AU2002332050A1

AU2002332050A1 - High-speed, low-temperature sterilization and sanitization apparatus and method

Info

Publication number: AU2002332050A1
Application number: AU2002332050A
Authority: AU
Inventors: Stephen Glahn; Parker C. Reist; Richard T. Smith
Original assignee: Pepsico Inc
Current assignee: Pepsico Inc
Priority date: 2001-10-05
Filing date: 2002-10-07
Publication date: 2003-07-03
Anticipated expiration: 2022-10-07

Description

[0001] HIGH-SPEED, LOW-TEMPERATURE STERILIZATION AND SANITIZATION APPARATUS AND METHOD

[0002] FIELD OF THE INVENTION

The present invention relates to a sterilization and/or sanitization process and

apparatus for containers used for aseptic packaging of products or ingredients

sensitive to microbiological spoilage or contamination. The present invention is

particularly useful in sterilizing or sanitizing polyethylene terephthalate (PET)

containers, especially those with openings of a relatively small cross-sectional area

compared to total internal surface area and those formed of non-heat set PET.

[0003] BACKGROUND OF THE INVENTION

For the purposes of this disclosure, sterilization is defined as a 6 log reduction of

spores of the bacteria Bacillus subtiUis var. globigii. whereas sanitization is defined

as a 5 log reduction of organisms that cause spoilage of high acid products (i.e., a

pH of 4.6 or less), as typified by ascospores of the yeast Saccharomyces cerevisiae.

Sanitization can be utilized for containers that are designed or used to store high

acid products (e.g., juices, juice beverages, acidified products), whereas

sterilization is preferably utilized for containers that are used to store low acid

products (e.g., tea, coffee, dairy products, nutraceuticals, pharmaceuticals). [0004] Various apparatuses and methods for sterilizing or sanitizing containers are

known. The known apparatuses and methods often use a sterilant such as

hydrogen peroxide (H₂O₂) vapor. After the hydrogen peroxide vapor is discharged

into the container at a relatively high temperature, the residual sterilant is then

purged from the container with a hot air flush at high temperatures.

[0005] However, these known apparatuses and methods are not suitable for

containers made of certain materials, such as PET and, more particularly, non-heat

set PET. For example, it is difficult to eliminate residual sterilant, such as

hydrogen peroxide, not only from the surface of the PET container, but also from

its polymer matrix. Upon dosing of hydrogen peroxide into a non-heat set PET

container, some peroxide becomes trapped in the polymer matrix and is not readily

removed with the hot air flush. Although this can be quite stable for several

minutes to hours, when a fluid product is introduced into the container, the

hydrogen peroxide moves from the polymer matrix into the body of the fluid

product, potentially compromising federal regulations for limits on peroxide

residuals.

[0006] In addition, because of the relatively low vapor pressure of hydrogen

peroxide at temperatures below 250 °F, most existing sterilization processes

depend on the use of a flush using large volumes of a gas that has been heated to a

temperature well above 250 °F. Because non-heat set PET possesses a glass

transition temperature of 163.4° F, it is not possible to expose such containers to temperatures much above 163° F without risk that the containers will deform.

Furthermore, the size of the opening (finish) in many containers prohibits the flow

of measurably large volumes of air into and out of the containers within the short

period of time required for high-speed operation.

[0007] SUMMARY OF THE INVENTION

The present invention provides an apparatus and method that can sterilize or

sanitize a variety of containers in a fast, economical way.

[0008] The present invention further provides an apparatus that can sterilize or

sanitize containers on a mass scale, yet occupies a relatively small area.

[0009] The present invention can effectively sterilize or sanitize PET containers

without deforming the containers.

[0010] The present invention can also sterilize or sanitize PET containers leaving

an amount of residual sterilant that does not exceed 0.5 mg/1 in a container filled

with water immediately after treatment. This value is equal to or less than the

limits for sterilant residual dictated by the U.S. Food and Drug Administration

(FDA). [0011] The present invention provides a sterilization and sanitization method and

apparatus for rapidly and relatively inexpensively sterilizing or sanitizing any type

of standard container used for packaging of pharmaceuticals, nutraceuticals, health

enhancing products as well as traditional high and low acid foods.

[0012] According to one aspect of the present invention, a method of sterilizing

and/or sanitizing a container includes the steps of generating a sterilant vapor and

positioning a nozzle through an opening in the container and no closer than 15 mm

from any internal surface of the container that is perpendicular to a principal

direction of flow of sterilant vapor through the nozzle. The method further

includes the steps of discharging the generated sterilant vapor through the nozzle

and into the container and purging the container of the discharged sterilant.

[0013] According to another aspect of the present invention, a method of sterilizing

and/or sanitizing a container, the container having an opening of a predetermined

diameter, with a ratio of the interior surface area of the container to the cross-

sectional area of the opening being at least 7.5, includes the steps of generating a

sterilant vapor and positioning a nozzle through the opening in the container, the

nozzle having a diameter no greater than one-half the predetermined diameter of

the opening of the container. The method further includes the steps of discharging

the generated sterilant vapor through the nozzle and into the container and purging

the container of the discharged sterilant. [0014] According to yet another aspect of the present invention, a method of

sterilizing and/or sanitizing a PET container includes the steps of generating a

sterilant vapor having a temperature no greater than 160° F and positioning a

nozzle through an opening in the container. The method further includes the steps

of discharging the generated sterilant vapor through the nozzle and into the

container and purging the container of the discharged sterilant with a heated gas

having a temperature no greater than 160° F, wherein the purging step is

completed no longer than 30 seconds from a beginning of the discharging step.

