REFERENCE TO RELATED APPLICATION

This application claims priority from Applicant's provisional application, U.S. Ser. No. 60/161,041, for BATCH PASTEURIZER FOR FLUIDS NOT FOR HUMAN CONSUMPTION, filed Oct. 25, 1999, which application is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus for pasteurizing or heat treating fluid products for consumption by animals or humans.

2. Description of the Relevant Art

Since the dawn of history, various methods and apparatus have been devised for the heat treatment of foodstuffs for human and animal consumption, including cooking, pasteurization and sterilization. Both pasteurization and sterilization have been used with milk and related products. U.S. Pat. No. 4,310,476 provides in columns 1 to 5 an extensive discussion of pasteurization and sterilization of milk, which is incorporated herein by reference. Column 30 of the same patent identifies legal U.S. standards for milk pasteurization, which are also incorporated by reference.

Dairy farmers and other producers of foodstuffs such as milk are often required to transport their produce to central plants for processing including pasteurization or sterilization and packaging. In less advanced countries, modern processing plants may be unavailable or inaccessible, so that dairy products must be utilized locally, with whatever processing is available. Excess milk may be used on the farm for feeding calves or other livestock, but may spoil or transmit disease if not pasteurized. There is an apparent need for portable, economical apparatus for pasteurizing such milk on site to permit its safe use for feeding calves and the like. There is also a need for portable, simple and economical apparatus for processing milk at or near the source in less advanced countries for both human and animal consumption.

Numerous patents disclose methods and apparatus for sterilizing food enclosed in containers. For example, U.S. Pat. No. 5,424,087 discloses methods of sterilizing canned food in a sterilizing kettle, using hot water for preheating and steam for sterilization.

U.S. Pat. No. 4,739,699 discloses apparatus for pasteurizing or sterilizing edible foodstuffs in containers.

U.S. Pat. No. 2,082,460 discloses apparatus for sterilizing and subsequently cooling food in closed containers, using a form of pressure cooker.

U.S. Pat. No. 5,280,748 discloses apparatus for uniformly cooking packaged foods in a “cook/chill” tank in which hot water is circulated to cook the food, then cold water is circulated to provide rapid cooling.

U.S. Pat. No. 5,080,164 discloses a process and device for heat treatment in continuous flow of a product mixture containing solids in liquid (i.e., a slurry), using a combination of heat exchangers to heat and then cool the slurry.

U.S. Pat. No. 3,780,644 discloses a mobile milk processing system mounted upon a motor vehicle, providing for field pasteurization, homogenization and packaging of raw milk. Water is heated or cooled and circulated as a heating and cooling medium. This system is intended to overcome the disadvantages of central processing plants which process milk in continuous flow.

U.S. Pat. No. 5,209,157 discloses a plant for manufacturing dairy preparations based upon skim milk and vegetable oils. A heater provides for brief heating and cooling of the product prior to packaging.

U.S. Pat. No. 4,534,986 discloses a system for the indirect “ultra-high” heat treatment of liquids such as milk with minimal thermal damage.

U.S. Pat. No. 4,515,823 discloses a process and apparatus for separation of raw milk into cream and skim milk, the latter of which is pasteurized and cooled by regenerative heat exchange in heat exchangers.

U.S. Pat. No. 4,446,781 discloses a process and apparatus for mechanical/thermal treatment of fluids such as melted cocoa masses, which can include sterilization and pasteurization.

U.S. Pat. No. 5,360,055 discloses a method and apparatus for heat treating fluid products such as milk, including a counter current heat exchanger.

U.S. Pat. No. 5,443,857 discloses a method and apparatus for sterilizing milk based liquid products, including indirect preheating and final heating to sterilization temperature by direct steam injection, followed by flash-cooling.

U.S. Pat. No. 3,973,048 discloses a method and apparatus for sterilizing liquids by brief heating, involving compression and pressure reduction to transfer heat and attain sterilization temperatures.

U.S. Pat. No. 4,738,302 discloses apparatus for heat-treating liquid products including series-connected multi-tube heat exchangers for heating and cooling the products.

U.S. Pat. No. 4,432,276 discloses apparatus for heating, pasteurizing and sterilizing fluid foodstuffs in which the substance to be heated is brought in direct contact with a heating fluid.

