Capabilities

Whatever the end-product, the manufacture of speciality and European pressed cheese involves the following main process stages:

• Milk treatment
• Starter culture addition
• Curd making
• Cooling/brining
• Finishing and storage

APV offers technology and process equipment for each of these key stages.

Milk treatment

Pasteurisation
In order to eliminate all non-sporogenous pathogenic and coliformic bacteria, it is common practice to pasteurise the cheese milk at 71-72øC for 15 seconds.

Removal of spores
Sporogenous micro-organisms can cause problems with blowing and atypical eye formation with some cheese types.

The development of these spores can be reduced by the addition of nitrate. However, this is becoming more and more undesirable and may even be prohibited in some countries. Spores can be removed by special separators and by means of microfiltration (MF). APV MF is highly recommendable because it efficiently solves the problems with spores without affecting the cheesemaking characteristics of the milk.

Fat and protein standardisation
Most of the milk for cheese making is fat standardised in order to achieve a specific ratio between fat and total solids content. The APV Compomaster System is designed for automatic in-line fat standardisation with high accuracy.

Protein standardisation of cheese milk by means of ultrafiltration (UF) is becoming more and more common in achieving a uniform protein content. The most important advantages are:

• More consistent and slightly higher cheese yield
• Easier control of weight accuracy
• Higher through-put in the cheese vat
• Lower rennet consumption.

Homogenisation
Milk for certain types of cheese is homogenised. When used - typically for Blue Mould cheese and Feta - the cheese will appear more pale and make the fat more susceptible to fat cleavage by means of lipase enzymes, which contribute to the characteristic flavour of these cheeses.

Starter cultures

Acidification of the cheese milk influences a number of conditions:

• Curdling
• Syneresis (release of whey from the curd)
• Texture of the cheese
• Preservation effect
• Maturation of the cheese

Equipment and systems for growing starter culture is also one of APV's specialities. The amount of starter culture is approximately 0.5-2.0% of the milk volume, depending on the type of cheese. Alternatively, highly concentrated cultures can be used.

Mould
These cultures create special appearances but also have a significant effect on flavour and texture.

Rennet enzymes
Rennet is essential in cheese making since this is the enzyme that makes the curd formation possible. Only very few cheese are made without the use of rennet. Typically 25-40 g rennet/100 l cheese milk is used.

Other additives
Calcium chloride may be added to promote a firmer curd if curdling is slow. Colour is added to some cheeses either to give them colour or to make them white.

Nitrate may be added to prevent blowing, but in some countries, its use is prohibited and, as mentioned before, spores can be eliminated by means of MF.

Curd making

The purpose of the curdmaking process is to transform the cheese milk into quality cheese curd with the highest possible yield. This depends on a large number of factors relating to:

• Milk composition and its treatment
• Additives used
• Composition of the final cheese
• Cheesemaking systems and the cheesemaking process itself.

As a general rule, the yield is approximately 1 kg cheese/10 kg milk for semi-hard types. For extra hard and soft types, the yield may be 0.8 kg and 1.5 kg cheese to 10 kg milk, respectively.

The cheesemaking process takes place in several steps. APV's CurdMaster is a good example of a flexible cheese vat which has proved its ability to produce quality curd for both hard and soft cheese types alike, and at the same time produce a very high yield due to minimal loss of casein fines and fat in whey.

Vat filling and renneting
Pre-treated milk is led to the cheese vat at approximately 30øC and the starter culture is added. When filled with milk and the desired pre-ripening level has been reached, rennet is added.

Thorough distribution of the rennet is important in order to avoid marbling of the cheese. The CurdMaster ensures excellent mixing due to the design of the stirring tool and the double O-shape of the vat. Coagulation time is typically 20-40 min.

Cutting
It is important for the yield that the curd has the same firmness each time cutting is started.

A good cutting process is critical to reducing loss of fat and fines in whey. Consequently, APVhas given special consideration to the design of the cutting tool of the CurdMaster. It has staggered knives made of thin special steel, a fact which is known to reduce loss of fat and fines. The stirrer blades are made of polypropylene allowing them to float during cutting so that they do not break the curd unintentionally.

