The most recent brand of sunflower butter (Mara Natha) that I've been using left a green tinted liquid inside the glass jar after I attempted to wash it out for recycling with water ~200°F/93°C and left the water in over night.

The liquid was not just floating oil on top, but a consistent transparent green, close to the darker green check of the cooking.se background.

I washed it out again, and the second time I just rinsed with warm tap water and left it again as an experiment this time, and it was a lightly tinged yellow color that one would expect/imagine would be left since that is close to the color of the oil that separates out before you mix it in.

Note, there is a bit of sea salt in the mixture of this one. Also, the sunflower seeds are listed as being roasted beforehand. This is not an organic product.

I thought, just maybe, I could have 'burned' the sunflower oil, so I checked around and found This page, that lists many different smoking points for the same oils and redundant and various stages of 'refinement.' However, the water was no longer boiling, and the lowest listed temp was 225°F/107°C on the various sources cited. I would think that a roasted sunflower seed would qualify as 'more refined' and therefore increase the smoking temperature of the oil crushed from it. Discussion of sunflower oil vs. peanut oil here.

What am I dealing with here?

  • 1
    Silly question warning: what was the jar made of? Glass is heat-safe, plastic isn't, and whatever dissolves in plastic usually dissolves in oil too.
    – rumtscho
    Sep 27, 2013 at 21:08
  • glass, yes… lol that would be scary if I'd poured near boiling water into a plastic container. I would have to delete my .SE account in shame. Question will be updated presently. Sep 27, 2013 at 22:11

2 Answers 2


Sunflower oil turns green in the presence of bases, such as baking soda. Most tap water in the US is alkaline with a pH value around 8, so that could also turn the sunflower oil green.

  • I like your answer, I guess I just don't understand why the hot/warm tap water didn't leach out more green. Could it be that boiling the water made it more alkaline? I guess logically it would, since you would be reducing water:mineral ratio? Oct 6, 2013 at 17:28
  • 1
    it's possible that heat factors in to this too, ie. more heat -> more green.
    – smcg
    Oct 10, 2013 at 15:57

I agree that any oil in containers exposed to high alkaline value will develop a green residue. My vegetable oil container is stainless steel and kept in a cool dry cabinet. It is wiped clean of drips each use and after some time a green tinge will appear on the hinge where tap water has rested. Clean with a very dry rough cloth at room temperature often. It does not contaminate the oil, which should be changed regularly if not used up within a few weeks.

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