<div class="application article clearfix" id="description">
<p class="printTableText" lang="en">New Zealand No 307127 International No PCT/AU96/00305 <br><br>
TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION <br><br>
Priority dates 18 05 1995, <br><br>
Complete Specification Filed 20 05 1996 <br><br>
Classification (6) A23L1/221.226, A23L3/00,36, A23C3/02.04, A61L2/06 <br><br>
Publication date 29 September 1999 <br><br>
Journal No 1444 <br><br>
NEW ZEALAND PATENTS ACT 1953 <br><br>
COMPLETE SPECIFICATION <br><br>
Title of Invention <br><br>
Method and apparatus for pasteurisation of sterilisiation of herbs and spices <br><br>
Name, address and nationality of applicant(s) as in international application form <br><br>
BOC GASES AUSTRALIA LIMITED, an Australian company of The BOC Gases Building, 799 Pacific Highway, Chatswood, New South Wales 2057, Australia <br><br>
4m, WO 9<>/3<>237 <br><br>
1 <br><br>
PCTM.U96/00305 <br><br>
METHOD AND APPARATUS FOR PASTEURISATION OR STERILISATION <br><br>
OF HERBS AND SPICES <br><br>
This invention relates to a method and apparatus for pasteurising or 5 sterilising herbs, spices and other materials prone to microbial spoilage <br><br>
Attempts have been made to develop methods for pasteurising or sterilising herbs aiid spices involving heat treatment However, these methods have been found to be impracticable as the heal treatment step results in the mobilisation and/or destruction of the volatile substances 10 which give the herbs and spices their functionality and appeal <br><br>
Traditionally, therefore, herbs and spices have been treated by exposure to ethylene oxide <br><br>
Unfortunately, such ethylene oxide processes have certain disadvantages For example, it has been found that while such processing 15 can result in a reduction in the bacterial numbers in the product, they have the disadvantages that bacterial and fungal spores commonly have a natural resistance to this sterilant so its effect is concentiation dependant and long exposuie times are required for penetration Further, the exposure to ethylene oxide of foods with high salt concentrations has been reported to 2 0 produce reaction products such as epichlorhydrin. which are potentially toxogenic <br><br>
Thus it is one object of the present invention to provide a method and apparatus for effectively pasteurising or sterilising herbs, spices and other materials prone to microbial spoilage, which has little or no adverse <br><br>
2 5 effect on their functionality <br><br>
Accordingly in a first aspect the present invention provides a method for pasteurising or sterilising heibs, spices and other materials prone to microbial spoilage comprising the steps of <br><br>
(1) cooling said herbs, spices or other materials to a temperature <br><br>
3 0 less than about OnC, <br><br>
wo 96/36237 PCT/ATJ96/00305 <br><br>
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(2) rapidly heating said cooled herbs, spices or other materials to a pasteurising or sterilising tempeiature, and <br><br>
(3) recooling said herbs, spices or other materials to about room temperatuie, <br><br>
5 wherein at least steps (2) and (3) are performed in an enviioninent(s) having a pressure of greater than 1 Bar <br><br>
Performing steps [2] and (3) under pressures greater than 1 Bar prevents loss of volatiles from the materials being treated In addition, use of such pressure in these steps is believed to positively contribute to colour 10 fastness and the reduction of microbe numbers Preferably, the piessures applied in steps (2) and (3) are greater than 3 Bar Once step (3) is concluded, the environment within which the materials are contained may be returned to atmospheric pressure <br><br>
Step (1) is prefeiably a rapid cooling step and may be completed in 15 0 05 to 5 0 minutes more preferably 0 5 to 3,0 minutes During step (1) the herbs, spices or other materials are preferably cooled to a temperature less than about -70°C. moie preferably, to a temperature of about -170°C It is also preferred that step (1) be performed in an environment(s) having a piessuie greater than 1 Bar 20 The rapid heating step (2) may be achieved by the application of heat from anv source radiative, conductive or convective, which may be generated by combustion by induction or dielectnc heating with electromagnetic radiation nuciowave, by infra red irradiation, or any othei means The heat is preferably applied for 0 05 to 5 0 minutes, more 25 preferably 0 1 to 3 0 minutes or longer dependent oil the material and its microbial bioburden <br><br>
