Food Preservation- Chemical Preservatives with Types, Examples

Food preservation is the process of preventing food spoilage and extending its shelf life. Food spoilage is caused by the growth and activity of microorganisms such as bacteria, molds, yeasts, and enzymes that degrade the quality and safety of food. Food preservation methods aim to inhibit or eliminate these factors by applying physical, chemical, or biological techniques.

Chemical preservatives are one of the most common and effective methods of food preservation. They are substances that are intentionally added to food to inhibit or kill microorganisms, retard enzymatic reactions, or prevent undesirable changes in the color, flavor, texture, or nutritive value of food. Chemical preservatives can be natural or synthetic, depending on their origin and mode of action.

Natural preservatives are substances that are derived from plants, animals, or microorganisms and have been traditionally used for centuries to preserve food. Examples of natural preservatives include salt, sugar, vinegar, honey, spices, wood smoke, alcohol, vegetable oil, and bacteriocins. Natural preservatives are generally regarded as safe for human health and do not require regulatory approval.

Synthetic preservatives are substances that are artificially produced in laboratories and have specific chemical structures and functions. Examples of synthetic preservatives include benzoates, sorbates, nitrites, nitrates, sulfites, propionates, parabens, acetates, and antioxidants. Synthetic preservatives are more effective and stable than natural preservatives but may have adverse effects on human health and the environment. Synthetic preservatives require regulatory approval and have limits on their usage and concentration in food.

Chemical preservatives are widely used in the food industry to extend the shelf life and ensure the safety of various food products such as dairy products, meat products, bakery products, beverages, sauces, jams, pickles, fruits, vegetables, and cereals. Chemical preservatives can also enhance the sensory qualities and nutritional value of food by preventing oxidation, browning, rancidity, and nutrient loss.

However, chemical preservatives also have some drawbacks and limitations. They may alter the natural taste and aroma of food or cause allergic reactions or toxicity in some consumers. They may also interact with other food components or environmental factors and reduce their effectiveness or create harmful by-products. Moreover, some microorganisms may develop resistance to chemical preservatives and pose a threat to food safety.

Therefore, chemical preservatives should be used with caution and in accordance with the regulations and guidelines of the relevant authorities. Consumers should also be aware of the benefits and risks of chemical preservatives and make informed choices about their food consumption.

Chemical preservatives are intentional food additives that are added to foods to prevent or delay spoilage, maintain quality, and enhance appearance, flavor, or nutritional value. There are different ways that food can get chemical preservatives, such as:

• Intentional addition during food production, processing, or packaging: This is the most common way of using chemical preservatives in food. For example, sodium benzoate (E211) is added to soft drinks, fruit juices, and jams to inhibit the growth of yeasts and molds. Sodium nitrite (E250) is added to cured meats, such as bacon and ham, to prevent the growth of Clostridium botulinum, which can cause botulism. Sulphur dioxide (E220) is added to dried fruits, wine, and beer to prevent browning and oxidation.
• Chemical migration from the packaging materials: Some packaging materials may contain chemical substances that can migrate into the food and act as preservatives. For example, bisphenol A (BPA) is a chemical used to make some plastics and epoxy resins that can leach into canned foods and beverages. BPA has antimicrobial properties and can also affect the hormone system of humans and animals.Ethylene vinyl alcohol (EVOH) is a polymer used as a barrier layer in some plastic films and bottles that can release acetaldehyde into the food. Acetaldehyde has antioxidant and antimicrobial effects and can also affect the flavor and aroma of the food.
• Due to a chemical reaction occurring in food: Some foods may contain natural or added substances that can react with other components of the food and form chemical preservatives. For example, nitrate (E251) is a naturally occurring compound in some vegetables, such as celery and spinach, that can react with proteins in meat and form nitrite (E250), which has antimicrobial and color-fixing properties. Ascorbic acid (E300), also known as vitamin C, is a natural antioxidant that can be added to foods to prevent oxidation and browning. However, ascorbic acid can also react with nitrite and form nitrosamines, which are carcinogenic compounds.
• Residues of pesticides, herbicides, and fungicides on raw food materials: Some agricultural chemicals used to protect crops from pests and diseases may remain on the raw food materials and act as preservatives. For example, chlorpyrifos is an insecticide that can be sprayed on fruits and vegetables to kill insects. Chlorpyrifos can inhibit the activity of acetylcholinesterase, an enzyme that regulates nerve impulses in humans and animals. Propiconazole is a fungicide that can be applied to cereals and fruits to prevent fungal infections. Propiconazole can interfere with the synthesis of ergosterol, a component of fungal cell membranes.
• Migration of disinfectants used on utensils or equipment into foods: Some disinfectants used to sanitize utensils or equipment in food processing or preparation may contaminate the foods and act as preservatives. For example, chlorine is a disinfectant that can be used to wash fruits and vegetables or sanitize water. Chlorine can kill microorganisms by damaging their cell walls and membranes. However, chlorine can also react with organic matter in water or food and form chlorinated compounds, such as trihalomethanes (THMs), which are potentially harmful to human health. Quaternary ammonium compounds (QACs) are disinfectants that can be used to clean surfaces or equipment in contact with food. QACs can reduce the surface tension of water and disrupt the cell membranes of microorganisms. However, QACs can also remain on the surfaces or equipment and migrate into the food, where they can affect the taste, odor, or texture of the food.

