A few weeks ago I shared a simple 2-step test to determine the purity of your olive oil. In the test, olive oil either passed or failed. If it passed, it’s pure. If it failed, it isn’t pure. (And likely diluted with polyunsaturated oils).
Turns out this topic is quite the hot debate!
Several readers chimed in with their thoughts and to note that the test wasn’t valid. The links left in the wake were a great resource in pursuing the validity of the fridge test a bit further.
Four weeks later (YIKES!) I’ve FINALLY been able to sift through the information, as well as some other data and articles related to the test. There are as many different viewpoints as there are types of oil, several of which are unmistakably conflicting, which makes it somewhat difficult to put in to plain words that we can all understand (lucky me!).
The only way it can really understandable is by putting all the cards on the table for you guys to read too. Most viewpoints belong on one side of the fence or the other: it either claims the test is true, or claims it’s false. There are some “other” data too though that I felt was too important to exclude, so those have its own section at the end.
Let’s hear from both sides of the story, shall we?
Sources Supporting the Fridge Test
Nourishing Traditions
Sally Fallon writes “Olive oil with its preponderance of oleic acid is the product of a temperate climate. It is liquid at warm temperatures but hardens when refrigerated,” on page 8 of her well-known and reputable book.
Science
Olive oil is naturally made up all three major fats: saturated, monounsaturated and polyunsaturated. The percentage of each fat that can be found in olive oil varies:
- Saturated fat: 8% – 26%
- Monounsaturated fat: 55% – 86%
- Polyunsaturated fat: 3.5% – 22%
As a general rule of thumb:
- Saturated fats are solid to semi-solid at room temperature and cooler (ex: butter, coconut oil and tallow) because of their molecular structure.
- Monounsaturated fats are liquid at room temperature, but solidify at cooler temperatures, also because of their molecular structure.
- Polyunsaturated fats are liquid at room temperature and remain liquid even at cooler temperatures.
Worst case scenario, an olive oil can be 22% polyunsaturated fat. This leaves 78% blend of saturated and monounsaturated fats. Given that both saturated fat AND monounsaturated fats solidify at cooler temperatures, it is highly likely that an oil with such a large percentage of these fats would solidify in the fridge.
Sources Claiming the Fridge Test is False and It is Better to Judge By…
Sensory Tests
There is a crowd that claims the only way to truly judge the purity of olive oil is to perform a sensory test. The color, smell, taste and feel of the oil in the mouth determine its quality. This is one way the International Olive Council (IOC) tests olive oils, however the IOC has very stringent requirements for someone seeking to be one of their qualified testers. The IOC also requires these same conditions of any independent lab seeking IOC accreditation. (source)
It should go without saying (but I’ll say it anyway) – the ordinary customer with an untrained palate does not qualify to perform sensory testing. In order to pass sensory testing, eight different testers must all agree that the oil has zero defects and at least some level of fruitiness.
Is that even reliable?
The way journalist Alex Renton explains it best in his review of Mueller’s book give me a nice chuckle:
I conducted a blind tasting of extra virgin olive oils a few years ago for a national newspaper that wanted “the truth on expensive olive oil.”
We had a dozen oils, and a panel consisting of an importer, an Italian deli owner and a couple of eminent foodies: the results were so embarrassing and confusing the piece was never published. The importer went into a fugue after he was informed that he’d pronounced his own premium product “disgusting”; the deli owner chose a bottle of highly dubious “Italian extra virgin” as his favorite (it had cost £1.99 [$2.59]at the discount store TK Maxx); and both the foodies gave a thumbs-up to Unilever’s much-derided Bertolli brand.
To add to the case, the Olive Oil Times reported in a February 2011 article that 74% of consumers disliked oils identified as high-quality by expert testers and that 44% of the consumers actually preferred oils labeled by the experts as defective in rancidity, fustiness and mustiness. (source)
The Results of the University of California-Davis Study
First, know that there are three studies on olive oil by UC Davis.
