Gelatin is actually a pure protein consisting of eighteen amino acids, eight of which are essential. It is mainly derived from the collagen found in pig skin, bovine bones and bovine hides; fish and poultry gelatin can also be found on the market but are less common.
Many people think that all gelatin is the same and think it’s just a gelling agent because of its association with water jelly and gummy sweets.
In actuality, gelatin is a highly diverse ingredient that has several useful properties and functionalities, and comes in many types that can be used in a variety of applications such as food, pharmaceuticals, medical equipment, photography and even wine-making.
Gelatin offers a wide range of properties / functionalities and, depending on the gelatin-type, a specific property or a functionality can be more or less developed. For example, some gelatins offer an important foaming functionality while others have variable gelling power.
Gelatin manufacturers are not confined to one single type of gelatin. In fact, they produce several hundreds, each of them having their own specific Bloom level (gel strength), viscosity level (thickness when in heated liquid form) and isoelectric point (this corresponds to the pH at which gelatin has a neutral charge).
For each food, pharma or technical application there is a specific gelatin that brings the exact functionalities required to achieve a perfect end-product with the right texture (in a gummy for example) or mouthfeel (in a dairy product) or transparency (softgel).
The needs of the pharmaceutical industry aren’t the same as the needs of food manufacturers. So rather than using something off the shelf, a precise gelatin-type should be tailor-made for a specific purpose.
Gelatin-type is characterized by its specifications, which are determined by the raw materials and the manufacturing process.
The raw materials refer to the source of the native collagen. The main sources are pig skin, bovine hides and bovine bones. Gelatin can also be made from fish and poultry; however, cow- and pig-derived gelatin occupies the goldilocks zone of higher yields and affordability, which is why it tends to be the main source.
The process refers to how the raw material is made into gelatin. In the pre-treatment stage, the main goal of the process is to break some of the intermolecular and intramolecular links of the raw collagen found in the skin or bones of animals; this enables the collagen to become soluble for hot-water extraction in the next stage.
There are two main types of pre-treatments:
- Acid treatment (results in gelatin with lower viscosity)
- Alkaline treatment (results in gelatin with higher viscosity)
The type of raw material used determines the process which then has an effect on the gelatin type. For example,
- pig skin can only be processed via acid treatment
- acid treatment produces gelatin with a lower viscosity
Beef bones and beef hides can be processed via both acid and alkaline treatment, which means if you need a gelatin-type with higher viscosity you would use raw material derived from cows and process it with an alkaline treatment.
After pre-treatment, the collagen is rendered soluble and the gelatin is extracted by hot water. The solution containing the pre-treated raw material is heated. Several successive extraction steps are usually done to make sure all the collagen is extracted. The gelatin exhibiting the higher Bloom (gel strength) comes from the early extractions while the gelatins with the lower Bloom come from later extractions.
So getting a specific Bloom or viscosity depends on the raw materials selected and the process itself.
Bloom is the specific measure for the gel strength/firmness of the gelatin. The Bloom values are determined by measuring the force (in g) required to depress the surface of a 6.67% gelatin gel (after gelling 16-18 hours at 10°C) to a distance of 4 mm. So, the higher the value, the stronger the firmness of the gel.
It is undoubtedly the number one criteria in choosing the right gelatin for a product. Let’s explain why with some examples.
Bloom is important for getting the right texture and chewiness. For example, take gummy bears and water jelly. The texture of these popular products is different. This is typically attributable to the gel strength and the gelatin concentration.
In marshmallows, higher Bloom gelatin is preferred, as the setting and gelling functionality of gelatin is important for stabilizing the aerated texture. But formulators will also strongly rely on its foaming functionality.
For wine fining - the process of removing unwanted turbid particles from wine - the ideal gelatin has a low molecular weight and could be selected between hydrolyzed gelatin to a low Bloom and low viscous acid gelatin (ex75 g). This kind of gelatin is particularly suited for red wine, beer, cider and apple juice clarification where it reduces turbidity and decreases the astringency of final beverages without negative impact on suitable flavor components. A high Bloom gelatin is not suitable for this process as it tends to gelify at the point of finning and causes excessive/uncontrolled precipitation.
Viscosity is the resistance to flow and is expressed in m.Pa.s (milliPascal-second). While bloom is measured on the gelified product, viscosity is measured on the gelatin solution.
