By Dr. Mercola
Olive oil, a dietary staple in Mediterranean regions, is now
a healthy favorite oil in the US, valued not only for its flavor
but also its health benefits.
Rich in monounsaturated fats, olive oil may help lower your
risk of heart disease and may even benefit insulin levels and
blood sugar control, helping to lower the risk of type 2
diabetes.
As with most foods, however, not all olive oil is created
equal. There’s a wide variation between high-quality and
low-quality oils, and even among the best varieties, rancidity
is a major problem.
4 Signs of Defective Olive Oil
When you spend the money on a quality bottle of olive oil,
you want to know that you’re getting what you pay for. However,
there are many factors that influence quality, from how long the
olives sat before processing to how long you’ve left the oil sit
out on your counter.
As The Olive Oil Times reported,
paying attention to these four potential defects can help
you weed out the good oils from the bad:
- Rancidity
Olive oil is highly perishable, but is generally said to
be ‘good’ for two years from the date it was bottled (this
will usually be the ‘Best By’ date). However, a better
indicator of freshness is to go by its harvest date, which
will tell you when the oil was actually made. Only select
oils that have this information on the bottle.
So the first step is finding an oil that was harvested as
recently as possible. From there, many other factors,
including storage temperature, exposure to air and light,
the level of antioxidants and chlorophyll content in the
oil, will also influence how resistant it is to going
rancid.
All olive oil will get rancid eventually, but if you're
like most people, you're probably leaving your bottle of
olive oil right on the counter, opening and closing it
multiple times a week (or even a day). Every time the oil is
exposed to air and/or light, it undergoes oxidiation and
will get rancid quicker.
Extra-virgin olive oil, in particular, also contains
chlorophyll that accelerates decomposition and makes the oil
go rancid even faster than semi-refined olive oils,
according to oil expert
Dr. Rudi Moerck. So how can you tell if your olive oil
is rancid?
- It smells like crayons or putty
- It tastes like rancid nuts
- It has a greasy mouthfeel
Unfortunately, as The Olive Oil Times reported:
“The sad truth is that most people in the US… are
accustomed to the flavor of rancid olive oil.”
- Fusty Oil
‘Fusty’ oil occurs when olives sit too long (even just a
few days) before they’re milled, leading to fermentation in
the absence of oxygen. Fusty flavors are incredibly common
in olive oil, so many simply think it’s normal. However,
your olive oil should not have a fermented smell to it,
reminiscent of sweaty socks or swampy vegetation.
“A good way to taste an example of the fusty
defect involves table olives,” The Olive Oil Times
reported.
“Look through a batch of Kalamata-style
olives and see if you can find any that are not purple
or maroon-black and firm, but instead are brown and
mushy. Eat one. THAT is the flavor of fusty.”
- Moldy Olives
If your olive oil tastes dusty or musty, it’s probably
because it was made from moldy olives, another occasional
olive oil defect.
- Wine or Vinegar Flavor
If your olive oil tastes like it has undertones of wine
and vinegar (or even nail polish), it’s probably because the
olives underwent fermentation with oxygen, leading to this
sharp, undesirable flavor.
Extra Virgin Olive Oil Is One of the Most Commonly Adulterated
Foods
The four defects above are examples of what commonly occurs
due to poor processing methods or handling. However, olive oil
is also a common target of food fraud, in which it is
deliberately adulterated at your expense, according to the U.S.
Pharmacopeial Convention's (USP) Food Fraud Database.
Even “extra virgin” olive oil is often diluted with other
less expensive oils, including hazelnut, soybean, corn,
sunflower, palm, sesame, grape seed and walnut. But these other
oils will not be listed on the label, nor will most people be
able to discern that their olive oil is not pure.
If you live in an area where olive oil is made, buying from a
local producer is the ideal solution as it allows you to know
exactly what’s in your oil. If not, try an independent olive oil
shop that can tell you about the growers, or at least seek out a
brand name that you trust to produce quality oil from your local
supermarket.