First study:
In July 2010, the university set out to evaluate oils sold in California and compare them with the standards set forth by the IOC and the United States Department of Agriculture (USDA) to detect adulterated extra virgin oils. In addition to IOC and USDA testing standards, they also used new testing methods adopted in Germany and Australia. According to this study, the oils were analyzed by a single sensory panel and various chemical tests. Of the oils that failed sensory testing, negative results were confirmed through IOC standard chemical test in 31% of the cases. Chemical testing using methods employed by Germany and Australia confirmed negative sensory testing in 85% of the cases. Researchers recommended incorporating the German and Australian chemical testing methods into the IOC/USDA standards. (source)
Second Study:
In 2011, the university continued to evaluate the quality of extra virgin olive oils, yet tested more samples of fewer brands. Two IOC-accredited sensory panels were used and the results range from a 56% to 94% failure rate. Like the 2010 study, it was suggested that IOC standards would be more effective in assessing and enforcing olive oil quality by including the methods used in Germany and Australia, and also recommended further investigation into the chemical markers of sensory defects. In plain English, the IOC standards are ineffective as they are currently in place, and the lab suggested finding a way to chemically measure what the senses can find. (source)
Third Study:
In 2012, the university evaluated fifteen olive oils labeled extra virgin that were sold to restaurant and food service sectors. In chemical testing, 14 out of 15 olive oils passed to be classified as extra virgin. The one failed sample was adulterated with canola oil. In sensory testing, 9 out of 15 olive oils failed. Tasters of the panel labeled these oils as rancid (describing the oils as “stale walnuts,” “crayons” and “waxy”), fusty/muddy sediment (“olive mill waste pond,” “baby diapers,” and “sweaty gym clothes”) and musty (“moldy” and “earthy”). All oils that failed sensory testing also failed additional chemical testing. (source)
While these studies are filled with great information, they do not create a clear-cut case for sensory testing. In fact, two of the three studies clearly suggest incorporating the specific chemical tests used in Germany and Australia. There is also no mention of refrigeration or cooling of oils in any of the UC Davis studies.
Finally, it is worthy to note that the 2010 and 2011 studies were funded by Corto Olive, California Olive Ranch and the California Olive Oil Council. Similar to canolainfo.org supporting the American Heart Association’s website on the “healthy” benefits of polyunsaturated oils (even though we know they offer NO nutritional value), one must be suspect of test results when the financiers have a vested interest.
Does the Price Make a Difference?
Sources who claim “any oil under this certain price” should be avoided (like Dr. Josh Axe) should eat their words. Consumer Reports (CR) did their own testing on olive oil and found only 2 of 23 to be worthy of the label “excellent.” One of those two bottles costs $58.49. The other was Trader Joe’s California Estate at a much more affordable $11.83. (source) Two additional “best buys” included Kirkland Signature Select Toscano from Costco, which also costs only $11.83 for one liter. (source)
Side note, CR notes that oil can be refrigerated if it’s not used often and that it will liquefy quickly at room temperature. If the oil is to liquefy, then it must solidify, right? 😉
Other Data to Consider:
- By mere definition of the product, the fridge test should only be considered for extra virgin olive oil. All other grades of olive oil are held to a lesser standard and results will not be as reliable.
- The fridge test will not always be 100% accurate. The region where the olives originate may play a part in the percentage of monounsaturated content. It is generally accepted that cooler regions (e.g. Tuscany) will yield oil with higher oleic acid than warmer climates. That is, a cool region olive oil may be more monounsaturated in content than a warm region oil. (source) This could explain why one “pure” olive oil would solidify while another wouldn’t (as in the reader’s comment noted in this article).
- Manufacturers of olive oil produced in the United States label their product according to the US Standards for Grades of Olive Oil published in April 2010. Olive Oil manufacturers are not legally required to follow USDA standards, rather they do so voluntarily. Adherence to these standards is not regulated nor monitored. Manufacturers may have their product tested by the USDA for a fee. The standards were merely designed to facilitate orderly marketing by offering a convenient basis for buying and selling and establishing quality control programs. (source)
What’s a Rookie Real Foodie to Do?
While this data is certainly interesting, there simply is no real clear cut answer. The fridge test isn’t certain, taste buds are unreliable, prices really don’t matter and UC Davis wants more testing. It’s enough to drive us bonkers!
Let’s not go crazy (yet). I’ve devised a second 3-step process that us “ordinary folk” can use to at least weed out the bad oils.
1. Do the fridge test.
I know… I KNOW! All this data just to come right back around where we started? Hear me out.
While the fridge test isn’t 100% true all of the time, it is at a minimum reliable. Because we know the molecular behavior of unsaturated fats. It filters out extra virgin olive oils that are so watered down that there’s barely any oleic acid left.
