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Unveiling Food Preservatives: Intersection Between Safety and Shelf Life

Edited by Ryan Jien

What is your favourite food? Allow this question to ruminate in your mind while I share with you about the fascinating and miraculous compounds that extend the shelf life of our food: food preservatives. In a world where longevity and convenience take over, the modern food industry has found itself entwined with the essential, yet controversial food preservatives. 

Preservatives are substances added to products such as food, beverages, pharmaceutical drugs and cosmetics to prolong its shelf life by preventing microbial growth. Preservation can be done chemically, through adding chemical compounds to the products, or physically, such as through the process of drying or freezing. 

Figure 1. Preserved Food

Food preservation pre-date the dawn of agriculture, in which traditional methods such as boiling, smoking, fermentation, freezing, and heating were widely used. Modern methods on the other hand, include pasteurisation, vacuum packing, artificial food additives, irradiation, biopreservation, and etc. Commonly used traditional preservatives are such as salt, which is used to draw out moisture from food to inhibit the growth of microorganisms. Besides, sugar, vinegar, and spices can also be used for the same purpose. 

In this fast-paced dynamic 21st century, traditional food preservatives may not provide the same level of effectiveness and convenience especially with the constant whirlwind of changes in the food industry. It is much more time consuming, requires more human monitoring for quality checks, and does not completely ensure protection to avoid food spoilage. This is where modern preservatives—which are usually added directly during the manufacturing processcome in handy. 

Figure 2. Structure of benzoate

Benzoate is the conjugate base of benzoic acid. In the food industry, sodium benzoate and benzoic acid are used as food preservatives to prevent spoilage from harmful bacterias and prevent change in taste and texture of the food. Some foods that commonly include sodium benzoate as food preservatives are sauces, soft drinks, condiments, and fruit juice. 

But the question that people always wonder about — are modern food preservatives safe? Sodium benzoate is recognized as a safe antimicrobial agent with the maximum usage of 0.1%. For example, the FDA (Food and Drug Administration) allowed the maximum level of sodium benzoate in drinking water as 5 parts per billion (ppb) so that it will not be a threat to human health (Zelman, 2023). However, in beverages like soft drinks, sodium benzoate is prone to combining with vitamin C, which will form a cancer-causing substance called benzene. Higher temperatures and prolonged exposure to light can increase benzene formation.

But fret not, the actual benzene content in soft drinks is typically much lower than the regulatory limits. In many cases, soft drinks on the market have benzene levels that are reported to be below the detection limit or close to zero. Similar to the FDA's maximum allowable limit of 5 ppb for benzene in drinking water, this serves as a reference point for soft drinks as well. As such, a low level of benzene does not become a health threat. 

Figure 3. Structure of sulphite

Sulphites occur naturally in some foods on low levels, but are also widely used as a food preservative to prevent microbial growth and preserve the colour of food. As examples, sodium sulphite is used in dried fruits, jams, and juices. Sulphites are also used as an antioxidant to prevent the browning of food. 

Sulphur dioxide (E220) and Sulphites (E221-228) has been a concern for high consumers as generally, many consumers are sensitive to sulphite additives (Australasian Society of Clinical Immunology and Allergy, 2021). This additive will cause adverse responses in 3% to 10% of adult asthmatics, with a proportion of them having life-threatening symptoms. Sulphites can also induce an allergic reaction with symptoms such as wheezing, hay fever, and urticaria. Moreover, sulphite can also trigger anaphylaxis in severe cases, causing the immune system to release a flood of chemicals and cause the body to go into shock.

Figure 4. Structure of Nitrite

Figure 5. Structure of Nitrate

Nitrates or nitrites are natural chemicals present in air, water, and soil. Nitrates are a set of compounds that involve nitrogen and oxygen molecules, and can be used to inhibit bacteria development. Nitrates are found in processed meat as it can prevent the growth of Clostridium botulinum, a harmful bacteria. Besides, nitrite can also halt the rancidity and odour of cured meat during storage. 

However, research has shown that too much intake of processed meat increases the risk of colon cancer (Mikstas, 2022). This is because nitrates are not broken down by stomach acid, which will be detrimental to human health. Other health risks of excessive nitrate intake include complications during pregnancy and methemoglobinemia in infants, better known as blue baby syndrome.  

Figure 6. Blue baby syndrome heart anatomy

In a nutshell, with modern food preservatives being a double edged sword, it is important to maintain a healthy balance between preserving food and maintaining our personal health. Thus, it is extremely crucial for manufacturers to be responsible and comply with the regulations and laws that govern the usage of modern food preservatives. And as for consumers, it is also fairly important to be educated on this matter as to have a healthy balanced lifestyle. For instance, consumers are advised to read food labels before purchasing and stay informed on the latest research, news, and guidelines to make informed choices. 



  1. Freedman, B. (1980). Sulphur dioxide in foods and beverages: its use as a preservative and its effect on asthma. PubMed. Retrieved September 25, 2023, from

  2. Mikstas, C. (2022, November 15). 8 Foods High in Nitrates and Why You Should Avoid Them. WebMD. Retrieved September 25, 2023, from

  3. Sulfite Sensitivity FAQ. (2021). Australasian Society of Clinical Immunology and Allergy (ASCIA). Retrieved September 25, 2023, from

  4. The Truth about Nitrates in Food. (2022, May 9). Unlock Food. Retrieved September 25, 2023, from

  5. Vally, H., & Misso, N. L. (2012). Adverse reactions to the sulphite additives - PMC. NCBI. Retrieved September 25, 2023, from

  6. Zelman, K. M. (2023). What is Sodium Benzoate? Is It Safe for Use as a Food Preservative? WebMD. Retrieved September 11, 2023, from

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