[0015] According to still another aspect of the present invention, an apparatus for

sterilizing and/or sanitizing a container includes a generator of sterilant vapor, a

nozzle communicating with the generator and a positioning mechanism for

positioning the nozzle through an opening in the container and to a position no

closer than 15 mm from any internal surface of the container that is perpendicular

to the principal direction of flow of the sterilant vapor. The apparatus further

includes a controller for controlling discharging of the generated sterilant vapor

through the nozzle and into the container and purging the container of the

discharged sterilant.

[0016] According to still yet another aspect of the present invention, an apparatus

for sterilizing and/or sanitizing a container, the container having an opening of a

predetermined diameter, with a ratio of the interior surface area of the container to

the cross-sectional area of the opening being at least 7.5, includes a generator of sterilant vapor and a nozzle communicating with the generator, the nozzle having a

diameter no greater than one-half the predetermined diameter of the opening of the

container. The apparatus further includes a positioning mechanism for positioning

the nozzle through the opening in the container and a controller for controlling

discharging of the generated sterilant vapor through the nozzle and into the

container and purging of the container of the discharged sterilant.

[0017] According to another aspect of the present invention, an apparatus for

sterilizing and/or sanitizing a PET container includes a generator of sterilant vapor

having a temperature no greater than 160° F, a nozzle communicating with the

generator and a positioning mechanism for positioning the nozzle through an

opening in the container. The apparatus further includes a controller for

controlling discharging of the generated sterilant vapor through the nozzle and into

the container and purging of the container of the discharged sterilant with a heated

gas having a temperature no greater than 160° F. The controller controls purging

to be completed no longer than 30 seconds from discharging of the sterilant.

[0018] According to yet another aspect of the present invention, a method of

sterilizing and/or sanitizing a container includes the steps of generating a sterilant

vapor, discharging the generated sterilant vapor into the container and purging the

container of the discharged sterilant with heated gas. Reduction of Bacillus spores

in the container by a predetermined amount X (log) is effected by satisfying the

following equation: X = (0.138 x a/b) + (0.066 T,) - (0.00083 x c/b) + (0.021 x T₂) +

(0.008347 x d) - 11.357,

wherein a is the mass of discharged sterilant vapor (mg),

b is the container volume (1),

c is the volume of purging gas (1),

d is the ambient relative humidity (%RH),

T, is the temperature of the discharged sterilant vapor (°F), and

T₂ is the temperature of the purging gas (°F).

[0019] According to yet another aspect of the present invention, a method of

vapor and discharging the generated sterilant vapor into the container. The method

further includes the step of purging the container of the discharged sterilant with

heated gas, wherein reduction of yeast ascospores in the container by a

predetermined amount Y (log) is effected by satisfying the following equation:

Y = (0.063 x a/b) + (0.023 x T,) - (0.00036 x c/b) + (0.052 x T₂) +

(0.009 x d) - 3.611,

wherein a is the mass of discharged sterilant vapor (mg),

b is the container volume (1),

c is the volume of purging gas (1),

d is the ambient relative humidity (%RH),

T, is the temperature of the discharged sterilant vapor (°F), and

T₂ is the temperature of the purging gas (°F). [0020] According to still another aspect of the present invention, a method of

container of the discharged sterilant with heated gas. Reduction of the sterilant in

the container to a predetermined amount Z (mg/1) is effected by satisfying the

following equation:

Z = (0.030 x a/b) - (0.043 x T,) - (0.040 x c b) - (0.075 x T₂) + 15.747,

wherein a is the mass of discharged sterilant vapor (mg),

b is the container volume (1),

c is the volume of purging gas (1),

T, is the temperature of the discharged sterilant vapor (°F), and

T₂ is the temperature of the purging gas (°F).

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic view of the overall sterilization sanitization system

according to the present invention.

[0022] Figure 2 is a cross-sectional side view of the delivery valve used in the

sterilization/sanitization system of the present invention.

[0023] Figure 3 is a cross-sectional plan view of the delivery valve shown in

Figure 2. [0024] Figure 4 is a graph showing a relationship between the reduction of

contaminants and sterilant dosage.

[0025] Figure 5 is a graph showing a relationship between residual sterilant and

flush time.

[0026] Figure 6 is an elevational view of the sterilization/sanitization apparatus

according to the present invention.

[0027] Figure 7 is a plan view of the sterilization/sanitization apparatus of the

present invention.

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A schematic view of the sterilization/sanitization system 10 of the present

invention is shown in Figure 1. System 10 includes a sterilant supply section 20

and a flush gas supply section 30. System 10 can sequentially supply sterilant

from sterilant supply section 20 and flush gas from flush gas supply section 30 to

container 12 by way of delivery valve 40. In order to contain the sterilant within

the system, the discharging and flushing or purging steps can be performed within

dose chamber or enclosure 14. [0029] Sterilant supply section 20 preferably utilizes hydrogen peroxide, and more

preferably 35% hydrogen peroxide, as the sterilant. A vapor generator 22

generates the hydrogen peroxide vapor in any known manner. The hydrogen

peroxide vapor is immediately passed into a heated, moisture- free air stream. The

peroxide and air mixture is passed through an insulated and heated mixing

chamber 23 that contains baffles in order to obtain a uniform or homogenous

mixture of peroxide in air. Unshown sensors are provided to monitor the

temperature, air flow rates and peroxide concentration. The sensors feed back to a

system controller 60, which can correct any deviations in the temperature, air flow

rates and peroxide concentration to ensure the peroxide vapor state is maintained.

