As a teaser for our lab on Wednesday, Mike brought us all
samples of the cookie we’d be analyzing, the infamous Ricciarelli de Siena.
It’s an oval-shaped cookie made specific to this region that, like olive oil,
is prone to fraud. Little did we know the cookie we tried that morning was
likely not the real thing. It was missing the stamp of authenticity.
The PGI label on the cookie packaging indicates that the
cookie is authentic, made from the only permitted ingredients: sweet almonds,
caster sugar, chicken’s egg whites, icing sugar, and raising agents. Most of
the fraud that occurs with this cookie replaces the almonds with apricot seed
kernels, which cost less and changes the taste of the cookie. The fake cookies
taste bitter and fruitier than they should and are made from de-greased almond
flour. Antonella describes how the only lipids allowed for the production of
the Ricciarelli are the lipids naturally found in almond flour; however, what
people are doing is de-greasing the almond flour and selling the lipids for
others uses. The purpose of our lab was to learn how to detect this fraud using
DNA analysis by looking at genetic SSR markers specific to almond and apricot
seeds. These markers are microsatellites, which are highly repetitive sequences
of DNA ranging from 2-6 base pairs in length. Because detecting this difference
could be as difficult as detecting the presence of a couple of base pairs, a
traditional PCR method using gel electrophoresis was not used. Instead, the DNA
of the cookies was extracted, sequenced, and visualized via peaks on the
computer, the higher peaks generally indicating the presence of almond DNA.
We tested two types of cookies in the lab: one that was authentic (received the PGI label) and one that explicitly stated the use of apricots in the ingredients. Antonella describes how this method was not particularly difficult because the method for DNA extraction was provided in a “DNA Miniprep Kit” she ordered. Everything, from there, was a simple as following a recipe. We prepared the solutions, lysed the cells, did a series of precipitations and filtrations, until we were ready for PCR. We completed the PCR using three specifically designed primers to amplify the DNA for whatever our cookie was composed of. If our cookie were made entirely from almond, it would bind to the primer specific for almond DNA, which differs in length from the primer for apricot. The whole procedure would take about two days to complete and, unfortunately, we weren’t able to complete the analysis portion for our sample. However, we did get to see some of Antonella’s previous results that clearly showed the presence of apricot DNA in the cookie we tested.
Interestingly enough, of the 13 “Ricciarelli” cookies Antonella has tested, she was able to detect the presence of apricot in four of the cookies. These cookies did not have the PGI label and truthfully listed this in the ingredients label. The difference between Ricciarelli and olive oil is that the Ricciarelli problem lies not with the product and the manufacturers but with consumers. They are not necessarily being lied to, just fooled by prettier packaging or a cheaper shelf price. Turns out, the quality of this product can be trusted in the PGI label. If it lacks this, then the ingredients sticker tells all!
We tested two types of cookies in the lab: one that was authentic (received the PGI label) and one that explicitly stated the use of apricots in the ingredients. Antonella describes how this method was not particularly difficult because the method for DNA extraction was provided in a “DNA Miniprep Kit” she ordered. Everything, from there, was a simple as following a recipe. We prepared the solutions, lysed the cells, did a series of precipitations and filtrations, until we were ready for PCR. We completed the PCR using three specifically designed primers to amplify the DNA for whatever our cookie was composed of. If our cookie were made entirely from almond, it would bind to the primer specific for almond DNA, which differs in length from the primer for apricot. The whole procedure would take about two days to complete and, unfortunately, we weren’t able to complete the analysis portion for our sample. However, we did get to see some of Antonella’s previous results that clearly showed the presence of apricot DNA in the cookie we tested.
Interestingly enough, of the 13 “Ricciarelli” cookies Antonella has tested, she was able to detect the presence of apricot in four of the cookies. These cookies did not have the PGI label and truthfully listed this in the ingredients label. The difference between Ricciarelli and olive oil is that the Ricciarelli problem lies not with the product and the manufacturers but with consumers. They are not necessarily being lied to, just fooled by prettier packaging or a cheaper shelf price. Turns out, the quality of this product can be trusted in the PGI label. If it lacks this, then the ingredients sticker tells all!
Sources:
(and of course, Antonella’s work)
Nice post. I hope Mike is reading this blog so he will know to start reading the labels!
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