As you can see, there are many ways that food can get chemical preservatives, either intentionally or unintentionally. Chemical preservatives have both benefits and risks for food safety and quality, as well as human health and environment. Therefore, it is important to use them wisely and follow the regulations and guidelines for their safe use.

Chemical preservatives are food additives that play an important role in making foods last longer or taste better. Specifically, chemical preservatives help to control and prevent the deterioration of food, providing protection against spoilage from microorganisms (e.g., bacteria, yeast, moulds), life-threatening botulism and other organisms that can cause food poisoning (antimicrobial function) . High-risk foods such as meat, seafood, dairy, and cheese serve as a breeding ground for potentially dangerous microorganisms, therefore, the addition of a chemical preservative is usually required to ensure food safety .

Chemical preservatives work by interfering with the cell wall, cell membrane, enzymatic activity, nucleic acids, etc., of the microorganisms to prevent their growth and activity . Different types of chemical preservatives have different modes of action. For example, organic acids like acetic acid, benzoic acid, lactic acid, propionic acid, sorbic acid, etc., are effective as preservatives for foods with a pH of less than 5. They cross the cell membrane of the microorganisms and release protons that acidify the cytoplasm, making energy unavailable for their growth . Another example is sodium nitrite, which is used to preserve cured meats. It inhibits the growth of Clostridium botulinum, the bacterium that causes botulism, by reacting with its iron-sulfur proteins and blocking their function .

By preventing microorganisms’ growth and activity, chemical preservatives also retard, prevent or control undesirable changes in flavor, color, texture, or consistency of food and nutritive value of food (antioxidant function) . Without the addition of a chemical preservative, certain foods may turn rancid or change in color due to oxidation or enzymatic reactions. For example, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ) are synthetic antioxidants that prevent the oxidation of fats and oils in foods . Another example is sodium benzoate, which inhibits the enzymatic browning of fruits and vegetables by chelating iron and copper ions that catalyze the reaction .

Ultimately, chemical preservatives protect the quality of foods and beverages, reduce food cost, improve convenience, lengthen shelf-life, and reduce food waste. However, they also have some limitations and challenges such as consumer perception, safety concerns, regulatory issues, and microbial resistance. Therefore, it is important to use them wisely and appropriately according to the guidelines and regulations.

Chemical preservatives can be classified into two main categories based on their origin and nature: Class I (Traditional) and Class II (Chemical).

Class I (Traditional) preservatives are natural substances that have been used for centuries to preserve food. They include common ingredients such as salt, sugar, vinegar, honey, spices, alcohol, vegetable oil, wood smoke, etc. These preservatives work by creating an unfavorable environment for microorganisms to grow and survive, such as lowering the water activity, pH, or oxygen level of the food. They also impart flavor, color, and aroma to the food. Class I preservatives are generally regarded as safe for human health and there is no imposed limitation on their use.

