Functional Value of Gelatin
A concise overview of gelatin is part of the website of Gelita. I use this as the basis and adapt it to overview its functional values in food formulations.
With gelatin, unique and tailored textures can be created. Gum-like that starts to melt as soon as you put it in your mouth, foamed as is required for marshmallows and chewy candy production and reduced-fat spreadable sausages. Gelatin is able to yield a variety of consistencies including creamy and firm. It prevents syneresis. Gelatin is responsible for a creamy mouthfeel and it can improve the stability and sliceability of whipped fillings.
GEL FORMATION AND VISCOSITY
The structure, molecular size and temperature of gelatin are responsible for the gel formation, viscosity and texture of gelatin. “Being a mixture of polymer chains of different lengths, gelatin forms colloidal solutions or sols. On cooling, these sols convert to gels; on warming, they revert to sols. This unlimited reversibility of the gelling process is an extremely important technological property of gelatin.” It is also the clue to the manipulation of its functional properties.
As the melting point of gelatin-based confectioneries is close to that of body temperature, a very smooth mouthfeel, a pleasant melting behaviour and optimal flavour release occurs. For harder gummy candies, higher Bloom Value gelatins are advisable, whereas lower Bloom Value gelatins create a softer texture. The gel formation ability of gelatin is the precondition for many functionalities and applications: gummy candies and gelled desserts, for example, would not be possible without gelatin, providing the quality, transparency and brilliance.
STABILIZING: ALWAYS IN GOOD SHAPE
“Creams and toppings can be stabilized with gelatin – a property that is also important in combination with other functionalities, such as foam forming or emulsifying. When it comes to cheese spreads or too creamy desserts, fillings or toppings, the required firmness can be adjusted with gelatin. With a higher level of firmness, they maintain their smooth and sharp contours and stay easy to slice, which is important when you think of beautiful pastries or cake fillings.”
WATER BINDING CAPACITIES
Gelatin has excellent water-binding properties. Not only important for fat reduction, adding gelatin to meat reduces the drip loss induced by baking, frying and grilling. “This is an economic factor for the industry that also enhances the end product quality, which is important for the consumer. Especially in low-fat meat products, water binding is extremely important. The addition of small amounts of gelatin hydrolysate improves both the softness and spreadability of meat products made from chopped meat and fat tissue. Gelatin can also bind water during thawing and cooking. In canned products such as corned beef, gelatin is added to absorb the meat juice, which is released during sterilization. It also holds the pieces together and improves slicing.”
A well-known problem in yoghurts and other dairy products, as well as meat products such as emulsified sausages, is syneresis. “This chemical or physical effect occurs during the storage of two-phase systems and can lead to compromised quality: the unsightly release of water caused by phase separation. In yogurt, it’s the whey separating from the yogurt curds. By lowering the interfacial tension and, at the same time, binding and thus immobilizing the water, gelatin emulsifies and stabilizes the compounds, prevents syneresis and ensures an appealing end product during the entire storage period.”
“With its excellent foam building properties, gelatin can also be used to incorporate air into multi-phase emulsions through whipping or gas injection – from marshmallows and mousse desserts to cheese preparations. Gelatin decreases the surface tension of the water, facilitating foaming. Within the foam, the gelatin binds the water during the gelling process and surrounds the fat globules with a thin film. As such, it also stabilizes the foam. Large amounts of air are retained in the product, and different bubble sizes mean that a range of textures can be produced, from creamy to fluffy. Thanks to gelatin’s gelling and stabilizing properties, product texture is maintained, even during long periods of storage.”
“In the case of marshmallows or aerated chews, gelatin prevents the recrystallization of sucrose. The ability to form and stabilize foams comes from the surface properties of gelatin: they are based on the fact that the gelatin side chains have charged groups and that certain parts of the collagen sequence contain either hydrophilic or hydrophobic amino acids. Both tend to migrate towards surfaces reducing the surface tension of aqueous solutions.”
STABLE OIL-IN-WATER EMULSIONS
“As gelatin is also an excellent oil-in-water emulsifier, it can be used to create stable emulsions. Oil-containing sauces such as vinaigrette, mayonnaise and salad dressings need an emulsifier and a stabilizing agent, particularly when they have a low-fat content and a high aqueous phase. Gelatin helps to prevent emulsions from breaking down. To avoid separation of the two phases, the surface tension of the interface can be adjusted. Stabilizing an emulsion can be done in two ways: by increasing the dispersed phase or by thickening the aqueous phase. Because of its ability to absorb up to 10 times its own weight in water, gelatin is a very effective water-binding agent – perfect for low-calorie emulsions with a smooth consistency, creamy texture and a nice gloss.”
“In ice-cream production, the same function is utilized: Gelatin stabilizes heterogeneous suspensions and dispersions, and enhances the formation of very fine crystals, thus preventing coarse crystallization. Here, multifunctional compounds of different gelatin types with tailored properties can be used. This enhances product storage stability and melting properties – perfect for low-calorie frozen desserts and fat-free ice creams. Also in confectionery products, gelatin controls the recrystallization of sucrose. In photographic applications, gelatin acts as a carrier for light-sensitive coatings.”
“The adhesive characteristics of gelatin are probably its most well-known property: it’s been used as a glue for 8000 years. Today, it still is used in many technical applications, but also in the food industry. For example, cereal bars with low water content are made with gelatin hydrolysate as binding (adhesion and cohesion) agent. Gelatin solutions are capable of fully covering the surface contours of the particles to be affixed to each other and, as a result, adhesion forces are built up. Once the gelatin solution has been evenly distributed over the surfaces to be joined, it starts to gel on cooling.”
IDEAL COLLOIDAL SOLUTIONS
“Technologically speaking, gelatin is a hydrocolloid; it forms colloidal solutions with water. They’re actually regarded as ideal colloidal solutions. Other hydrocolloids are, for example, pectin, carrageenan, gum arabic, xanthan, guar gum and locust bean gum, to name just the most important ones. In the food industry, they are used for their functional properties; but, compared with gelatin, their functionalities are rather limited. In many formulations, Gelatin can replace one or more hydrocolloids with only little adjustments.”
“Gelatin also enables the development of delicious half-fat, low-fat and “light” products, as it has enormous water binding capacities. Thus, calorie-free water can be incorporated to replace high-calorie fat. With the according technical knowledge, you get the same volume and comparable mouthfeel, and fewer calories. In products such as half-fat butter, reduced fat cheese and fat-free ice cream, gelatin helps to minimize the fat content without compromising on taste. In pizza cheese for example, gelatin not only reduces the fat content but also improves the melting properties. When replacing fat with water, giving structure and texture to the water is important. Gelatin scores points by being able to create a fat-like matrix in emulsions that exhibits shear-thinning properties and a fat-like creaminess. Thus, the addition of gelatin results in a smooth, creamy texture and mouthfeel – with fewer calories and a compatible appearance and taste.
In meat products, its functional proteins can be used to create sliceable aspics, sausages and spreadable products, all of which have significantly fewer calories than other meat or sausage products. Spreadable sausages in particular, with their high-fat content, are perfect candidates for fat reduction. Here, gelatin provides excellent texture and improved spreadability – while reducing the fat and calorie content.”
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