U.S. Pat. No. 4,446,778 discloses a pasteurization system for dairy farming products, including several basins wherein the pasteurization cycle is effected in sequence, the heat taken from one basin during its cooling phase being used to heat at least one other basin. A refrigerating circuit, heat pump and heat exchanger are used to heat and cool the basins.

U.S. Pat. No. 4,310,476 discloses apparatus for treating fluids at sterilization temperatures in which the fluid is heated by direct contact with steam while it is in the form of a thin, free-falling film or stream.

Most of these patents disclose apparatus and methods for the continuous processing of milk or other foodstuffs, and most of these systems are complicated and expensive. There remains a need for a simple, economical portable apparatus for batch processing of milk on dairy farms and the like.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide portable apparatus for the batch pasteurizing or heat treatment of liquid products in various locations, especially food products for consumption by animals or humans. Another object of the invention is to provide such portable apparatus which can be used with typical hot and cold tap water and electrical current available in dairy barns and the like. Another object is to provide for convenient field pasteurization of excess dairy products, which can then be fed to calves or other young livestock with reduced chances for the spread of disease. Still another object of the invention is to provide apparatus that can be quickly and effectively cleaned between uses to minimize health hazards. Yet another object of the invention is to provide portable apparatus of various sizes to meet the needs of diverse dairy sites. A further object is to fabricate portable apparatus from various commercially available components to provide units having varied sizes and capabilities. Still another object is to provide programmable time-temperature profiles to accommodate various processing needs. A further object is to provide a system which will allow about a sixty minute heating/cooling cycle for typical volumes of milk. A final object is to simplify the design and assembly of the apparatus so that the average dairyman can operate and service the unit with minimum downtime.

These and other objects and advantages are attained by apparatus of the present invention, comprising apparatus for the batch heating and cooling of fluids in bulk containers, comprising:

at least one heating/cooling coil to be inserted into the fluid to be heated and cooled;

at least one impeller to circulate the fluid to be cooled around the heating/cooling coil;

connections for sources of pressurized heating and cooling fluids;

temperature sensing means for measuring the temperature of the fluid to be heated and cooled;

valve means and switching means for successively turning on and off the heating and cooling fluids;

thermostat and control means for shifting from heating to cooling fluids in the coil when the treated fluid has been at the preset temperature for a sufficient time, and for turning off the cooling fluid to terminate a cycle when the treated fluid has attained the desired cooled temperature.

In preferred embodiments, the apparatus comprises a dome top fastened to the heating/cooling coil and the impeller shaft, the dome top being so dimensioned so that it can be fastened to the top of the container holding the fluid to be treated and thus protect the fluid from the atmosphere. Heating and cooling means can be provided to adjust the temperature of the heating and cooling fluids. Preferably, at least one pump is provided to direct the heating and cooling fluids through the coil. The heating and cooling fluids can either be returned to their sources for reuse or directed to drains. Means can be provided to conveniently hoist the apparatus out of the container of fluid treated, and to lower it in for a treatment cycle. Means are provided for efficient cleaning of the coil and other components between cycles.

Further in accordance with the invention, methods are provided for carrying out heat treatment processes such as pasteurization of dairy products using the apparatus of the invention, comprising steps of:

inserting the heating/cooling coil into a container of fluid to be treated;

attaching the dome top to the container to separate the fluid from the atmosphere;

activating the impeller to circulate the fluid to be treated about the coil;

directing heating fluid through the coil for a period effective to raise the fluid to be treated to a predetermined treatment temperature and hold it there for a predetermined time;

shutting off the heating fluid and promptly directing cooling fluid through the coil to quickly reduce the temperature of the treated fluid to a stable lower temperature for use or storage;

shutting off the cooling fluid to complete the cycle; and

removing the apparatus from the container of treated fluid.

By “portable” it is meant that the apparatus can be moved from place to place with relative ease, using manpower or simple lifting/hauling devices, and can be employed wherever suitable sources of electrical power and heating/cooling fluids are available. Such apparatus can be used in various dairy barns or other facilities at a single site and moved from site to site as well. By “bulk” containers it is meant that the fluids to be treated are contained in open containers allowing access to the apparatus of the invention, in contrast to sealed containers such as tin cans.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the objects and advantages thereof will be readily obtained by perusing the following detailed description and appended claims in combination with the accompanying drawings, wherein:

FIG. 1

is an exploded perspective view of the apparatus of the invention and a fluid container;

FIG. 1A

is a side perspective view of an adaptive collar for the apparatus.

