Integrierte Vermeidung und Verminderung der Umweltverschmutzung

Chapter 2
To start the process, bacteria cultures known as starters are added to the raw material to be
fermented. The preparation of starter cultures is a sensitive process since the risk of airborne
infection must be reduced to an absolute minimum. Starter cultures must, therefore, be prepared
in a separate room supplied with filtered air with a slight positive pressure compared to normal
atmospheric pressure. The equipment cleaning system must also be carefully designed to
prevent detergent and sterilant residues from coming into contact with the cultures and spoiling
them. These very high hygiene constraints, coupled with the requirements of the temperature
regulation, i.e. heat treatment of the substrate first and then cooling, require a specific energy
consumption and use of cooling water.
2.1.4.5 Coagulation (D.5)
2.1.4.5.1 Objective
Coagulation is the agglomeration of suspended particles and separate solids from liquids or vice
versa.
2.1.4.5.2 Field of application
Coagulation is used in cheese production and in the recovery of casein from milk. It is often
used in milk processing to separate the curd from the whey and it is also called curdling.
2.1.4.5.3 Description of technique, methods and equipment
Temperature is one of the key factors that influence milk curdling. The required temperature is
obtained by using either heat-exchangers or by direct injection of steam into the curdling vat.
The temperature must be between 30 and 40 °C. Starters and other ingredients are added to the
milk. These ingredients help determine the specific characteristics of the final product. Curdling
is carried out in suitable vats or tanks, using either enzymatic coagulants, i.e. animal or
microbial rennet or acidifying starters.
When enzymatic coagulants or acidifying starters are used, a casein jelly is formed which
encloses the fat. The jelly will have different characteristics depending on which coagulant
method is used. This is important for achieving the desired final production. The curd is
produced by the separation of the whey, which is then gathered and sent for further processing
as appropriate. To obtain further separation of the whey, e.g. to obtain a hard or semi-hard
cheese, another heat treatment is given to the curd under stirring at up to 40 to 53 °C. For other
kinds of cheese, such as mozzarella or provolone, as well as the curd being heated at a higher
temperature, mechanical processing is also carried out to obtain the characteristic
stretching/melting properties. Furthermore, organic acids are used to control the pH and to hold
the curd at the right pH for the stretching properties to form.
2.1.4.6 Germination (D.6)
2.1.4.6.1 Objective
The objective of germination is to activate and develop the enzyme system in the grain kernel.
This activated enzyme system is necessary to activate the starch and protein breakdown at the
mashing stage before the later brewing process.
2.1.4.6.2 Field of application
Germination is an important processing step within the malting process of cereals. Malted
cereals, mainly barley, are used for beer production and the production of distilled drinks, e.g.
whisky. Malt is also used in food flavouring.
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