Tuesday, September 11, 2018
PCR for Peanut Chloroplast DNA
This article from Science Daily summarizes a recently published article in the Journal of Agricultural and Food Chemistry about a new method involving DNA to detect trace amounts of peanuts in baked goods, chocolate and tomato sauce. This is extremely practical in the sense that peanut allergies are one of the most common allergies, and there are at least 3 million people in the US alone that suffer from this type of food allergy (1). A lot of people with this type of allergy can suffer from anaphylaxis when the allergy is triggered, even from only trace amounts of peanut. Anaphylaxis can be life-threatening and usually involves breathing difficulty, rashes, and nausea; if not treated with the Epipen, it can lead to unconsciousness or death in extreme cases.
The team chose to study the chloroplast DNA of the peanut for several reasons. First, there had been previous research involving testing for the proteins in the peanut. This research is effective, but many of the proteins in peanuts can be destroyed during food processing. The nuclear DNA in the peanut can also be tested for with PCR, or polymerase chain reaction. However, it may prove challenging to find nuclear DNA sequences unique to only the peanut. The team wanted to try a new approach with chloroplast DNA in peanuts because chloroplasts are more abundant in the peanut compared with having only one nucleus per cell. The peanut chloroplast DNA is unique to the peanut only, so the team did not have to worry about overlapping sequences with other foods.
The team was able to successfully use PCR to test for three sequences in the peanut chloroplast DNA. Having three regions to test made their results even more convincing that the DNA is from peanuts, and not any other plant. The PCR successfully detected trace amounts of peanut in all of the food they tested, and were able to test for the peanut traces as low as 1 PPM. This is an improvement upon the 10-50PPM limit in PCR that tests for peanut nuclear DNA.
The reason I chose this article and enjoyed it was because of my personal connection. I have a severe egg allergy, and it too can be set off by trace amounts of egg, and it can even be triggered by breathing in the air containing eggs. I understand how serious these allergies can be because there can be cross-contamination with pots and pans and that is enough to trigger an allergic reaction. I am very happy to know that PCR can now detect trace amounts of peanut chloroplast DNA, but eggs do not have chloroplast. Maybe another team can develop a PCR method that detects mitochondrial DNA unique to eggs. It makes me very happy to know that there is research out there that is helping food allergy suffers make their lives a little easier. Maybe one day they will invent some kind of food scanner that can tell an allergy sufferer if the food contains the allergen. We're not there yet, but maybe one day.
Scientists Have Identified A Key Gene Linked To Peanut Allergies