Food preservation needs to be considered from two different perspectives. The first is protecting food against microbial activity, preventing microbial spoilage and keeping food from becoming microbiologically unsafe.
The second concerns changes that occur naturally over time, independently of microbial activity. It involves delaying or preventing the loss of freshness, structure, appearance, nutritional properties and flavor.
Foods without added preservatives—especially those with a high water content—will naturally lose their characteristic properties within a short time and subsequently spoil.
Sterilized products without added preservatives, such as canned foods and UHT milk, have a longer shelf life, but they too become unsuitable for consumption after sufficient time. Likewise, drying only extends a product’s shelf life. Whatever the circumstances, food will eventually lose its characteristic properties and deteriorate [1].
In this context, the fact that consumers demand that the food they buy always be fresh, healthy and have all the characteristics expected from that food, regardless of how far it comes from and how long it stays on the shelf, complicates the situation for producers.
Of course, it is very difficult for a product put on the shelf to still maintain its first day’s freshness and appearance throughout its shelf life (1 month for some food, 12 months for some food).
Ensuring this has made it necessary to use preservatives in the food industry. However, nowadays public health concerns against preservatives cause society to distance itself from preservative food additives. As a result, there has been a paradox between the demanded product (fresh and with all the characteristics of food) and health expectations.
Adding antimicrobial preservatives to food provides the advantage of preventing microbial growth in the product even after the package has been opened. After unpacking, foods are exposed to microorganisms from a wide variety of vectors.
Most simply, after the product is opened, microorganisms in the air fall onto the open food and can develop rapidly in a rich nutrient environment [2]. The addition of antimicrobial preservatives to the food also prevents the problems that may be caused by microorganisms in the process after the packaging of the food is opened.
Preservatives are used in almost all industrial foods, especially beverages, baked goods, processed meats, oils and margarine, cereals, sauces, snack foods, fruit and vegetable products.
The most commonly used preservatives are ascorbic acid (vitamin C, E 300), tocopherols (vitamin E; alpha-tocopherol (E 307), gamma-tocopherol (E 308), delta-tocopherol (E 309)), citric acid (E 330), sodium benzoate (E 211), calcium propionate (E 282), sodium erythorbate (E 316), sodium nitrite (E 250), sodium nitrate (E 251), potassium sorbate (E 202), BHA (E 320), BHT (E 321), EDTA (E 385), nisin (E 234) and natamycin (E 235).
As noted earlier, preservative food additives serve two different purposes. Additives such as sodium nitrite, sodium nitrate, nisin and natamycin are used to prevent microbial spoilage.
Ascorbic acid, tocopherols, BHA, BHT and EDTA are generally used to prevent the chemical deterioration that occurs naturally in food. These compounds act as antioxidants. By preventing oxidation, antioxidants can help prevent discoloration and the development of a rancid taste.
Nitrate and nitrite are used in industrially produced meat products to inhibit the growth of Clostridium botulinum. Because their intake can pose health risks, their use and consumption are subject to limits. International assessments have established acceptable daily intake values of 3.7 mg/kg body weight for nitrate and 0.06–0.07 mg/kg body weight for nitrite. Sulfur dioxide and sulfites are used to inhibit microorganisms that cause spoilage in dried fruits, fruit juices and wines.
Nisin and natamycin are antibiotics produced by microorganisms. While nisin prevents the growth of some bacteria, natamycin has a protective effect against molds and yeasts.
Alongside preservatives that are used today, some preservatives that were used until relatively recently are now prohibited. Some food preservatives may be prohibited in certain countries while being permitted in others.
For example, BHA (E 320) and BHT (E 321) are not subject to a blanket ban in all foods in the United Kingdom. The food categories in which they are permitted and the applicable maximum levels are specified in the relevant legislation. (Food Standards Agency, 2026) Calcium sorbate (E 203) can be given as an example of an additive that is banned in Turkey.
For public health, it is important to keep track of which additives countries prohibit and why, to conduct scientific studies on these issues, and to regulate additive authorizations and prohibitions accordingly.
Mold on Purchased Food: Possible Causes
Today, most consumers demand that the product they buy is both fresh, sound and does not contain any preservatives. Naturally, when they observe the growth of microorganisms in a product such as yogurt, cheese, juice, etc. they buy, they naturally complain about the manufacturer.
The following point deserves attention: microbial growth in the product may result from three different causes:
1. The pasteurization or commercial sterilization process may not have been applied effectively during the production phase of the product. In this case, a similar problem can be observed in all batch products coming out of that production. The firm is at fault in this scenario.
2. There may be microbial contamination in the product or at any stage of the production process. Depending on the degree of contamination, microbial growth can be observed in a single product or some or all of the products produced. The company is also at fault in this scenario.
3. Even if the pasteurization or commercial sterilization process is applied effectively and contamination is completely avoided, there may be microorganisms that survive the heat treatment and these surviving microorganisms can grow in the product.
As is known, pasteurization and commercial sterilization do not guarantee the destruction of all microorganisms contained in the food. In these processes, not all microorganisms in the raw material can be killed; however, it is stated that microorganism inhibition is provided at varying rates such as 99.9% or 99.999% depending on the effectiveness of the process (this rate varies according to the norm and efficiency of the process).
The expression “99.999% inhibition achieved” means: “If there are 100,000 microorganisms in the raw material, 99,999 of these bacteria were killed by heat treatment and only 1 living microorganism remained.”
That one surviving microorganism will enter one of the products in the batch and grow in it. In this scenario, the company is not at fault, but the consumer has been unlucky: they have selected the affected product from a large batch of otherwise sound products.
From these scenarios, the consumer should understand the following: a company whose products show microbial growth is not using antimicrobial preservative food additives in those products.
