Dishwashing detergents:
composition, mechanisms and principles of operation

These everyday products are based on scientific advances in colloid chemistry, enzymology and materials science. They are complex chemical compositions designed to effectively remove various contaminants from kitchen utensil surfaces.

Modern detergents work due to the complex interaction of surfactants, enzymes and auxiliary components, which together form an effective system for removing fat, proteins, starch and other food contaminants. In this case, not only the active components play an important role, but also their ratio, as well as the physical and chemical processes that occur during dishwashing.

Chemical composition of dishwashing detergents

Surfactants as a basis for detergents

Surface-active substances (SAS) are the main active component of any dishwashing detergent. Their molecular structure determines the ability to reduce the surface tension at the boundary of two environments, which allows them to penetrate between the dirt and the surface of the dishes. The SAS molecule has a hydrophilic "head" that is attracted to water, and a hydrophobic "tail" that has an affinity for fats and oils. This amphiphilic nature allows SAS to create a bridge between water and fatty dirt, making it possible to remove it.

The concentration of surfactants in hand dishwashing detergents is usually between 20 and 45% of the total composition, making them the main active component. These substances not only separate dirt from the surface, but also keep it suspended in water, preventing it from settling back on the dishes.

Types of surfactants and their role

Dishwashing detergents use several types of surfactants, each of which performs its own function:

Anionic surfactants form the basis of most detergents, their share can reach 35%. These substances carry a negative charge in an aqueous solution and have high cleaning capacity and good foaming. These include sodium alkyl sulfates (for example, sodium lauryl sulfate), alkyl benzene sulfonates, and others. Anionic surfactants effectively break down dirt on dishes, but can have an irritating effect on the skin with frequent contact.

Nonionic surfactants do not have an electric charge in solution and are usually used in quantities 3-8 times smaller than anionic surfactants. They are gentler on the skin and are used primarily in baby dishwashing detergents. Nonionic surfactants work well with greasy stains and help to soften the possible negative impact of anionic surfactants.

Amphoteric surfactants such as betaines, amine oxides and alkyl amphoacetates are added to dishwashing detergents to stabilize foam and improve foaming in hard water. They combine the properties of both anionic and cationic surfactants, changing their charge depending on the pH of the environment. Amphoteric surfactants are characterized by their gentle effect on the skin and good degreasing properties.

Hydrotropic surfactants are often added to concentrated products with a high electrolyte content. They prevent separation of the composition and increase the cloud point of non-ionic surfactants, contributing to the stability of the product.

Auxiliary components and their functions

In addition to surfactants, dishwashing detergents contain many auxiliary components:

Water is the primary solvent in most dishwashing detergents. As the “universal solvent,” it can dissolve more substances than any other liquid. When combined with detergents and surfactants, water becomes an effective cleaning agent.

Thickeners regulate the viscosity of the product, making it more convenient to use. They facilitate dosing and reduce product consumption. Non-ionic surfactants (e.g. diethanolamine) and other polymer compounds are often used as thickeners.

Softening additives compensate for the possible negative impact of surfactants on the skin of the hands. These include glycerin, panthenol, various plant extracts, which help protect the skin from overdrying and irritation.

Flavors and colorants are added to give the product a pleasant smell and attractive appearance, which affects the consumer properties of the product.

Preservatives ensure microbiological stability of the product throughout its shelf life, preventing the growth of bacteria and the development of mold.

Physicochemical principles of contaminant removal

Mechanism of interaction with fats and oils

The process of removing greasy stains from dishes is based on several physical and chemical principles. When a dishwashing detergent comes into contact with a dirty surface, the surfactants are oriented in such a way that their hydrophobic "tails" interact with the fat molecules, and their hydrophilic "heads" remain facing the water.

When subjected to mechanical action (rubbing with a sponge or brush), fat molecules are torn away from the surface and surrounded by surfactant molecules, forming microscopic droplets called micelles. In these micelles, fat is enclosed inside, and on the outside are the hydrophilic parts of the surfactant molecules, which ensure the solubility of the entire structure in water.

Water temperature is also an important factor. Higher temperatures help solid fats melt and make them more susceptible to surfactants. In addition, warm water accelerates chemical reactions and increases the mobility of molecules, which increases the efficiency of the cleaning process.