If at all possible, taste the oil before you buy it. While
this won’t necessarily be a guarantee of quality (especially if
you’re not skilled at picking out all the potentially subtle
taste differences), it can help you to pick out the
freshest-tasting oil possible (and if you open a bottle at home
and find that it tastes rancid or ‘bad,’ return it to the store
for a refund).
The Fridge Test: Not a Good Measure of Olive Oil Quality
Earlier this year, The Dr. Oz Show featured a segment on the
olive oil ‘fridge test,’ which suggested that you can tell your
extra virgin olive oil is pure if it solidifies in the fridge.
The US Davis Olive Center decided to test the theory out and
found that this is actually a very unreliable way to detect
olive oil purity.
In fact, the Olive Center researchers refrigerated seven
samples of oil and found that none of them congealed
after 60 hours in the fridge.
While some had areas that had hardened, due to the varying
levels of saturated fats in the oil, none solidified completely.
So you can save yourself the effort and avoid using this test.
“All olive oils contain a small amount of saturated
fatty acids that solidify at refrigerator temperatures,”
said Paul Vossen, UC Cooperative Extension advisor. “The
amount of solidification is equal to the amount of saturated
fatty acids in the oil, which depends mostly on the
varieties of olives used to make the oil and to a lesser
extent where the olives were grown. Solidification does not
indicate freshness, purity, flavor, extra virgin grade, or
any other quality parameter.”
Are You Cooking With Olive Oil? Stop!
Olive oil is an ideal oil when it’s used cold, such
as drizzled over a salad or on top of homemade hummus. However,
it's important to realize olive oil is NOT good for cooking. Due
to its chemical structure and a large amount of monounsaturated
fats such as oleic acid, cooking makes extra virgin olive oil
very susceptible to oxidative damage.
Consuming oxidized, rancid oil is not going to benefit your
health, so when you need an oil to cook with,
coconut oil is the ideal choice, because it is one of the
only commonly used vegetable fats stable enough to resist
heat-induced damage. Remember, olive oil is excellent when used
for cold dishes, but cooking with it is virtually guaranteed to
damage this highly heat-sensitive oil.
Tips for Keeping Your Olive Oil Fresh
Once you’ve chosen a bottle of olive oil (being careful to
choose a trusted brand and check dates on the bottle), what you
do with it once you get it home can make a difference in its
shelf life. To best protect the oil, Dr. Moerck recommends
treating it with the same care as you would sensitive omega-3
oils:
- Keep in a cool, dark place -- dark is key because light
will most definitely oxidize the fats in olive oil
- Purchase smaller bottles rather than larger to ensure
freshness
- Immediately replace the cap after each pour
To further help protect extra virgin olive oil from
oxidation, Dr. Moerck suggests putting one drop of astaxanthin
into the bottle. You can purchase astaxanthin, which is an
extremely potent antioxidant, in soft gel capsules. Just prick
it with a pin and squeeze the capsule into the oil. The
beautiful thing about using astaxanthin instead of another
antioxidant, such as vitamin E, is that it is naturally red,
whereas vitamin E is colorless, so you can tell the oil still
has astaxanthin in it by its color. As the olive oil starts to
pale in color, you know it's time to throw it away.
Generally speaking, olive oil is best consumed within a year
of harvest, although most will last for up to two years
from harvest when unopened and kept in a cool dark place. Oils
that have a more bitter, peppery flavor have a higher polyphenol
content, and these oils will generally keep better than oils
made from ripe olives, which have a softer flavor. The latter
should be used within six months to a year at most.
This is yet another reason to purchase olive oil in small
bottles, rather than large, as it is easier to use up in a
shorter period. If you purchase a large amount of olive oil you
may be tempted to keep it even though it has gone rancid.
© Copyright 1997-2013 Dr. Joseph Mercola. All Rights Reserved.