FIG. 2

is a perspective view of the apparatus alone;

FIG. 3

is a schematic diagram of a control system for the apparatus;

FIG. 4

is a detailed view of the switch/indicator panel;

FIG. 5

is a perspective view of the underside of the dome top of the apparatus;

FIG. 6

is a rear perspective view of the dome top showing hose connections;

FIG. 7

is a top perspective view of the chassis plate showing the impeller motor and electrical connections;

FIG. 8

is a detailed perspective view of the controller components mounted on the chassis plate;

FIG. 9

is a perspective view of typical inline heater;

FIG. 10

is a side view of a cleaning system for the apparatus; and

FIG. 11

is a side view of a wall bracket and support system permitting the apparatus to be transferred from one container to another alongside.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Although a preferred embodiment of the present invention has been designed for pasteurizing milk on dairy farms and the like, and the invention will be discussed in that context, systems within the scope of the invention can be used for processing or heat treating all sorts of fluid materials. The fluids will normally be liquids of low to moderate viscosity such as milk, but can also be more viscous dairy products such as ice cream mix or cheeses. Naturally, the characteristics of the material to be treated must be studied and understood before effective heat treatment can begin. For example, it is necessary for each product to determine the appropriate temperature-time relationships for optimum treatment. It is well known that the pasteurization or sterilization of milk and milk products involves a delicate balance between providing enough heat (through specified combinations of time and temperature) to kill target microbes without adverse effects on the flavor and other characteristics of the product. Different products, and even milk from various species such as goats, will require different temperature-time profiles for optimum treatment. Generally, the best results with milk products are obtained by brief heating at relatively high temperatures, followed by prompt and fast cooling. The apparatus of the present invention can be adjusted and programmed to provide heat treatments, including cooking, pasteurization or sterilization treatments, for a variety of milks and milk products (e.g., cream, reconstituted milk, ice cream mixes, puddings, candies and condensed or evaporated milk), fruit juices, ciders, fermented beverages such as beer and wine, yeast and meat extracts, slurried materials such as soups and stews, vegetable oils and chemical preparations. Thus, while a preferred embodiment will be disclosed for the pasteurization of cow's milk, the broad capabilities of the apparatus and methods disclosed should be kept in mind.

Turning now to the drawings,

FIG. 1

illustrates a batch pasteurizer

16

of the invention partially inserted into a container

40

which holds a fluid to be heat treated (not shown). In the dairy context, container

40

can be a 55 or 20 gallon drum; the pasteurizer

16

can be sized or adapted to fit various types and sizes of containers which may be encountered in the field, with volumes ranging from about 10 to 250 gallons. Such containers can be any standard product designed for dairy farm use, but are preferably made of stainless steel or durable plastics such as fiberglass, polypropylene, polyethylene, nylon or polytetrafluoroethylene (Teflon™), which are light and can be cleaned effectively. The containers preferably include a spigot or other liquid transfer means near the bottom to facilitate transfer of the treated liquid into buckets or other secondary containers. Hoisting ring

18

(an eye bolt) provides a connection for lifting and transporting the apparatus to a position where it can be lowered into an open container for use. Such a unit is portable in that it can be used at various stations within a dairy barn or other site, or moved from site to site. A typical dairy unit should weight about fifty pounds, but the weight will vary according to size and materials.

Dome top

19

is fabricated to contain connections for heating and cooling fluids (discussed below), a motor-driven impeller and control systems and to position the heating/cooling coil and the impeller on its shaft. The dome top

19

is dimensioned to fit the top of container

40

and separate the contents from the atmosphere, with the help of adapting collar

24

with rolled edge

25

.

FIG. 1A

illustrates a collar

24

with conforming edge

25

and a riser lip

23

to receive the pasteurizer unit. The collars can be produced in sizes to accommodate any combination of containers and pasteurizer units, using stainless steel. Although gravity alone produces a good seal, optionally a gasket of suitable elastomeric or resilient material (not shown) can be used between the collar and container. Dome top

19

is fabricated of fiberglass or durable plastics as described above for the container, so as to withstand constant scrubbing.

