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Medical Forum / General / Nutrition / February 2005Rancitidity of cooking oil and its spread
If cooking oil goes rancid in a container then would any oil poured into that same (unwashed) container go rancid more quickly? (1) I have the impression that a trace of rancid oil acts like a sort of catalyst for rancidity in non-rancid oil. (2) If the container were washed but the merest hint of oil rancid oil were left behind then is this sufficient to accelerate rancidity in any new oil? You really shouldn't be messing with this very dangerous stuff in the first place. Use stable oils like coconut or palm kernel. Now, to answer your question: let's say you've got high quality olive oil, rich in antioxidants. Then you pour it into this container that has a trace of the old rancid oil in it. The amount of the rancid oil will be taken care of by the antioxidant rich olive oil. The problem is that low quality olive oil, for example, doesn't need help from this trace amount - it's ready to go rancid very quickly once exposed to air. If you keep the jar closed, and use one of those stoppers that can be vacuum sealed, it will not go rancid. However, this stuff will go rancid inside your body, unless you eat a very antioxidant rich meal. So again, why mess with this stuff to begin with? > You really shouldn't be messing with this very dangerous stuff in the > first place. Use stable oils like coconut or palm kernel. Now, to [quoted text clipped - 8 lines] > go rancid inside your body, unless you eat a very antioxidant rich > meal. So again, why mess with this stuff to begin with? This post is perhaps the silliest nonsense I have ever read. It is so bad that I do not even know where to start criticizing it.  SignaturePeter Aitken Remove the crap from my email address before using. > > You really shouldn't be messing with this very dangerous stuff in the > > first place. Use stable oils like coconut or palm kernel. Now, to [quoted text clipped - 11 lines] > This post is perhaps the silliest nonsense I have ever read. It is so bad > that I do not even know where to start criticizing it. I suggest you try. Use primary sources as references. > You really shouldn't be messing with this very dangerous stuff in the > first place. Use stable oils like coconut or palm kernel. Now, to [quoted text clipped - 8 lines] > go rancid inside your body, unless you eat a very antioxidant rich > meal. So again, why mess with this stuff to begin with? I belive it is you that has mentioned that in the US we do not have quality olive oil. Any suggestions on where to order good quality extra virgin olive oil? I get my coconut oil from Garden of Life http://www.nutritionwarehouseoutlet.com/product_info.php?cPath=3&products_id=32 or Wilderness Family Naturals http://www.wildernessfamilynaturals.com/mall/virgin_coconut_oil.asp Ren? > If cooking oil goes rancid in a container then would any oil poured > into that same (unwashed) container go rancid more quickly? Yes. Any remaining oil will act as an initiator for the free radical chain reaction. See: http://www.britanniafood.com/common/invite_17.htm >> If cooking oil goes rancid in a container then would any oil poured >> into that same (unwashed) container go rancid more quickly? [quoted text clipped - 4 lines] > See: > http://www.britanniafood.com/common/invite_17.htm Did you bother to read your reference? Do you understand it? I did, and I see no reference to trace quantities of rancid oil hastening the deterioration of new oil. SignaturePeter Aitken Remove the crap from my email address before using. > Did you bother to read your reference? Do you understand it? I did, and I > see no reference to trace quantities of rancid oil hastening the > deterioration of new oil. Although its not written in this article, it is basic organic chemistry- radical reactions (like the one when oils go rancid) start faster when a radical starter (like rancid oil) is present. http://www.meta-synthesis.com/webbook/14_radical/radical.html > If cooking oil goes rancid in a container then would any oil poured > into that same (unwashed) container go rancid more quickly? > > (1) I have the impression that a trace of rancid oil acts like a > sort of catalyst for rancidity in non-rancid oil. No, this is not true. Rancidity is the result of the oil reacting (slowly) with oxygen in the air. A trace of old rancid oil will not hasten the deterioration of new oil - but it will affect the flavor. > (2) If the container were washed but the merest hint of oil rancid > oil were left behind then is this sufficient to accelerate rancidity > in any new oil? As per above, no. A good washing will in any case remove all the old oil. SignaturePeter Aitken Remove the crap from my email address before using. > No, this is not true. Rancidity is the result of the oil reacting (slowly) > with oxygen in the air. A trace of old rancid oil will not hasten the > deterioration of new oil - but it will affect the flavor. This is not true, in fact. The products of fat oxidation are (among others) Epoxides and Peroxides. (besides chain fragments, aldehyds etc). Peroxides work as starters of radical chain reactions. Epoxides can react (with oxygen) to Peroxides. Thus: having old oxidized oil in your new unoxidized oil will speed up the oxidation process (mostly by reducing the antioxidant capacity in the new oil). >> No, this is not true. Rancidity is the result of the oil reacting >> (slowly) with oxygen in the air. A trace of old rancid oil will not [quoted text clipped - 10 lines] > oxidation process > (mostly by reducing the antioxidant capacity in the new oil). You are way beyond my knowledge of organic chemistry so I'll accept what you say. But the question remains. Regardless of what goes on theoretically, does a trace of old oil actually make a practical difference in how long you can keep oil in the kitchen? For example will your oil go rancid in 2 weeks instead of 2 months? Or will it go rancid in 59 days instead of 60 days? SignaturePeter Aitken Remove