Now, cooked food under varsity lens

Cocktail effect of pesticide residues in ingredient vegetables

In a move aimed at enhancing food safety standards, Kerala Agricultural University (KAU) is planning to carry out regular laboratory analysis of cooked food to assess the chemical cocktail effect of pesticide residues in the vegetables.

The Pesticide Residue Research and Analytical Laboratory under the KAU will be equipped to analyse samples of staple vegetarian dishes such as sambar, aviyal and thoran, Vice Chancellor P.Rajendran said.

“To assess the toxic impact of chemicals on health, it is important to assess how much of pesticide residues are left after cooking. Though most pesticides are known to break down on exposure to heat, some may become more toxic in combination with others. The cocktail effect could be more in dishes which are a combination of several vegetables.”

The pesticide residue lab carries out periodic analysis of vegetable samples by testing them in isolation but scientists feel that it is more important to address the manner in which chemicals mix and react with each other.

Analysis of cooked food samples presents a different kind of challenge for scientists. Unlike testing vegetables in isolation which follows validated methods, cooked food samples will have to analysed individually and in combination.

It is a highly complex process, admits Thomas Biju Mathew, Professor and principal investigator of the project. Changing dietary habits can also pose a challenge in analysing cooked food for pesticide residue.

“Initial investigations revealed that 85 to 90 per cent of pesticide residue in amaranthus decomposes on cooking while in the case of chilli, there is no significant reduction on exposure to heat. Depending on the chemistry, the cocktail effect can intensify or diminish in some preparations,” Prof. Mathew said.

Periodic tests carried out at the KAU laboratory have revealed heavy pesticide contamination of vegetables imported from neighbouring States, in contrast to those grown domestically.

Curry leaf, coriander leaf, mint leaf, and green chilly regularly supplied from big farms across the border showed heavy load of profenofos and chlorpyrifos, organophosphorous fertilizers not recommended for vegetables. High levels of pesticide residue were also detected in samples of okra, cabbage, and cauliflower.

Set up under the All India Network Project on Pesticide Residues, the KAU laboratory is equipped with sophisticated instruments such as gas chromatograph, liquid chromatograph, and mass spectrometer to detect even minute traces of pesticide.

Staple dishes such as sambar, aviyal, and thoran to be analysed
Cocktail effect more in dishes which are a combination of vegetables
Cocktail effect of pesticide residues in ingredient vegetables