On Thursday afternoon, I described how olive oil is
adulterated with other seed and nut oils to my mother because we cook with
olive oil on almost a daily basis and she needed to know that we might not be
getting the products we are paying for. When I began to tell her of how
difficult hazelnut oil is to detect in adulterated oil, she interrupted me with
a gasp of realization. “That’s why I get sick sometimes after having olive
oil,” she exclaimed. And it hit me that although the FDA does not consider olive
oil to pose a public health threat as long as there are no toxins in the oil
sold in the United States, for all of those with allergies the lack of proper
regulation could result in reactions ranging from unpleasant to dangerous. I
wondered why hazelnut oil adulteration is so difficult to detect and how much
of a threat olive oil spiked with hazelnut oil is to consumers with hazelnut
allergies.
A
study by Amaral et al characterized a variety of hazelnut cultivars in terms of
their chemical, fatty acid and sterol (a specific class of phenols)
compositions. Using gas-liquid chromatography after oil extraction (first
crude, then extraction with petroleum ether solvent), the fatty acid and sterol
compositions of each cultivar was determined. It was found that oleic acid is the major lipid in hazelnut oil, as it is in olive oil. The
range in total sterol content for hazelnut oil was found to be slightly higher
when compared to samples of olive oil from different geographical regions;
however, the ranges had significant overlap, which would make determining olive
oil adulteration with hazelnut oil based on total sterol content pretty tricky.
Comparison of specific sterols appears to be a possible way to determine
hazelnut adulteration in the future because, for example, the campesterol
content of every hazelnut cultivar studied exceeded the 4% upper limit of
campesterol content in olive oil, as established by the EU. Unfortunately, it
was noted that these differences in specific sterol content have not yet been
successful in the determination of hazelnut contamination of olive oil.
After
learning a bit more about hazelnut oil’s characteristics in the context of
olive oil, I found another study the examined the presence of hazelnut
allergens in adulterated olive oil. The study discussed differences between
cold-pressed and solvent extracted hazelnut oil. Much like the differences we
discussed for those processes concerning olive oil, the two extractions of
hazelnut oil yielded slightly different oils. I found interesting that while
the solvent extracted hazelnut oil retained the allergenic proteins, the
cold-pressed oil did not. In fact, even when olive oil was spiked with as low a
level as 1% of solvent extracted hazelnut oil, the proteins were found using a
specific type of gel electrophoresis and the Western blotting technique (Bio
142 anyone?) and then exposed to X-ray film. The potential risk for allergic
reaction was not thoroughly investigated in this study but an immunoblotting of
the proteins indicated that an allergenic protein was recognized by a patient
with a sensitivity to two specific hazelnut allergens. This seemed like a very
good indication to me that hazelnut adulteration poses a health risk for people
with hazelnut allergies, especially because people with tree nut allergies tend
to be allergic to more than one type of nut, increasing their chance of
consuming olive oil adulterated with a nut oil they are allergic to. In my
opinion, the current olive oil fraud is a threat to public health and I hope
that government agencies realize it (and more importantly, make real changes in
regulation) before people experience dangerous allergic reactions due to olive
oil consumption.
Sources:
Extra
Virginity by Tom Mueller
You bring up a very interesting concern. The solvent extraction, though effective in increasing yield, is not selective.
ReplyDeleteI'm glad you are making real-world connections with our readings!
I thought this was a very intriguing concern as well. I'd never thought about the effect of oil adulteration on people with nut allergies, but like your mom said, it's definitely a legitimate concern!
ReplyDeleteI did some further research on this topic, because I thought there has to be some sort of regulation about listing allergens in food. I mean, practically every food label nowadays says "product may contain nuts" even if I think there's no possible way there could be any trace of nuts. I came across the Food Allergen Labeling and Consumer Protection act, which was passed in 2004 and came into effect in 2006, requires manufacturers to say on the food label whether the product may contain any of the 8 most common food allergens, which includes tree nuts. And not only does it say the allergen must be mentioned, the law says the allergen must be listed as its "common name," so it would have to say "may contain tree nuts." Not to do so would result in civil and criminal penalties for the manufacturer.
I read this and thought, "Hey, olive oil companies should be getting in serious trouble for mixing with hazelnut oil!" But then I scrolled down and saw under the section EXCEPTIONS that the law does not apply to "any highly refined oil derived from [one of the eight food allergens] and any ingredient derived from such highly refined oil." So the act specifically excludes oil from its new regulations. The fact that it singled out olive oil was really curious and honestly kind of frustrating.
There seems to be no light at the end of the tunnel for the battle against fraudulent olive oil manufacturers if olive oil keeps slipping through the cracks like this. (See what I did there? Slipping through the cracks? Because olive oil is slippery... never mind)
Oops... sources. Right.
ReplyDeletehttp://www.fda.gov/food/labelingnutrition/FoodAllergensLabeling/GuidanceComplianceRegulatoryInformation/ucm106187.htm
http://www.fns.usda.gov/fdd/facts/nutrition/foodallergenfactsheet.pdf
http://www.illinoisfaea.org/is-it-olive-oil-or-hazelnut-oil/