Class II (Chemical) preservatives are synthetic substances that are made in the laboratory. They include compounds such as benzoates, sorbates, nitrites, nitrates, sulfites, propionates, parabens, etc. These preservatives work by interfering with the metabolic processes or cellular structures of microorganisms, such as inhibiting enzymes, disrupting membranes, or damaging DNA. They are effective at low concentrations and can extend the shelf life of food significantly. However, Class II preservatives may have adverse effects on human health and the environment if used excessively or improperly. They are subject to strict regulation and control by food authorities and must be declared on the food label with their E numbers or names.

The choice of chemical preservative depends on several factors such as the type of food, the desired shelf life, the target microorganisms, the consumer preference, the cost-effectiveness, and the legal requirements. Some foods may require a combination of different preservatives to achieve optimal protection and quality. For example, cured meats may contain both nitrites and salt to prevent bacterial growth and oxidation. Some foods may also contain microbial preservatives that are produced by beneficial bacteria and inhibit the growth of harmful bacteria. For example, nisin is a bacteriocin that is used to prevent the growth of Clostridium botulinum in cheese and other dairy products.

Class I traditional preservatives are natural food additives that have been used for centuries to prevent food spoilage and enhance food quality. They include substances like salt, sugar, honey, vinegar, alcohol, spices, vegetable oil, wood smoke, etc. These preservatives are derived from plants, animals, fungi, or algae and are generally regarded as safe for human health .

Some of the benefits of using traditional preservatives are:

• They inhibit the growth of microorganisms that can cause food poisoning or spoilage by lowering the water activity, changing the pH, or producing antimicrobial compounds .
• They enhance the flavor, color, texture, or aroma of food by adding sweetness, sourness, spiciness, smokiness, etc .
• They preserve the nutritional value of food by preventing oxidation or enzymatic reactions that can degrade vitamins, minerals, proteins, or fats .

Some of the drawbacks of using traditional preservatives are:

• They may alter the taste or appearance of food in a way that some consumers may not prefer .
• They may not be effective against all types of microorganisms or spoilage factors and may require additional processing methods like heating, drying, or refrigeration .
• They may have adverse effects on human health if consumed in excess or if contaminated with harmful substances like heavy metals, pesticides, or pathogens .

Some examples of traditional preservatives and their applications are:

• Salt: It is one of the oldest and most widely used preservatives. It reduces the water activity and creates an unfavorable environment for microbial growth. It is used to preserve meat, fish, cheese, pickles, sauces, etc .
• Sugar: It also lowers the water activity and prevents microbial growth. It also adds sweetness and enhances the color and texture of food. It is used to preserve fruits, jams, jellies, candies, syrups, etc .
• Honey: It has similar properties as sugar but also contains enzymes and phenolic compounds that have antimicrobial and antioxidant effects. It is used to preserve fruits, nuts, breads, cakes, etc .
• Vinegar: It is a diluted solution of acetic acid that lowers the pH and inhibits microbial growth. It also adds sourness and flavor to food. It is used to preserve vegetables, pickles, sauces, condiments, etc .
• Alcohol: It is a solvent that dissolves and denatures microbial proteins and membranes. It also adds flavor and aroma to food. It is used to preserve fruits, wines, beers, liquors, etc .
• Spices: They are plant-derived substances that contain various phytochemicals that have antimicrobial, antioxidant, anti-inflammatory, or anti-carcinogenic effects. They also add flavor and color to food. They are used to preserve meat, fish, cheese, sauces, soups, etc .
• Vegetable oil: It forms a protective layer on the surface of food that prevents oxygen and moisture from reaching the food. It also adds flavor and texture to food. It is used to preserve cheese, nuts, seeds, dried fruits, etc .
• Wood smoke: It contains various compounds that have antimicrobial and antioxidant effects. It also adds flavor and color to food. It is used to preserve meat, fish, cheese, etc[

