CHEESE TECHNOLOGY

Module 16. Mechanized cheesemaking

Lesson 32
MECHANIZATION AND AUTOMATION IN CHEESE MAKING

32.1 Introduction

Before starting discussion on mechanization and automation, it is a pre-requisite to understand the basic difference between mechanization, automation and continuous production. Mechanization is a system in which almost all the stages are carried out by machinery instead of manually, as in the case of traditional practices. Automation is a mechanized system, which is controlled by an instrument fed by a programmer. Mechanization is a necessary precondition for automation, but has different meaning. In a continuous system, raw materials are fed to the machine at one end and product comes out of the machine from the other end continuously. In cheese production, milk is fed to the machine at one end and it is continuously converted into curd and cheese during passage through the machine.

The pretreatments of milk for cheesemaking like standardization, bactofugation, pasteurization, etc. were already mechanized but with the developments taking place in the area of mechanization and automation, now almost each and every stage of cheese manufacturing is mechanized. Steps like starter production, curd making, cutting, cheddaring, hooping, conveying, packaging, block forming, etc. have been mechanized for continuous and automated cheese production. APV and Tetrapak are two of the leading industries which manufacture and supply mechanized systems of cheese production. Some of their machines are discussed in this chapter.

32.2 Cheese Vats: Double -O-vat

Tetra Damrow™ Double-O-Vat and Curd Master by APV.

The Tetra Damrow Double-O-Vat 8 is specifically designed for the production of high quality cheese curd and whey. The vat is suitable for the production of most cheese types like Cheddar, Emmental, Gouda, Blue, Feta as well as Pasta Filata. The design of the Tetra Damrow Double-O-Vat is based on the double circle principle, which ensures an optimum, efficient, yet careful treatment of the cheese curd.

Curd Master is another double O type vat fabricated by APV. It facilitates fast foamless filling, rapid mixing of all added components including rennet, gentle and precise cutting, fast whey draw, controlled and fast heating and cooling, vertical vat with two outlets for fast emptying, efficient and gentle stirring. It is fully automated with touch screen and the vat can be cleaned by cleaning-in-place (CIP).

32.3 Mould Fillers

Tetra Tebel Casomatic is manufactured by TetraPak. It works in combination with two buffer tanks. Each column is continuously fed by a pump with curd and whey mixture from a buffer tank. The mixture is pumped to the top of the column. The curd settles under the level of whey. Via three perforated sections, whey is drained from the column. The speed of the whey drainage is controlled by adjusting the drainage valves, depending on the pressure measured in these sections. As the curd moves down inside the column, it is compressed progressively until a curd block can be separated.

32.4 Mechanised Cheddaring Machine

The Tetra Tebel Alfomatic is designed for continuous production of fused and stirred Cheddar and Pasta Filata cheese types. It is a totally enclosed machine, designed to automatically drain, acidify, texture, mill, salt and mellow cheese curd.

The most common version of the machine is equipped with four conveyors mounted above each other in a stainless steel frame. The cooked mass (curd/whey mixture) is uniformly distributed on a special drainage screen where most of the whey is removed. The curd is then passed through the four conveyors one by one. The role of each of the conveyors is

First conveyor---- it is equipped with stirrers to facilitate further whey removal.

Second conveyor--- matting and fusing starts on this conveyor.

Third conveyor---- the mat is inverted and cheddared. At the end of the conveyor, curd is milled.

Fourth conveyor----salting takes place on this conveyor.

Fig. 32.1 Mechanised system for Dewheying, Cheddaring, Milling and salting (Alfomatic by TetraPak)

(Courtesy: Tetra Pak Processing Systems AB, Lund, Sweden)

In the production of Mozzarella cheese, where salting is not required before stretching, a machine with two or three conveyors is sufficient.

Fig. 32.2 Continuous Cheddaring machine with three conveyors suitable for Mozzarella cheese

(Courtesy: Tetra Pak Processing Systems AB, Lund, Sweden)

The other mechanized system for Cheddar cheese making is manufactured by APV. It has been given the trade name of Cheddar master. It is used for curd draining, cheddaring, milling, salting and mellowing. It is available in the capacity ranging from 1000-9000 kg/h of cheese curd. APV also manufactures Mozzarella master for continuous production of Mozzarella cheese.

32.5 Cooking And Stretching of Pasta Filata Types Of Cheese

Pasta Filata (plastic curd) cheese is characterised by an ‘elastic’ string curd obtained by cooking and stretching cheddared curd. The cheddared curd is worked in hot water at 82-85°C until they are smooth, elastic, and free from lumps. This step is necessary in order to develop elasticity in cheese which is peculiar to such varieties. Continuous cooking and stretching machines are used in large-scale production. The speed of the counter rotating augers is variable so that an optimal working mode can be achieved. The temperature and level of cooking water are continuously controlled. The cheddared curd is continuously transferred into the hopper or cyclone of the machine, depending on the method of feeding – screw conveyor or blowing.

Fig. 32.3 Continuous Stretcher for Mozzarella cheese

The systems discussed so far are mechanized systems for major steps in cheese making. Other than these systems, many other systems are also available like pre-press machines for pressing the curd before cheddaring, final pressing to remove residual whey/moisture, mould emptier, rack filler, rack brining system, rack unloader and rack washer. All these systems when installed in line, continuous and mechanized cheese making can be carried out. Processing lines for some varieties of cheese will be discussed in the following sections.

32.6 Continuous Cheddar Cheesemaking

Standardized and pasteurized milk is received in the vat where it is ripened, rennet is added to form curd, and curd is then cut and cooked. All these stages are completed in this vat. The double–O-vats described earlier are mostly used to perform all these operations. The cooked curd and whey mixture is then pumped to cheddaring machine where dewheying, cheddaring, milling and salting take place. The curd is then fed to the block forming machine where the milled curd fuse together and blocks of uniform shape and size are formed. After this, the blocks are sealed by vacuum sealer, weighed, packed in cartons and kept for ripening. The process is shown in Fig. 32.4.

Fig. 32.4 Processing line for Cheddar cheese manufacturing

(Courtesy: Tetra Pak Processing Systems AB, Lund, Sweden)

32.7 Continuous Gouda Cheese Manufacturing

In Gouda cheese making, the peculiar step is cooking the curd in whey through addition of about 20% hot water. Before addition of water, about one third whey is drained. This process of heating curd with whey and hot water is called scalding. In mechanized system of Gouda cheese manufacturing, the standardized milk is taken in the vat (1) and all other steps upto scalding are carried out in this vat. After scalding, the content of the vat is transferred to a buffer tank (2) so that the contents of more than one vat can be stored in the tank till further processing. This tank is equipped with agitators and is jacketed to supply chilled water in case activity of starter organisms need to be curbed down. The curd is then pumped to the pre-pressing machine (3) like Casomatic (TetraPak), where whey is removed and blocks of cheese are also formed. A fully mechanized system also comprises of:

• Mechanical lidding (4) of the moulds

• Transfer of moulds to conveyor or tunnel presses

• Filling and emptying of the presses

• Transport of moulds via a de-lidding station (6), a mould turning device (7), a mould emptying system (8) and a weighing scale (9) to an advanced brining system (10).

Fig. 32.5 Processing line for Gouda cheese manufacturing

(Courtesy: Tetra Pak Processing Systems AB, Lund, Sweden)

Any variety of cheese production can be mechanized keeping in view the particular step that distinguishes one variety from other. For example, in the production of Mozzarella cheese, cheese cooker and stretcher are required which can be installed after Mozzarella cheddaring machine.