Granted there may be a chance that a really expensive or high quality oil doesn’t solidify. But to be quite honest, one can really only claim an oil to be high quality if they’re absolutely sure of the source (as in you know the farmer). And the chances of most Crumbs readers splurging on a $60 bottle of olive oil is just not very likely. This a frugal real food blog as it is.
2. Educate Ourselves on Olive Oil
Tom Mueller is a journalist and author of a riveting book titled “Extra Virginity: The Sublime and Scandalous World of Olive Oil.” (He’s also editor of TruthInOliveOil.com.) He submersed himself in everything olive oil for five years and wrote a book that reads like a mystery novel. Mueller unfolds the deceit and fraud that underline the olive oil business (it’s backed by the mob!).
So intrigued by the reviews on Amazon, I bought a copy for myself! Beyond the scandalous stories, he offers excellent and practical advice for those looking to buy true, extra virgin olive oil. I don’t know if I’ll ever get to step #3, but at least I’m doing my homework and I’ll be better equipped at the grocery store!
3. Become an Olive Oil Connoisseur
If you’re one to pour a bit of extra virgin olive oil onto a saucer alongside a delicious balsamic vinegar, swirl a piece of homemade sourdough bread between the two, allowing the flavors to meld and the bread to soak them up before taking a luscious bite… outside of the local Italian restaurant, then get to know what a good olive oil tastes like. Learn how to swirl, roll and decipher between musty, rancid and fusty like the pros and enjoy the learning process (and the great oils discovered!).
If you’re like me and just want some olive oil to make homemade salad dressings, some rosemary olive oil bread or even to lightly flavor grilled vegetables – then the fridge test (supplemented with some good reading) will work just fine.
How Do the Fridge Test Results Compare?
I thought it would be interesting to note how our own fridge tests compared with those done by UC Davis. Below are the tests that were done in the Crumbs Test Kitchen. As well as the oils noted by you guys, the readers. See for yourself how the results compare.
Oils That Remained Liquid (i.e. not pure extra virgin olive oil)
- Bertolli – failed UC Davis
- Filippo Berio – failed Davis
- Star – failed Davis
Oils That Solidified (i.e. labeled correctly as extra virgin olive oil)
- Costco Organic – passed UC Davis
- Costco Signature Toscano (Crumbs second round test, pictured at the top of the post) – not tested by UC Davis, but recommended by Tom Mueller
- CA Olive Ranch – passed UC Davis
- Trader Joe’s – recommended by Consumer Reports
I had done the fridge test and commented on your original article. I’d tested the Bertolli and also a Da Vinci brand and both failed. However, a few days ago I mixed up a batch of Italian dressing and used some of both oils (finishing up what was left of each) and the dressing solidified after about 24 hours. The bottle was placed in the door which I don’t think is even the coldest spot in the fridge. So I’m not really sure what to think. I guess I’ll stand by my previous comment and continue using the oil sparingly – knowing that it may not be 100% pure. I appreciate all the work you’re doing to consolidate the research and share what you learn with us!
Valerie,
The more I researched olive oil the harder it was to come up with a clear definitive answer, but think your suggestion of using it sparingly is best. The spices and other ingredients you used to make the dressing could have impacted it’s solidification, but it’s hard to know for sure. Thank you for your kind words and encouragement! ~Tiffany
Interesting that the oils that failed the fridge test, also failed the “studies” – and the oils that passed the fridge test, passed the studies and/or other testing.
I’d lean towards the fridge test being a little more accurate than some may actually believe. It seems to be pretty reliable based on the research you’ve done !!
It is very interesting Mary Katherine. I didn’t put two and two together until the very end of the research, but I found that to be the best part! Thanks for the encouragement! 🙂 ~Tiffany
I also commented on the original post about my Bertolli not solidifying… I left it in the fridge for 4 or 5 days and it did eventually solidify. I don’t know what to think anymore, but I really appreciate all of your research and effort on our behalf 🙂
Thanks for your kind words Lindsay. 🙂 I don’t know what to think either, but I’m still leaning towards the fridge test. The science just makes sense to me. Unless I can vouch for an awesome oil that DOESN’T solidify, this is just easier for me to go by right now. ~Tiffany
Just to let you know that Bertolli is from Uniliver, owned by corrupt hedge fund OWG, George Soros.
