Oil Processing

     Around the web and even in nutrition text books, we often  are referred to the vague term processing in regards to food stuffs manufacturing. I think most health conscious individuals acknowledge that processing is generally deleterious to the health providing qualities of food. For example refined flour, refined sugar, refined oil, etc. However I have often found that understanding the so called processing that takes place, even if only in a rudimentary manner, gives me further motivation to not eat industrialized food stuffs. I guess one might say actually knowing the methods behind the madness makes the food that much more unappeasing. Today I wanted to go over the steps from which a soybean, cotton kernel, corn kernel, and other seeds become industrial oils. I attribute much of the following information to be sourced from the online Encyclopedia Brittanica and Fats that Heal, Fats that Kill* by Udo Erasmus.

      The initiation of the process that takes a commodity seed to oil begins with general cleaning of the seed and possibly cooking. On one hand, the cooking is neccessary. Many of the seeds used, such as soy beans contain anti-nutrients such as trypsin inhibitors (1) that are only inactivated with heat. The raw oil would otherwise be inedible. Another advantage of this specific step is that heating the seed makes the pressing process (this is the following step) or the chemical extraction process (to be explained later) easier by denaturing the cell membranes which encompass the desired oils. However on the other other hand, the cooking process greatly accelerates the onset of rancidity exposing the oils to both air and heat, and possibly light (Textbook of Medical Biochemistry, Ramakrishnan, P.41) . This is confounded by the fact that most of the common commercial oils contain high proportions of the more delicate polyunsaturated fats( Ramakrishnan, P. 267).

Typical oil seeds; corn, cotton, soy, sunflower

     The next step in the process is the mechanical pressing of the seeds to extract oil. We often see this on the label of more traditional oils such as coconut, palm, and olive oils as expeller pressed. The method essentially involves subjecting the raw material to high amounts of mechanical pressure. Often times what is called a screw press is used (illustration below). This involves a continuoulsy rotating screw shaped auger pushing the seeds forward against a metal press. The friction created by the rotating auger combines with the high heat to squeeze the oil out of the seeds.The oil is released by of hole or slits in the press while the remaining solid mass(seed mash) is left behind for further processing. Accoridng to Erasmus, (p. 95) it is said that the pressing temperature takes place at 85 to 95 degrees Celsius or185 to 203 F, which subsequently  greatly increases the rate of lipid rancidity. When the end product of this mechanical extraction is sold without further processing, we have the true unrefined oils.

screw press, sounds like a resistance training exercise.

     Another consideration here is that saturated fats such as coconout and palm are less prone to be damaged by the high temperatures used (Ramakrishnan, P. 39,41). Although some companies claim to use cold pressed, Erasmus states there is not a set industry standard for this criterion or claim. The next procees described is solvent extraction, a more modern industrial practice used to further enhance the oil extraction from the seed mash, or that can be used independent of mechanical pressing.

      Solvent extraction is a very efficient means of oil extraction used by large scale industrial operations. Solvents such as heptane or hexane are used to dissolve ground seed meal or the remaining seed mash described above whilst also using mechanical agitation (think stirring on steroids). The solvent-oil mixture is separated from the naturally occuring protein and carbohydrate portion of the original seed. The same thing is going on here as the saying about oil & water dont mix. The heptane is similar to oil so it mixes while the protein, carbs, and water are repelled.) The solvent can then be evaporated at roughly 150 degrees Celsius or 302 F. The seed oil is then left behind with very minute quantities of the solvents left behind. The ranges I have found are in the range of  10-21 ppm (2). Although I am not a fan of hexane, I will say that the concentration left behind in oils does not seem to be a major casuse for concern (although there are many). What may be disconcerning to some health conscious consumers is that the solvent extracted oil may still be labeled as unrefined at this point, again placing greater importance to choosing  the expeller pressed brands if hexane is a key concern for the consumer.For the more commonly sold vbegetable oils and the oils labeled as refined, such as Spectrum refined coconut oil or NOW brands natural coconut oil, further chemical processing takes place.