The company could have concealed faulty production by adding preservatives. In that case, it could have offered low-quality products while disregarding consumer health.
Alternatively, it could have used antimicrobial preservatives to prevent the microorganisms that survived heat treatment from growing and spoiling the affected products. In this way, it could have kept all its products sound and maintained a favorable public image.
Today, a consumer who draws attention to a defective product on social media can influence how millions of people perceive a company. No company wants a single product to damage its brand image among millions of consumers.
Companies whose products show microbial growth may or may not have made production errors; this requires investigation. However, it is clear that they do not use antimicrobial preservatives and therefore take public health concerns into account. Products showing microbial growth must never be consumed and should be returned.
[1] As an exception, honey can preserve its natural state for quite a long time without spoiling. Theoretically, it can be preserved for up to 500 years without spoiling. It should be protected from sunlight and moisture during storage; It should be protected to prevent any foreign matter or water from entering.
[2] Researchers state that the microbial load in the air has decreased today compared to the past and that air quality has made great progress in the last 20 years in terms of microbial. This means that food left uncovered may spoil after a longer time than in the past. Although there is an improvement in air quality such as a decrease in the microorganism load, there are still microorganisms in the air and these microorganisms fall into the uncovered food. To protect the food against microorganisms that can be transmitted from the air, it is necessary to keep it covered at all times. On the other hand, landing flying insects like flies into the food or falling into the food is prevented by covering the food.
References
Altuğ, T. (Ed.). (2017). Gıda Katkı Maddeleri. Sidas Medya.
Saldamlı, İ. (Ed.). (2021). Gıda Kimyası. Hacettepe Üniversitesi Yayınları.
Erkmen, O. (Ed.). (2021). Gıda Mikrobiyolojisi (6. baskı). Efil Yayınevi.
Ray, B., & Bhunia, A. (2021). Temel Gıda Mikrobiyolojisi (5. baskıdan çeviri; D. Heperkan, Çev. Ed.). Nobel Akademik Yayıncılık.
World Health Organization. (2023). Food additives.
U.S. Food and Drug Administration. (2024). Types of Food Ingredients.
Food Standards Agency. (2026). Approved additives and E numbers.
European Food Safety Authority. (2017). Nitrites and nitrates added to food: EFSA explains risk assessment.
Halil İbrahim Akgül
Halil Ibrahim Akgul, Ph.D., is an Assistant Professor of Food Engineering at Bayburt University, where he works in the Division of Food Sciences within the Faculty of Engineering. He received his B.Sc. in Food Engineering from Akdeniz University in 2010, followed by an M.Sc. and a Ph.D. in Food Engineering from Atatürk University in 2015 and 2020, respectively. His formally recognised academic fields are Food Sciences and Engineering, Food Technologies, Dairy and Dairy Products Technology, and Food Microbiology.
Dr. Akgul has more than fifteen years of professional, research, and academic experience in food science. Between 2011 and 2013, he worked as the food engineer responsible for operations at the Pilot Dairy and Bread Factory of Atatürk University’s Directorate of Agricultural Enterprises. This industrial experience, combined with his subsequent academic research, gave him extensive practical and scientific knowledge of milk processing, dairy production, food quality, hygiene, and product development.
His research is primarily focused on milk and dairy products, dairy microbiology, starter cultures, lactic acid bacteria, exopolysaccharides, butter technology, and the physicochemical, microbiological, sensory, and nutritional properties of foods. His studies have examined the quality and fatty-acid composition of traditional butter, aroma formation in butter produced with different starter cultures, raw-milk quality, the characterisation and antioxidant activity of bacterial exopolysaccharides, traditional dairy products such as çökelek and karın kaymağı, colostrum powder, and the use of fruit-derived ingredients in ice cream production.
His academic record includes peer-reviewed research articles published in national and international journals, including Mljekarstvo, Acta Scientiarum Technology, the Journal of Food Safety and Food Quality, the International Journal of Food Engineering, the Atatürk University Journal of Agricultural Faculty, and ATA Food Journal. Four of the research articles currently listed in his university profile were published in SCI-Expanded-indexed journals. He has also contributed to twelve national and international conference papers and presentations covering dairy products, food microbiology, butter quality, fatty-acid composition, starter cultures, exopolysaccharide-producing bacteria, colostrum, traditional foods, and functional ice-cream formulations.
Dr. Akgul has participated as a researcher or adviser in eleven completed scientific and applied research projects. These projects have addressed the modernisation of pilot dairy-processing facilities; the production and quality characteristics of colostrum powder; the physicochemical and microbiological quality of butter and raw milk; the identification of exopolysaccharide-producing lactic acid bacteria; the development and production optimisation of starter cultures for mould-ripened cheese; the standardisation of traditional dairy products; and the use of sloe berry and persimmon fibre in ice-cream production.
His teaching experience spans undergraduate, associate-degree, and graduate education. The courses he has taught include Food Chemistry, Analytical Chemistry, General Chemistry, Organic Chemistry, Fermented Dairy Products Technology, Butter Production and Processing Technology, Healthy Living and Nutrition, Organic Agriculture and Food, Popular Science, Digital Literacy, and Information Technologies. Through these courses, he combines fundamental food chemistry and engineering principles with dairy technology, nutrition, scientific literacy, and the practical communication of scientific knowledge.
He is the founder and Editor-in-Chief of Gıda ve Sağlık, a multilingual digital publication devoted to food, nutrition, health, food chemistry, food microbiology, and culinary science. Through this platform, he draws upon his academic background, teaching experience, research activity, and practical knowledge of food production to present scientifically grounded information in a detailed and accessible form for an international readership.