I have observed that various foods cooked using coconut oil spoil much faster than foods cooked using groundnut oil. One good example is Asian coconut milk curry. Even with proper refrigeration, this food item cannot last more than 2 or 3 days typically. This is in very sharp contrast to food items cooked with groundnut oils which can last for much longer, possibly a few weeks. I have been looking up various Internet sources and some have cited the presence of natural enzymes, such as lipoxygenases and peroxidases, which are present in these coconut oils, while oils like groundnut oil and palm oil, do not contain these natural enzymes.

Looking at the chemical composition of the fats was also something I did. As shown here, most of the fatty acids found in coconut oil are saturated fatty acids, with lauric acid making up a large part of them. In fact, as shown here, groundnut oils seem to contain more unsaturated fatty acids than coconut oil, which we would expect to be more reactive and liable to degradation. Thus, the difference in the composition of the fats in the oils may not be what is responsible for the observed quicker rate of spoilage of coconut oil.

I would like to ask if anyone knows more to share regarding this issue. For now, it seems that the presence of enzymes may be the likely underlying reason for the faster rate of spoilage of coconut oils.

  • $\begingroup$ Do you have more than your personal experience as evidence of this difference in stability? Have you tested different brands etc? My first instinct was also to think about degrees of saturation and I would have followed the same reasoning as you. Also, the enzyme hypothesis sounds weak. I am not sure enzymes would remain in significant concentration after the sort of treatments used to purify oils, even less tolerate the treatment and remain active in the oil. $\endgroup$ – Buck Thorn Feb 12 '19 at 12:14
  • $\begingroup$ I think this thing about coconut oil spoiling is reasonably common to experience among people in my country. It is a common understanding that coconut milk-based foods spoil very fast. It does not just apply to curry, even certain traditional peranakan cakes and desserts made with coconut milk also spoils incredibly fast. $\endgroup$ – Tan Yong Boon Feb 12 '19 at 13:03
  • $\begingroup$ I'd just add that coconut milk and coconut oil are probably worlds apart in treatment. The coconut milk is pasteurized and stabilized in some way, but retains a menagerie of compounds not found in simple oil. They may have in common: there may be free organic acids that accelerate the "saponification" of the milk and oil. $\endgroup$ – Buck Thorn Feb 12 '19 at 13:27

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