How To Test Cooking Oil For Adulteration

How To Test Cooking Oil For Adulteration

In this article, I will try and talk about what adulteration is, its effects, how to check if your oil is adulterated or not, in as simple words as possible. Let's dive in!

What is Adulteration?

According to the Oxford Languages, Adulteration is simply defined as The action of making something poorer in quality by the addition of another substance. Which means, a substance is adulterated if something is added to it, to raise its quantity while decreasing its quality. This is done mainly for making more money out of less quantity, and sometimes to keep up with the rate of consumption of the substance.

When it comes to food, adulteration can lead to even harmful effects in health as we end up eating the food. In India, to prevent adulteration, the Food Safety and Standards Authority of India (FSSAI), has passed laws to determine whether food is adulterated or not. The Prevention Of Food Adulteration Act, 1954, has stated that there are 13 different ways in which food will be considered adulterated.

The food is adulterated,

  1. If it is sold not of how it should be; that is, the food is not to the quality of what it is supposed to be.
  2. If it contains other substances, and it decreases its purity and is harmful to the consumer.
  3. If any cheaper substance is added to the food whether completely or even partly to raise its quantity while reducing its quantity.
  4. If any part of it is abstracted from a substance whether completely or even partly that is harmful to health.
  5. If it is prepared in unsafe environments or eaten in unclean surroundings.
  6. If it is rotten, filthy and is still sold or consumed, whether completely or partly.
  7. If it is prepared from a dead animal.
  8. If it has any toxic or poisonous ingredients that are harmful to health.
  9. If it is prepared and stored in a container that is toxic or poisonous that are harmful to health.
  10. If colouring substance added is harmful to health, or reduces the quality of the food.
  11. If it contains banned preservatives or permitted preservative is harmful to health upon consumption
  12. If quality of it is below the level of consumption and is harmful to health
  13. If quality of it is below the level of consumption but is not harmful to health.(1)

By looking at this, we can see that the government is taking serious measures to stop food being adulterated

Types Of Adulterants

There are two types of adulterants. Intentional, where the adulterants are added intentionally added to boost the quantity, to change colour of natural foods, etc., and Unintentional where adulterants get added because of negligence or lack of proper cleaning and unhygienic protocols - these include insect infested foods, rotten food mixing with clean food etc..

Unintentional adulterants can be avoided by storing food in sanitary environments, conducting proper checking and cleaning before consumption

What are the Harms of Adulteration?

The long term effects of consuming adulterated content as well as short term effects are alarming. An article by Rudrajit Paul, Department of Critical Care Medicine, Institute of Postgraduate Medical Education and Research and SSKM Hospital, Kolkata, West Bengal, India, titled "Poison In The Frying Pan" particularly talks about the instances where adulteration of edible oils has affected the people gravely, giving permanent problems to health.

The article shows how serious adulteration of oils is, particularly the harmful effects of TCOP (Tri-Ortho-Cresyl-Phosphate) when mixed with edible oils(2)

How is Cooking Oil Adulterated?

Cooking oil, or edible oils such as groundnut oil, sesame oil, mustard oil, coconut oil and other such oils are adulterated to raise the quantity of the oils and sold, partly to make more money out of less and to meet the consumption demands of the buyers.

Sesame oil, one of the costliest oils available, is mixed with other oils and sold, so the sellers can make profit. Mustard, Sesame, and groundnut oils are mixed with argemon oil and yellow butter - they do not smell different, nor is it identifiable through the naked eye to see if it is adulterated or not. Coconut oil is mixed with palm kernel olein and is sold. Tri-Ortho-Cresyl-Phosphate (TOCP) is also a popular adulterant as it easily mixes along with other and cannot be detected naturally.

All these adulterants when consumed have known to cause health issues in long term, and immediate symptoms such as indigestion and diarrhoea as well.

How do you Test for Adulterated Oil?

When it comes to testing to spot adulterated oils, the quick tests in large scale, in labs done usually is the FTIR (Fourier Transform Infrared) Spectroscopy. Fourier transform infrared spectroscopy (FTIR) is a technique which is used to obtain infrared spectrum of absorption, emission, and photoconductivity of solid, liquid, and gas. It is used to detect different functional groups in PHB. FTIR spectrum is recorded between 4000 and 400 cm−1.

If you did not understand, don't worry, all you need to know is that this test is used to find and test adulterated oil in large scale, and is very efficient at it. Here is a test done for checking adulteration of sesame oil through FTITR

How to Purity Test at Home?

There are many different ways to test the different oils for purity, mentioned here are a few for each of the popular oils used here in India. The FSSAI (Food Safety and Standards Authority of India) has given easy methods to test oils for adulteration, and checking their website is recommended

Groundnut oil adulteration test

Groundnut oil is usually adulterated with TCOP (Tri-Ortho-Cresyl-Phosphate). It can be checked for purity by taking a small amount of the oil in a cup and dropping a bit of butter in it. If it contains TCOP, the colour of the oil will immediately change to pinkish red

Sesame oil adulteration test

Sesame oil is also generally adulterated using TCOP (Tri-Ortho-Cresyl-Phosphate). So, this oil can also be tested for adulteration with the same method, a bit of butter turning the oil pinkish red can indicate the presence of TCOP in the oil

Coconut oil adulteration test

Coconut oil is often mixed with other oils and sold as coconut oil. To test coconut oil for its purity, a simple way to find out is to pour some oil in a glass and refrigerate it for 30 minutes. when removed, the coconut oil would have thickened and settled down the bottom while other oils will be seen on top, forming a separate layer.


Mustard oil adulteration test

Mustard oil is adulterated by mixing it with argemone oil. To test this oil, you will need nitric acid and a test tube;

  1. Take 5ml of the oil in a test tube
  2. Mix 5ml of nitric acid
  3. Shake well

If the mixture turns pinkish red, then it contains argemone oil along with mustard oil and is not pure

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How Can We Prevent Oils From Being Adulterated?

The first step to make sure you ae not buying adulterated oil should be to look at the packaging carefully. Sellers of oils tend to put the name in the front and say the ratio of the oil mixed with other oils at the back in tiny letters. Please be aware and check if whatever oil you buy is 100 percent the oil you are buying. This is the way to ensure that it is not adulterated. Keep checking everytime and do not get fooled by the picture in the front.

Author: Soap And Oil

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