Cellulose Sausage Skins via the Lyocell Process

Topics Covered

Background

Traditional Sausage Casing

Sausage Casings via the Lyocell Process

How the Lyocell Process Works

Advantages of the Lyocell Process

Summary

Background

Whether it’s bratwurst or blutwurst, German’s eat an average of 70 grams of sausage a every day. Mettwurst, schinkenwurst, and bierwurst and hundreds of other mouthwatering varieties have been a staple of German diets for many years. While consumers obviously appreciate the use of fresh lean pork, bacon and beef, the protracted smoking process and the array of spices and seasonings used in making authentic German sausages, they perhaps don’t realise the importance of the role played by the artificial skin materials that lock in the flavour, preserve the texture and maintain the shape of these German delicacies. Fortunately, scientists at the Fraunhofer Institute for Applied Polymer Research, IAP, understand the need for improved casings over existing materials, and so have developed a new process for manufacturing environmentally friendlier, cost-effective casings that enable skins to be perfectly tailored for specific sausages.

Traditional Sausage Casing

In order to protect and retain the shape of the sausage, most varieties are wrapped in an artificial casing, the structure of which dramatically influencing the final flavour and texture of the sausage. Traditionally, this casing has been made from regenerated cellulose, also known as cellophane, but the material brings with it a number of disadvantages. These include the generation of by-products such as salts, water, and H2S and CS2 gases, the presence of which can affect the flavour of the sausage.

For manufacturers, the production of such gases and the associated processing complexities make the standard method for making casing material somewhat environmentally unfriendly in nature. And, as it is quite a lengthy production process, there are manufacturing costs to consider.

Sausage Casings via the Lyocell Process

By contrast, the new Lyocell process, developed by scientists at the Fraunhofer IAP together with Teepak NV is a far less complicated method that creates no by-products, and is cost effective as the manufacturing process is significantly shorter.

How the Lyocell Process Works

Blown cellulose film is now being manufactured using the Lyocell process. The process uses chemically-converted pulp that is dissolved in N-methylmorpholine-N-oxide (NMMO) and H2O. This solution is conveyed to a regenerating bath, where the solvent is released. The cellulose solution passes through an air gap and is extruded through a ring nozzle, permitting close control of the casing characteristics.

Advantages of the Lyocell Process

This processing step enables the variation of film thickness and offers the chance to control wet and dry mechanical properties, smoke and water permeability and calibre consistency in order to maintain a constant weight and size. For larger sausages, casings can be coated and reinforced in order to retain the shape of the sausage as well as to give additional shelf life. As Dr Peter Weigel from IAP explains, the superior mechanical properties make the blown film casing advantageous in comparison to cellophane. ‘For economic and ecological reasons and owing to its compact technology, high processing speeds, closed processing loops and product variety, the NMMO method offer itself as a promising alternative,’ he says.

Summary

So if German sausages taste even better in the future, it could be thanks to the Lyocell prose: enabling the full flavours of the meats to be developed and preserved while not adding any unwanted by-products. Meanwhile, the researchers are looking beyond sausages with the technology - they are also applying the process in the manufacturing of a wide variety of different products, including textiles, specialty papers and other meat packaging.

 

Source: Materials World Vol. no. pg. 20, August 2002.

 

For more information on this source please visit The Institute of Materials, Minerals and Mining.

 

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