Class II chemical preservatives are artificial or synthetic substances that are made in the laboratory. They are not naturally found in food or derived from natural sources. They are added to food to inhibit the growth of microorganisms, prevent spoilage, and extend shelf life. Some examples of Class II chemical preservatives are:

• Nitrites and nitrates (E249-E252): These are used to preserve cured meats, such as bacon, ham, salami, and sausages. They prevent the growth of Clostridium botulinum, which causes botulism, a deadly food poisoning. They also give the meat a pink color and a characteristic flavor. However, nitrites and nitrates can react with amino acids in the meat to form nitrosamines, which are carcinogenic compounds. Therefore, their use is regulated and limited by law.
• Propionates (E280-E283): These are used to prevent mold growth in bread and bakery products. They also inhibit the growth of some bacteria that cause spoilage and souring. Propionates are generally considered safe for human consumption, but some people may be allergic or sensitive to them and experience symptoms such as headaches, nausea, or skin rashes.
• Parabens (E214-E219): These are used to prevent yeast and mold growth in jams, jellies, syrups, sauces, dressings, and cosmetics. They also have antibacterial and antifungal properties. Parabens are controversial because they can mimic estrogen in the body and disrupt the hormonal balance. Some studies have linked them to breast cancer and reproductive problems. Therefore, their use is restricted and banned in some countries.
• Benzoates (E210-E213): These are used to prevent microbial growth in acidic foods and beverages, such as fruit juices, soft drinks, pickles, sauces, and condiments. They also enhance the flavor and color of the food. Benzoates are generally safe for human consumption, but some people may be allergic or intolerant to them and experience symptoms such as asthma, hives, or anaphylaxis.
• Acetates (E260-E262): These are used to control the pH and acidity of food and beverages, such as vinegar, wine, cheese, and canned vegetables. They also inhibit the growth of some bacteria that cause spoilage and fermentation. Acetates are generally safe for human consumption, but some people may experience gastrointestinal discomfort or irritation if they consume large amounts of them.
• Sorbates (E200-E203): These are used to prevent mold and yeast growth in cheese, wine, dried fruits, margarine, and baked goods. They also extend the shelf life and freshness of the food. Sorbates are generally safe for human consumption, but some people may be allergic or sensitive to them and experience symptoms such as itching, swelling, or diarrhea.
• Sulfur dioxide and sulfites (E220-E228): These are used to prevent browning and oxidation of fruits, vegetables, wine, beer, and dried fruits. They also inhibit the growth of bacteria and fungi that cause spoilage and fermentation. Sulfur dioxide and sulfites are generally safe for human consumption, but some people may be allergic or asthmatic to them and experience symptoms such as wheezing, coughing, or anaphylaxis.

Class II chemical preservatives have advantages and disadvantages for food preservation. On one hand, they can effectively prevent microbial growth and spoilage of food and extend its shelf life. On the other hand, they can have negative effects on human health and the environment if they are used excessively or improperly. Therefore, their use should be regulated and monitored by authorities and consumers should be aware of their presence and quantity in food products.

Microbial preservatives are natural antimicrobial substances produced by microorganisms, such as bacteria, fungi, algae, or plants. They can inhibit the growth of spoilage and pathogenic microorganisms in food by interfering with their cell membrane, enzyme activity, nucleic acid synthesis, or metabolic pathways . Some examples of microbial preservatives are bacteriocins, lysozyme, nisin, natamycin, and plant extracts .

Bacteriocins are proteinaceous compounds that are produced by some strains of lactic acid bacteria and other gram-positive bacteria. They have a narrow spectrum of activity against closely related bacteria or bacteria with similar cell wall structure . Nisin is a bacteriocin that is widely used as a food preservative. It inhibits the growth of gram-positive bacteria, especially spore-forming bacteria such as Clostridium botulinum and Bacillus cereus, which can cause food poisoning. Nisin is effective at low pH and high temperature and can be used in cheese, dairy products, meat products, canned foods, and beverages .

