Before hitting the panic button when you read ingredients on food labels, such as "sodium benzoate" or "potassium sorbate," slow down a second and consider that food technologists are people too. They eat and drink the same things as you. Even today, few experts disagree with researchers at the University of Surrey who stated in 1992 that preservatives "confer substantial benefits on man." Foods keep longer, taste better and are less likely to make you ill. However, if it were that simple, modern-day food technologists and consumers wouldn't be looking for alternatives.
Traditional Preservatives
Food preservatives are not new. According to the University of Hawaii at Manoa, preservation techniques date from ancient times. Historically, meat and fish have been preserved by curing where salt is rubbed into the food. Salt has a natural antibacterial effect and by slowing the growth of spoilage microorganisms, ancient societies could store foods safely for prolonged periods. You could think of salt as the original chemical preservative, after all, its chemical name is sodium chloride.
Industrial Food Preservatives
Just like salt, modern food preservatives such as sorbates or benzoates have antimicrobial effects. Dr. Olga Padilla-Zakour of Cornell University recognizes that processors are increasingly looking to avoid their use by adjusting processing techniques or changing recipes. However, she maintains that "in some cases, the use of chemical preservatives is necessary to ensure the safety of a food product." Modern consumers expect food to keep fresh for long periods and even with refrigeration, much more food would have to be discarded if chemical preservatives were not used. Sorbates and benzoates are the two main classes of chemical preservatives used.
Sorbates and Benzoates
Sorbate may be used in many forms such as sodium sorbate and calcium sorbate. However, it is most commonly used in the form of potassium sorbate. Potassium sorbate breaks down to form sorbic acid when it is added to water. This has strong antimicrobial effects. It is used in a vast range of foods, such as dips, yogurt, olives, smoked fish and confections.
Benzoates, again may be used in many forms but it is the benzoic acid form that is effective against microbes. However, the most commonly used form is sodium benzoate because it is highly soluble in water. Benzoate is used in more acidic foods, such as beverages, jams and relishes. It is particularly effective against yeasts and molds, but also effectively controls the growth of pathogenic bacteria that cause food poisoning.
Natural Alternatives
Professor of food science, Milena Sinigaglia, describes advances in research to reduce the reliance on chemical preservatives. Natural antimicrobial substances, such as essential oils from herbs, lysozyme from egg white and chitosan from crustacean shells are increasingly proving effective preservatives. However, natural antimicrobials often still have to be used in conjunction with improved techniques or novel processes, such as high-pressure treatment and pulsed electric fields. Where different antimicrobial controls are used together this is called a "hurdle technique."
Understanding the Label
All preservatives used in foods must be clearly labeled with an indication of the reason for their use. For example, "mold inhibitor" or "to retard spoilage." You might also find preservatives such as BHA or BHT listed as "antioxidants." However, if Sinigaglia is correct, items like these will be increasingly replaced by natural essential oils and protein products.
References
- PubMed.gov: Food Additives and Contaminants; Safety aspects of food preservatives; Parke DV & Lewis DF; September October 1992
- New York State Agricultural Experiment Station: Chemical Food Preservatives: Benzoate & Sorbate
- "International Journal of Food Science and Technology": Prolonging Microbial Shelf Life of Foods Through the Use of Natural Compounds and Non-Thermal Approaches
- University of Hawaii at Manoa: Food Preservation Methods
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