GB2294191A - Cheese manufacture - Google Patents

Abstract

The amount of whey recovered in a cheese-making process is increased by separating the whey into fines and clarified whey, isolating the clarified whey, separating the clarified whey into whey, cream and sludge, containing further whey and cream, isolating the sludge and decanting solid sludge from liquid whey. Sweet whey 6 from cheese manufacture 4 is clarified in a clarifier 10 to produce fines and clarified whey. The fines are recycled to cheese making 4 and the clarified whey is separated into cream, separated sweet whey and sludge in a separator 15. The sludge is decanted in a decanter 20 to produce decanted solids and sweet liquid whey. The sweet liquid whey from the decanter 20 is recycled to the separator 15. In a second embodiment (Fig. 2), salt whey (44) produced in cheese making is dosed with hot water to achieve a fat content of 4% by weight in advance of clarification (45). Clarified salt whey (47) is separated and sludge from the separator (50) is decanted (52), decanted salt liquid whey being treated in a nanofiltration plant (63). <IMAGE>

Description

"Cheese Manufacture" Introduction The invention relates to a process for manufacturing cheese. In particular, it relates to a process which includes an improved whey recovery system.

One of the main problems encountered during cheese making is the treatment and disposal of.the waste water. This waste water includes whey which is rich in nutrients and therefore is a valuable resource. Because of this, efforts have been made to recover as much of the whey as possible. However, as these efforts have only met with limited success most cheese plants still produce waste water streams rich in nutrients which need to be disposed of.

There are two types of whey produced during industrial cheese making, namely, sweet whey which is produced before salting of the curd and salt whey which is expressed from the salted curd. At present both of these waste streams are treated similarly. The whey is first clarified to produce fines and clarified whey. The clarified whey is separated to produce cream, separated whey and sludge.

With sweet whey the cream and separated sweet whey are utilised and the sludge is disposed of.

In the case of salt whey, only the separated cream is utilised. This separated salt whey is disposed of due to its high salt levels which make it unusable. The sludge is also disposed of.

It is an object of the invention to overcome these problems by providing a process for manufacturing cheese with increased processing efficiency, optimised resource use, and reduction of pollution potential.

Statements of Invention According to the invention there is provided a process for manufacturing cheese comprising the steps of: cooling whole milk to a temperature of 4"C; pasteurising the milk; adding the milk and a cheese culture to a cheese vat to form curds and whey; collecting whey from the cheese manufacturing process in a whey storage tank; clarifying the whey to produce fines and clarified whey; collecting the clarified whey in a storage tank; separating the clarified whey into cream, separated whey and sludge from the separators including residue whey and cream; collecting the sludge in a sludge storage tank; decanting the sludge from the whey separators to form decanted solids and liquid whey; and collecting the liquid whey in a liquid whey storage tank.

In one embodiment of the invention the whey is salt whey generated in cheese making.

In a preferred embodiment of the invention, the salt whey is diluted to achieve a fat content of from 3% to 5% by weight and preferably approximately 4% by weight in advance of clarification.

In a particularly preferred embodiment of the invention, the salt whey is diluted to a volume ratio of approximately 2 parts water to 1 part salt whey.

In one embodiment of the invention, the salt whey is heated to a temperature of from 36"C to 40"C, preferably 38"C, before clarification.

In a preferred embodiment of the invention, the salt whey is heated by addition of heated water to the salt whey.

In one embodiment of the invention the process includes the step of controlling the flow rate, separator feed pressures and separator back pressures to achieve maximum separation conditions and fat recovery.

In another embodiment of the invention, the process includes the step of collecting any spillages from the whey separators and delivering them to the sludge storage tank for decanting.

In a preferred arrangement the sludge is decanted in a decanter.

In a particularly preferred arrangement, the fines from the clarifier are added to the sludge in the decanter.

In one embodiment of the invention, the liquid whey from the decanter is delivered to a nanofiltration plant.

In another embodiment of the invention the whey includes sweet whey from cheese making. In a preferred arrangement the liquid whey from the decanter is returned to the separator storage tank for further separation and decanting.

In a particularly preferred embodiment of the invention the fines are returned to the cheese manufacturing process.

Detailed Description of the Invention The invention will be more clearly understood from the following description thereof, given by way of example only with reference to the accompanying drawings in which: Fig. 1 is a block diagram illustrating one aspect of the process of the invention; Fig. 2 is a block diagram illustrating another aspect of the process of the invention.

Referring to Figs. 1 and 2 there is illustrated a process for manufacturing cheese which comprises the steps of first cooling whole milk 1 to a target temperature of 4"C in a plate heat exchanger 2 and, using a whole milk pump 4, delivering the cooled milk to a pasteuriser 3 where the milk is heated to approximately 73"C for 15 seconds. The milk is then cooled to 30"C approximately and delivered to a cheese manufacturing plant 4 by a pump.

Referring particularly to Figure 1 the sweet whey produced in the cheese manufacturing plant 4 is pumped along a sweet whey line 6 by a pump 7 to a sweet whey storage tank 8 and pumped on demand by a pump 9 to a clarifier 10 where the sweet whey is clarified to produce fines and clarified whey. The fines are delivered along a fines line 11 back to the cheese manufacturing plant 4. The clarified whey is delivered to a storage tank 12 along a clarified whey line 13 from where it is pumped on demand by a pump 14 to a separator 15 where it is separated into cream, separated sweet whey and sludge including residue whey and cream.