Natamycin is another microbial preservative that is produced by a strain of Streptomyces natalensis. It is a polyene macrolide antibiotic that binds to the sterol groups in the fungal cell membrane and disrupts its integrity and function . Natamycin is effective against molds and yeasts, but not bacteria. It can be used to prevent fungal spoilage of cheese, bread, meat products, fruits, and vegetables .

Lysozyme is an enzyme that is found in egg white, saliva, tears, and other biological fluids. It hydrolyzes the peptidoglycan layer of the bacterial cell wall and causes cell lysis . Lysozyme is effective against gram-positive bacteria and some gram-negative bacteria. It can be used to prevent bacterial spoilage of cheese, wine, beer, and meat products .

Plant extracts are natural substances that are derived from various parts of plants, such as leaves, flowers, fruits, seeds, roots, or bark. They contain various phytochemicals that have antimicrobial properties, such as phenolic compounds, flavonoids, terpenoids, alkaloids, and essential oils . Plant extracts can inhibit the growth of bacteria, fungi, and viruses by affecting their cell membrane permeability, enzyme activity, metabolic pathways, or gene expression . Some examples of plant extracts that are used as food preservatives are rosemary extract, thyme oil, garlic extract, cinnamon oil, clove oil, and tea tree oil .

Using microbial preservatives can help reduce the use of synthetic chemical preservatives that may have adverse effects on human health or the environment. Microbial preservatives are generally regarded as safe (GRAS) by the Food and Drug Administration (FDA) and have been approved by the European Union (EU) and other regulatory agencies for food applications . However, some microbial preservatives may have limitations such as low solubility in water or oil, high cost of production or extraction, undesirable flavor or odor, or potential allergenicity or toxicity . Therefore, careful selection and optimization of microbial preservatives are necessary to ensure their safety and efficacy in food preservation.

Food preservatives are substances added to food to maintain or improve its safety, freshness, taste, texture, or appearance. However, they should not be used in excessive amounts that may pose a risk to human health. Therefore, the European Union (EU) has established maximum levels for the use of food preservatives in different food categories and also defined acceptable daily intake (ADI) values for each preservative. ADI is the amount of a substance that can be consumed every day over a lifetime without appreciable health risk.

The following table shows some examples of food preservatives and their ADI values according to EU regulation. The E numbers are codes for substances used as food additives in the EU.

These ADI values are based on scientific assessments of the safety of these substances by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the European Food Safety Authority (EFSA). They are expressed as milligrams of the substance per kilogram of body weight per day. For example, an ADI of 25 mg/kg means that a person weighing 50 kg can consume up to 1250 mg of the substance per day without adverse effects.

However, these ADI values are not intended to be used as exact limits for individual consumers. They are meant to be used as guidance for regulators and food manufacturers to ensure that the average intake of these substances by the population does not exceed the safe levels over a long period of time. Consumers should also be aware of the presence and amount of these preservatives in the foods they eat by reading the labels and choosing foods with less or no added preservatives whenever possible.

Chemical preservatives are not equally effective against all types of microorganisms or in all types of foods. Their antimicrobial activity depends on several factors, such as:

• Chemical preservative properties: The solubility, toxicity, and stability of the preservative affect its ability to penetrate the microbial cell and interfere with its vital functions. For example, organic acids are more effective in acidic foods where they exist in their undissociated form and can cross the cell membrane more easily .
• Microbial factors: The inherent resistance of microorganisms to chemical preservatives varies depending on their species, strain, and genetic mutations. Some microorganisms can develop adaptive mechanisms to survive in the presence of preservatives, such as altering their cell membrane composition, producing efflux pumps, or forming biofilms . The initial microbial load, growth rate and phase, and stress reaction of microorganisms also influence their susceptibility to preservatives.
• Intrinsic factors of food: The pH and water activity of food are important determinants of the effectiveness of chemical preservatives. Low pH and water activity inhibit the growth of most microorganisms and enhance the activity of some preservatives, such as organic acids and sorbates . Other food components, such as proteins, fats, carbohydrates, minerals, and vitamins, may also interact with preservatives and reduce their availability or activity .
• Extrinsic factors: The storage time and temperature, gas composition, atmosphere, and relative humidity affect the growth of microorganisms and the stability of preservatives in food. Higher temperatures and longer storage times may increase the degradation or evaporation of some preservatives, such as sulfur dioxide and nitrites . The presence of oxygen or light may also cause oxidation or photodegradation of some preservatives, such as ascorbic acid and tocopherols.
• Use of additional preservative methods: The combination of chemical preservatives with other preservation methods, such as heating, cooling, drying, irradiation, high pressure, or modified atmosphere packaging, can enhance the antimicrobial effect and reduce the required concentration of preservatives. This is known as the hurdle concept or approach . Some natural substances, such as herbs, spices, essential oils, bacteriocins, or enzymes, can also act as synergists or enhancers of chemical preservatives .

Chemical preservatives are substances added to foods to inhibit the growth of microorganisms, prevent oxidation, or enhance the flavor and appearance of foods. They can be either natural or synthetic, and they have different modes of action and effectiveness depending on the type of food, the pH, the water activity, the storage temperature, and the microbial load. Some of the most common chemical preservatives used in the food industry are:

• Acidulants: These are organic or inorganic acids that lower the pH of foods and create an unfavorable environment for microbial growth. Some examples are citric acid, acetic acid, lactic acid, malic acid, tartaric acid, and phosphoric acid. They are widely used in beverages, jams, pickles, sauces, and dairy products.
• Sorbates: These are salts or esters of sorbic acid, a natural organic acid that inhibits the growth of yeasts, molds, and some bacteria. Some examples are potassium sorbate, calcium sorbate, and sodium sorbate. They are commonly used in cheese, wine, bread, fruit juices, dried fruits, and salad dressings.
• Benzoates: These are salts or esters of benzoic acid, a natural organic acid that inhibits the growth of yeasts, molds, and some bacteria. Some examples are sodium benzoate, potassium benzoate, and calcium benzoate. They are often used in soft drinks, fruit juices, jams, sauces, and condiments.
• Nitrites and nitrates: These are salts of nitrous acid and nitric acid that prevent the growth of Clostridium botulinum and other anaerobic bacteria that cause food poisoning. They also enhance the color and flavor of cured meats. Some examples are sodium nitrite, potassium nitrite, sodium nitrate, and potassium nitrate. They are mainly used in bacon, ham, sausages, salami, and corned beef.
• Sulfites: These are salts or esters of sulfurous acid that prevent browning and oxidation of foods. They also inhibit the growth of some bacteria and molds. Some examples are sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium metabisulfite, and sulfur dioxide. They are frequently used in wine, beer, dried fruits, fruit juices, and seafood.
• Propionates: These are salts or esters of propionic acid, a natural organic acid that inhibits the growth of molds and some bacteria. Some examples are calcium propionate, sodium propionate, and potassium propionate. They are commonly used in breads, cakes, pastries, and cheese.
• Parabens: These are esters of para-hydroxybenzoic acid (PHBA), a synthetic organic acid that inhibits the growth of yeasts, molds, and some bacteria. Some examples are methylparaben, ethylparaben, propylparaben, and butylparaben. They are often used in cosmetics, pharmaceuticals, and personal care products, but they can also be found in some foods like jams, jellies, syrups, and beverages.

These are some of the most widely used chemical preservatives in the food industry, but there are many others with different functions and applications. The choice of preservative depends on various factors such as the type of food, the desired shelf life, the consumer preference, the cost, the availability, and the regulatory requirements .

Organic acids are one of the most widely used chemical preservatives in the food industry. They are effective against a variety of microorganisms, especially bacteria and fungi, that can cause food spoilage or foodborne illnesses. Organic acids include acetic acid, benzoic acid, lactic acid, propionic acid, sorbic acid, and citric acid. They are often added to acidic foods such as pickles, sauces, jams, juices, soft drinks, cheese, and bread.

