1.Introduction
Stabilizers' use and functionality in food items is not new; they have been used for more than a half-century. However, it is only in recent years that a broad range of new dairy products have been introduced that rely heavily on the functionality of stabilisers [1]. One of the primary goals of dairy manufacturers is to produce dairy products with desirable quality characteristics (appearance, texture, and flavour) and a long shelf life. To accomplish this goal, dairy manufacturers have used ingredients such as stabilisers to enhance the kinetic stability of food emulsions. A dispersion of droplets of one immiscible liquid in another in the presence of stabiliser molecules is described as an emulsion.
Emulsifiers serve two primary purposes: Providing colloidal stability to the droplet by creating an electrically charged layer at its interface with the continuous phase and lowering interfacial tension, resulting in less energy intensive droplet formation. An emulsifier's hydrophilic/lipophilic structure facilitates its concentration at the interface of immiscible liquids, where it creates an interfacial film. Food emulsions are classified as either oil-in-water (o/w) emulsions (e.g., liquid cream or milk), in which oil is the disseminated phase, or water-in-oil (w/o) emulsions (e.g., margarine), in which water is the dispersed phase and oil is the continuous phase. Many dairy goods contain low molecular weight emulsifiers (e.g., mono- and diglycerides) and non-dairy stabilisers (e.g., alginates, carrageenans, gums, and gelatine).
Emulsifiers are used to stabilise oil in water emulsions and are frequently used in conjunction with stabilisers in beverage preparation. Stabilizers with high water binding capacity thicken and gel in dairy products such as yoghurt and keep product stability during the manufacturing and storage of other dairy products. Some polysaccharide stabilisers work together with milk proteins and other milk components to create a combined effect. During the manufacturing of dairy products, the function of the interacting polysaccharide must be considered. A general example is the synergy that exists between kappa carrageenan and kappa casein, which can be used in dairy applications where gel strength is needed. However, the sort of emulsifier or stabiliser used, as well as the timing of their addition, play a role.
2. Emulsifier in milk
Milk is both a complicated dietary emulsion and a colloidal solution. The emulsion component is made up of fat droplets distributed in a protein-containing aqueous phase. The protein exists in the shape of casein micelles, colloidal particles, and whey protein monomers in solution. Milks with varying fat contents, low or reduced lactose content, and fortified with nutrients such as vitamin A, vitamin D, and calcium, all with an acceptable shelf life and taste quality, are widely available. The susceptibility of polyunsaturated fatty acids to oxidative rancidity has limited milk fortification with functional food ingredients such as omega-3 fatty acids, but this issue has been overcome using an antioxidant.
Mono- and di-glycerides of fatty acids are among the most commonly used emulsifiers in milk. Mono- and diglycerides are esters formed by catalytic transesterification of glycerol with triglycerides, with hydrogenated soybean oil serving as the typical triglyceride source; they can also be synthesised directly from glycerol and fatty acids under alkaline conditions. The fatty acid mono- and di-glycerides that are incorporated into milk contribute to the formation of the milk-fat globule membrane, which is needed to cover the increased surface area of the fat globule derived during milk homogenization.
The dark seaweed Phaeophyceae's main structural polysaccharide component is alginates. They are found in seaweeds as sodium, potassium, calcium, and magnesium salt mixtures.
3. Emulsifier in yoghurt
Yoghurt is the most well-known and widely consumed cultured milk product in almost every nation. Yoghurt typically comprises 10-13% nonfat milk products and 0-3.5% fat. The milk ingredients in the set and stirred yoghurts give gel strength or viscosity as well as water-binding properties. The main goal of adding stabilizers to yoghurt is to improve desirable properties such as viscosity/consistency, appearance and mouthfeel, body and texture, and they are frequently used in low-calorie yoghurts.
Natural and modified gums, seaweed products (carrageenans, alginates), and gelatine are some of the stabilisers found in yoghurt. Because these ingredients can form gel networks, their incorporation allows to production yoghurts with a firm texture, excellent resistance to syneresis, and lower levels of milk solids.