The process of formation and work of micelles

Micelle formation is a key process in the operation of dishwashing detergents. Micelles are formed only when the concentration of surfactants exceeds the so-called critical micelle concentration (CMC). When this concentration is reached, surfactant molecules spontaneously organize into spherical structures.

In an aqueous solution, micelles are spherical particles, where the hydrophobic "tails" of the surfactant molecules are facing inward, and the hydrophilic "heads" are facing outward, toward the aqueous medium. When in contact with fat, reverse micelles are formed, where the fat molecules are trapped inside, and the hydrophilic parts of the surfactant molecules ensure the solubility of the entire structure in water.

Micelles are able to solubilize (dissolve) water-insoluble substances such as fats and oils, making it possible to remove them from the surface of dishes. After the micelles are formed, the contaminants remain suspended in the water and are washed away during rinsing.

The Role of Water in the Dishwashing Process

Water plays a multifunctional role in the dishwashing process. First, it serves as a medium for dissolving the detergent and forming an active solution. Second, water is involved in transporting separated contaminants from the surface of the dish. Third, when rinsing, water removes the remains of the detergent together with the solubilized contaminants.

Water quality significantly affects the effectiveness of washing. Hard water containing calcium and magnesium ions can reduce the detergent’s cleaning ability, since these ions interact with anionic surfactants, forming insoluble compounds. To compensate for this effect, chelating agents that bind hardness ions are often included in detergents.

Water temperature also matters: warm water (30-45°C) usually provides the best results, as it helps melt fats and speed up chemical reactions without causing the denaturation of protein contaminants that can occur at high temperatures.

Enzymes in modern detergents

The principle of action of proteases and amylases

Enzymes (or ferments) are biological catalysts that speed up chemical reactions. Modern automatic dishwasher detergents widely use various types of enzymes that can break down specific types of dirt.

Proteases specialize in breaking down protein contaminants such as meat, egg, or dairy residue. These enzymes break the peptide bonds in protein molecules, breaking them down into smaller fragments – peptides and amino acids – that can be easily washed away with water.

Amylases are designed to break down starch and other polysaccharides found in potato, rice, pasta and bakery residues. They convert complex carbohydrates into simple sugars that dissolve well in water.

Some formulas also contain lipases, enzymes that specialize in breaking down fats and oils. They break down triglycerides into glycerol and fatty acids, which are more easily removed by surfactants.

The peculiarity of enzymes is that they are not consumed during the reaction process, but can repeat their action many times. One enzyme molecule is capable of breaking down millions of molecules of dirt, which makes them extremely effective even at low concentrations (usually less than 2% of the detergent composition).

Benefits of Enzyme Formulas

The use of enzymes in detergents has a number of significant advantages:

High efficiency at low concentrations. Even small amounts of enzymes can provide significant cleaning effect due to their catalytic nature. The typical enzyme content in a detergent is only about 2%, compared to 7% or more for phosphate formulas.

Specificity of action. Each type of enzyme acts on a specific type of contamination, which allows you to create targeted formulas for different tasks.

Ability to work at lower temperatures. Many modern thermostable enzymes are active already at 40-50°C, which allows saving energy when using dishwashers.

Less environmental impact than traditional chemical components such as phosphates. Enzymes are biodegradable and do not accumulate in the environment.

Compatibility with other components of detergents, which allows creating complex formulas with a synergistic effect.

Ecological aspect of enzyme use

Enzymes are a more environmentally friendly alternative to traditional chemical components of detergents. Unlike phosphates, which can cause eutrophication of water bodies, enzymes naturally decompose in the environment.

The production of enzymes for detergents is carried out using microorganisms, such as Bacillus licheniformis bacteria, which are grown in special bioreactors. The resulting enzymes are isolated, stabilized and added to detergents.

After use and discharge into wastewater, enzymes gradually lose their activity and are decomposed by the environment. They become food for normal bacteria, which facilitates their complete decomposition without the formation of harmful by-products.

Replacing phosphates with enzymes in detergents is an important step towards reducing the negative impact of household chemicals on ecosystems. This is especially relevant in light of the restrictions on the use of phosphates introduced in many countries.

Special components to enhance cleaning ability

Chelating agents and their importance

Chelating agents (chelates) are substances capable of forming stable complexes with metal ions such as calcium, magnesium, iron and copper. Their main function in detergents is to soften water and prevent the formation of insoluble salts with surfactants.

Ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) are typical examples of chelating agents used in detergents. They bind calcium and magnesium ions present in hard water, preventing them from interacting with detergent components and forming a precipitate.

Chelates also help remove stains containing metals, such as rust or hard water stains. They form complexes with the metal ions in the stain, making them more soluble and easier to remove.

Modern formulas increasingly use biodegradable alternatives to EDTA, such as methylglycinediacetic acid (MGDA) and other aminocarboxylates, which have good chelating properties with less environmental impact.

Builders (builders) in the composition of cleaning products

Builders are components that enhance the action of the main cleaning agents and perform several important functions:

Softening water by binding calcium and magnesium ions, which increases the effectiveness of surfactants. Traditionally, sodium tripolyphosphate (STPP) has been used for this purpose, which has a high ability to bind heavy metals and calcium ions.

Maintaining an optimal pH level, which contributes to a better cleaning effect. Alkaline salts, such as sodium carbonate, create a favorable environment for the work of cleaning components.

Preventing the re-settling of removed dirt on the surface of the dishes. This is especially important for automatic dishwashers, where the dishes undergo a long wash cycle.

Due to environmental restrictions on the use of phosphates in many countries, modern formulas often include alternative builders such as zeolites, polyacrylates, sodium citrates and polycarboxylates. For example, zeolite type A exhibits excellent ion exchange and hard water softening properties, and is an environmentally friendly material.

Foam and shape stabilizers

Foam stabilizers ensure that stable foam is formed when using a hand dishwashing detergent. Although foam itself does not improve cleaning performance, it serves as an indicator of the product’s activity and is psychologically associated with the effectiveness of the product by consumers.

Amphoteric surfactants such as betaines are often used to stabilize foam, ensuring the formation of fine and stable foam even in hard water. They also mitigate the possible irritating effect of anionic surfactants on the skin.

In contrast, automatic dishwasher detergents often use antifoams because excessive foaming can interfere with the operation of the machine, affect the water level sensors and lead to leaks through the door seals.

Form or consistency stabilizers help maintain the viscosity and homogeneity of the product throughout its shelf life. These include various polymers that prevent the product from separating and provide a stable consistency at different storage temperatures.

Features of products for different types of application

Hand dishwashing detergents

Hand dishwashing detergents have a number of specific requirements that determine their composition:

High foaming. Abundant and stable foam serves as a visual indicator of the product’s activity and the cost-effectiveness of its use. For this purpose, the formula includes anionic surfactants with good foaming properties, as well as foam stabilizers.

Gentle on the skin of the hands. Since these products are in direct and prolonged contact with the skin, they must contain components that reduce the irritant potential, such as non-ionic and amphoteric surfactants, as well as softening additives (glycerin, panthenol).

Good cleaning and degreasing properties. The formula should effectively remove a variety of food stains, including fat, starch and proteins. To achieve this, a combination of different types of surfactants with a synergistic effect is used.

Easy to rinse. The product should be easy and completely rinsed from dishes, leaving no traces or chemical taste. This is especially important, as residues can get into food.

The total surfactant content in hand dishwashing detergents is usually 20-45%, with anionic surfactants being up to 35% of the total formula. Nonionic surfactants are added in smaller quantities (3-8 times less than anionic surfactants). Amphoteric surfactants are used to stabilize foam and soften the effect of anionic surfactants on the skin.

Formulas for automatic dishwashers

Detergents for automatic dishwashers differ significantly from those for hand washing:

Low foaming. Excessive foam can interfere with the operation of the dishwasher, affect the water level sensors and lead to leaks. Therefore, these products use low-foaming surfactants or add defoamers.

High alkalinity. Dishwashing detergents often have a high pH (10-12), which helps to effectively remove grease and protein stains. For this purpose, alkaline salts such as metasilicates, alkali metal hydroxides, and sodium carbonate are included in the composition.

Enzyme content. Automatic products often contain a combination of enzymes (proteases, amylases, sometimes lipases) that effectively destroy various types of food contaminants at temperatures of 40-60°C.

The presence of bleaching agents that destroy and discolor organic contaminants. Modern formulas usually contain oxygen-containing bleaches instead of chlorine-containing ones, which makes them more environmentally friendly.

Anti-corrosion additives (often sodium silicate) that prevent corrosion of metal parts of the dishwasher and dishes.