The recooling step (3) is also pieferably a rapid cooling step and may be completed in 0 05 to 5 0 minutes, more pieferably 0 1 to 2 0 minutes In a second aspect the present invention piovides apparatus for 30 conducting the method of the first aspect of the invention <br><br>
WO 95/35237 <br><br>
PCT/AU95/f><)305 <br><br>
The method may be performed on batches of materials or continuously Thus, an apparatus according to the invention for batch treatments may comprise, <br><br>
a vessel compnsing, <br><br>
5 an inlet means through which a batch of herbs, spices or other materials susceptible to microbial spoilage may be introduced, <br><br>
means for cooling said batch to a temperature less than about 0°C, means for rapidly heating said cooled batch to a pasteurising or sterilising temperature, <br><br>
10 means for recooling said batch to about room temperature, <br><br>
means for applying and/or regulating a pressure within the vessel during heating and recooling of gieater than 1 Bar, and outlet means for removing the treated batch from said vessel Preferably, the apparatus for batch treatments comprises a pressure 15 vessel constructed to sanitary standards which feeds out through a valve to an aseptic filer sourced commercially A batch of matenal for treatment is introduced through an infeed hopper equipped with a valve into the vessel were stirring is instigated by a motonsed stirrei The product is rapidly cooled to less than 0°C by the cooling effects of expanding coolant sparged 20 through the matenal being treated, which may be liquefied nitrogen, liquefied carbon dioxide or a mixture of both, or other gas, either in combination or alone and may be humidified prior to application Immediately the desired cooling step temperature (e g temperature of between -70°C and -170°C) and pressure (e g pressure greater than 1 Bar) is 25 reached a pressure regulating valve is closed, the inflow of coolant reduced and then controlled to maintain a pressure of gieatei than 1 Bar, more preferably greater than 3 Bar While this pressure is maintained, the matenal is exposed to heating for a treatment duration sufficient to reduce the total microbial content by the desired factor, dependant on the bacterial 30 and fungal bioburden of the infeed material <br><br>
#W0 96/36237 <br><br>
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PCT/AU96/00305 <br><br>
The applied heat source is preferably arranged on the vessel so as to optimise the application and penetration of the heat, thus minimising the treatment time needed and the resultant pioduct damage Fast response sensitive pressure and temperature sensors may be provided to monitor 5 progression of the treatment and the outputs from these are feed to a control circuit which in turn regulates the application of heat and pressure The control circuit typically includes a programmable logic controller and a supervising, control and data acquisition computer <br><br>
An apparatus according to the invention for continuous treatments 10 may comprise a first vessel comprising an inlet means through which herbs, spices or other materials susceptible to microbial spoilage may be conbnuoxisly introduced, and means for cooling said herbs spices or other materials to a temperature less than about 0°C, <br><br>
15 a second vessel comprising, means for rapidly heating said cooled herbs, spices or other materials, and means for applying and/or regulating a pressure of greater than 1 Bar, and a third vessel compusing means for recooling the herbs, spices or other materials to about room temperature, means foi applying and/or 2 0 regulating a pressure of greater than 1 Bar, and outlet means for removing the tieated herbs, spices or other materials from said vessel, <br><br>
wherein said first vessel is connected to said second vessel and said second vessel is connected to said third vessel, the arrangement being such that the heibs, spices or othei materials introduced into the first vessel may be 25 continuously and progiessively transfened to the second and then third vessels <br><br>
The material treated by this invention may be in addition to herbs and spices, for which it was specifically developed, other foods, pharmaceuticals, leaf matenal in various forms for example tobacco oi <br><br>
WO 96/36237 <br><br>
PCT/AU96/00305 <br><br>
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various free flowing powdered materials which are prone to microbial spoilage <br><br>
The invention will now be further descubed by way of the following, non-limiting examples and accompanying figuies <br><br>
5 <br><br>
Brief Description of Accompanying Figures <br><br>