       Degumming, or alkali refining is a process that removes the phospholipids naturally occuring in seed oils, such as soy lecithin (phospholipid wiki). Left behind proteins and polysaccharides (complex carbohydrates) from the preceeding extraction methods are also removed during degumming. As far as the possible health worries Erasmus claims that degumming removes chlorophyll, calcium, magnesium, iron, and copper. The degumming process is generally carried out at roughly 140 F (Erasmus, P. 96).

      During the process known as water refining or just refining, oils are mixed with strong bases  (proton or hydrogen ion acceptors that completely dissolve in water) such as sodium hydroxide (NaOH). Refining is meant to further remove free fatty acids from oils.The free fatty acids form soaps with the bases (eg NaOH) and dissolve in the hydrophilic (water loving) portion of the mixture. This aqueous solution is then drained off, or centrifuged and then drained off from the oil. The temperature at which refining takes place is roughly 75 degrees celcius or 167 F. Phospholipids, polypeptides, and minerals are also lost in this process (Erasmus, P. 96). Before moving on, I have to make note that at this point, the proccessing of the oil has not only removed health promoting components of the oil like lecithin and minerals like iron, zinc, and so forth, but that they are then sold back to consumers in the form of soap, soy lecithin, etc.Its pretty crazy. Although pigments may still remain., theyl'l be gone soon enough. Next up are bleaching and deodorizing.

     Bleaching is used if removal of the pigments is desired. The remaining oil treated with various bleaching agents, which may include fuller’s earth (a natural earthy material that will decolorize oils), activated carbon, or activated clays. The bleaching agents mentioned remove beneficial pigments such as chlorophyll and beta-carotene.Magnesium is stored in the chlorophyll and beta carotene is a pre cursor to Vitamin A. Additionally if the centrifuge method was not used during refinement, additonal FFAs may be removed during bleaching. The temperature at which this process takes place is 110 Celsius or 230 F. According to Erasmus, this process forms toxic peroxides as well (Erasmus P. 96).

    Deodorizing involves steam distillation under pressure. The deodorization removes any aromatic compounds that impart any remaining pungent taste or odor to the oil.  Erasmus notes that deodorization takes place a highly destructive temperatures in the range of 240 to 270 degrees Celsius or 465-520 F! And this process is said to last 30 to 60 minute depending on the oil. These temperatures are high enough to result in carcinogenic mutations to the remaining fats in the oil (3).  Trans-fatty acids are also formed at such high temperatures. Although deodorization removes some of the peroxides formed during earlier stages of processing , as well as pesticide residues, tocopherols (Vitamin E) and plant sterols are also removed as well. (Erasmus P.97)

      At this point, the oil processor has yielded a valuable commodity. Flavorless, colorless, tasteless oil (yum!) that can be further handled to add flavors, textures, colors, etc. that meet the consumer's demands for highly palatable cheap frankenfood. However, with the exception  of some of the healthier oils, such as palm, coconut, and olive oil, most of these will have synthetic antioxidants added in back as well, such as butylated hydroxytoluene (BHT), or tertiary butyhydroquinone (TBHQ). These replace the plant's natural antioxidants such as the above mentioned phytochemical, Vitamin E, and beta carotene.

     As you can establish for yourselves at this point, the processing of oils, while an intriguing science, does not appear to be the optimal method of foos extraction for promoting good health. In fact up until the late 20th century there were wide spread nutrient deficiencies due to processing food without the realization that key nutrients were lost. It was believed that  biologically complete diets need only to consistr sufficient proteins, carbohydrates, fats, inorganic salts, and water (4). Unfortunately or fortunately it was later discovered that we needed micronutrients in the form of vitamins, minerals, and phytochemicals. While fortification of foods with certain nutrients has probably helped, I still don't believe it's enough. Below I have created a table based the calculations of Weton A. Price in Nutrition and Physical Degeneration (P.246 & 247) to show just how lacking the American diet was compared to traditional diets in his time.The numbers are how many times more of the listed nutrient (eg Ca) that the traditional cultures recieved in contrast to urbanized  Americans at the time (mid 1930's) through diet. Its pretty amazing.