Viscosity can be tailored to different applications requiring specific levels of thickness and creaminess (food applications). The relative viscosity of gelatin will determine the overall texture and creaminess when practically applied.
For instance, the texture of gummies can range from short to long, with shorter texture being softer. This is linked to the viscosity of the gelatin.
The desired creaminess of a dairy product is dependent on the gelatin type and the concentration being used. For example, removing fat from dairy takes away some of the mouthfeel and structure - gelatin helps to replace this. A reduced-fat dairy product needs a gelatin with medium to high Bloom. High Bloom gelatin is used at lower concentration than medium Bloom gelatin. The concentration used has a direct impact on syneresis (higher concentration will decrease presence of liquid at the surface of yogurt).
For jelly found in meat products, such as Aspic, a high Bloom gelatin is preferred for a firmer and transparent gel. This kind of gelatin brings stabilizing power, transparency and water binding.
In pharma, the choice of gelatin will depend on the applications :
Hard capsules are two-piece capsules (cap and body), composed mainly of gelatin, opacifying agent (TiO2) and coloring agents. Process consists of stainless mold pins dipped into a concentrated gelatin solution, coating them in film. After film dries, the capsules are removed from the molds and cut to length. Next, caps and bodies are assembled together and completed capsules are packed.
They are typically produced with high Bloom gelatin and filled with powder, possibly sealed (banding) after filling. High Bloom gelatin is necessary for obtaining resistant film protecting the API. Acid or alkaline gelatins could be used.
Softgels are one-piece, hermetically sealed capsules, consisting of a liquid or semi-liquid fill enveloped by an elastic outer shell. The shell is composed of gelatin and plasticizer such as glycerol and coloring agents.
Soft capsules are formed, filled and sealed in a continuous operation, preferably by rotary die process. They are typically filled with oil and non-aqueous liquid, and a medium Bloom gelatin is preferred for a more elastic / softened plasticized film. Acid or alkaline gelatins could be used.
Medium alkaline Bloom gelatin (160 Bloom) is often used for pharmaceutical and nutrition products.
200 Bloom acid gelatins with lower intrinsic viscosity allow higher gelatin concentration, so higher dry matter in the shell. They are used for hygroscopic or water sensible drugs, when formulation has to contain less water and dry quickly.
Mixture of low Bloom or Hydrolyzed gelatin and medium Bloom has been proposed for chewable capsules.
Fish gelatin: as an alternative to bovine, but gelling, setting, drying are different from mammalian; so, formulation and process conditions have to be adjusted.
For tableting, non-gelling gelatin (hydrolyzed gelatin) is used in direct compression. Gelling gelatin solutionis used after granulationof the powderin compression.
The gelling gelatin gives cohesiveness, resistance and hardness to the tablets.
The dissolution of the tablet depends on the type of gelatin used: higher the gel strength, higher the physical properties (cohesiveness) of the tablet, but longer the dissolution time.
At the opposite end, the non-gelling gelatin allows a fast (instantaneous) dissolution of tablets, but those tablets will be weak in terms of resistance and cohesiveness.
This is how fine or coarse the gelatin is. A good analogy is ground coffee: some methods of coffee-making require finely ground coffee, while with others it’s better to use coarsely ground coffee.
In dairy applications the gelatin needs to be finely ground to allow it to disperse in cold milk and dissolve during pasteurization. In yogurt, gelatin can be dispersed before fermentation, in cold milk and, thanks to fine mesh gelatin (more about mesh later in this blog), can be dissolved during homogenization and pasteurization.
Whereas in the making of hard capsules, the gelatin is dispersed in hot water so it needs to be coarsely ground. Coarser particles avoid producing lumps.
Particle size is measured in millimeters (mm) which is then converted into a numerical value known as ‘mesh’. The higher the mesh value the finer the gelatin grain.
Gelatin has some amazing properties that allow it to serve a wide range of functional needs. However, it isn’t a one-size-fits-all ingredient. Gelatin needs to be fine-tuned to meet the specific requirements of the product.
Bloom, viscosity and particle size are the three most important factors when it comes to choosing the right gelatin. Each gelatin-type has to go through a specific process that ensures careful selection of raw materials and the correct pre-treatment method.
The end result is a highly versatile product that can be used in multiple applications across various industries.
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