Okay. I did the test on an olive oil I bought at the Weston A. Price Foundation(Olea Estates) and Kirkland cosco olive oil. The Olea Estates oil solidified to about 95% after a week. The Kirkland oil solidified about 50% after about a month. I am going to keep them in the fridge and see if after two months they solidfy. Great article thanks!
Kathy
You’re welcome Kathy! If WAPF recommends Olea Estates and it DOESN’T solidify within 24 hours, then that appears to be a case where quality oil wouldn’t solidify. I think that if left long enough, even the highest quality oil would solidify. For the fridge test, 24-48 hours should be plenty. But then again, here you have an excellent that didn’t… what a crazy topic!! ~Tiffany
I for one know it’s valid, I even tested it on fresh pressed olive oil that my in-laws picked and pressed themselves.
I always try it on different brands, and many have failed… unfortunately it’s difficult to find quality commercial oil, too bad I can’t always make my own.
As for store bought olive oil, I use Whole Foods 365 brand, it partially solidifies when put in the fridge.
Thanks for the update on WF365 Audry. I believe Consumer Reports recommended that brand too. So the olive oil your in-laws made solidified? I’m starting to wonder if making our own is really the only way to know for sure. 🙁 ~Tiffany
I appreciate all the research you did, and your final tips for a real foodie. (You don’t phone it in, girl!) But you left out an important fact. Lower grades of olive oil have the same monounsaturated fat content as the extra virgin, so those will also solidify in the fridge. The same goes for evoos adulterated with other monounsaturated oils like canola, for example. That is why the fridge test doesn’t work (even though it appears to sometimes). Yes, the real thing usually solidifies, but unfortunately, so do many of the fakes.
Carol Ann! You make an excellent point and I had read that, but completely forgot to include it – thank you! *singing merrily* I need an olive farm…. 😉 ~Tiffant
This is fascinating! One would hope that it would be easier to purchase “pure olive oil.” So sad that we can’t even believe what is on the label.
Right?! I was thinking the same thing – it really shouldn’t be THAT difficult! Alas, these are the times we live in… 🙁 ~Tiffany
I could be wrong, but I thought in your last article I read olive oil and lemon juice are the top 2 items that aren’t authentic. any thoughts on how to do a lemon juice test or have something in the works? I love to add lemon to our water kefir, but don’t dare buy the juice after I read that.
Yes Marissa, you read that correctly. I haven’t had the opportunity to do any lemon juice testing yet, but I wouldn’t rule it out for the future! For now, I can only suggest reading the labels. Look for an ingredient list that only contains “lemon juice.” Or if lemons are inexpensive, buy them whole and juice them yourself. You can always freeze it in ice cube trays for easy measuring later. ~Tiffany
*Sigh* trying to eat right can be so overwhelming! Thanks so much for laying out the info so clearly, though and provided a balanced perspective 🙂
Thanks so much for sharing this on Waste Not Want Not Wednesday, I’ve pinned it.
I spent two seasons “Become[ing] an Olive Oil Connoisseur.” in California and learned that there is a lot of corruption in the olive oil business.
One of the things I learned through this journey is that the UC Davis Olive Oil Center exists to bring attention to itself and the olive oil industry; the consumer comes last and is not protected by Center’s olive oil standards-labeling campaigns.
Unfortunately, most California produced olive oil has been watered down by the mechanical processing it undergoes when it is crushed. You will notice this as a mellower flavor–or as a flavor “cut” or washed out by excessive water used during processing. The machines most California olive crushers use come from Italy.
In my opinion, the best olive oil comes from Spain.
I have crushed my own olives and experienced the freshest olive oil possible.
Jay,
Thank you for sharing. My gut feeling on UCD was that they’re there for educational purposes, but not exactly to inform nor protect nor guide the consumer. Your comment reiterated my feeling! All the research I’ve read on olive oil has certainly brought new attention to it. I can’t walk through a store without wanting to read all the labels! Thanks for your tip on the oil from Spain. I’ll add that one to try next! ~Tiffany
For me tasting is the best way to know if an evoo is good, but then I grew up with a Lebanese mother …so I suggest find someone from the Mediterranean area and ask them what brand they buy. I found that some $10-12 bottles taste much better than the so called quality high priced ones.
A man at the Farmer’s Market told me to put an oil sample in the refrig.
and see if there are multiple colors afterwards. I did this w/ Costco Extra Virgin and there were two distinct colors (it had solidified). According to the man this indicates there are two different oils in there. Of course, he was trying to sell me his $18/pint California oil, still have to wonder what else is in the Costco oil?
Interesting JB… I don’t know if the man’s opinions on “two colors = two oils,” but it does make us all wonder what’s in our oil.
Fridge tested OLIVARI EVOO. It solidified in 12 hours and was a solid color. This is a very inexpensive oil mixed from various sources.
Thanks for the update Rick!
hi i lived here in Dubai i just bought olive oil from Palestine i put it in the fridge it does not freeze but there are white streaks in it and sort of cloudy thing on the bottom what does it means
Thank you Dexter!
Is there any significance re quality if it takes longer for the olive oil to solidify completely. I had a store brand solidify within 12 hours and another brand from Greece is not yet solid after 24 hours but is thickening. Could we have more suggestions for what to buy at major Canadian chains such as Metro, No Frills, Food Basics etc. for those of us who cannot access Costco.
FWIW – my grandparents put vegetable oil in the fridge … and it solidifies … so I’m not sure how that necessarily factors in to this because it seems like if non-olive oil can solidify then the fridge test isn’t so helpful.
Hi Sophie – this post was updated with a part 2. Feel free to read it for more on this topic!
Thanks, Tiffany … can you share the link? I read parts one and two so would be interested in a follow up post. I tried finding it on your website without success. It’s probably staring right at me, but I just don’t see it 🙂
Wow! Thank you for all of your research. I am just now hearing about this and I know your post dates back over a year. My copy of Life Extension magazine arrived today with this story on the cover. I had no idea about this insanity so I took to my computer. Well, first I tasted my Colavita EVOO. It was only purchased a few weeks ago at Kroger. I could not believe the results when my husband and myself tasted this horrid stuff. It was so bitter that even thirty minutes later I can’t get that awful taste out of my mouth.
I have to believe it is literally rancid. This may not be an indicator of counterfeit EVOO but I think it MAY indicate that we have been consuming free radicals which terrifies me. The reason I buy EVOO is for the health benefits. I know how dangerous the cancer causing free radicals are according to all of the research.
I’m honestly considering filing a lawsuit against the company. I swear it.
I have my test oil in the fridge now and will take a look tomorrow. Solid or not it sure does not pass the taste test. I know this could be from poor handling and storage before it reached the grocery shelf but that’s just not acceptable.
I am disgusted by this situation and am so angry that greedy mobsters have compromised our health and they would laugh if they read this. They don’t care!
I’ll likely be buying the Trader Joe’s which is an hour drive for me but in these summer months with the heat, I worry about the shipments baking in the sun at a distributorship and won’t shop online until it cools down outside.
This is maddening.
Thanks again for your experiments and good health to you and yours.
Phoebe in Virginia
Hi! I tried it with Trader Joe’s Spanish Organic for 48 hours in the fridge and it ended up like jelly, not solid (like how coconut oil solidifies). Does that count or is it filler?
Is it possible that passing the fridge test is “necessary but not sufficient”? For example, “lampante” olive oil is chemically largely equivalent to other olive oil, but could be rancid, contaminated, etc. and probably would pass the fridge test, but not a sensory test – unless it is mixed with majority “good olive oil,” at which point it tends to pass the test too (as I saw demonstrated in a documentary with expert panels on German TV (ZDF).
It could be Peter. Rememeber that this isn’t a scientific test, and doesn’t necessarily rule “in” olive oils, but can be used to rule “out” non-pure olive oils.
Oh what a mess.
When this whole Olive Oil thing hit I remember hearing that the Olive Oil I buy passed the lab test (A New Zealand brand Pam’s) but yesterday I put some Olive Oil in tiny dipping bowls, one extra light one extra virgin, and neither solidified after 12 hours.
I am going to try again, putting them in bottles, turning the fridge from 4C down to 3C (digital control) and put further back (note, the back on my fridge was freezing things at 3C.
If that doesn’t solidify within 24 hours I will insist that Pam’s produce a lab test and if they can’t shout it loudly.
I hope it works for you, Jonathan!