From burgers and fries to Chinese takeaways, most fast food items contain chemicals. These chemicals are added for a variety of reasons including as preservatives, artificial colours, and artificial flavours. As we explain below, the most common chemicals found in fast food include:

  • Sodium benzoate
  • Potassium sorbate
  • Phthalates
  • Monosodium glutamate

Continue reading to learn more about the different chemicals in fast food, as well as the potential impact on human health.

The popularity of fast food

The popularity of fast food and takeaways has continued to rise over recent years, with sales reaching £21.37 billion in the UK in 2022. But it’s not just Brits who’ve fallen in love with convenience food. According to recent statistics, the global fast food restaurant industry is predicted to be worth $978.4bn in 2023.

Quick to prepare, easy to access, and comparatively inexpensive, it’s easy to see why fast food has become so popular. Thanks to the surge in fast food apps, you don’t even need to leave the comfort of your sofa to get your favourite meal delivered to your door. However, while fast food is undeniably convenient (and tasty), there’s growing concern over its impact on our health.

Close up of a fast food burger

Some people are justifiably worried about the presence of chemicals and artificial preservatives in fast food. Most junk food is also high in calories, saturated fat, and salt – all of which can have long-term negative effects on human health. The obesity epidemic and rise in cases of type 2 diabetes and cardiovascular disease, for example, are largely attributed to an unhealthy diet. 

Yet with sales booming and fast food restaurants virtually ubiquitous in urban areas, our love of convenience food shows no signs of slowing.

Preservatives in fast food

Many of the ingredients in foods like burgers, chicken nuggets, and French fries are pre-processed in factories before they’re distributed to the restaurant chains. This helps to keep food production times down, ensuring the restaurant is both efficient and profitable. To be able to prepare such large quantities of food in advance, manufacturers add chemical preservatives to their products. These preservatives prevent the growth of bacteria and fungi, thereby extending the shelf life of the food.

Here are some of the most common preservatives used in fast food products:

Sodium benzoate

Also known as benzoate soda, sodium benzoate is the salt produced by the neutralisation reaction between benzoic acid and sodium hydroxide. It exists as a white crystalline substance at room temperature and has the chemical formula C6H5COONa. 

Sodium benzoate or E211 in powder form in a petri dish
Sodium benzoate is a commonly used food preservative with the E number E211

Sodium benzoate is commonly used as a food preservative and is very useful in pickling food. It’s also added to salad dressings, carbonated drinks, fruit juices, and frozen yoghurt toppings.

Potassium sorbate 

Potassium sorbate is a salt produced by the neutralisation reaction between sorbic acid and potassium hydroxide. Odourless and tasteless, the substance is a white crystalline solid at room temperature. 

Potassium sorbate is often used as a preservative to inhibit the growth of moulds and yeasts. It’s commonly added as a preservative to things like cheese, wine, dried meats, dehydrated fruits, and baked goods.

A basket of mouldy bread


Phthalates aren’t actually added as preservatives in convenience foods; they’re incidental contaminants that come from the packaging used in fast food restaurants. In one study, about 70% of the fast food items examined were found to be contaminated by phthalates. 

Otherwise known as plasticizers, phthalates are used to manufacture plastics as they help to make them more durable. They’re also used to manufacture lubricating oils and personal care products like shampoos and hair sprays.

How do flavour enhancers work?

Human taste buds can distinguish between five basic types of taste – sweet, sour, bitter, salty and umami, or savoury. Flavour enhancers target the taste buds for umami taste. Just like the primary colours, the different basic taste qualities can be combined in a myriad of ways to produce specific flavours. These can be enhanced by making the taste bud receptors more sensitive to the chemical signals of the food flavours.

Monosodium glutamate (MSG) is commonly used as a flavour enhancer in many types of processed foods, including Chinese takeaway dishes. It has the chemical formula C5H8NO4Na and IUPAC name sodium 2-aminopentanedioate. The glutamate in MSG interacts with the umami component of the taste buds, amplifying the signals in the receptors and thereby enhancing the taste. It also stimulates the salivary glands, which in turn helps to dissolve the flavours.

You can learn more about the chemistry of food additives and preservatives here.

The impact of artificial colours & flavours

Artificial colours and flavours help to make fast food items look and taste better, which makes them more popular with consumers. However, they’ve also been linked to various health problems. Artificial colours, for instance, can cause allergic reactions in some people and hyperactivity in children. Although artificial flavourings don’t directly pose a serious health threat, they’re typically used in food products that are unhealthy and high in saturated fat.

Chemicals from packaging

As we’ve already mentioned, some of the harmful chemicals found in fast food items are present because of contamination from the packaging. Phthalates, for example, can contaminate refrigerated or frozen products such as cheese and burger patties. Over recent years, phthalates have been linked to various health issues including ADHD, asthma, diabetes, obesity, and fertility problems.

To minimise the risk to consumers, it’s important to have biologically safe and hypoallergenic packages. At ReAgent, you can rest assured that all of our products are packed or re-packed to the highest standards and in line with strict industry regulations. You can read more about our rigorous quantity control processes here.

ReAgent packs MG Chemicals products ready for shipping

Health implications of chemical consumption

The chemical additives found in fast food are potential allergens and can therefore have serious health implications for some people. There’s also evidence to suggest that long-term consumption of such chemicals can increase your risk of developing certain types of cancer. 

However, the main health risks are not actually from the chemicals but the quality of the fast food itself. A high-calorie, high-fat, and high-sugar diet is not healthy and can eventually lead to chronic illnesses such as cardiovascular disease and diabetes.


Chemicals are added to fast foods for a variety of reasons, such as to extend the shelf life and improve the flavour, taste or colour. Some of the common chemicals added to fast food include sodium benzoate, potassium sorbate, and monosodium glutamate. Phthalates may also be present due to contamination from fast food packaging. Long-term consumption of chemicals can potentially be detrimental to your health. However, the biggest risk comes from eating fast food itself, which tends to be high in calories, fat and salt.


All content published on the blog is for information only. The blog, its authors, and affiliates cannot be held responsible for any accident, injury or damage caused in part or directly from using the information provided. Additionally, we do not recommend using any chemical without reading the Material Safety Data Sheet (MSDS), which can be obtained from the manufacturer. You should also follow any safety advice and precautions listed on the product label. If you have health and safety related questions, visit