The hydrogen peroxide vapor flows through sterilant supply passage 24 to delivery

valve 40. When valve 40 is not actuated for delivery, it recirculates peroxide-laden

air back to mixing chamber 23 through sterilant return passage 26.

[0030] Sensors are also provided in dose chamber 14 to detect the temperature and

humidity therein. These conditions are monitored by controller 60 in order to

control the ambient temperature and humidity during treatment. Should the

chamber temperature exceed 165 °F or should the chamber humidity exceed 75%, a

controller 60 prevents start of the sterilization cycle. Delivery valve 40 can be

opened to continuously deliver ambient air until the chamber temperature and

humidity stabilize. [0031] Flush gas supply section 30 can provide ambient air or a pure gas such as

nitrogen. When air is used to flush containers, it may be drawn into the system

from the immediate environment 32. The air passes through air passage 33,

through a moisture trap 34 and then through a HEP A air filter 35. The air is drawn

by blower 36, which directs its discharge to heater 37. The heated air is then

supplied to delivery valve 40. Air delivered to the dose chamber, whether used to

condition the chamber or to flush containers, is removed from the dose chamber

through return passage 38. Air enters passage 38 as a consequence of either a

slight over pressure from air delivered through valve 40, a negative pressure

generated through the action of blower 36 or a vacuum along passage 51 , or some

combination of both of these actions as balanced by manual operation of valve 52.

Peroxide carried by the flush air from dose chamber into passage 38 is converted to

water vapor and oxygen by action of a catalytic converter 39. Air that is free of

peroxide exits the catalytic converter and can either be re-circulated if it is directed

by valve 52 into passage 33 by way of passage 53 or it can be eliminated from the

system through passage 51. Alternatively, valve 52 can be positioned to bleed air

in various proportions to both passages 51 and 53. Thus, sterile, dry, heated air can

be delivered in order to flush the sterilant.

[0032] Delivery valve 40 and delivery nozzle 50 are shown in more detail in

Figures 2 and 3. Delivery valve 40 includes inlet ports 42a and 42b for connecting

with sterilant passage 24 and flush air passage 33, respectively. Not shown are

connections to sterilant return passage 26. Each inlet port is connected to a respective valve chamber 43a, 43b in which a valve 44a, 44b resides. Each valve

44a, 44b is connected to a valve stem 45a, 45b movable by a respective solenoid

48a, 48b. Each valve is normally closed against respective valve seats 46a, 46b by

the bias of springs 47a, 47b. When a particular valve is lifted off its respective

valve seat, the respective valve chamber 43a, 43b can commumcate with discharge

passage 49a which includes a discharge port 49b. Delivery nozzle 50 is connected

to discharge port 49d. Each solenoid 48a, 48b is independently actuable to lift

valves 44a, 44b off valve seats 46a, 46b to selectively allow sterilant vapor from

passage 24 or flush air from passage 33 to flow through the valve passage and

discharge passage into delivery nozzle 50. Delivery valve 40 is heated so as to

eliminate the potential of the sterilant vapor from cooling and condensing before

reaching the container surface.

[0033] In operation, the container to be sanitized or sterilized is positioned in dose

chamber 14 and nozzle 50 is inserted into an opening of the container. Delivery

valve 40 is then actuated to deliver a dose of sterilant vapor through nozzle 50 into

the container. After a predetermined wait period, delivery valve 40 is actuated

once more to deliver a supply of flush gas through nozzle 50 to evacuate the

residual sterilant.

[0034] The present invention can be used for sanitizing or sterilizing internal and

external surfaces of containers, which is necessary to permit aseptic packaging of

products. The containers may be formed of glass, paperboard, plastic or composites thereof. The invention is especially useful in sterilizing or sanitizing a

blow-molded PET container having a bottle finish or opening that is small relative

to the total volume or maximum diameter of the container. Containers having an

opening with a diameter no more than one-half the maximum diameter of the

container meet this definition. If the ratio of the interior surface area of the closed

container to the cross-sectional area of the opening equals or exceeds 7.5, the

container also meets the defimtion. The process is particularly useful for low cost,

non-heat set PET containers. In addition, the process is particularly adaptable to

rapid sterilization or sanitization of containers or packages that have non-uniform

surface designs, such as rippled or ribbed surfaces, embossed surfaces, pistol grip

handles, center divides or enclosed pockets.

[0035] Throughout the specification and claims, the dimensions of the containers

used in the present invention are given as diameters. However, the invention is not

limited to use with containers of circular cross-section. Rather, the present

invention can be used with containers of any shape. Accordingly, the term

"diameter" used throughout the specification and claims can read on any

corresponding dimension of a non-circular container.