    With that said, processed oils (along with processed sugar and flour) just make up too much of the American diet. The USDA recently reported that we are consuming 1.4 billion pounds of cottonseed oil, alone, annually (see here).We are eating the oils of these seeds in proportions that we would never eat in the form of real food. I have blogged on this previously as well (here). The nutrient density is just not there in addition to the synergistic effect that I believe real food nutrients provide when eaten together as one in the context of real food.



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* While I found Erasmus's book helpful for this post, I think it is important to disclose he does sell his own oil blends that are focused more on the EFA rather than the coconut oil, palm, and olive oil I would reccomend. I believe eating the fat from sources like coconuts and olives that are mostly fat, when found in nature, is probably more suitable for humans in that eating large amounts of fat from these foods is not new to us as a species.

Nutraceuticals: Vinegar

One of the first dietary "supplements"...vinegar.

The term "nutraceutical" was coined by combining "nutrition" and "pharmaceutical" in 1989 by Stephen DeFelice, MD. According to DeFelice, "A nutraceutical is any substance that is a food or a part of a food and provides medical or health benefits, including the prevention and treatment of disease." I plan to start a series on a small number of whole food dietary adjuncts that I think should be adopted nearly universally based on science and anecdote. Whether vegan or "meatitarian" they may be of some value and worth considering adding to the diet. I will start with vinegar.



First off there are whole books on vinegar and it's purported health benefits. I want to keep this post readable, so I'll mostly, not entirely, focus vinegars role in regulating glycemia and insulin. This is of particualr importance to those concerned with Type II Dieabetes management, weight loos, and possibly athletes (vinegar may be implicated in improving glycogen re-synthesis as well). I also try to focus mainly on the scientific research that supports these claims and delve into the possible mechanisms by which vinegar maybe working.


Vinegar has a pretty lengthy track record. Its been reported in the literature that  Hippocrates, the father of medicine used vinegar medicinally to manage wounds as far back as the 5th century BC. Sung Tse, one of the 10th century creators of forensic medicine, preached practice of hand washing with sulfur and vinegar to avoid infection during autopsies (1). According to the Folk Medicine History of Archives many common ailments including poison ivy, croup, and stomach-ache were treated with vinegar. Before the production of glycemic regulating pharmaceuticals (e.g. metformin), vinegar tinctures were commonly consumed by diabetics to help manage their condition (2).


A lot of the more recent research involving vinegar has investigated its effects on postprandial glycemic regulations. In simpler terms, it has looked at the glucose response to a meal with or without vinegar added to the meal, either with the meal, or some extended time before hand; say 5 hours.  In comparison to fasting blood glucose and hemoglobin A1c, postprandial glycemia (PPG) is considered the earliest dysglycemic marker for cardiovascular disease (CVD) and the onset of Diabetes. It has been reported that PPG is linearly related to CVD risk across nondiabetic and diabetic ranges (3). The adverse effects of elevated PPG, even when fasting blood glucose or hemoglobin A1c concentrations are normal, lies in that even acute elevations in blood glucose are implicated  in the formation of free radicals and inflammatory mediators (4).


Several studies have found a relationship of varying degree implicating that vinegar has the ability to 
lower the glycaemic response to a large carbohydrate load (3,5,6,7). However the mechanisms behind the action of vinegar remain unknown for the most part. Earlier investigators in the field speculated that improved glycaemic and insulin responses to a white bread reference meal was probably due to delayed gastric emptying evoked by the vinegar somehow (6). In 2005, Ostman and colleagues also witnessed that the addition of vinegar to a meal based on white bread reduced postprandial responses of blood glucose and insulin, and increased the subjective rating of satiety. Here too, the investigators speculated that the mechanism was impaired gastric emptying or due to  or to the inhibition of digestive enzymes. In cultured Caco-2 cells, the addition of acetic acid, but not other organic acids such as citric or lactic acids, inhibited sucrase, maltase, trehalase and lactase activity (3). However the inhibition of these enzymes in vitro (see here) does not neccessarily mean that the same will occur in humans.




