Abstracts from      

(original article is only in German language available) 

Lowering the a_w-value by increasing the salt concentration and reducing the water content are of prime significance in product safety and conservation of raw ham. Fast and controlled achievement of sufficient salt concentration inside the meat pieces is therefore a priority objective for the desired microbiological stabilising of the products.
The speed-determining steps during production of raw ham are the diffusion time for curing salts in the core of the ham and the diffusion time for water during drying and ripening. Against this background we have developed a new method for producing cured ham comprising combined nitrogen and low pressure application, in which the curing is carried out in a stainless steel pressure system (Model VT 003, Vivotec GmbH, Kalkar, Germany) suitable for this purpose.Nitrogen displays low solubility in water, fats and oils and is extremely slow to react, which is why it is well suited for use as an inert gas for the said purposes. Under low pressure (1.48.MPa), the curing salts penetrate into the meat pieces quickly, uniformly, very gently and without injuring the tissue, resulting in high microbiological stability of the products.
In a comparison of the various curing methods tested on rolled fillet of ham (‘Lachsschinken‘), the injection-cured ham proved to be microbiologically distinctly more contaminated than goods produced by dry curing or the N₂-low-pressure curing method. This was particularly conspicuous in the sliced products packed under vacuum or
modified gas atmosphere. In the course of three-week storage, the anaerobic mesophilic germ count in the injection-cured hams rose by about 3 log₁₀ stages and germ counts of 10⁶ cfu/g were reached. By contrast, the dry-cured hams and hams produced using the
N₂-low-pressure method displayed germ counts of 10¹ cfu/g at the same process stage (packaged sliced products and piece goods).Altogether the results show that process operations can be steered well and are controllable with the new N₂-low-pressure method, making it possible to produce raw hams that not only satisfy the demands made of high sensory quality, but also display high microbiological safety. 

 
Authors' address
Dir. und Prof. Dr. Dr. habil. Manfred Gareis und Jan Kabisch, Max-Rubner-Institut (MRI),
Bundesforschungsinstitut für Ernährung und Lebensmittel, Institut für Mikrobiologie und
Biotechnologie, E.-C.-Baumann-Str. 20, 95326 Kulmbach