[0036] The parameters necessary for effective sterilization or sanitization of the

containers vary depending upon the container dimensions and material. For

example, to sanitize a two-liter PET container for storing high acid product would

require a sanitization time of 14-19 seconds, at a hydrogen peroxide vapor concentration of about 60 mg/1 and flow rate of about 2 cfm at about 125°F,

whereas a 0.30 liter container would require a sanitization time of 4-5 seconds. On

the other hand, sterilization of a two-liter container for storing a low acid product

would require a sterilization time of 24-33 seconds, while the 0.30 liter container

would require 5-7 seconds. Herein, sterilization time is defined as a period

beginning from the start of relative motion between a container and the nozzle

toward one another and ending when the relative motion positions the container

where its opening is clear of the nozzle tip and includes sterilant dose time, hold

time and flush time.

[0037] Based on exhaustive experimentation, it was determined that the parameters

for sterilization and sanitization can be based on mathematical models. In each of

the tests, spores of the bacteria Bacillus subtiUis var. globigii or ascospores of

Saccharomyces cerevisiae were applied to the surfaces of PET containers, dried

overnight and then treated with hydrogen peroxide vapor according to the system

shown in Figure 1. The peroxide was removed by flush air to a quantity of

sterilant equal to or below the FDA defined limit for sterilant residual

concentration. The surviving spores were immediately recovered in a large volume

neutralizing buffer and plated on appropriate recovery medium.

[0038] During the course of experimentation, 1,360 data points were collected in

an analysis of yeast ascospore kill by peroxide vapor, 2,320 data points were

collected in the analysis of kill of Bacillus spores by peroxide vapor, and 6,834 data points were collected in the analysis of peroxide residual. The data collected

during experimentation included the temperature of the heater, the temperature of

the delivery valve 40 during dosing and air flush, the temperature of the nozzle 50

during dosing and flushing, the temperature of the air flush exiting the nozzle, the

temperature of the peroxide exiting the nozzle, the chamber 14 humidity, the

chamber peroxide concentration, the concentration of peroxide at the exterior of

the chamber, the differential pressure across the delivery nozzle 50, the residual

peroxide, and the surviving population of spores relative to initial concentration.

The data were collected and tabulated to permit regression analysis.

[0039] Regression analysis was performed to establish relationships between

observed log reduction of Bacillus spores (or yeast ascospores) as a function of log

reduction peroxide dose and air flush parameters and the elimination of peroxide

residual as a function of peroxide dose and air flush parameters. The regression

analysis indicated that the death of microorganisms was a log linear function and

the removal of peroxide residual was a linear function within the range of test

parameters.

[0040] The determined relationships are as follows:

(1) Log reduction of Bacillus spores OO:

X = (0.138 x a/b) + (0.066 x T,) - (0.00083 c/b) + (0.021 x T₂) + (0.008347 x d)

- 11.357 [0041] (2) Log reduction of yeast ascospores (Y):

Y = (0.063 a/b) + (0.023 x T,) - (0.00036 x c/b) + (0.052 x T₂) + (0.009 d) +

3.611

[0042] (3) Hydrogen Peroxide residual (after 24 hours) (mg/D:

(Z): Z = (0.030 x a b) - (0.043 x T,) - (0.040 c/b) - (0.075 x T₂) + 15.747,

wherein a is the mass of hydrogen peroxide per dose (mg),

b is the container volume (1),

c is the volume of flush air (1),

d is the relative humidity within the chamber 14 (%RH),

T, is the temperature of the hydrogen peroxide vapor ( °F), and

T₂ is the temperature of the flush air (°F).

[0043] Figure 4 is a graph that demonstrates the impact of varying hydrogen

peroxide doses and the calculated elimination of surface adhering bacterial spores

and yeast ascospores.

[0044] Figure 5 shows the relationship of residual hydrogen peroxide versus air

flush time. The dosages of hydrogen peroxide and the temperatures of the

hydrogen peroxide vapor and the flush temperature were varied. The flow of the

flush air was 14.5 cfm (6.85 1/s). Based on the mathematical relationships

discussed above, solutions can be generated for any range of parameters. That is, for a bottle of known volume or surface area, in order to achieve the desired 6 log

Bacillus reduction for sterilization or 5 log ascospore reduction for sanitization, the

hydrogen peroxide dosage, flush air volume, relative humidity and temperatures of

the peroxide and flush air can be determined.

[0045] It has been further discovered that the sterilization of exterior surface areas

of the container that comprise the finish (opening) and shoulder of the container is

critical to ensuring that the sterility of the container is maintained following

treatment. To this end, delivery of the sterilant through nozzle 50 is preferably

initiated before the nozzle is inserted into the container in order to permit the upper

portion of the container exterior to become bathed in sterilant almost

simultaneously with initiation of sterilization of the container interior.

[0046] In addition, it has been discovered that after nozzle 50 has been inserted

into the container, the extent of the insertion of the nozzle impacts performance.

The sterilization process optimization depends on proper positioning of the dose

nozzle. For PET and plastic containers it is particularly effective when the tip of

the nozzle is inserted through the opening of the container to a depth of between

1/6 and 5/6 the height of the container while sterilant is dosed. Container height is

defined as the maximum column height between the top of the container finish and

the lowest point of contact between filled product and the base of the container.

Within this range, hydrogen peroxide delivery and removal of residual peroxide

was found to be superior when compared to other positions relative to the container height. For containers having shoulders, it has been discovered that it is most

effective to insert nozzle 50 through the opening of the container to just below the

shoulder of the container. Further, it is critical that the tip of the nozzle be at least

15 millimeters from those surfaces of the container that are perpendicular to the

principal direction of flow of peroxide from the nozzle. If the nozzle is any closer,

vaporized sterilant can be released directly onto the container and create problems

with residual peroxide.