Impeller

38

is attached to shaft

36

, which is driven by driving means

17

, conventionally an electrical motor. Various types of propellers having at least two blades and other types of impellers can be used, provided they produce the desired thorough circulation of the treated fluid. Although the impeller is normally rotated to drive the fluid upward past the heating/cooling coil, the motor can be reversed. Multiple impellers and/or shafts can be used if required by the configuration of the product container. The motor should be an industrial grade electrical motor which is suitable for damp environments. Motor

17

is supported by chassis plate

28

, which is sealingly secured into dome top

19

in a watertight manner by screws

29

, washers

22

and nuts

20

, or other suitable fasteners. Chassis plate

28

can be fabricated of aluminum or suitable plastics. Control system

30

, also secured to chassis plate

28

, is discussed below. Water inlets

14

and outlets

15

are also discussed below. Thermocouple

26

preferably reaches to approximately the lower third of the fluid in the container when the unit is assembled, and senses the temperature of the circulating fluid when the system is operating. The positions of the coil, impeller and thermocouple permit operating with a partially full container of product. Coil mounts

32

and screws

34

are used to fasten the two ends of heat exchange coil

42

to chassis plate

28

. The ends of coil

42

provide male attachment sites for tubing to be clamped inside dome top

19

. The components attached to the dome top and chassis plate, including coil

42

, shaft

36

and thermocouple

26

, are attached securely and braced with suitable brackets or shields (not shown) to prevent damage while the unit is being handled.

Heating/cooling coil

42

, more easily seen in

FIG. 2

, extends downward from the dome top via inlet and outlet sections to concentrate the main heat exchange sections near the bottom of the container of fluid to be treated. The lower section of the coil has a helical conical form; that is, as shown in the figures, it describes circles of decreasing diameter from bottom to top, starting with a diameter which is nearly that of the container itself. While any suitable configuration can be used for the coil which optimizes heat transfer between the fluids inside and the fluid to be treated, this helical conical form is considered effective because the impeller drives the fluid to be treated from the bottom of the container past many sections of the coil, whence it circulates throughout the container to achieve rapid and uniform temperature change for the treated fluid. This configuration maximizes surface area exposure of the tubing for heat transfer and cleaning purposes. The impeller illustrated an rotate at about 45 to 60 RPM. Multiple coils can be used in certain configurations of the apparatus, at the expense of greater complexity For example, a faster transition between heating and cooling phases can be made if separate coils are used for heating and cooling fluids, with cooling fluid turned on as heating fluid is shut off.

FIG. 3

is a schematic diagram of a control system for the operation of the apparatus and method of an embodiment of the invention. It must be emphasized that a variety of control systems assembled from commercially available controllers, switches, valves and the like can be used for this purpose. The controller uses an off-on-start type switch similar to the ignition switch in a car. The controller monitors and displays the temperature of the circulating liquid and turns the various devices on and off as required. The controller illustrated is microprocessor-based, but analog controllers can also be used. In the most basic version, or perhaps an alternative version, the apparatus can be manually controlled, provided that a thermometer or other appropriate temperature sensor is available. Preferably, the controller comprises a programmable logic controller (PLC), which would allow many other desirable programming options including data logging and interfacing with personal computers Suitable controllers should have thermocouple inputs, plus at least two event-driven contacts which can be set or programmed to energize or deenergize based upon current temperature conditions. Suitable controller components are commercially available from the Barber-Colman Co. of Loves Park, Ill., Honeywell and other sources.

As shown in

FIG. 3

, control system

60

comprises a controller

30

which communicates with solenoid inlet valves relay

68

, heater

70

, display

50

, thermocouple probe

26

, motor

17

, main switch

44

, circulating pump

78

, optional cooler

77

and solenoid outlet valves relay

80

. In operating the system, after placing the dome top on the container (preferably securing same in place) and connecting water hoses and power, main switch

44

is turned on and hot water solenoid inlet valve

57

is opened to allow entry of hot water from source

64

. Heater

70

is normally turned on to heat the hot water to the proper pasteurizing or sterilizing temperature. Heater

70

should be adequate to produce water at pasteurizing or sterilizing temperatures from sources such as ordinary hot water heaters which may be used in dairy barns. Such hot water heaters produce water in the 175 to 200 deg. F. range. If such hot running water is not available, additional or more powerful inline heaters can be used. Alternatively, if a source of steam is available, steam may be injected into the hot water intake system to heat the water, as disclosed in U.S. Pat. No. 3,780,644, which is incorporated herein by reference.