The surfactant content in dishwasher detergents is significantly lower than in hand washing detergents – usually around 0.5-2% in the finished product. The main emphasis is on enzymes, builders, bleaches and anti-corrosion additives.

Specialized products for special types of dirt

In addition to universal dishwashing detergents, there are specialized products designed to combat specific types of stains:

Heavy-duty burn-on food removers contain a higher concentration of alkaline ingredients that effectively break down carbonized food residues. They may include ingredients such as sodium or potassium hydroxide, which saponify burnt-on fats.

Silver and other non-ferrous metal cleaners have a special composition that prevents oxidation and tarnishing of metal surfaces. They usually contain mild abrasives and antioxidants, but exclude aggressive bleaching agents.

Baby dishwashing detergents are distinguished by their increased safety of composition. They contain mainly non-ionic and soft amphoteric surfactants, do not include potential allergens, dyes and aggressive fragrances.

Dishwasher descalers and degreasers contain acids (citric, lactic) that can dissolve mineral deposits, as well as surfactants to remove greasy stains from the interior surfaces of the machine.

Each of these specialized products has its own unique formula, optimized for a specific task. They are developed taking into account not only the cleaning efficiency, but also the safety for the surfaces they come into contact with.

Modern trends in the development of detergents

Greening of compositions and biodegradability

One of the key trends in the development of modern dishwashing detergents is to improve their environmental safety:

Replacing phosphates with alternative builders. Due to the ban or restriction of the use of phosphates in many countries (for example, in the EU from January 1, 2017 for automatic dishwashers), manufacturers are actively developing alternative components with similar functions. These include zeolites, polycarboxylates, citrates and other biodegradable compounds.

Use of plant-based surfactants instead of petrochemicals. Many modern products contain surfactants derived from palm, coconut, or other plant oils. These compounds often have better biodegradability than traditional petrochemical surfactants.

Increasing the concentration of active components, which allows to reduce the volume of packaging and transportation costs. Modern concentrated products provide the same cleaning effect with lower product consumption.

Developing solid and powder alternatives to liquid detergents, which reduces the use of plastic packaging. Tablets and powders for dishwashers, as well as solid bars for hand washing of dishes, are becoming increasingly popular.

Implementation of packaging reuse systems. Some manufacturers offer reusable containers and refill systems, which helps reduce waste.

Innovations in enzyme technology

The development of enzyme technologies plays an important role in improving detergents:

Creation of thermostable enzymes capable of working effectively at high temperatures (50-70°C), which increases their cleaning ability to remove heavy stains.

Development of enzymes with increased stability in the presence of bleaching agents and other chemical components of detergents, which allows the creation of more effective complex formulas.

Using directed evolution and genetic engineering to create enzymes with improved properties, adapted to specific operating conditions (pH, temperature, types of contaminants).

Combination of different types of enzymes (protease, amylase, lipase) for a synergistic effect. Research shows that such combinations significantly increase the effectiveness of removing complex contaminants.

Development of granulated and encapsulated forms of enzymes that are activated only when dissolved in water, which increases their stability during storage and safety for the consumer.

Regulatory restrictions and their impact on formulas

Legislative restrictions significantly affect the composition of modern detergents:

The ban on phosphates in the European Union has led to a major restructuring of detergent formulas and a search for alternative builders. The restrictions were introduced due to the ability of phosphates to cause eutrophication of water bodies – excessive growth of algae, which leads to oxygen deficiency and the death of aquatic organisms.

The requirements for surfactant biodegradability adopted in many countries stimulate the use of surfactants with improved environmental characteristics. Current regulations require surfactants to undergo primary biodegradation by 80% and complete biodegradation by 60% within 28 days.

Restrictions on the use of certain preservatives, flavors, and colors, especially those that may cause allergic reactions or have potential hormonal effects, have led to many traditional formulas being reconsidered and safer alternatives being sought.

Requirements for transparency of information on product composition, which oblige manufacturers to indicate all potentially dangerous ingredients on the packaging. This stimulates the development of products with simpler and more understandable formulas for the consumer.

Tightening of environmental standards for the production and packaging of detergents, which affects not only the chemical composition, but also the materials and design of the packaging, as well as production technologies.

These regulatory restrictions, while creating some challenges for manufacturers, ultimately result in safer and more environmentally friendly products, which meets growing consumer demand for eco-friendly cleaning products.