[0047] The size of nozzle 50 is also a critical feature of the invention. The delivery

of sterilant and removal of residual sterilant are best promoted with a delivery

nozzle 50 that has a diameter no greater than one-half the diameter of the opening

of the container. For example, for a container with a 28 millimeter diameter finish,

the nozzle diameter should be no more than 14 millimeters. A nozzle so designed

maximizes the gas exchange from the sterilization system to the container and

from the container to atmosphere.

[0048] In order to allow the sterilant sufficient time to act on the contaminants, yet

prevent the sterilant from being absorbed by the material of the container, the

period between sterilant discharge and purging is controlled. For a 2-liter non-heat

set PET container with a 28 mm finish, the complete sterilization cycle period is 30

seconds. Sterilization of smaller containers or containers with larger diameter

finishes can be effected in shorter periods of time. In addition, in order to prevent

damage to the PET, the temperature of the sterilant vapor and the temperature of the purge air should be no more than 160° F, which is less than the 163 ° F glass

transition temperature of non-heat set PET.

[0049] The sterilization/sanitation system 10 of the present invention is most

effectively and efficiently utilized in an apparatus 100 for mass sterilizing or

sanitizing the containers. This sterilization/sanitization apparatus 100 is shown in

more detail in Figures 6 and 7. In order to most efficiently convey and sterilize or

sanitize the containers, the apparatus is preferably of a carousel design. With this

arrangement, the containers to be sterilized or sanitized are constantly moving

throughout the various steps in the process to maximize the number of containers

that can be processed in a given time period.

[0050] Based on the three mathematical relationships described above, the time

required to sterilize or sanitize containers and subsequently remove residual

peroxide can be determined and the size requirement for the carousel design can be

determined. For example, given processing speed requirements of 625 10- to 20-

ounce bottles per minute (bpm), 550 1-liter bpm or 300 2-liter bpm, the diameter of

the sterilization/sanitization apparatus can range from 8.5-25.7 feet. Based on the

large number of containers that can be processed per unit time, the area required

for accommodating such an apparatus is relatively small. If need be, dosing could

be effected on one carousel and elimination of residual could be effected on a

second carousel, with the two carousels together occupying only slightly more

floor space than would a single carousel that accomplished both tasks. [0051] In apparatus 100, the previously-described sterilant supply section 20, flush

gas supply section 30 and controller 60 can be incorporated in a unitary housing

102. Housing 102 includes the fluid connections 24, 33 and electrical connections

109 communicating with a carousel 106. Carousel 106 includes a base 108, as

well as guide section 120, drive section 130 and gas delivery section 140. Guide

section 120, drive section 130 and gas delivery section 140 are all housed within

dose chamber or enclosure 114 (or a class 100 clean room) to contain the sterilant

vapors within the apparatus and exclude airborne microbiological contaminants.

[0052] Because in the preferred embodiment the sterilant vapor is applied to the

exteriors of the containers 12 as well as their interiors, apparatus 100 is designed to

cause relative movement between containers 12 and corresponding delivery

nozzles 50. In the prefeπed embodiment, the delivery nozzles 50 are not moved in

the vertical direction, but rather containers 12 are raised and lowered relative to the

nozzles. Alternatively, the nozzle assembly can be adapted to be lowered into the

containers, which do not change their plane of rotation during the sterilization

cycle. Further, the bottles can be raised to an intermediate position as the nozzle

assembly is simultaneously lowered toward the intermediate position. To

accomplish the embodiment wherein the nozzles are stationary, containers 12 are

positioned on platforms 121, each connected at its lower end to a lifting rod 122.

Each lifting rod 122 includes a follower roller 123 that follows a lift cam 124. Lift

cam 124 has such a shape as to cause each lifting rod to rise from an in- feed zone

up toward a sterilization and flush zone and then lower to an out-feed zone. Each lift rod 122 is connected to a drive wheel 125 by a bushing 126. Lift rods 122 are

free to move relative to bushings 126 in the vertical direction. As drive wheel 125

rotates, guide rods 125 follow in a rotational direction to cause follow rollers 123

to ride along lift cam 124.

[0053] Lift rods 122 can be biased by unshown springs to a normally-raised

position or to a normally- lowered position. Alternatively, lift rods 122 can be

biased to be normally lowered by gravity. In any arrangement, containers 12

resting on platform 121 rise and fall with the path of the lift cam 124 as they rotate

about the apparatus.

[0054] Drive wheel 125 is connected to a rotatable turret 127 that is journaled to

base 108. Guides 128 and 129 are also connected to turret 127 and include

surfaces for guiding and stabilizing the containers in circular and vertical

movements. Tuπet 127 is driven by drive system 130. A motor 132 transmits

motive force through transmission 131 that engages a gear 133 provided on the

periphery of the turret. Motor 132 can be controlled by controller 60 provided in

housing 102.

