Food or edible material: processes – compositions – and products – Processes – With mixing or agitating – e.g. – homogenizing – etc.
Reexamination Certificate
2002-01-11
2002-11-19
Yeung, George C. (Department: 1761)
Food or edible material: processes, compositions, and products
Processes
With mixing or agitating, e.g., homogenizing, etc.
C099S348000, C099S453000, C099S462000, C426S582000
Reexamination Certificate
active
06482460
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates generally to the field of food processing technology and, more particularly, to food processing for production and processing of semi-liquid food products, specifically, cottage cheese.
Traditionally cottage cheese is made in horizontal vats. After coagulation of the cheese curds, the curds are cut by a wire or blade cutters and then cooked by heating with gentle agitation. The heat is usually supplied by the direct introduction of steam into the vat or by recirculating heated whey.
The “Jet Cooking System” manufactured by Stoelting Inc. is in widespread use commercially and is an example of a heat supply unit which may be used for a cottage cheese cooking process. In such a system, cooking is accomplished by continuously withdrawing whey at the top of the vat with a centrifugal pump, injecting culinary steam into the whey, and returning the heated whey to the upper part of the vat. Problems with such a system, and generally with the concept based on direct introduction of steam into the whey, include the need for utilization of expensive culinary steam which at the end of the process is wasted with the separated whey. Furthermore, direct introduction of the heating steam into the system results in a continuous addition of condensate to the curds-whey mixture in the vat. This complicates the cheese making process control in terms of maintaining acceptable process parameters such as an optimal level in the vat, physical-chemical properties of the whey and curds being cooked, and the heat and mass transfer situation in the processor.
The above-described Jet Cooking System does offer an option to the method of direct introduction of culinary steam into the product. This concept is based on utilization of an indirect heat exchanger located in the whey recirculating line. A heating medium, such as heated water or steam, is introduced into the indirect heat exchanger, and a special immersed strainer/suction tube assembly, located in the top of the vat, is used for continuous intake of circulating whey from the upper part of the whey layer in the vat. The heated whey is returned to the vat through a horizontal discharge jet pipe incorporated in the immersed strainer/suction assembly and located just below the surface of the whey along one side of the wall of the vat. A major disadvantage of this method of cheese processing is that the heat flow which is needed to cook the curd in the vat is continuously supplied to the top layer of whey rather than to the lower layer of the curd particles which tend to settle at the bottom part of the vat after cutting of the coagulum.
In order to continually expose the curd particles to the recirculating heated whey, the prior art cheese making methods provide mechanical agitating means which suspend the fragile curd in the whey. Numerous processing devices are known to the art for agitating and stirring the curd particles and whey in the vat. Problems with prior art mechanical agitating means have, however, been recognized, including the limited ability to pick up, dispense and mix the easily fragmented curd particles located at the bottom, ends, and corners of the vat.
The Verti-Stir Sanitator of the type manufactured by the Stoelting Co. is an example of prior art mechanical agitating means used in the industry. This method of agitation is based on a mechanical paddle-type device which creates a vertical stirring motion that suspends the curd particles in the upper layer of the heated whey in the vat. Because of the improved agitation of the process materials throughout the depth of the bed, the Stoelting process is quite effective for smaller vessels but becomes less efficient with increases in size due to the need to create two-dimensional horizontal movement within the vat contents in order to produce a final product having the same degree of mix consistency. Furthermore, most prior art mechanical agitating means which are used for larger vats are moved longitudinally along the length of the vat at limited speed in order to prevent damage to the delicate cottage cheese particles.
At the localized introduction of the recirculating heated whey in the vat such as with the Stoelting Jet Cooking System, the prior art mechanical agitating means, including the Stoelting Verti-Stir method, are inefficient in terms of overall mixing of the vat contents and maintaining a uniform temperature distribution in the processor. These deficiencies result in a final product having varying degrees of cooking consistency rather than the desired uniform consistency.
In the conventional cheese making vats which are heated by means of the recirculating whey system, the whey is continuously withdrawn from the upper layer of the whey in the vessel and, after being heated in the heat exchanger, is introduced back into this upper layer. This can result in a short-circuiting of the heated whey in the upper portion of the vat. This makes the cottage cheese cooking process less efficient and more difficult to control in terms of maintaining the required product temperature in the vat.
Furthermore, the conventional cheese making process suffers from another significant drawback which is related to the introduction of a higher velocity stream of recirculating heated whey into the upper portion of the vat by means of a horizontal jet pipe. In order to provide the required product heating rate in the vat, the flow rate of the recirculating heated whey, being the only source of the heat supply in the conventional system, is usually maintained relatively high. The introduction of the high velocity and highly turbulized jet stream of the heated whey into the upper portion of the conventional vat in an attempt to provide a maximum possible penetration and distribution of the hot whey into all of the upper layer of the whey/curd contents, causes a disintegration of the very fragile and easily fragmented cottage cheese curd particles in the vicinity of the jet, This results in a higher concentration of fines in the product which causes great difficulties in the system control and reduces the yield of the process.
Other prior art related to the subject matter of the invention is disclosed in the patent entitled “Closed Cheese Making Vat with Recirculating Whey”, U.S. Pat. No. 4,321,860. In this system a vertical shaft is mounted for rotation within the vat, and the shaft carries a frame that extends radially outward from the shaft. A series of vertical blades are mounted on the frame. When the shaft is rotating the blades provide a stirring or agitating action. In this prior art apparatus, during the agitation of the precut curds, whey is continuously withdrawn from the upper portion of the vat and after being heated, is recirculated to the lower portion of the vat. The introduction of the recirculating heated whey into the vat is provided through a stationary inlet pipe which is incorporated into the side wall of the vat at the bottom level. When the shaft is rotated in the stirring direction the blades move the mass of curds within the vat to continually expose the curds to the recirculating whey entering the vat. The incoming jet of the whey passes upwardly through the curd to effect the primary agitation.
Despite the fact that, unlike all of the prior art known to the present inventors, the system according to U.S. Pat. No. 4,321,860 provides the heat supply to the curd by recirculating heated whey introduced into the lower portion of the vat, this method still suffers from two significant drawbacks. One of the drawbacks is the necessity to continuously move the entire mass of curds through the vat by rotating the agitator so that the incoming heated whey will contact and agitate the product being cooked. This intensive mechanical energy application provided by the pushing action of the rotating agitator blades leads to extensive fragmentation of the fragile curds thus reducing the yield of the process due to solids loss of cheese curds into the whey.
Another drawback is caused by the stationary location of the
Grant George
Pikus Ilya
Swanson Kevin
Hosokawa Bepex Corporation
Johnston R. Blake
Rudnick Piper
Ryther James P.
Yeung George C.
LandOfFree
Method and apparatus for processing cottage cheese does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for processing cottage cheese, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for processing cottage cheese will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2933945