Because of the presence of hydrogen or carboxyl radicals, or of a salt with the ability to sequester calcium ions, the molecules of stabiliser can create a network of linkages between themselves and the milk constituent. (s). According to Ingenpass and Dexter, the negative groups are concentrated at the interface, and the stabiliser achieves water binding into the basic mix in the following process. The water of hydration is linked to the components in the mix. Water binding to milk constituents (proteins) increases their hydration, which stabilises the protein molecules and allows them to create a network that slows the free movement of water.
Stabilizers can be used as a separate compound or as a blend in yoghurt. The goal of blending stabilisers is to accomplish a specific function or, in most cases, to overcome one of the limiting properties of a specific compound. A single stabiliser may be appropriate to produce fruit-flavoured yoghurt but may not be appropriate for the production of other kinds of yoghurt. As a result, the choice of a specific type of stabiliser is influenced by factors such as functional properties, the impact or mode of action of the stabilizer, and the optimum concentration to be used.
The fermentation of lactose (milk sugar) into lactic acid gives yoghurt its distinctive gel-like texture and flavour. Emulsifiers are used to improve texture, creaminess, and fat distribution. Microbial growth is also hampered. Common emulsifiers include mono- and diglycerides of fatty acids (E471) and sucrose esters of fatty acids. (E473).
4. Emulsifier in ice-cream
Ice cream is a complex-colloidal system that contains 10-17% milk fat, 13-17% sugar, 8-11% non-fat milk dry mass (lactose, proteins, mineral salts), 0.2-0.5% stabilisers/emulsifying agents, and primary component, water. Ice cream production begins with the formulation, pasteurization, homogenization, and cooling of the emulsion premix, which is then aerated and frozen in a rotating cylindrical sieve whose external surface is constantly scraped with blades to remove the extruded frozen product prior to packaging. Blends of emulsifiers and stabilisers that work best in full-fat, low-fat, or non-fat ice desserts are used. Emulsifiers create dramatic body and textural effects in low-fat ice cream despite being used at a fraction of a percentage. There are several benefits to using emulsifiers in ice cream.
Ice cream's flavour and texture are determined by two surfaces the fat/water interface and the air/water interface, as well as proteins. A prevalent emulsifier found in ice cream is mono-glyceride. Mono-glycerides contend with milk proteins at both the fat/water and air/water interfaces, causing the fat emulsion to partially destabilise. Denatured milk proteins, partly destabilised fat, and agglomerated fat globules all help to keep the air/water interface stable.
Ice cream, an aerated emulsion of fat, proteins, sugars, gum, and emulsifiers containing ice crystals, is undoubtedly one of the most complex food products. With a delayed meltdown rate, the emulsifiers provide a smooth, creamy, fine texture. They also aid in reducing chilling time, improving whipping, and stabilising air cells. Mono- and diglycerides of fatty acids (E471), polyoxyethylene sorbitan esters (E432 - E436), and sugar esters of fatty acids are common emulsifiers. (E473).
5.Conclusion
The introduction of an exciting new range of high-rheology dairy products, such as liquid milk (and particularly functionalized milk), yoghurt, and ice cream, has only been made possible by the incorporation of emulsifiers and stabilisers into these food colloids. In the formulation of functionalized liquid milk, the combination of emulsifiers and stabilisers has demonstrated to be effective. Stabilizers are required in cultured milk products such as yoghurts to improve favourable qualities such as viscosity, appearance, mouthfeel, and texture. The addition of a small proportion of emulsifiers to low-fat ice cream results in excellent body and texture. Understanding the chemical and physical interactions of these additives with caseins, proteins, lipids, and water in native milk is critical for the creation of future products.
6. Reference
https://belitsa.co/en/application-of-emulsifiers-stabilizers-in-dairy-products-of-high-rheology/#:~:text=Low%20molecular%20weight%20emulsifiers%20(e.g.,used%20in%20many%20dairy%20products%20.
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