Pre-stirring
When stirring before whey draining, it is important to handle the curd gently as it is still soft, although stirring is necessary in order to prevent the curd from sedimenting and clotting. The CurdMaster offers optimum stirring effect even at low stirring speeds. The effect is further increased by the large stirrer blade on the agitator.

The CurdMaster is very versatile and able to produce high-quality hard and soft cheese curd, even low-fat types.

Whey draining
The CurdMaster is equipped with a continuous whey draining device with continuous whey suection oran automatic whey strainer.Alternatively whey draining can take place through valves in the vat wall.

Heating
Usually, the whey is diluted with hot water in order to wash out the lactose content and promote syneresis for reduction and adjustment of the moisture content in the cheese grains. Consequently, heating is a necessary curdmaking factor for all the hard cheese types such as Emmental and Gouda. For most cheese types, a final stirring period is important in order to adjust the firmness of the cheese grains. The curd and remaining whey are then pumped from the cheese vat to further processing.

Curd treatment/handling
The semihard types are typically pressed lightly after filling. The semisoft and soft types, however, are only pressed by their own weight during resting and turning.

Draining via a draining belt or a vibration strainer, and mould filling are important process steps. APV's ContiFiller is an automatic draining and filling system providing high weight accuracy and rapid change of cheese format. It is used in combination with automatic or semiautomatic handling of the cheese moulds.

The ContiPress System
Production of speciality cheese involves many handling functions which APV has optimised using modular units. These are interconnected by conveyors, forming flexible, customised plants.

For semi-hard and semi-soft types, which only require a moderate pressing pressure, the continuous pressing system is an ideal solution.

The Perfora small scale range
APVcan also offer its customers a whole range of unit systems and cheese lines for small- to medium-scale cheese production.

Perfora cheese moulds
Cheese moulds are available in both plastic and stainless steel. The wide range of APV cheese moulds is unparalleled in terms of size, perforation and customised design. The moulds are made in varied sizes and shapes as single, double or multimoulds.

For manual and semiautomatic plants, single moulds are mainly used. For automatic plants, single moulds are typically used for large cheeses, such as 15 kg Euroblock or 15 kg Gouda. Double moulds are used for medium-sized cheeses of 6-9 kg and multimoulds for small cheeses such as 2-3 kg loaf-shaped or ball Edam. Multimoulds are also used for speciality cheese such as Port Salut, Tilsit, Feta and Blue mould types.

Cheese brining

The majority of SPC types are brine salted before they are transferred to maturation storage. A cheese brine is usually saturated, containing approximately 21% pure salt solution. The salt content can vary greatly, from less than 1% in fresh cheese to 3% in Blue Mould cheese and higher still in Feta. For Port Salut, the salt content is usually 1.5-2.0%.

Brining time varies from less than an hour for small cheeses with a high moisture content, to several days for large cheeses with a low moisture content such as Gruyere and Parmesan. Brining temperature typically ranges between 12 and 17 ° C.

The function of a cheese brining system is to ensure:

• Gentle transport of the cheese to and from brine
• Hygienic residence of the cheese in the brine
• Optimum and even salt absorption
• Batch identification of the individual cheese
• Optimum control of temperature, salt content and circulation

Ourcheese brining range basically consists of : the DeepBrine System, the RackBrine System, and the TrayBrine System. In addition, APVcan provide customised solutions to suit specific customer requirements.

Cheese brine treatment
Efficient sanitation of cheese brine has become very important to the dairy industry in recent years. This is due to the increasing awareness of the possibility of post-contamination of cheeses in the brine, especially by pathogenic bacteria.

In order to solve these problems, APVhas developed various methods of sanitising the brine.

Thermal treatment
Periodic pasteurisation of the brine will reduce bacteriological problems, but will, however, change the native composition of the brine.

Microfiltration
The microfiltration process is usually based on ceramic filter elements with a pore size which allows all soluble components to pass, while bacteria and spores are separated. This means that the brine passes through the membrane without any significant changes in the chemical composition.

APVis a major supplier of membrane filtration plants and processes to the food and dairy industries and has developed a specially-designed microfiltration plant for filtration of cheese brine.

Finishing and storage

After brining, the last step in the production process is maturation. Storage temperature, time and humidity are factors which influence and control the maturation process, moisture evaporation and rind formation.