the crap from my email address before using. >>> No, this is not true. Rancidity is the result of the oil >>> reacting (slowly) with oxygen in the air. A trace of old [quoted text clipped - 18 lines] > kitchen? For example will your oil go rancid in 2 weeks instead > of 2 months? Or will it go rancid in 59 days instead of 60 days? That is a good question. Let's hope someone amswers it 'cos I too would like to know. You are worrying about the wrong thing. I don't know what that guy's problem is, but in a scientific debate, you make your case, you don't say that you "don't know what to do to begin to address it" or whatever. That is the silliest thing I've ever heard an "expert" say, and that's saying something. And I'm not the first to say what I've said. I've cited scientific papers on this NG over and over again. Just go do a search for montygram and you'll see. In rec.food.cooking montygram <nazztrader@lycos.com> wrote: > That is the silliest thing I've ever heard an "expert" say, > and that's saying something. Given the identity of the guy who said it, you still have not heard an expert say it. SignatureIn the councils of government, we must guard against the acquisition of unwarranted influence, whether sought or unsought, by the military-industrial complex. The potential for the disastrous rise of misplaced power exists and will persist. -- Dwight David Eisenhower From: "montygram" "You really shouldn't be messing with this very dangerous stuff in the first place. Use stable oils like coconut or palm kernel. " ------------------- Palm oil and coconut oil are BAD stuff, if you're trying to keep your arteries clear. Come on. Do better than this. Present some primary source study that supports your case. It looks like you are just stating a preprogramed response. > From: "montygram" "You really shouldn't be messing with this very > dangerous stuff in the > first place. Use stable oils like coconut or palm kernel. " > ------------------- > Palm oil and coconut oil are BAD stuff, if you're trying to keep your > arteries clear. > Come on. Do better than this. Present some primary > source study that supports your case. It looks like > you are just stating a preprogramed response. You're right. Trans fats are a bigger problem, not saturated fats per se. gtoomey Do you realize, nancree, that peoples have used these oils for thousands of years, are very "primitive" in terms of Western medicine, and yet have incredibly low rates of heart disease and other "chronic diseases?" Get a grip. Go to the WHO website and do some research. I'm not asking anyone to "believe" me. The scientific evidence is what it is. And if you want a more precise reason why highly saturated fats are among the healthiest things you can eat, search here for montygram. Even in Willett's "Nutritional Epidemiology," he makes the point that "red meat" is dangerous for all kinds of reasons - saturated fatty acids are not one of those reasons. Found this study that just made its way to pubmed.com It's consistent with the points I've made on this NG time and time again. "Nutrition. 2005 Feb;21(2):240-8. Related Articles,Links Changes in lipid metabolism and antioxidant defense status in spontaneously hypertensive rats and Wistar rats fed a diet enriched with fructose and saturated fatty acids. Girard A, Madani S, El Boustani ES, Belleville J, Prost J. Universite de Bourgogne, UPRES Lipides Nutrition EA 2422, Faculte des Sciences Gabriel, Dijon, France. OBJECTIVE: Larger doses of fructose and saturated fat have been associated with oxidative stress and development of hypertension. The effects of modest amounts of fructose and saturated fatty acids on oxidative stress are unknown. METHODS: To increase knowledge on this question, 10-wk-old spontaneously hypertensive rats and Wistar rats were fed for 8 wk with a control diet or an experimental diet enriched with fructose (18%) and saturated fatty acids (11%; FS diet). The total antioxidant status of organs and red blood cells was assayed by monitoring the rate of free radical-induced red blood cell hemolysis. Sensitivity of very low-density lipoprotein and low-density lipoprotein (VLDL-LDL) to copper-induced lipid peroxidation was determined as the production of thiobarbituric acid-reactive substances. Antioxidant enzymes and vitamins were also measured to establish the oxidative stress effect. RESULTS: The FS diet did not affect blood pressure in either strain, but it increased plasma insulin concentrations only in Wistar rats without affecting those of glucose of either strain. The FS diet significantly enhanced plasma and VLDL-LDL triacylglycerol concentrations without affecting concentrations of VLDL-LDL thiobarbituric acid-reactive substances. The decreased content of arachidonic acid and total polyunsaturated fatty acids in VLDL-LDL by the FS diet may have prevented lipid peroxidation in this fraction. Moreover, FS consumption by both strains was accompanied by a significant increase in total antioxidant capacity of adipose tissue, muscle, heart, and liver. This may have resulted from increased tissue ascorbic acid levels and glutathione peroxidase and glutathione reductase activities in tissues. CONCLUSIONS: These findings clearly indicate that the FS diet did not alter blood pressure of spontaneously hypertensive rats and Wistar rats. The FS diet resulted in hypertriglyceridemia but increased the total antioxidant status, which may prevent lipid peroxidation in these rats." > Found this study that just made its way to pubmed.com It's consistent > with the points I've made on this NG time and time again. How was the lifespan in both groups? Does hyperinsulinism and hypertriglyceridemia or the higher AOC take over here? What was the food composition of the control group? What was the food composition of the test group? What level is meant by "higher" and "increased"? I'm eager to read the full article as soon as it comes available- the abstract leaves too many questions open to discuss it at this point. |
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