Preferably, the separator is an Alfa Laval WRPX 214 TGV separator, rated to separate whey at 2750 gallons/hour.

The cream from the separator 15 is delivered to a cream storage tank 16 along a cream line 17 and the separated sweet whey is delivered to a separated sweet whey storage tank 18 along a separated sweet whey line 19. The sludge is pumped by a pump 21 along a sludge line 22 to a decanter 20 where it is decanted to produce decanted solids and sweet liquid whey. Preferably, the decanter 20 is an Alfa Laval/Sharples Super-D-decanter, Type P1600, operating at 4650 rpm and a feed flow rate of 1500 litres/hour.

The decanted solids are pumped to a solids storage tank 23 by a pump 24. The sweet liquid whey is collected in a sweet liquid whey storage tank 25 and pumped on demand by a pump 26 back to the storage tank 12 from where it is delivered to the separator 15 for further separation and decanting.

Referring now particularly to Fig. 2, the salt whey produced in the cheese manufacturing plant 4 is pumped along a salt whey line 41 by a pump 42 to a salt whey storage tank 43 and pumped on demand along a line 44 to a clarifier 45. As will be described in more detail below, hot water is dosed into the salt whey line 44 along a hot water line 46. The addition of the water dilutes the whey to achieve a fat content of 3% to 5%, preferably approximately 4%, by weight in advance of clarification.

The hot water addition also heats the salt whey to a temperature of 36"C to 40"C, most preferably approximately 38"C, before clarification. The temperature of the salt whey downstream of the hot water line 46 is continuously monitored and the temperature of the hot water added along the hot water line 46 is controlled accordingly.

The clarified salt whey from the clarifier 45 is delivered along a clarified whey line 47 to a salt whey storage tank 48 from where it is pumped on demand by a pump 49 to a separator 50 which separates it into cream, separated salt whey and sludge including residue whey and cream. The cream is delivered to a cream storage tank 16 along a cream line 51 and the separated salt whey is delivered to a separated salt whey storage tank 52 along a line 53.

The sludge is pumped by a pump 55 along a salt sludge line 56 to a decanter 54 where it is decanted to produce decanted solids and salt liquid whey. The decanted solids are pumped to a salt whey solids storage tank 57 by a pump 58. The salt liquid whey is recycled along a salt liquid whey line 59 by a pump 60 to the separated salt whey storage tank 52. The contents of this tank 52 are pumped on demand along a line 61 by a pump 62 to a nanofiltration plant 63 where the whey is filtered to remove a substantial amount of the salt present. The retentate from the nanofiltration plant 63 is collected in a retentate tank 64.

The fines produced by the clarifier 45 are delivered along salt fines line 65 to the decanter 54 by a pump 66.

The process of the invention optimises the recovery of nutrients from waste streams in cheese manufacture and minimises effluent treatment costs.

It will be appreciated that a number of separators may be used to separate the clarified whey.

It will also be appreciated that by using appropriate cleaning procedures some of the same equipment may be used in treating both salt and sweet whey.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.

Claims (16)

1. A process for manufacturing cheese comprising the steps of: cooling whole milk to a temperature of 4"C; pasteurising the standardised milk; adding the milk and a cheese culture to a cheese vat to form curds and whey; collecting whey from the cheese manufacturing process in a whey storage tank; clarifying the whey to produce fines and clarified whey; collecting the clarified whey in a storage tank; separating the clarified whey into cream, separated whey and sludge from the clarifiers including residue whey and cream; collecting the sludge in a sludge storage tank; decanting the sludge from the whey separators to form decanted solids and liquid whey; and collecting the liquid whey in a liquid whey storage tank.

2. A process as claimed in claim 1 wherein the whey is salt whey generated in cheese making.

3. A process as claimed in claim 2 wherein the salt whey is diluted to achieve a fat content of from 3% to 5% by weight in advance of clarification.

4. A process as claimed in claim 3 wherein the fat content of the salt whey in advance of clarification is approximately 4% by weight.

5. A process as claimed in claim 3 or 4 wherein the salt whey is diluted to a volume ratio of approximately 2 parts water to 1 part acid whey.

6. A process as claimed in any of claims 2 to 5 wherein the salt whey is heated to a temperature of from 36"C to 40"C before clarification.

7. A process as claimed in claim 6 wherein the salt whey is heated to a temperature of approximately 38"C.

8. A process as claimed in claim 6 or 7 wherein the salt whey is heated by addition of heated water to the salt whey.

9. A process as claimed in any of claims 1 to 8 including the step of controlling the flow rate, and separator back pressures of the separators to achieve maximum separation conditions and fat recovery.

10. A process as claimed in any preceding claim including the step of collecting any spillages from the whey separators and delivering them to the sludge storage tank for decanting.

11. A process as claimed in any preceding claim wherein the fines from the clarifier are added to the sludge in the decanter.

12. A process as claimed in any preceding claim wherein the liquid whey from the decanter is delivered to a nanofiltration plant.

13. A process as claimed in any preceding claim wherein the whey includes sweet whey from cheese making.

14. A process as claimed in claim 13 wherein the liquid whey from the decanter is returned to the separator storage tank for further separation and decanting.

15. A process as claimed in claim 13 or 14 wherein the fines are returned to the cheese manufacturing process.

16. A process substantially as hereinbefore described with reference to the accompanying drawing.