Motor

17

is started to rotate the impeller

38

and circulate the fluid to be pasteurized, and pump

78

removes the hot water after it has circulated through coil

42

. Such a pump is preferably used to circulate water within the apparatus, and larger or additional pumps could be installed if normal water pressure is unavailable. However, with water pressure at least that of normal household water systems, it is possible to operate such a system on water pressure alone. Hot water flow continues until the temperature in the circulating fluid under treatment reaches the predetermined temperature (e.g., 161 deg. F. for bovine milk to be pasteurized) and a timer

52

is started to maintain the temperature for a predetermined time (e.g., 30 minutes for normal milk pasteurization at 145 deg. F., or 15 seconds at 161 F.). At this point, heater

70

is shut off, and after the elapsed time hot water solenoid valve

68

is closed.

Cold water solenoid valve

68

is then promptly opened, and a flow of cold water maintained until the temperature of the circulating fluid is reduced to the proper level for immediate use (i.e., about 100 deg. F.) or storage (about 38 deg. F.). Naturally, the colder the water the faster the treated liquid can be cooled and the longer the product will last without spoiling. Normal cold tap water is sufficient at moderate ambient temperatures, but for faster cooling and/or chilling to storage temperatures, chilling or refrigeration systems can be used in the cold water intake system, represented by cooler

77

in FIG.

3

. Such systems can be as simple as a chamber containing ice over which the intake water flows, or can incorporate conventional inline refrigeration systems such as used to produce chilled drinking water. U.S. Pat. No. 3,780,644 discloses such systems in columns 4 and 7. Once the liquid is cooled to the desired temperature, all solenoid valves are closed, pump

78

and motor

17

are shut off, and the pasteurized milk (or other heat-treated fluid) can be drawn for use such as feeding calves.

As suggested above, such control systems can be assembled and set up for operation on a manual basis, but are preferably capable of fully automatic operation and are programmed to execute the complete cycle as outlined above with a simple actuation by the operator. The objective is to permit the pasteurization or other heat treatment to proceed with a minimum of attention from the operator. Display panel

27

provides visual signals (using LED light-emitting diodes or the like) while the system is operating, identifying the heating and cooling stages, and preferably includes audible signals as well. The operator may be busy with other tasks, but will want to utilize the product promptly when the cycle is complete, and perhaps initiate another cycle with a fresh container of product.

FIG. 4

illustrates a typical switch/display panel

27

for the apparatus. Switch

44

is similar to an automotive ignition switch in that it has three positions—power off, power on, and “start,” to initiate a programmed heat treatment cycle. For more basic models or an alternative to the programmed cycle, switching can be provided to initiate the heating and cooling cycles separately (not shown). Digital display

49

displays the temperature measured by thermocouple

26

in the circulating liquid. Signal lights

51

light up for power on and the heating or cooling cycles, as discussed below. At least two buttons

41

are provided for programming heating and cooling temperatures and other functions used in setting up the apparatus for standard cycles.

FIG. 5

illustrates the underside of the dome top

19

with the chassis plate removed. Lifting eye

18

is attached by nut

12

, load support

10

and washers

11

. Thermometer module

50

is connected to thermocouple

26

(not shown here) and registers the temperature of the treated fluid on digital display

49

. The thermometer module

50

fits into recess

56

in the dome top. Signal lights

53

,

54

and

55

are red, amber and yellow respectively, and light up to signal the heating, cooling and power stages of the heating/cooling cycle. These lights can be any suitable type, but are preferably light-emitting diodes (LEDs). Preferably, the light signals also actuate an audible signal (not shown here) to alert the operator to the progress of the cycle. Fastener/sealer

59

secures the back of thermostat

50

, and switch box

61

is attached to switch

44

. Fasteners/connections

63

provide power to signal lights

53

,

54

and

55

. Double electric solenoid valves

57

and

58

control the inlet and outlet of hot and cold water, and are actuated as described above in the control system, using simple on-off control. The valves are connected to hose fittings (not shown here) on the outside of the dome top, to which ordinary utility hoses can be attached to connect the apparatus to sources of heating and cooling water as shown in FIG.

6

. Hoses

86

connect to the inlet and outlet fittings. An electrical in-line heater

70

is provided within the hot water circuit to bring the heating water to the proper predetermined temperature for the cycle. The heater is actuated as discussed above. Heater

70

and circulating pump

78

can be mounted on chassis plate

28

, as shown in FIG.

7

.

