Weeding out pest...icide residues
With the sheer volume of food arriving on our shores every day, not every single food item in the market can be inspected and tested.
Rather, a risk-based approach is adopted for food safety. This means that food that are of higher risks are subjected to more stringent checks.
Samples of imported food are collected at the point of import, and tested for a wide range of food borne hazards. This is where Joanna comes in.
A Senior Scientist at NCFS, she is part of a 7-man team that tests for the presence of pesticide residues in food.
Put to the test
Joanna’s day starts in the morning when the food samples arrive at the NCFS lab. These include fruits and vegetables from importers at the Pasir Panjang Wholesale Centre, as well as meat and other processed food products like milk powder.
As many of these food items are perishable, the tests have to be conducted quickly.
Tool #1 Speed
“Fruits and vegetables have a shorter shelf life, so we cannot afford to take a long time to do our tests.
It can be pretty fast-paced in the lab — the samples are sent to us in the morning, and we have to process and complete the pesticide residue tests for fruits and vegetables all within the same day.
The results are typically sent to our colleagues in the Joint Operations Division in the evening. For those that fail our tests, our colleagues will follow up with the importers, including rejecting the affected consignments and requiring importers to rectify the issue with their suppliers overseas.”
The science behind it
Unknown to the man on the street, a sizeable amount of time and effort goes into preparing the samples before they are ready to be tested for pesticide residues.
Some people have the impression that we just have to place the food samples into a machine, and we can get the results just by pressing a button with the machine doing most of the work.
That’s not how it actually works. First, we have to prepare the samples for testing by extracting the pesticide residues. Different types of pesticides may be used in food products, so we have to work with a wide range of compounds, which can make our analysis tougher.
We also have to ensure that there is no contamination or interference that could affect the test results.
Next, we have to prepare a solution with a known concentration of the pesticide, for us to compare the sample against. This solution is known as the pesticide reference standard, and provides a basis of comparison for us to identify and quantify the actual amount of pesticide present in the sample.”
A balancing act
Apart from conducting food safety tests, Joanna also balances her time between maintaining the lab instruments and keeping up to date with new emerging food safety trends.
Tool #2 Multi-tasking
“To ensure that our test results are accurate, we do regular maintenance and conduct performance checks on all our lab instruments to ensure that they are working properly.
We also do literature research, participate in international forums and exchange insights with our food safety counterparts overseas. These enable us to keep abreast and equip ourselves with knowledge on new food safety trends.”
An evolving science
Having worked in the pesticide residue lab for close to two decades now, Joanna shares that it doesn’t necessarily mean the work gets easier.
“If anything, it might have become more challenging!” she quips.
Tool #3 Staying nimble
With new emerging pesticides and advancements in lab instruments, the Chemistry major has seen her work evolve over time to keep up with the changing food safety sphere.
“As new pesticides make their way to the market, we have to develop methods to validate and test for these new pesticides in our lab. This is where R&D comes in.
We also develop new testing methods to enhance our food safety testing capabilities.”
The work in ensuring food safety doesn’t end here though. After all, food can be contaminated anywhere along the supply chain.
“Food safety is a joint responsibility. While we do our laboratory testing, food safety can be better assured if the industry plays an active role by ensuring that their food imports meet our food safety standards and requirements. Consumers also play a part in keeping their food safe.
For example, a 30-second rinse of your vegetables followed by a 15 minutes soak and a final rinse can help remove a significant portion of pesticide residue!
So, whether you’re a scientist or food supplier or home cook, all of us have a part to play in food safety.”