All Go At Davidstow - Tetra Pak Supply Processing Equipment for Dairy Crest's New Cheddar Plant
30 January 2005
In the middle of Cornwall’s green pastures, Dairy Crest has built a new plant capable of producing 150 tonnes of cheddar cheese per day. Tetra Pak Processing is the main processing equipment supplier of this new cheese making plant.
The existing plant needed expansion and modernisation, and Tetra Pak Processing were given responsibility for the design, engineering, installation and commissioning of the new milk treatment and cheese making equipment. Dairy Crest is one of the leading suppliers of dairy products in the UK with an annual turnover of nearly £1.4 billion. The company focuses on strong branded products. In the cheddar cheese market, Dairy Crest’s leading brand is Cathedral City, which offers a range of maturities up to 14 months.
Nearby Milk Production
From the eight 350,000 litre silos, the milk enters the processing room for pasteurisation. There are two pasteurisers each with a capacity of 85,000 litres per hour. A proportion of the milk is separated in order to get skim milk for the standardisation of the cheese milk.
Curd production is carried out in eleven horizontal Tetra Tebel OST V cheese vats. Each vat holds up to 33,000 litres. The cheese making sequences in the Tetra Tebel OST vats are controlled using pre determined recipes stored in the control panel. Manual operations are limited to adding the starter and checking the coagulum before cutting begins.
Continuous Cheddaring
After stirring and heating, the curd is ready for cheddaring in the Tetra Tebel Alfomatic. Here, the curd and whey mixture enters from the top on to a perforated screen, where most of the whey is separated off. The curd falls on to a series of conveyors where the curd is allowed to mat and fuse before being stretched and upturned for cheddaring to take place.
From this point, the curd is milled to chips of uniform size, and dry salt is added to reach the desired concentration. The salt and chips are mixed in a rotating mixing drum before being conveyed to a final conveyor where the chips are mellowed.
The six Tetra Tebel Blockformer TwinVac produces well-formed uniform blocks by utilising a simple system of vacuum treatment and gravity feed. The units in Davidstow are of the TwinVac type with two vacuum levels for higher capacity.
At the bottom of the column, a knife assembly cuts off 20kg cheese blocks every 45 seconds, which are bagged, weighed, vacuumised and sealed before maturing for up to 14 months.
Whey Treatment
The collected sweet whey is clarified in two parallel Tetra Centri 918 clarifiers, each with a capacity of 70,000 litres per hour. The recovered fines are brought back to the cheese making process.
The whey cream is separated in two Tetra Centri whey cream separators and pasteurised before being delivered to other Dairy Crest creameries. The ”fines and fat-free” whey is evaporated and sold as a valuable whey concentrate.
Total Process Control
Running a complex processing plant like the Davidstow dairy requires a sophisticated computerised system such as the Tetra PlantMaster.
With the system’s built-in logical sequences, the operator in the central control room has full control of every aspect. All valves are automatic and each remote controlled valve is capped with a ThinkTop unit for both actuation and feedback.
Having control of all the details makes it possible to write reports and subsequently trace the production parameters for a specific piece of cheese – a widely requested function in European food production today.
The Tetra PlantMaster system also has functions for the Tetra Pak Processing technical service team to check the status and service intervals of each component on line.
The plant is designed for 19 hours production a day, with five hours for cleaning by five central CIP units.
Good Teamwork
Building a greenfield plant like this requires experience and technical competence. The cooperation between Dairy Crest and Tetra Pak Processing staff at all levels and across many functions has been a key factor for success in the completion of this major project.
Dairy Crest has already won a number of quality prizes for its Cathedral City and Davidstow cheddar cheese. No doubt, Dairy Crest now has the opportunity to win many more quality prizes with the cheddar produced in the completely new cheese factory.