Figure 1 piovides a schematic elevational representation of a preferred apparatus according to the invention for batch treatments of herbs and spices <br><br>
10 Figure 2 provides a schematic elevational representation of a preferred apparatus according to the invention for continuous flow treatments of herbs and spices <br><br>
EXAMPLE 1 Batch Apparatus 15 As shown in Figure 1, the sanitary designed piessure vessel (1) has a tapered conical base, is equipped with a motonsed stirrer (2), infeed liopper/valve (3) and outfeed hopper/valve (4) A safety vent (7) is also piovided <br><br>
A preweighed batch of matenal to be treated is introduced through 2 0 infeed hopper/valve (3) and stirring commenced with stirrer (2) Coolant is introduced through sparging ports (10) and allowed to escape through a pressure legulator valve (6) until the desired cooling step temperature is recorded by the thermocouple (9) in contact with the matenal being treated In the next stage, coolant gas flow is reduced and the pressure 25 regulating valve (6) is servo driven to maintain the desired pressure (greater than 3 Bar), sensed by a pressure transducer (8) Heating is then commenced, applied from heaters (5) to a temperature of between 70-90°C for pasteurisation and between 105-150°C for sterilisation The duration of exposure is optimised to piovide the maximum reduction in bioburden 30 while maximising the flavoui and other functionality of the material being <br><br>
^ WO 96/36237 <br><br>
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PCT/AU96/00305 <br><br>
treated Typically, heating energy/batch mass can be balanced to attain treatment times of only 0 1-3 0 minutes This short time/high temperature processing yields at least 4 and often 6 log reductions in microbial bioburden <br><br>
5 At the end of the penetrative heat treatment stage the protective post treatment cooling is commenced This is mandatory to protect the delicate aromatic flavour and functional components Cooling is immediately effected while still underpiessureby again controlling cooling inflow at sparging ports (10) and its release at the pressure legulator valve (6) Rapid 10 cooling reduces the temperature of the matenal being treated to less than 20DC and then coolant inflow is ceased and the pressure within the vessel is allowed to return to atmospheric pressure <br><br>
Stirring is continued throughout the process and until the matenal is discharged directly into the aseptic filler located at (11) <br><br>
15 <br><br>
EXAMPLE 2 Continuous Flow Apparatus <br><br>
In an alternative arrangement the steps of the method according to the invention maybe applied to material conveyed through three vessels similarly equipped to the batch process so that each stage of the treatment 20 can be applied in a continuous mannei Each vessel is separated by lotary locks and each vessel has a discrete conveyor mechanism A suitable appai atus is depicted in Figure 2 <br><br>
The apparatus shown in Figure 2 employs open conveyor belts however it is to be understood that screw conveyor(s) could be used as an 25 alternative <br><br>
The components (3)-(6) (9) and (10) shown in Figure 2 are as described in Example 1 <br><br>
"WO 96/36237 <br><br>
PCT/AU96/00305 <br><br>
EXAMPLE 3 - Preliminary Tests <br><br>
Test A <br><br>
Aim <br><br>
To assess the potential of applying heat to herbs and spices to reduce 5 the microbial bioburden Method <br><br>
Target Material Basil <br><br>
Whole peppercorns both with known high bacterial bioburden 10 (greater than 10H cfu/gram) <br><br>
Equipment <br><br>
A device was constructed foi these trials which consisted of a plastic pressure tank from a garden spray with a volume of approx 3 litres This was chosen so that it had adequate stiength to allow for the pressures The 15 pressure entry port was modified by the installation of a car tyre valve A screw down O-ring sealed inlet port was present nonnally for the addition of spray and water Also piesent was a safety pressure release valve which was strengthened appropriately <br><br>
The device, which appeared to be made from natural high or 20 ultrahigh density polyethylene or similar plastic, was tested at pressures gieater than intended to be reached in the test and found to withstand in excess of 3 Bar even when heated <br><br>
Heating was effected in a 750 Watt domestic microwave oven equipped with a rotating caiousel This was adapted to hold the plastic 25 vessel which was microwave transparent and did not heat appreciably when exposed to microwave energy on its own It was found that if it was loaded with approx 15inl of water and exposed for 5 minutes at 2 Bar overpressure all contact surfaces were sterilised and then the vessel could be dried out with the continuation of the heating at atmospheric pressure This piocess 30 was employed before each new trial. <br><br>