The main mechanism by which organic acids inhibit the growth and activity of bacteria is by disrupting their cell membrane and cytoplasmic pH. The cell membrane is a semi-permeable barrier that separates the inside of the cell from the outside environment. It regulates the transport of nutrients, waste products, and ions across the cell. The cytoplasm is the fluid inside the cell that contains various enzymes, proteins, and other molecules that are essential for the cell`s metabolism and function.

Organic acids are weak acids that can exist in two forms: protonated (uncharged) and dissociated (charged). The ratio of these two forms depends on the pH of the solution. At low pH (acidic), most of the organic acid molecules are protonated and uncharged. At high pH (alkaline), most of the organic acid molecules are dissociated and negatively charged.

The protonated form of organic acids can easily cross the cell membrane of bacteria because they are uncharged and lipid-soluble. Once inside the cell, they encounter a neutral or slightly alkaline cytoplasmic pH. This causes them to dissociate and release protons (H+) into the cytoplasm. The protons lower the cytoplasmic pH and interfere with the normal biochemical reactions and enzyme activities of the bacteria. This reduces their growth rate and viability.

The bacteria try to maintain their cytoplasmic pH by pumping out the excess protons using their energy (ATP). However, this process consumes a lot of ATP and reduces the energy available for other cellular functions. Moreover, as more protonated organic acid molecules enter the cell, more protons are released into the cytoplasm. This creates a vicious cycle that eventually leads to the death of the bacteria.

The effectiveness of organic acids as preservatives depends on several factors, such as:

• The type and concentration of organic acid
• The type and sensitivity of bacteria
• The pH and water activity of food
• The presence of other preservatives or antimicrobial agents
• The storage time and temperature

Generally, organic acids are more effective against gram-positive bacteria than gram-negative bacteria because gram-negative bacteria have an outer membrane that acts as an additional barrier to organic acid penetration. Also, organic acids are more effective at lower pH and higher concentrations because more protonated molecules are available to cross the cell membrane. However, too high concentrations of organic acids can also have adverse effects on food quality and safety, such as affecting flavor, color, texture, and nutritional value. Therefore, it is important to use organic acids at optimal levels that balance their antimicrobial efficacy and sensory acceptability.

The Department of Food Technology and Quality Control (DFTQC) is one of the three departments under the Ministry of Agriculture and Livestock Development, Government of Nepal. It is responsible for regulating food and feed safety and quality in the country.

The DFTQC has issued various directives and guidelines for using chemical preservatives in food, based on the Food Act 2023 and the Feed Act 2033. Some of these are:

The DFTQC also publishes a list of new registered and renewed dietary supplement products every month on its website, which shows the names of the products, their manufacturers or importers, their ingredients and their preservatives.

The DFTQC monitors and inspects food and feed establishments to ensure compliance with its directives and guidelines. It also conducts laboratory tests on food and feed samples to check their quality and safety. It has the authority to take legal action against violators of its regulations.

The DFTQC aims to protect public health and promote consumer awareness by ensuring safe and quality food and feed in Nepal.

Chemical preservatives are widely used in the food industry to prevent spoilage and extend shelf life of food products. However, they also have some limitations and drawbacks that consumers should be aware of. Some of the limitations of chemical preservatives are:

• They cannot improve the quality of poor raw materials or mask the signs of deterioration.
• They may alter the taste, color, texture, or nutritional value of food if used excessively or improperly .
• They may cause adverse reactions or allergies in some individuals who are sensitive to certain preservatives.
• They may interact with other food components or environmental factors and reduce their effectiveness or create harmful by-products.
• They may pose health risks if consumed in large amounts over a long period of time, especially for children, pregnant women, and people with chronic diseases.
• They are subject to strict regulations and guidelines that vary by country and region, and require proper labeling and monitoring .

Therefore, chemical preservatives should be used with caution and moderation, and only when necessary to ensure food safety and quality. Consumers should also read the labels carefully and choose foods that contain natural or minimal preservatives whenever possible. Alternatively, they can opt for other methods of food preservation, such as freezing, drying, canning, or fermenting .

As a famous quote says, "Preservatives can be used to extend the expiration dates of food but unfortunately not of people." Thus, we should be mindful of what we eat and how it affects our health and well-being.

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