GB2458739A

GB2458739A - A method of ultrasonic treatment of a medium

Info

Publication number: GB2458739A
Application number: GB0816367A
Authority: GB
Inventors: Howard Malcolm Read; Philip John Slapp
Original assignee: SONIWAVE Ltd
Current assignee: SONIWAVE Ltd
Priority date: 2008-03-31
Filing date: 2008-09-08
Publication date: 2009-10-07
Anticipated expiration: 2028-09-08
Also published as: GB2458739B; GB0805800D0; GB0816367D0; GB0806177D0

Abstract

A method of treatment of a medium using sound waves of ultrasonic frequency, and an apparatus for performing said treatment 1, is disclosed. The apparatus 1, which comprises an ultrasonic generator 7 and ultrasonic transducers (22, 23 figure 3) located in abutment with a container wall (24, figure 3), may include a heat exchanger 3, 4. The treatment may be applied to a liquid and/or solid foodstuff, optionally placed in a flavoured liquid, and optionally subjected to agitation further to that generated by the ultrasonic waves. The apparatus may comprise a chiller 8 for subsequent cooling of the foodstuff. The ultrasonic transducers (22, 23 figure 3) may be positioned in a 'V' shaped arrangement.

Description

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METHODS OF TREATMENT OF MEDIUM AND/OR LIOUID AND/OR SOLID

FOODSTUFF AND ULTRASONIC PROCESSOR

Field of the Invention

The invention relates to methods of treatment of medium and/or liquid and/or solid 2o foodstuff as well as ultrasonic processors.

Background to the Invention

In the text book entitled Food Engineering Operations published in 1976 by Applied Science Publishers Ltd, London, the use of ultrasonic cleaning is discussed for effecting the loosening of contaminants e.g. grit in vegetables, grease or wax on fruits or dirt on eggs. Once the ultrasonic cleaning method is completed, the contaminants are removed by conventional methods. Generally ultrasonic frequencies are above 16 kllz. Insonation of a fluid such as water with ultrasonic waves at frequencies of 20 to 100 kIlz produces a rapidly alternating pressure in the path of the waves which leads to the rapid formation and collapse of bubbles in the fluid. These effects are called cavitation and decavitation respectively which cause the release of energy in the system leading to the violent agitation of particles immersed in the fluid.

As far as the Applicant(s) is/are aware insonation (the use of ultrasonics) is used for other purposes as well such as measurement of vessels and testing apparatus.

S In the field of ready to eat ready meals, the manufacturer fully cooks the product through conventional heat exchangers such as an oven prior to chilling the product and transporting it to its point of sale.

Cuffently, legislation and manufacturers constantly strive to eliminate as far as possible food-borne bacteria such as Escherichia Coli. Manufacturers tend to tarnish the quality of food products by overcooking. This problem is compounded by the consumer who, having bought a ready-meal prepared to today's stringent standards, often simply recooks the food which even further damages the food prior to consumption.

is The following prior art documents are acknowledged: DE 2950384, US 6233844, US4464401, JP59055 175, US2002040643, and US 3846565.

Summary of the Invention

In a first broad independent aspect, the invention provides a method of treatment of liquid and/or solid foodstuff comprising the steps of: * submitting said foodstuff to a container; * employing a heat exchanger to control the temperature level of said foodstuff; * generating ultrasonic sound waves; and * focusing ultrasonic sound waves onto said foodstuff; whereby said foodstuff may be heated.

This method is particularly advantageous because it allows the achievable shelf life of produce to be increased. This benefit is particularly applicable to raw meat products which require cooking above a certain level to reduce or eliminate the presence of microbiological bacteria. This method may also simply allow minimal processing of foodstuff to reduce the loadings of pathogens and bacteria to either produce ready to eat foods or allowing longer shelf lives due to reduced loads.

This method is also particularly advantageous because it reduces the heating level required to meet food safety levels. In particular, it reduces the risk of potentially cooking meat or other such produce twice. It also improves the overall tenderness of the produce in a similar manner as meat which has been steamed. In addition, this method improves the penetration of sauce, marinade, stock, brine or any other appropriate flavour bearing liquid into solid foods such as meat.

In summary, it allows food to be heat treated at a temperature below conventional heat treatment levels whilst meeting stringent food safety requirements and improving flavour and texture properties.

In a subsidiary aspect, the method comprises the steps of placing said foodstuff in a flavoured liquid solution which is itself exposed to the ultrasound waves and through which said sound waves are transferred onto said foodstuff. This configuration is particularly advantageous in order to cause a flavour to penetrate the foodstuff in an improved manner and at a greater speed when compared to prior art heat treating methods.

2o In a further subsidiary aspect, the method comprises the step of cooling heated foodstuff in a chiller and extracting heat from said foodstuff and transferring said heat to contribute to the heating of said foodstuff. This configuration reduces the overall energy requirement.

In a further subsidiary aspect, the step of heating said foodstuff to a temperature between and 60 degrees Celsius may be provided. At these temperatures, the combination of heating and the ultrasonic treatment causes food-borne bacteria such as E. Coli or even viruses to be eliminated or virtually eliminated so as to meet the stringent safety requirements.

This approach also reduces the overall power consumption which has secondary advantages for the environment and in terms of cost reduction.

In a further subsidiary aspect, the method comprises the step of agitating said solution and/or said foodstuff in addition to any agitation caused by said ultrasonic sound waves.

This allows the sound waves as well as the heat to deeply penetrate the foodstuff for improved uniform heating at lower temperatures.

In a second broad independent aspect, the invention provides an ultrasonic processor for treating liquid and/or solid foodstuff comprising a container into which said foodstuff is placed; a heat exchanger for controlling the temperature level of said foodstuff; and an ultrasonic transducer which is located in sufficient proximity to said foodstuff for ultrasonic sound waves to be transferred onto said foodstuff.

This configuration is particularly advantageous because it results in produce of a microbiological safe standard whilst the foodstuff undergoes a heat treatment which would be below the usual temperature required in the conventional cooking field of preparing ready meals. The produce of the cooker would also achieve a tenderness level comparable to steamed produce. This would also achieve an increased shelf life for produce. The produce will lend itself to cooking by the consumer without resulting in dry overcooked and therefore undesirable produce. The cooker avoids potentially cooking the

meat or other foodstuff twice as in the prior art.

In a subsidiary aspect in accordance with the invention's second broad independent aspect, the container incorporates a jacket through which the heat medium circulates to exchange heat with the container and a foodstuff receiving cavity; said transducer being a piezo-electric transducer located against the inner wall of the jacket to transfer ultrasonic sound waves through said inner wall and into the foodstuff receiving cavity of the container.

This configuration is particularly advantageous because the transducer may be accurately controlled. Furthermore, if means for controlling sound emissions are provided, these may monitor the sound levels and readily adjust the vibration of the transducer to control sound emissions.

In a further subsidiary aspect, the processor comprises an agitator for agitating said foodstuff. This configuration is particularly advantageous because it allows the processor to achieve a uniform degree of temperature spread throughout the foodstuff.

In a subsidiary aspect, the processor operates in conjunction with a chiller and means for transferring heat from the chiller to said heat exchanger are provided. This reduces the overall energy requirement of the combination of the ultrasonic processor and the chiller.

In a further subsidiary aspect, the transducers are driven by an ultrasonic generator located remotely from said container. This allows the generator components to be at a lower temperature than the temperature of the processor.

Brief Description of the Figures

Figure 1 shows a perspective view of an ultrasonic cooker associated with a cooling tank.

Figure 2 shows a prospective view of an ultrasonic tank cooker with its lid open in accordance with a second embodiment of the invention.

2o Figure 3 shows a cross-sectional view of the cooker in accordance with a third embodiment of the invention.

Detailed Description of the Figures

Figure 1 shows an ultrasonic processor in the form of a cooker generally referenced 1 with a tank 2 and an inner cavity (see figure 3) for receiving foodstuff. Transducers are located in the lower part of the tank in abutment against the inner wall (see figure 3) of the tank in order to transfer ultrasonic sound waves through said inner wall and into the foodstuff receiving cavity of the container. The sound waves are selected to generate heat in order to treat the foodstuff. When the foodstuff is solid, for example one or more pieces of meat, it is envisaged that a liquid solution is provided between the solid foodstuff and the inner wall in order to allow the transfer of the waves to the fluid which then creates the rapid formation and collapse of bubbles. This release of energy in the system causes violent agitation of particles to kill bacteria and contribute or carry out the entire heat treatment of the food. The foodstuff is preferably directly exposed to the sound waves i.e. no packaging is therefore provided.

The tank may be of stainless steel of a food quality grade. The tank may incorporate a heating medium jacket around the outside of the food receiving cavity in which a heating medium circulates. An inlet 3 and an outlet 4 for the heating medium are provided which are illustrated as projecting laterally from the jacket. A drain at the bottom of the tank is also envisaged to empty its contents (not shown in figure 1). In addition, a sound sensor may be incorporated into or in the vicinity of the tank in order to assess sound emissions and to control the frequency of the ultrasonic transducers if the levels of emissions go beyond predetermined values. The heating medium may be circulated through the jacket and controlled in order to maintain the temperature at an optimum operational temperature such as 50 degrees Celsius. In certain circumstances, the heating medium may either remove heat when it acts as a cooler or heat when acting as a secondary heater. In one embodiment, it is therefore envisaged for the heat treatment to result only from the ultrasonic soundwaves.

In operation, the tank is filled with a liquid solution when the foodstuff is primarily solid.

2o The liquid temperature is preferably within the range of 30 degrees Celsius and 60 degrees Celsius. In addition to the sound sensor, a temperature sensor is envisaged to accurately monitor and then adjust, if necessary, the temperature of the cooker. The solution into which solid food is immersed when the foodstuff consists of a mixture of solid and liquid may simply be water or any appropriate flavoured liquid for improved penetration of flavour into the foodstuff.

In practice the foodstuff may be weighed and then fed through hopper 5 into the heating cavity. Current may be supplied from an ultrasonic generator 7 to the ultrasonic transducers through a wire 6. It is envisaged that the ultrasonic transducers are preferably o energised for a period of time between 5 and 45 minutes depending upon the foodstuff being heat treated. In addition, it is envisaged that a mechanical agitator (not shown in the figures) is employed and fitted to the tank to agitate the foodstuff to achieve a substantially equal distribution of heat. Once the fluid has undergone heat treatment, mechanically driven augers or other appropriate means such as a conveyor or even a flow pipe displace the foodstuff through the sonicated medium inside the tank at an appropriate rate dependent upon the foodstuff which is being heat treated. When the desired time in the medium has been reached, the product is then elevated mechanically to a second tank 8 through auger 9. The foodstuff is then cooled in tank 8.

The cooling tank 8 also comprises a jacket in which cooling liquid circulates which is either connected to a chiller or redirected to preheat the heating medium of tank 2 thus saving energy.

The foodstuff having reached its desired chilled temperature is then elevated from the tank through an auger 10 or any other appropriate transporting means to a temperature controlled area for further processing such as packaging.

Figure 2 shows an ultrasonic tank 11 with an upper lid 12 hinged onto tank 11 through hinges 13 and 14. A cavity 15 is shown which is of suitable size for receiving foodstuff.

An inlet and an outlet 16 and 17 project outwards from the tank and are suitable for connection to a liquid heater/cooler. A pump (not shown in the figures) may be provided to cireulate the liquid through the tank. The heated liquid would circulate in an outwardly located jacket thus acting as the necessary means to transfer heat to the produce located in the cavity. The tank also is provided with a drain 18 located on the same face of the tank as the inlet and outlet. Ultrasonic transducers would be located in the bottom of the tank 11 in sufficient proximity to the liquid in the cavity or directly exposed to the liquid in the cavity to transmit sound waves into the liquid. An ultrasonic generator 19 is provided at a remote location from the tank but in communication with the transducers in the tank through a wire 20.

Figure 3 shows the cross-section of a tank generally referenced 21 with transducers 22 and 23 located against or as part of an inner wall 24 of tank 21. In this embodiment, the transducers are located on either side of a V-shaped bottom portion of the foodstuff containing cavity 25. Liquid circulates in the jacket 26 of the tank or directly in the foodstuff receiving cavity in order to heat the content of the cooker.

The power level for the ultrasonic processor is preferably between 15 and 200 Watts per litre.

Claims

CLAIMS1. A method of treatment of a medium comprising the steps of: * obtaining medium from a laboratory container; * submitting said medium to a container of an ultrasonic processor; * generating ultrasonic sound waves; and * focusing ultrasonic sound waves onto said medium.
2. A method of treatment of liquid and/or solid foodstuff comprising the steps of: * Submitting said foodstuff to a container; * Employing a heat exchanger to control the temperature level of said foodstuff; * Generating ultrasonic sound waves; and is * Focusing ultrasonic sound waves onto said foodstuff.
3. A method according to claim 2, comprising the steps of placing said foodstuff in a flavoured liquid solution which is itself exposed to the ultrasonic sound waves and through which said sound waves are transferred onto said foodstuff.
4. A method according to either of the preceding claims, comprising the step of cooling heated foodstuff in a chiller and extracting heat from said foodstuff and transferring said heat to contribute to the heating of said foodstuff.
5. A method according to any of the preceding claims, comprising the step of heating said medium or said foodstuff to a temperature between 30 and 60 degrees Celsius.
6. A method according to any of claims 1 to 5, comprising the step of agitating said medium and/or said foodstuff in addition to any agitation caused by said ultrasonic sound waves.
7. A method according to any of claims 2 to 6, wherein said foodstuff is selected without any packaging and submitted directly to said treatment.
8. An ultrasonic processor for treating medium and/or liquid and/or solid foodstuff comprising a container into which said medium and/or foodstuff is placed and/or transferred; a heat exchanger for controlling the temperature of said medium and/or foodstuff; and an ultrasonic transducer which is located in sufficient proximity to said medium and/or said foodstuff for ultrasonic sound waves to be transferred onto said foodstuff.
9. An ultrasonic processor according to claim 8, wherein said container incorporates a V-shaped base wall with ultrasonic transducers located on both sides of the V.
10. An ultrasonic processor according to either of claims 8 and 9, wherein the container incorporates a jacket through which heated medium circulates to heat the container and a medium and/or foodstuff receiving cavity; said transducer being a piezo-electric transducer located against the inner wall of said jacket to transfer ultrasonic sound waves through said inner wall and into the medium and/or foodstuff receiving cavity of the container.
11. An ultrasonic processor according to any of claims 8 to 10, comprising an agitator for agitating said medium and/or foodstuff.
12. An ultrasonic processor according to any of claims 8 to 11, operating in conjunction with a chiller and means for transferring heat from the chiller to said heat exchanger.
13. An ultrasonic processor according to any of claims 8 to 12, wherein the transducers are driven by an ultrasonic generator located remotely from said container.
14. An ultrasonic processor according to any of claims 8 to 13, further comprising a duct for transferring medium from a culture dish to said container.
15. An ultrasonic processor according to any of claims 8 to 14, wherein said medium is a mixture of gel and a liquid.
16. A method of treatment of liquid and/or solid foodstuff substantially as hereinbefore described and/or illustrated with reference to any appropriate combination of the accompanying text and/or drawings.
17. An ultrasonic processor substantially as hereinbefore described and/or illustrated with reference to any appropriate combination of the accompanying text and/or drawings. l2Amendment to the claims have been filed as follows I. A method of treatment of a medium comprising the steps of: * submitting said medium to a container of an ultrasonic processor; said container comprising an inner wall and transducers located in abutment against said wall; * generating ultrasonic sound waves as said transducers act against said wall; and * focusing ultrasonic sound waves onto said medium.2. A method of treatment of liquid and/or solid foodstuff comprising the steps of: * submitting said foodstuff to a container of an ultrasonic process; said container comprising an inner wall and transducers located in abutment against said wall; * employing a heat exchanger to control the temperature level of said foodstuff; * generating ultrasonic sound waves as said transducers act against said wall; and * focusing ultrasonic sound waves onto said foodstuff.3. A method according to claim 2, comprising the steps of placing said foodstuff in a flavoured liquid solution which is itself exposed to the ultrasonic sound waves and through which said sound waves are transferred onto said foodstuff.4. A method according to either claim 2 or claim 3, comprising the step of cooling heated foodstuff in a chiller and extracting heat from said foodstuff and transferring said heat to contribute to the heating of said foodstuff. S... S...* 5. A method according to any of the preceding claims, comprising the step of heating said *:*. medium or said foodstuff to a temperature between 30 and 60 degrees Celsius.6. A method according to any of claims 1 to 5, comprising the step of agitating said medium and/or said foodstuff in addition to any agitation caused by said ultrasonic sound waves.7. A method according to any of claims 2 to 6, wherein said foodstuff is selected without any packaging and submitted directly to said treatment.8. An ultrasonic processor for treating medium and/or liquid and/or solid foodstuff comprising a container into which said medium and/or foodstuff is placed and/or transferred; a heat exchanger for controlling the temperature of said medium and/or foodstuff; and an ultrasonic transducer which is located in abutment against the inner wall of said container; whereby ultrasonic sound waves are transferred onto said medium and/or foodstuff.9. An ultrasonic processor according to claim 8, wherein said container incorporates a V-shaped inner wall with ultrasonic transducers located on both sides of the V. 10. An ultrasonic processor according to either of claims 8 and 9, wherein the container incorporates a jacket through which heated medium circulates to heat the container and a medium and/or foodstuff receiving cavity; said transducer being a piezo-electric transducer located against the inner wall of said jacket to transfer ultrasonic sound waves through said inner wall and into the medium and/or foodstuff receiving cavity of the container.11. An ultrasonic processor according to any of claims 8 to 10, comprising an agitator for agitating said medium and/or foodstuff.12. An ultrasonic processor according to any of claims 8 to 11, operating in conjunction with a chiller and means for transferring heat from the chiller to said heat exchanger.. :13. An ultrasonic processor according to any of claims 8 to 12, wherein the transducers are S...driven by an ultrasonic generator located remotely from said container. *..SS S...* ....14. An ultrasonic processor according to any of claims 8 to 13, further comprising a duct for S...transferring medium from a culture dish to said container. * S * * .* **...I5. An ultrasonic processor according to any of claims 8 to 14, wherein said medium is a mixture of gel arid a liquid.16. A method of treatment of liquid and/or solid foodstuff substantially as hereinbefore described and/or illustrated with reference to any appropriate combination of the accompanying text and/or drawings.17. An ultrasonic processor substantially as hereinbefore described and/or illustrated with reference to any appropriate combination of the accompanying text and/or drawings. S... * . *S *S.. * I I... *SII S... S... * S *S.. S. S * . . * .. S...S S...