[0055] Gas delivery section 140 includes a gas distribution manifold 141, which is

connected to the top of tuπet 127 and rotates with the tuπet. Sterilant supply line

24 and flush gas supply line 33 are connected to gas distribution manifold 141 by

manifold supply lines 142 that are disposed within the hollow interior of turret 127. Manifold supply lines 142 are preferably stationary, but can communicate with gas

distribution manifold 141 by ports communicating with arcuate slots, for example,

such as is shown and described in U.S. Patent No. 2,824,344. A number of exit

lines 143 are connected to manifold body 142 to supply sterilant vapor or flush gas

to valves 40. The number of exit lines 143 corresponds to the number of valves 40

designed in the apparatus. Valves 40 can be controlled mechanically by action of

unshown cams or can be controlled by controller 60 with signals sent via electrical

connections 104.

[0056] In operation, containers 12 enter apparatus 100 by being conveyed to in-

feed turnstile 101 and, after processing, exit the apparatus through out- feed

turnstile 103. Containers 12 are initially fed from in-feed turnstile 101 onto one of

the platforms 121, with turret 127 continuously rotating. In the first stage after in-

feeding, the container rises, due to the ramping action of the cam and follower

roller, toward one of the delivery nozzles 50. Guides 128 and 129 include guide

surfaces for each container to align the container with its coπesponding delivery

nozzle. In the preferred embodiment, each nozzle 50 discharges sterilant before it

enters the opening of the container so as to spray sterilant around the upper exterior

of the container.

[0057] The container is then further raised so that nozzle 50 enters the opening and

is positioned within the container. Preferably, at its deepest extent, the end of

nozzle 50 is disposed no closer than 15 millimeters from the bottom surface of the container and no closer than 1/6 the height of the container from the bottom

surface. The sterilant continues to be discharged through the nozzle and the

container enters a hold stage or zone.

[0058] After a predetermined holding period, which begins upon cessation of

delivery of sterilant, the container enters the flush zone where valve 40 opens to

discharge flush gas into the container. After the flushing process ends, container

12 is lowered and enters out-feed turnstile 103 to be discharged from the apparatus.

[0059] While the present invention has been described as to what is cuπently

considered to be the prefeπed embodiments, it is to be understood that the

invention is not limited to these embodiments. To the contrary, the invention is

intended to cover various modifications and equivalent aπangements within the

spirit and scope of the appended claims. The scope of the following claims is to be

accorded the broadest inteφretation so as to encompass all such modifications and

equivalent structures and functions.

Claims

WHAT IS CLAIMED IS:

1. A method of sterilizing and/or sanitizing a container, said

method comprising the steps of:

generating a sterilant vapor;

positioning a nozzle through an opening in the container and to a

position no closer than 15 mm from any internal surface of the container that is

peφendicular to a principal direction of flow of sterilant vapor from the nozzle;

discharging the generated sterilant vapor through the nozzle and into

the container; and

purging the container of the discharged sterilant.

2. A method according to Claim 1, wherein after said

positioning step, the nozzle is positioned no closer than 15 mm from the bottom of

the container.

3. A method according to Claim 1, wherein the container

comprises a shoulder below the opening and in said positioning step the nozzle is

positioned just below the shoulder.

4. A method according to Claim 1, wherein after said

positioning step, the nozzle is inserted within 1/6 and 5/6 the height of the

container.

5. A method according to Claim 1, wherein the sterilant comprises hydrogen peroxide.

6. A method according to Claim 1, further comprising the step

of heating the nozzle.

7. A method according to Claim 1, wherein the container is

formed at least in part of PET.

8. A method according to Claim 1, wherein said purging step

comprises forcing heated gas into the container through the nozzle.

9. A method according to Claim 1, wherein the nozzle has a

diameter no greater than one-half the diameter of the opening of the container.

10. A method according to Claim 1, wherein the sterilant vapor

used in said discharging step and a gas used in said purging step are at

temperatures no greater than 160° F.

11. A method according to Claim 1, wherein said purging step is

effected no longer than 30 seconds from said discharging step.

12. A method according to Claim 1, further comprising the step

of positioning the nozzle above the opening of the container and discharging the

sterilant vapor onto the exterior of the container.

13. A method of sterilizing and/or sanitizing a container, the

container having an opening of a predetermined diameter, a ratio of the interior

surface area of the container to the cross-sectional area of the opening being at

least 7.5, said method comprising the steps of:

generating a sterilant vapor;

positioning a nozzle through the opening in the container, the nozzle

having a diameter no greater than one-half the predetermined diameter of the

opening of the container;

discharging the generated sterilant vapor through the nozzle and into

the container; and

purging the container of the discharged sterilant.

14. A method according to Claim 13, wherein the sterilant

comprises hydrogen peroxide.

15. A method according to Claim 13, further comprising the step

of heating the nozzle.

16. A method according to Claim 13, wherein the container is

formed at least in part of PET.

17. A method according to Claim 13, wherein said purging step

comprises forcing heated gas into the container through the nozzle.

18. A method according to Claim 13, wherein after said

positioning step, the nozzle is disposed no closer than 15 mm from any internal

surface of the container that is peφendicular to the direction of flow from the

nozzle.

19. A method according to Claim 13, wherein after said

positioning step the nozzle is inserted within 1/6 and 5/6 the height of the

container.

20. A method according to Claim 13, wherein the sterilant vapor

used in said discharging step and a gas used in said purging step are at

temperatures no greater than 160° F.

21. A method according to Claim 13, wherein said purging step is

effected no longer than 30 seconds from said discharging step.

22. A method according to Claim 13, further comprising the step

of positioning the nozzle above the opening of the container and discharging the

sterilant vapor onto the exterior of the container.

