV of five different kinds of crude rapeseed oils were from 2.15 to 3.59 mg KOH/g and decreased significantly after neutralization, ranging from 0.29 to 0.45 mg KOH/g.