^ WO 96/36237 <br><br>
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PCT/AU96/00305 <br><br>
To overcome some initial uneveness of heating a system was devised to tilt the vessel as it was iota ted by the cai ousel, thus mixing the target mateual during exposure Exposures: <br><br>
times and microwave powers and the temperatures achieved were taken with an electronic thermometer equipped with a fast response thermocouple <br><br>
This was repeated with 1 and 2 Bar overpiessure generated with 10 conipiessed air and read by an external pressure gauge to assess the effect of attained pressure on the tempeiatures achieved by varying the times and microwave power <br><br>
From this data a range of exposuies were chosen so that a spectrum of attained temperatures ranging from 70 to 140 deg C could be predicted 15 and duplicate exposures of each target material were made with 1 and 2 Bar compressed air overpressure This was released immediately after the exposure was completed Results <br><br>
5 <br><br>
100 gram samples of each target material was exposed to varying <br><br>
20 <br><br>
Observations - condensation was present but minimal <br><br>
-a noticeable volatile aroma was present on release of the overpressure <br><br>
Target Matenal <br><br>
25 <br><br>
- loss of at least 30% of the oiganoleptic properties of the matenal was estimated Particularly efiected were the high flavour notes and after taste <br><br>
Microbiological Analyses <br><br>
30 <br><br>
- Reduction in microbial bioburden paralleled time and temperature with greater than 6 log reductions in Standard Plate Count achieved by the longer times and temperatures employed <br><br>
^ WO 96/36237 <br><br>
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PCT/AU96/00305 <br><br>
Conclusions <br><br>
Significant reductions in microbial counts were observed, easily achieving product pasteurisation and commercial sterility. <br><br>
10 <br><br>
15 <br><br>
Target Material Equipment <br><br>
Test B Aim <br><br>
To develop a means of preventing the loss of volatiles during heating of the herbs and spices by the use of protective cooling and overpressure Method <br><br>
As for Test A <br><br>
As for Test Abut employing overpressuie generated from bottled compressed food grade carbon dioxide contiolled by a regulator This was then used to assist with cooling, while maintaining the overpressure, after the target material had been exposed to heat Additional cooling was piovided by immersing the vessel in an ice bath Exposures As for Test A <br><br>
2 0 Results <br><br>
Observations - condensation was maikedly reduced as was the volatile aroma Target Material - the material was now colour fast <br><br>
- theie was a considerable reduction m the 25 organoleptic profiles <br><br>
Microbiological Analyses <br><br>
- Not significantly different from Test A <br><br>
Conclusions <br><br>
Without losing microbial effect a definite improvement in the <br><br>
3 0 condition and functionality of the materials were seen following treatment. <br><br>
WO 96/36237 <br><br>
PCT/AU96/00305 <br><br>
10 <br><br>
30 712 7 <br><br>
While this was thought to be of some value means by which the losses of volatiles could be further reduced were sought <br><br>
10 <br><br>
TestC Aim <br><br>
To further enhance the reduction of volatile loss by the use of a piecooling -tep in the process Method <br><br>
Target Matenal Equipment <br><br>
Exposures <br><br>
As for Test A <br><br>
As for Tests A and B plus either, <br><br>
- piecooling with carbon dioxide sparging (-70 deg C) in the vessel, or <br><br>
- immersion in liquid nitrogen (-170 deg. C) As foi Tests A and B <br><br>
15 Results <br><br>
Observations Target Material <br><br>
- As forTest B <br><br>
- no discernible loss in volatiles or functionality weie detectable bv organoleptic evaluation for either means of piecooling <br><br>
20 Microbiological Analyses <br><br>
- ieductions m miciobial bioburden of greatei than 7, approaching 8 log in the case of the mtiogen precooled material <br><br>
Conclusions <br><br>
25 The aim of achieving a commercially significant reduction in the loss of organoleptic functionality of herbs and spices while maintaining reductions in the microbial bioburden was achieved <br><br>
30 <br><br>
WO 96/36237 PCT/AU96/00305 <br><br>
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