23. A method according to Claim 13, wherein the predetermined

diameter of the opening of the container is no more than one-half the maximum

diameter of the container.

24. A method of sterilizing and/or sanitizing a PET container,

said method comprising the steps of:

generating a sterilant vapor having a temperature no greater than

160° F;

positioning a nozzle through an opening in the container;

discharging the generated sterilant vapor through the nozzle and into

the container; and

purging the container of the discharged sterilant with a heated gas

having a temperature no greater than 160° F, wherein said purging step is

completed no longer than 30 seconds from a beginning of said discharging step.

25. A method according to Claim 24, wherein the sterilant

comprises hydrogen peroxide.

26. A method according to Claim 24, further comprising the step

of heating the nozzle.

27. A method according to Claim 24, wherein the container is

formed in part of PET.

28. A method according to Claim 24, wherein in said purging

step, the heated gas is discharged into the container through the nozzle.

29. A method according to Claim 24, wherein in said positioning

step, the nozzle is disposed no closer than 15 mm from any intemal surface of the

container that is peφendicular to the direction of flow from the nozzle.

30. A method according to Claim 24, wherein after said

positioning step the nozzle is inserted within 1/6 and 5/6 the height of the

container.

31. A method according to Claim 24, wherein the opening of the

container has a predetermined diameter, a ratio of the interior surface area of the

container to the cross-sectional area of the opening is at least 7.5, and the nozzle

has a diameter no greater than one-half the predetermined diameter of the opening

of the container.

32. A method according to Claim 24, further comprising the step

of positioning the nozzle above the opening of the container and discharging the

sterilant vapor onto the exterior of the container.

33. An apparatus for sterilizing and/or sanitizing a container, said

apparatus comprising:

a generator of sterilant vapor;

a nozzle communicating with said generator;

a positioning mechanism for positioning said nozzle through an

opening in the container and to a position no closer than 15 mm from any internal

surface of the container that is peφendicular to the direction of flow of sterilant

vapor from the nozzle; and

a controller for controlling discharging of the generated sterilant

vapor through said nozzle and into the container and purging of the container of the

discharged sterilant.

34. An apparatus according to Claim 33, wherein said positioning

mechanism positions the nozzle no closer than 15 mm from the bottom of the

container.

35. An apparatus according to Claim 33, wherein the container

comprises a shoulder below the opening and said positioning mechanism positions

said nozzle just below the shoulder.

36. An apparatus according to Claim 33, wherein said positioning

mechanism inserts the nozzle within 1/6 and 5/6 the height of the container.

37. An apparatus according to Claim 33, wherein the sterilant

comprises hydrogen peroxide.

38. An apparatus according to Claim 33, further comprising a

heater for heating said nozzle.

39. An apparatus according to Claim 33, wherein the container is

formed at least in part of PET.

40. An apparatus according to Claim 33, wherein in purging, said

controller controls forcing of heated gas into the container through said nozzle.

41. An apparatus according to Claim 33, wherein the opening of

the container has a predetermined diameter, a ratio of the interior surface area of

the container to the cross-sectional area of the opening is at least 7.5, and said

nozzle has a diameter no greater than one-half the diameter of the opening of the

container.

42. An apparatus according to Claim 33, wherein said controller

controls the sterilant vapor and a purge gas to be at temperatures no greater than

160° F.

43. An apparatus according to Claim 33, wherein said controller

controls purging to be effected no longer than 30 seconds from discharging of the

sterilant.

44. An apparatus according to Claim 33, wherein said controller

further controls positioning of the nozzle above the opening of the container and

discharging of the sterilant vapor onto the exterior of the container.

45. An apparatus for sterilizing and/or sanitizing a container, the

container having an opening of a predetermined diameter, a the ratio of the interior

surface area of the container to the cross-sectional area of the opening being at

least 7.5, said apparatus comprising:

a generator of sterilant vapor;

a nozzle communicating with said generator, said nozzle having a

diameter no greater than one-half the predetermined diameter of the opening of the

container;

a positioning mechanism for positioning said nozzle through the

opening in the container; and a controller for controlling discharging of the generated sterilant

vapor through said nozzle and into the container and purging of the container of the

discharged sterilant.

46. An apparatus according to Claim 45, wherein the sterilant

comprises hydrogen peroxide.

47. An apparatus according to Claim 45, further comprising a

heater for heating said nozzle.

48. An apparatus according to Claim 45, wherein the container is

formed at least in part of PET.

49. An apparatus according to Claim 45, wherein in purging, said

controller controls forcing of heated gas into the container through said nozzle.

50. An apparatus according to Claim 45, wherein said positioning

mechanism positions said nozzle no closer than 15 mm from any internal surface

of the container that is peφendicular to the direction of flow from the nozzle.

51. An apparatus according to Claim 45, wherein said positioning

mechanism inserts the nozzle within 1/6 and 5/6 of the height of the container.

52. An apparatus according to Claim 45, wherein said controller

controls the sterilant vapor and a flush gas to be at temperatures no greater than

160° F.

53. An apparatus according to Claim 45, wherein said controller

controls purging to be effected no longer than 30 seconds from discharging of the

sterilant.

54. An apparatus according to Claim 45, wherein said controller

further controls positioning of the nozzle above the opening of the container and

discharging of the sterilant vapor onto the exterior of the container.

55. An apparatus according to Claim 45, wherein the

predetermined diameter of the opening of the container is no more than one-half

the maximum diameter of the container.