Final aspects of the mechanisms of action of detergents

Synergistic effect of components

The effectiveness of modern dishwashing detergents is explained not only by the action of individual components, but also by their synergistic interaction. A correctly selected combination of different types of surfactants (anionic, nonionic, amphoteric) provides a higher cleaning capacity than the sum of the effects of each surfactant separately.

Synergy is also demonstrated in the interaction of enzymes with surfactants: enzymes break down complex contaminants into simpler compounds, which are then more effectively removed by surfactants. Chelating agents, by binding water hardness ions, create optimal conditions for the work of surfactants and enzymes, increasing the overall effectiveness of the detergent.

It is important to note that the detergent formula must be balanced, taking into account all possible interactions between the components. For example, some enzymes may lose activity in the presence of certain surfactants or at high pH values, so the composition must ensure their stability and compatibility.

Balance between efficiency and safety

Modern dishwashing detergents are the result of a careful balance between cleaning power and safety for both humans and the environment. Manufacturers strive to create formulas that effectively remove dirt, but at the same time have minimal impact on the skin of the hands and do not harm aquatic ecosystems.

This is achieved by:

• Replacing aggressive surfactants with milder alternatives
• Reducing the proportion of synthetic components in favor of substances of natural origin
• Addition of protective and softening components for the skin of the hands
• Developing biodegradable formulas that do not accumulate in the environment

However, often increasing safety can lead to decreasing efficiency, and vice versa. Therefore, the development of detergents requires a scientific approach and a compromise between various aspects of performance and safety.

Prospects for further development of technologies

The future of dishwashing detergents lies in several areas of technological development:

Nanotechnology can lead to the creation of new types of surfactants and other active components with improved properties at the molecular level. For example, nanostructured surfactants are being developed that interact more effectively with contaminants.

Biotechnology opens up the possibility of creating new enzymes with specified properties that can work in a wider range of temperatures and pH. This will allow the creation of detergents that are effective even at low temperatures, which will reduce energy consumption.

Green chemistry encourages research into plant-based surfactants and other components derived from renewable resources. This is especially important in light of growing concerns about environmental issues.

Digital technology could lead to the creation of “smart” dosing systems that automatically determine the optimal amount of detergent based on water hardness, type of dirt and volume of dishes.

These areas reflect the general trend towards creating more effective, safe and environmentally friendly dishwashing detergents, which meets growing consumer demands and environmental standards.

Methods for testing the effectiveness of detergents

Laboratory tests and quality standards

The effectiveness of dishwashing detergents is assessed using a number of standardized methods and tests:

A soil removal test measures the percentage of soil removed from a surface in a standard period of time under given conditions. Special devices such as Leenert’s Improved Detergency Tester are used to compare the effectiveness of different formulas.

Foaming capacity is measured as the volume and stability of foam formed under specified mixing conditions. For hand dishwashing detergents, high and stable foaming capacity is an important quality indicator.

Biodegradability tests assess the rate and completeness of decomposition of detergent components in the environment. Standard methods include measuring CO₂ production or oxygen consumption by microorganisms as they decompose the test substance.

Dermatological tests verify the safety of a product for hand skin. They include an assessment of the potential for skin irritation, allergenicity, and other possible negative effects.

Compatibility tests with various materials determine whether the detergent will cause damage to the surfaces of dishes (glass, ceramics, metals, plastic) during prolonged contact.

Factors influencing consumer choice

When choosing a dishwashing detergent, consumers are guided by a number of factors:

Cleaning efficiency is the main criterion, but it is assessed by consumers subjectively, often based on indirect signs such as abundant foaming or the ability to remove visible dirt.

Health safety is becoming an increasingly important factor. Consumers prefer products with a minimum content of potentially dangerous chemicals and additives that can cause allergic reactions.

The eco-friendliness of a product influences the choice of environmentally conscious consumers. They prefer biodegradable formulas and products produced with minimal impact on the environment.

Efficiency and price remain important factors for most consumers. Concentrated formulas, which require less product per wash cycle, are often perceived as better value.

Ease of use, including packaging design, ease of dosing and no need to wear protective gloves, also influences consumer preferences.

The aroma and appearance of the product play a significant role in consumers’ perception of the quality of the product, although they are not directly related to its cleaning properties.