More recent recent research has revealed that vinegar may act through other potential mechanisms, which is what I suspect personally. A 2009 study by Arline Salbe, Carol Johnston (the rock star of vinegar research lol), and colleagues seems to have ruled out the possibility of delayed gastric emptying (8). The researchers suppressed insulin secretion using an oral octreotide/insulin suppression test (OOST) designed to quantify the rate of glucose absorption without the confounding effects of variable glucose clearance due to rising endogenous insulin secretion. The OOST  suppressed endogenous insulin secretion for the first 100 minutes of data collection following the assigned meal. During this time, the  rise of glucose was modestly but significantly (P = .01) greater after vinegar ingestion compared to placebo, suggesting that vinegar does not act to decrease glycemia by interference with enteral carbohydrate absorption.


With gastric emptying ruled out, I would say the best bet is probably that inegar improves insulin sensitivity. A 2004 study also done by Johnston seems to support this. Johnston and fellow researchers found that vinegar improved insulin sensitivity to a high carbohydrate meal in subjects (9). The study included nondiabetic subjects who were either insulin sensitive (controls) or insulin resistant and subjects with type 2 diabetes. Here the subjects recieved a diluted vinegar solution (20 g apple cider vinegar, 40 g water, and 1 tsp saccharine) or placebo drink and, after a 2-min delay the test meal, which was composed of a white bagel, butter, and orange juice for a total of 87 carbohydrates. Blood samples were collected at fasting and 30 and 60 min postmeal for glucose and insulin analyses.


Compared with the placebo drink, vinegar ingestion raised whole-body insulin sensitivity during the 60-min post meal interval in insulin-resistant subjects (34%, P = 0.01, paired t test) and in subjects with type 2 diabetes (19%, P = 0.07). Postprandial fluxes in insulin were significantly reduced by vinegar in healthy subjects as well (% not reported).  I think it is interesting to note that the normal subjects postprandial glucose was not significantly altered but that it took less insulin to regulate the response. So far this is the most solid evidence I have found to support the use of vinegar in improving insulin sensitivity. However there is animal research as well.


A 2001 rat study found that acetic acid feeding enhanced muscle glycogen repletion in rats(10). Any exercise physiology text will read that insulin is antagonistic to glucagon in that it inhibits the breakdown of glycogen and aids in the repletion process. Furthermore two more recent rat studies  have replicated these findings (11 & 12). In fact the most recent of these studies found that the rats fed the acetic acid  had a significantly  lower ratio of insulin to glucagon than the control group at the same point of analyses. Despite this, the acetic acid group had significantly greater liver and gastrocnemius muscle glycogen concentrations. Now granted, I am making some extrapolations here by assuming what worked in rat works for humans, but coupled with the limited direct evidence available, it does appear to strengthen the potential of this mechanism as a possibility.


Lastly, I came across yet another investigation led by Johnston that did not look at insulin directly but found that vinegar ingestion decreased blood glucose response to the same test meal described earlier and improved satiety as well (13). Consumption of vinegar with the high carb test meal was associated with a a reduction of roughly 200-275 Calories throughout the day, sugeesting an improvement in insulin control.


How might one incorporate vinegar?


In order to blind the subjects, researchers typically disguise the vinegar by adding saccahrine and food coloring. Personally I just drink a couple sips of the vinegar straight up followed by water. However other people using vinegar anecdotally are using more palatable concotions such as mixing with honey to make oxymel or mixing it with stevia. In regards to kind and type of vinegar, in the U.S. apple cider vider vinegar is the most commonly used, however it seems coconut, white wine, balsamic, and so forth would work just as well because they all contain the acetic acid. The studies I read were using heinz and claim that the advocation of the "the mother" found in most of the organic, unpasteurized varieties is unsubstantiated. Personally I always buy a brand that includes the mother based on the assumption of it has a long track record, and at the very worst, it probably cant hurt. Depending on one's goals it seems appropriate to have some vinegar with regular meals and/or or peri-workout nutrition.


*Studies in the field have many peculiarities. For example in the investigations  by Johnston et al (3), 10 g of a vinegar in a diluted solution produced significant effects in lowering the glycaemic response to a large carbohydrate load, whereas 20 g did not. In the trial conducted by Ostman et al. (5) there was an observed inverse dose-response relationship between the level of acetic acid (1.0, 1.4 and 1.8 g) and the PPG response to a 50-gram carbohydrate load.