56. An apparatus for sterilizing and/or sanitizing a PET container,

said apparatus comprising:

a generator of sterilant vapor having a temperature no greater than

160° F;

a nozzle communicating with said generator;

a positioning mechanism for positioning said nozzle through an

opening in the container; and a controller for controlling discharging of the generated sterilant

vapor through said nozzle and into the container and purging of the container of the

discharged sterilant with a heated gas having a temperature no greater than 160° F,

wherein said controller controls purging to be completed no longer than 30 seconds

from discharging of the sterilant.

57. An apparatus according to Claim 56, wherein the sterilant

comprises hydrogen peroxide.

58. An apparatus according to Claim 56, further comprising a

heater for heating said nozzle.

59. An apparatus according to Claim 56, wherein the container is

formed at least in part of PET.

60. An apparatus according to Claim 56, wherein in purging, said

controller controls forcing of the heated gas into the container through said nozzle.

61. An apparatus according to Claim 56, wherein said positioning

mechanism positions said nozzle to a position no closer than 15 mm from any

internal surface of the container that is peφendicular to a principle direction of

flow of sterilant vapor from the nozzle.

62. An apparatus according to Claim 56, wherein said positioning

mechanism inserts the nozzle within 1/6 and 5/6 the height of the container.

63. An apparatus according to Claim 56, wherein the opening of

the container has a predetermined diameter, a ratio of the interior surface area of

the container to the cross-sectional area of the opening is at least 7.5, and said

nozzle has a diameter no greater than one-half the diameter of the opening of the

container.

64. An apparatus according to Claim 56, wherein said controller

further controls positioning of the nozzle above the opening of the container and

discharging of the sterilant vapor onto the exterior of the container.

65. A method of sterilizing and/or sanitizing a container, said

method comprising the steps of:

generating hydrogen peroxide sterilant vapor;

discharging the generated sterilant vapor into the container; and

purging the container of the discharged sterilant with heated gas,

wherein reduction of Bacillus spores in the container by a predetermined amount X

(log) is effected by satisfying the following equation

X = (0.138 x a/b) + (0.066 x T,) - (0.00083 x c/b) + (0.021 x T₂) +

(0.008347 x d) - 11.357,

wherein a is the mass of discharged sterilant vapor (mg), b is the container volume (1),

c is the volume of purging gas (1),

d is the ambient relative humidity (%RH),

Tj is the temperature of the discharged sterilant vapor (°F), and

T₂ is the temperature of the purging gas (°F).

66. A method according to Claim 65, wherein the spores are

Bacillus subtilis var. globigii.

67. A method according to Claim 65, wherein the predetermined

reduction amount (X) of the spores in the container equals at least 6 log.

68. A method according to Claim 65, wherein the residual

sterilant is reduced in said purging step to a desired level (Z) (mg/1) by satisfying

the following equation:

Z - (0.030 x a/b) - (0.043 x T,) - (0.040 x c/b) - (0.075 x T₂) +

15.747.

69. A method according to Claim 65, wherein the sterilant

comprises 35% hydrogen peroxide.

70. A method of sterilizing and/or sanitizing a container, said

method comprising the steps of: generating a hydrogen peroxide sterilant vapor;

discharging the generated sterilant vapor into the container; and

purging the container of the discharged sterilant with heated gas,

wherein reduction of yeast ascospores in the container by a predetermined amount

Y (log) is effected by satisfying the following equation

Y = (0.063 a/b) + (0.023 x T,) - (0.00036 c/b) + (0.052 x T₂) +

(0.009 x d) - 3.611,

wherein a is the mass of discharged sterilant vapor (mg),

b is the container volume (1),

c is the volume of purging gas (1),

d is the ambient relative humidity (%RH),

T, is the temperature of the discharged sterilant vapor (°F), and

T₂ is the temperature of the purging gas (°F).

71. A method according to Claim 70, wherein the ascospores are

of the yeast Saccharomyces cerevisiae.

72. A method according to Claim 70, wherein the predetermined

reduction amount (Y) of the ascospores in the container equals at least 5 log.

73. A method according to Claim 70, wherein the residual

sterilant is reduced in said purging step to a desired level (mg/1) (Z) by satisfying

the following equation: Z = (0.030 x a/b) - (0.043 T,) - (0.040 x c/b) - (0.075 x T₂) + 15.74.

74. A method according to Claim 70, wherein the sterilant

comprises 35% hydrogen peroxide.

75. A method of sterilizing and/or sanitizing a container, said

method comprising the steps of:

generating hydrogen peroxide sterilant vapor;

discharging the generated sterilant vapor into the container; and

purging the container of the discharged sterilant with heated gas,

wherein reduction of the sterilant in the container to a predetermined amount Z

(mg/1) is effected by satisfying the following equation

Z = (0.030 a/b) - (0.043 x T,) - (0.040 x c/b) - (0.075 x T₂) +

15.747,

wherein a is the mass of discharged sterilant vapor (mg),

b is the container volume (1),

c is the volume of purging gas (1),

T, is the temperature of the discharged sterilant vapor (°F), and

T₂ is the temperature of the purging gas (°F).

76. A method according to Claim 75, wherein the sterilant

comprises 35% hydrogen peroxide.

77. A method according to Claim 75, wherein the predetermined

amount is 0.5 mg/1 at 24 hours after said purging step.