FIG. 9

provides a detailed view of a typical inline heater, which is commercially available from Infinity Fluids. As shown, leads

73

provide power to heating element

74

, in response to signals from leads

75

. Other suitable heaters are available commercially from Electro-Pak, Inc. of Reading, Pa. Various types of commercially available gas-powered inline heaters can also be used.

FIG. 6

, a perspective view of the dome top

19

from another side, reveals hose connections

64

and

66

for hot and cold water inlets, respectively, as well as hot and cold outlets

82

and

84

. Hoses

86

are attached to both inlets and outlets (not shown here).

FIG. 7

illustrates the mounting of the controller components

46

,

52

,

71

,

13

,

71

,

79

and

47

, plus inline heater

70

and circulating pump

78

on chassis plate

28

, from which motor

17

has been detached. Motor

17

is normally held in place by motor mount bolts

21

.

FIG. 8

illustrates these components in detail. Components of controller

30

include multiple relay switches

46

, timer

52

and separate relay switches for the heater (

71

), motor (

13

) and pump (

79

), all mounted on a standard DIN mounting strip

47

. All these components are electrically interconnected to function with the control system

60

described above and in FIG.

3

. Inline heater

70

and pump

78

are mechanically fixed to chassis plate

28

by conventional fasteners (not shown), and electrically connected and plumbed as described above.

FIG. 10

illustrates a detergent dispenser

60

for cleanup of the apparatus between cycles. Once the apparatus has finished a pasteurizing cycle, it is raised from the pasteurizing container

40

and returned to a suitable cleaning/storage drum (not shown) where cleaning takes place. The detergent dispenser

60

is plumbed into hot water line

72

so that detergent can be injected into the line. In use, the operator pushes button

67

to dispense a predetermined amount of detergent into vacuum straw

65

. Detergent bottle

62

is removably attached to the top of the dispenser and releases detergent through a valve (not shown) actuated by button

67

. The operator then turns spring timer valve

69

to the “on” position to initiate hot water flow for a set period of time, and hot water with detergent flows into the high pressure cleaning nozzles (not shown), which are mounted on or near the bottom of the cleaning/storage container. The timer is normally set for about ten minutes, five minutes of which the water will carry detergent, followed by a five minute rinse. The nozzle in the bottom of the cleaning/storage container can be a clean-in-place tank nozzle such as the ScrubMate™ by BETE, other clean-in-place sprayers such as those used in dairy bulk tanks, plastic high pressure spray nozzles strategically placed in the drum, or rotating spray arms such as those used in dishwasher manufacture. When the cleaning cycle is complete, the apparatus is allowed to drain and stay stored in the cleaning drum until its next use in pasteurization. The cleaning/storage drum includes at least one drain port in the bottom of the drum to allow cleaning water to escape to floor drains.

FIG. 11

illustrates a simple wall mounting bracket assembly

90

, fabricated from a single plate of sheet metal

92

, which allows the apparatus to be elevated and swung from one drum to another, provided they are located side by side. Wall bracket

92

is fastened to the wall securely with bolts or screws (not shown) through holes

94

. A one-piece solid shaft is bent at a right angle to form vertical (

98

) and horizontal (

96

) sections, and the vertical section hinges within simple tube hinges

100

and

102

. The unit is secured in place with cotter pin

104

or the like. The horizontal portion

96

of the shaft can then be fastened to the lifting eye

18

of the apparatus via eye bolt

108

and conventional hoisting apparatus (not shown). Once the apparatus is elevated and thus attached, it can be swung clear of the first container and placed over another alongside.

EXAMPLE

The operation and value of the apparatus and methods of the invention will be further illustrated by the following non-limiting example. A prototype pasteurizer of the invention was used in a dairy operation for about six months to pasteurize waste milk for consumption by a group of Holstein and Jersey calves. An average of about 45 calves were being fed the product at any given time over this period. Health problems in the calves, along with labor and medical expenses, were significantly reduced (by about 90 percent overall) during this period. New cases of scours (diarrhea) and related illnesses such as joint ill, septicemia, pneumonia, etc. were reduced about 90 percent, with concurrent reductions in labor and medical costs. Significant increases were noted in weight gain, and immediate savings were realized by the elimination of the need to supplement the calves' feed with expensive milk replacer. It is anticipated that even greater improvements will be seen over the next two years as the results of the decrease in pathogens spread will become apparent when these calves grow into replacement cows and come into milk. The operators of the herd are very pleased with the initial results.

Clearly, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein.