AU2015208412B2 - Method and device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants - Google Patents
Method and device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants Download PDFInfo
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- AU2015208412B2 AU2015208412B2 AU2015208412A AU2015208412A AU2015208412B2 AU 2015208412 B2 AU2015208412 B2 AU 2015208412B2 AU 2015208412 A AU2015208412 A AU 2015208412A AU 2015208412 A AU2015208412 A AU 2015208412A AU 2015208412 B2 AU2015208412 B2 AU 2015208412B2
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
- A23C3/00—Preservation of milk or milk preparations
- A23C3/02—Preservation of milk or milk preparations by heating
- A23C3/03—Preservation of milk or milk preparations by heating the materials being loose unpacked
- A23C3/033—Preservation of milk or milk preparations by heating the materials being loose unpacked and progressively transported through the apparatus
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D19/00—Degasification of liquids
- B01D19/0036—Flash degasification
Abstract
The invention relates to a method and a device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants, in which untreated milk or the fractions thereof, cream and skimmed milk (M), that has/have not undergone heating to a high temperature to deactivate thermophilic bacteria is/are subjected in this state to a thermal treatment in a further treatment process in a recuperative heat exchanger, at least in a temperature range of 50°C to 70°C, wherein the optimum temperature (Top) for the optimal growth of the thermophilic bacteria lies in a temperature range of 63°C to 68°C (63°C < Top < 68°C). The method according to the invention and the device for carrying it out ensure an increase in the lifetime of the recuperative heat exchangers that are exposed to untreated milk or the fractions thereof (cream and skimmed milk) and are in particular operated regeneratively. This is achieved by a method in which, before its thermal treatment, which is performed • either in the region of the optimum temperature (Top) • or when passing through the region of the optimum temperature (Top) in one direction or the other, the non-deaerated skimmed milk (M) provided in the treatment process undergoes deaeration and thereby becomes deaerated skimmed milk (M*).
Description
The invention relates to a method and a device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants, in which untreated milk or the fractions thereof, cream and skimmed milk (M), that has/have not undergone heating to a high temperature to deactivate thermophilic bacteria is/are subjected in this state to a thermal treatment in a further treatment process in a recuperative heat exchanger, at least in a temperature range of 50°C to 70°C, wherein the optimum temperature (Top) for the optimal growth of the thermophilic bacteria lies in a temperature range of 63°C to 68°C (63°C < Top < 68°C). The method according to the invention and the device for carrying it out ensure an increase in the lifetime of the recuperative heat exchangers that are exposed to untreated milk or the fractions thereof (cream and skimmed milk) and are in particular operated regeneratively. This is achieved by a method in which, before its thermal treatment, which is performed · either in the region of the optimum temperature (Top) · or when passing through the region of the optimum temperature (Top) in one direction or the other, the non-deaerated skimmed milk (M) provided in the treatment process undergoes deaeration and thereby becomes deaerated skimmed milk (M*).
(57) Zusammenfassung:
[Fortsetzung auf der nachsten Seite]
WO 2015/110258 Al llllllllllllllllllllllllllllllllllllllllllllllllll^
CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG).
Erklarungen gemaB Regel 4.17:
— Erfindererklarung (Regel 4.17 Ziffer iv)
Veroffentlicht:
— mit internationalem Recherchenbericht (Artikel 21 Absatz 3) — mit geanderten Anspriichen und Erklarung gemass Artikel 19 Absatz 1
Die Erfindung betrifft ein Verfahren und eine Vorrichtung zur Reduzierung des Wachstums thermophiler Keime in Warmeaustauschem molkereitechnischer Prozessanlagen, bei denen Rohmilch oder deren Fraktionen Rahm und Magermilch (M), die keiner Hocherhitzung zur Inaktivierung thermophiler Keime unterzogen wurde/wurden, in diesem Zustand in einem weiteren Behandlungsprozess eine thermische Behandlung in einem rekuperativen Warmeaustauscher wenigstens in einem Temperaturbereich von 50 °C bis 70 °C erfahrt/erfahren, wobei das Temperaturoptimum (Top) zum optimalen Wachstum der thermophilen Keime in einem Temperaturbereich von 63 °C bis 68 °C (63 °C < Top < 68 °C) liegt. Das erfmdungsgemafie Verfahren und die Vorrichtung zu seiner Durchfuhrung stellen sicher, dass die Standzeit der mit Rohmilch oder deren Fraktionen (Rahm und Magermilch) beaufschlagten rekuperativen Warmaustauscher, insbesondere der regenerativ betriebenen, erhoht wird. Dies wird durch ein Verfahren erreicht, bei dem die in dem Behandlungsprozess bereitgestellte nicht entgaste Magermilch (M) vor ihrer thermischen Behandlung, die · entweder im Bereich des Temperaturoptimums (Top) · oder beim Durchlaufen des Bereichs des Temperaturoptimums (Top) in der einen oder der anderen Richtung erfolgt, einer Entgasung unterzogen und dadurch zu einer entgasten Magermilch (M*) wird.
2015208412 19 Apr 2018
Method and device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants
TECHNICAL FIELD
The invention relates to a method for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants, wherein the optimum temperature for the optimal growth of the thermophilic bacteria lies in a temperature range of 63 °C to 68 °C. Indirect heat transfer occurs in a recuperative heat exchanger, between two substance flows separated by a diathermic wall. The skimmed milk may, for example, be milk produced in a processing room of a dairy processing plant downstream of a separator to separate untreated milk into cream and skimmed milk, that is subsequently passed to another processing step with or without heat treatment, or that is passed into an evaporator after being stored in a storage tank and cooled to storage temperature. The reduction of the growth of thermophilic bacteria and thereby the reduction of thermophilic bacteria per se in the original skimmed milk does affect the bacterial content significantly in the downstream skimmed milk products.
BACKGROUND OF THE INVENTION
In heat exchangers in dairy processing plants, irrespective of the design as either plate or pipe heat exchangers, thermophilic microorganisms or bacteria from the untreated milk or fractions thereof (skimmed milk and cream) that were not subjected to heat treatment and therefore not inactivated, or the metabolic products of these bacteria can adhere to the surface and form what is known as a biofilm. This biofilm is most prevalent in a heat exchanger, particularly in a regeneratively operated one, where the milk is generally thermally treated in a temperature range of approximately 50 °C to 70 °C. At temperatures over 50 °C, while pathogenic bacteria can no longer grow, the pathogens mentioned above can, i.e. the thermophilic microorganisms and bacteria. Hereinafter the term thermophilic bacteria will largely be used for thermophilic microorganisms or bacteria. Thermophilic bacteria use a temperature range of approximately 40°C to 80 °C, while the temperature range for optimum growth of thermophilic bacteria is in a range of approximately 63 °C to 68 °C (known as the optimum temperature, i.e. the most favourable growth temperature (optimum)) (see for example mikrobiol.de/Teil A (103-104) HO). As well as this optimum temperature, there must also be sufficient nutrients and oxygen for growth.
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During operational lifetime of the heat exchanger, its so-called service life between two adjacent cleaning cycles (CIP cleaning), based on a bacterial count of 5xl02 CFU/ml in the advance line to the heat exchanger, there can be an increase in the heat exchanger itself to considerably more than 4xl05 CFU/ml after 4 to 6 hours (note: CFU stands for colony-forming units). This increase can result from accretions in the low-flow areas of the heat exchanger. It can be assumed that this is the case in most heat exchangers of the kind addressed here. The content of thermophilic bacteria is relatively even in untreated milk in Germany. Tests at two dairies showed bacterial counts in each of approximately 200 to 600 CFU/ml.
If the skimmed milk is added to a concentration in evaporation plants, the proportion of organic acids that are formed by the metabolism of thermophilic bacteria and that form the biofilm is inevitably concentrated. When the pH in the concentrate is reduced to 6.20, the end of the service life is reached and the evaporation units have to be cleaned. Plants that process the milk further, such as cheese dairies or milk drying plants otherwise will run into technological difficulties as the concentrate is no longer marketable. In part, bacterial levels of under 2xl05 CFU/ml are required in the specifications for the skimmed milk concentrates.
This cannot be achieved with the current production conditions.
DE 10 2005 015 713 Al describes a method to deaerate and maintain a continuous volume flow of a milk to be treated in an ultra-high-temperature (UHT) plant with indirect heating (recuperative heating in heat exchangers) and an integrated separator for the milk fat standardisation and an interim storage of a (standardised) milk leaving the arrangement comprising a separator. The method is characterised among other things by the fact that the volume flow is continuously treated as described in steps a) to d) below in an arrangement with a deaerating and storing unit downstream of the arrangement comprising a separator, whereby
a) the volume flow generates a point symmetric film flow which when viewed from a radial perspective flows from the inside to the outside, initially horizontally and then radiating downwards,
b) the film flow is generated at the level of one surface of a storage volume in the deaerating and storing unit and then layered on this surface,
c) a piston flow evenly distributed transversely across the storage volume is generated in the storage volume oriented against gas bubble buoyancy
d) the volume flow is obtained from the storage capacity centrally at the lower end.
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The known method deaerates milk standardised according to its fat content, which is then transferred to a UHT plant. Standardised milk is defined as milk with a predefined fat content. It has been demonstrated that an air content of less than 8 mg atmospheric oxygen/dm3 milk has a favourable effect on the service life for the heat exchangers in these UHT plants with indirect heating. Above a threshold value for this there is an increased risk of burning, particularly in heat exchangers of the heating zone and heat retention units, whereby the service life of these heat exchangers is significantly reduced.
The defined object of the method described in DE 10 2007 037 941 Al is the avoidance of burning, particularly in heat exchangers in the heating zone and heat retention unit of UHT plants, by reducing the air content to below 8 mg atmospheric oxygen/dm3 milk.
According to a preferred design, this is characterised by a liquid product, particularly a liquid food such as cheese milk, cream or UHT milk, namely in form of a total flow of a gas-loaded product is fed to an inlet of a distributor pipe. In the distributor pipe, the gas-loaded product is transformed or respectively branched into at least one forced partial flow; the partial flow(s) is(are) transported against gravity into a gas discharging collection chamber, and after the flow direction is changed is(are) transformed into film flows radiating with the force of gravity with a free surface in the direction of the collecting chamber. The partial flows that are respectively generated by the film flows of a product to be deaerated are deaerated by separating the gas bubbles in the gravity field of the earth, and subsequently collected and supplied as a total flow of the deaerated product to an outlet of the collecting chamber.
WO 2006/011 801 Al describes a method for conditioning particularly the oxygen content in pasteurised milk or pasteurised milk products, wherein improved microbiological quality, improved physical and / or chemical stability of the respective product is envisaged. This prior art does not go beyond the prior art, which has been recognized above. The inhibition of thermophilic bacteria in skimmed milk with the object of inhibiting the growth rate of the biofilm formed by these bacteria in recuperative heat exchangers, particularly in heat exchangers operated regeneratively, is not disclosed or suggested.
The content of air or atmospheric oxygen and other gas admixtures in untreated milk, cheese milk (vat milk), cream or UHT milk and the need to reduce these gas admixtures was and is given special attention, because the reduction serves to optimise the quality and the above-mentioned negative effects are evident. The number of thermophilic bacteria in dairy products so far played a minor role and was therefore not considered from a technical perspective. In future, this bioburden will
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018 certainly be quantified between users and will become a part of the quality reports for the traded products. In this context, the level of thermophilic bacteria in skimmed milk is of particular importance. In this regard, the relationship between the results for the content of thermophilic bacteria from the untreated milk in skimmed milk and the negative impact of these bacteria on the formation of a biofilm in primarily renewably powered heat exchangers in the non-boiling zone of processing plants (reduction of service life) has so far not been recognized or at least not taken into account, and therefore there have also been no effective solutions to date.
The object of the present invention is to create a method of the generic type, so that the service life of recuperative heat exchangers that come into contact with untreated milk or fractions thereof (cream and skimmed milk), particularly if they are regeneratively powered, is increased.
SUMMARY OF THE INVENTION
In one aspect, there is provided a method to reduce the growth of thermophilic bacteria in heat exchangers of dairy processing plants in which non-deaerated skimmed milk (M) that has not undergone heating to a high temperature to deactivate thermophilic bacteria is subjected in this state to a thermal treatment in a further treatment process in a recuperative heat exchanger, at least in a temperature range of 50 °C to 70°C, wherein the optimum temperature (Top) for the optimal growth of the thermophilic bacteria lies in a temperature range of 63 °Cto 68 °C, wherein before its thermal treatment, which is performed • either in the optimum temperature range (Top) • or when passing through the optimum temperature range (Top) to a temperature above the same, the non-deaerated skimmed milk (M) provided in the treatment process is subjected to deaeration and therefore becomes deaerated skimmed milk (M*).
In another aspect, there is provided a device for performing the method according to the above aspect, wherein the device is formed as a container, that has a central discharge pipe for the deaerated skimmed milk (M*) at its bottom end, that is penetrated concentrically by an advance pipe for the skimmed milk (M) to be deaerated engaging into the container from beneath, that the
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018 advance pipe forms a connection to a peripheral ring gap between a distributor screen and a baffle plate that is smaller than the distributor screen in terms of its flat dimensions and arranged concentrically and with a space above the distributor screen and with a space above the distributor screen and that the distributor screen extends horizontally transverse to the longitudinal axis of the container and subsequently extends radially downward sloping with gravitational force and ends outside at the same level as the level of the skimmed milk (M) to be deaerated in a storage volume in the container.
In another aspect, there is also provided the device for performing the method according to the above aspect, wherein the device comprises a collection chamber oriented in the direction of gravity that is delimited circumferentially by a container casing, on the base by a container base and at the headspace by a container lid, that at least one riser pipe is provided that penetrates the container base, extends into the container casing and terminates open, that there is provided a collection pipe opening from the collection space in the region of the container base that is connected with an outlet for an entire flow of the deaerated skimmed milk (M*), that a distributor pipe is provided that branches below the container base into the at least one riser pipe, that a gas pipe is provided into which the collection chamber in the region of the container lid opens, that the riser pipe is formed at its open end as an overflow edge, wherein a partial flow of the skimmed milk (M) to be deaerated fed to the riser pipe generates a film flow that spreads with gravitational force onto the exterior surface of the riser pipe and that has a free surface in the direction of the collecting chamber, that the riser pipe is designed in the shape of a pipe, that the overflow edge of the riser pipe generates a complete film flow on the exterior surface of the riser pipe, that a single riser pipe or more than one riser pipe arranged in a circular or matrix shape is/are provided in the first container casing, and that the distributor pipe is connected with an inlet for an entire flow of the skimmed milk (M) to be deaerated.
The fundamental solution concept of the invention assumes that up to now the relationship between the results of the content of thermophilic bacteria in skimmed milk and the negative impact of these bacteria on the formation of a biofilm (reduction of service life) in primarily renewably powered recuperative heat exchangers of the non-boiling zone of dairy processing plants (temperature range of approximately 50 ° C to 70 ° C) has not been recognized or at least has not been taken into consideration. The growth and in turn the increase in the content of thermophilic bacteria are both only possible by virtue of the available oxygen and the presence of nutrients in the substrate at the applicable optimum temperature for bacterial growth. As the presence of nutrients and the temperature conditions are inevitable in a dairy process, the only parameter that can change the
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018 speed of growth and thus limit the reproduction of thermophilic bacteria is a reduction in the oxygen content.
This is the approach the inventive solution takes, wherein the air oxygen content is reduced by sufficient deaeration of the skimmed milk. The solution is that the non-deaerated skimmed milk that is provided during the treatment process has not been subjected to high-temperature heating for inactivation of thermophilic bacteria, in a temperature range below 63 ° C, is subject to a deaeration and thereby becomes a deaerated skimmed milk. The deaerated skimmed milk undergoes a further treatment process in a thermal treatment in a recuperative heat exchanger, wherein the thermal treatment above 63 ° C.
As the thermophilic bacteria have a very short generation time with a high metabolic rate, they are also equally sensitive in terms of their speed of growth if oxygen is no longer available. The deaeration according to the invention allows sufficient deaerated skimmed milk into the heat exchanger and the thermophilic microorganisms or bacteria thus have insufficient oxygen as a necessary nutrient for their reproduction. This slows down the growth speed of the thermophilic microorganisms. As oxygen is or may be already encapsulated in the existing cells of the microorganisms and the process does not guarantee complete deaeration, one to two generations of growth are expected. The production of organic acids associated with the reproduction of the microorganisms only has a minor effect on the skimmed milk. Thus, the processing plant can be operated for longer while maintaining the necessary quality parameters, and the service life can be extended. The thermophilic bacterial count is maintained at a correspondingly low level and the development of a biofilm is inhibited.
An embodiment of the method provides that the thermal treatment of the deaerated skimmed milk lies in a temperature range of 63°C to 68°C (63°C < top < 68°C), the optimum temperature range defined for the optimum growth of thermophilic bacteria.
The method provides that the deaeration is performed at a deaeration temperature below the optimum temperature. This measure ensures that on the one hand the deaeration is supported by raising the deaeration temperature, and on the other hand the growth of the thermophilic bacteria remains inhibited during the deaeration process. The deaeration temperature is generally below 63 °C, while preferably a range between 53 °C and 58 °C is provided, with a preferred deaeration temperature of 55 °C.
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2015208412 19 Apr 2018
The method provides in an embodiment that the deaerated skimmed milk is added in its state after deaeration immediately after a treatment process subsequent to the deaeration. This process can be advantageous if during the course of the process the skimmed milk is at an optimum deaerating temperature and this temperature is used for deaerating, and this course of process does not provide for the skimmed milk to be cooled down to storage temperature with subsequent stacking at this storage temperature.
In all other cases it is expedient, as the method alternatively suggests, to use an optimum deaerating temperature for the deaerating which is first given in the course of the process or can be easily realised, and then to cool the deaerated skimmed milk down to a suitable storage temperature after deaerating, and to store it at this temperature. It has been shown to be appropriate if this temperature is between 8 °C and 15 °C.
Another advantageous embodiment of the method provides that deaerating is carried out for a period that can be freely adjusted to the needs of the deaerating process. This measure means virtually all separable gas components of the skimmed milk in the designated deaerating facility have the chance to separate within what is known as the mean dwell time (a parameter determined by the time) of the skimmed milk to be deaerated.
The method according to the invention can be carried out in two preferred, known per se devices, that are relatively simple in their design, and in which the mean dwell time of the skimmed milk to be deaerated is freely adjustable within limits.
The first device is designed as a container having a central discharge pipe for the deaerated skimmed milk at its bottom end, which is penetrated concentrically by an intake pipe for the skimmed milk to be deaerated engaging concentrically into the container from beneath. The intake pipe connects to a peripheral ring gap which is formed between a distributor screen and a baffle plate that is smaller than the distributor screen in terms of its flat dimensions and arranged concentrically and with a space above the distributor screen. The distributor screen extends horizontally transverse to the longitudinal axis of the container and subsequently extends radially downward sloping with gravitational force and ends outside at the same level as a level of the milk to be deaerated in a storage volume in the container.
The second device comprises a collection chamber oriented in the direction of gravity that is delimited circumferentially by a container casing, on the base by a container base and at the headspace by a container lid. At least one riser pipe is provided that penetrates the container base,
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018 extends into the container casing and terminates open. Furthermore, there are provided a collection pipe opening from the collection space in the region of the container base that is connected with an outlet for the entire flow of the deaerated milk, a distributor pipe that branches below the container base into at least one riser pipe and a gas pipe into which the collection chamber in the region of the container lid opens. The riser pipe is formed at its open end as an overflow edge, wherein a partial flow of the skimmed milk to be deaerated fed into the riser pipe generates a film flow that spreads with gravitational force onto the exterior surface of the riser pipe and that has a free surface in the direction of the collecting chamber. The riser pipe is designed in the shape of a pipe and the overflow edge of the riser pipe generates a complete film flow on the exterior surface of the riser pipe. A single riser pipe or more than one riser pipe are provided in a circular or matrix shape in the first container casing, and the distributor pipe is connected with an inlet for the entire flow of the skimmed milk to be deaerated.
The deaeration of the skimmed milk can be accelerated in both of the devices defined above, if a vacuum source is connected to the headspace of the device, which acts on the skimmed milk to be deaerated.
BRIEF DESCRIPTION OF THE DRAWINGS
A more detailed presentation of the results which can be achieved with the invention with a view to reducing the growth of thermophilic bacteria in a recuperative heat exchanger of a dairy processing plant is shown in the following description and the appended figures of the drawing and from the claims. The drawings show in:
Figure 1 is a schematic representation of a plant part of a dairy processing plant in which the effectiveness of deaerating according to the invention was investigated in skimmed milk and
Figure 2 is a diagram showing a selection of measurement results obtained in the part of the plant according to Figure 1, representing a dependence of the logarithmically presented thermophilic bacteria count in CFU/ml on the linear time shown in hours.
DESCRIPTION OF THE TEST ARRANGEMENT AND COMMENTING ON THE TEST RESULTS
Test arrangement
A plant part of an existing and real producing process plant 100 (Figure 1) is fed through an advance line 3 from a source SR for non-deaerated skimmed milk M or deaerated skimmed milk M*. This
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018 source SR may be a storage tank or a stacking container, the outlet from a heat exchanger or another process aggregate (e.g. a separator) of the processing plant or the outlet of a deaeration device. Correspondingly, the skimmed milk Μ, M* is fed into the advance line 3 at a storage temperature TS if it originates from the storage tank, at a processing temperature TP if it originates from a heat exchanger or process aggregate, or at a deaeration temperature TD if it originates from a deaeration device. From here the skimmed milk Μ, M* passes through a first pump 11 to a junction where the advance line 3 branches into a first and a second advance line section 4, 5. The first advance line section 4 leads to a regeneratively operated first heat exchanger 1 and the second advance line section 5 leads to a regeneratively operated second heat exchanger 2. The outlet of the first heat exchanger 1 on the product side is connected to a first return line section 6, and the outlet of the second heat exchanger 2 on the product side is connected to a second return line section 7. The first and second return line sections 6 and 7 open at a connection point in a return line 8, which leads into an area designated as target TR, which operates the process plant for further processing of the skimmed milk Μ, M*.
The first heat exchanger 1 is pressurized via a first heating circuit line 9 and a second pump 12 in counterflow to the first heat transfer medium, for instance with vapours VP, and the second heat exchanger 2 is pressurized via a second heating circuit line 10 and a third pump 13 in counterflow with a second heat transfer medium, for instance skimmed milk concentrate SMC. As the heat exchangers 1 and 2 are generally operated at different temperature levels, a desired mixed temperature can be set in the return line 8 by means of a control valve 16 arranged in the second return line section 7.
In the advance line 3 seen in the direction of flow, an initial sampling point 14 is provided upstream of the first pump 11, where a first sample Pl can be collected at a first sample temperature Tl. A second sample collection point 15 is arranged in the first return line section 6, where a second sample P2 can be taken at a second sample temperature T2.
Test results
The test results shown below were collected in an existing processing plant under the local severe operating environment and not in a laboratory. Measuring deviations or any measuring errors and scatter of the measuring results are unavoidable and should therefore be accepted. No measuring values collected in the context of the tests presented below were suppressed.
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The test results from tests 1.1 and 4.2 discussed below document the state of the art in terms of the growth of thermophilic bacteria in non-deaerated skimmed milk M by thermal treatment in a regenerative first heat exchanger 1. The content of thermophilic bacteria before and after the thermal treatment are recorded and documented as a result of sample collection Pl, P2 at the first and second sample collection points 14,15. Test 4.1 shows how the application of the method according to the invention affects the growth of thermophilic bacteria in deaerated skimmed milk M*.
Test 1.1 (temperatures TP = 15 °C and TS = 8 °C in advance line 3)
Test 1.1 (figure 2; label: curve with 1.1-V; listed in the legend as 1.1 advance - not deaerated) ran for a total of 13 hours and was operated over the entire test time with non-deaerated skimmed milk M. Up to the time t = 6 h, the non-deaerated skimmed milk M passes from a plate heat exchanger into the advance line 3 at a processing temperature TP of approximately 15 °C. After the time t = 6 h the non-deaerated skimmed milk M passes into the advance line 3 at a storage temperature TS of approximately 8 °C.
The curve 1.1-V shows the initial bacterial contamination (bacterial count CFU/ml) of the nondeaerated skimmed milk M fed into advance line 3 under the above conditions. The measuring results are from the first sample Pl of the first sample collection point 14 in the advance line 3. The measured values stagnate approximately in a range of t = 0 to 4 hours at 230 (minimum) to 420 CFU/ml (maximum) and then increase until t = 6 h to approximately 19,000 CFU/ml (first test section). At 19,000 (minimum) and 1,100,000 CFU/ml (maximum), the non-deaerated skimmed milk M added from the tank storage from the time t = 6 h to t = 13 h at TS = 8 °C (second test section) has a much higher bacterial count than the non-deaerated skimmed milk M in the first section of the test.
The non-deaerated skimmed milk M is heated in the first heat exchanger 1 according to the above curve 1.1-V to an output temperature of approximately 62 °C. A second sample P2 is taken of this non-deaerated skimmed milk M at the second sample collection site 15. The assigned measuring values are shown in the curve 1.1-62 °C in Figure 2 (label: listed in the legend as 1.1-62 °C - nondeaerated).
Until the time t = 6 h according to the curve 1.1-62 °C, a significant increase in the thermophilic bacterial count can be seen, namely of 330 (minimum) to 2.300.000 CFU/ml (maximum for t = 5 h). This increase correlates with the start of the biofilm in the first heat exchanger 1.
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From the time t = 6 h according to the curve 1.1-62 °C, the high initial bacterial count in the advance line 3 leads to a significantly higher proportion of thermophilic bacteria also in the first heat exchanger 1. Throughout the period from t = 6htot = 13h these were 1,700,000 CFU/ml (minimum) and 4,300,000 CFU/ml (maximum), therefore consistently above the proportion in the advance line 3 (curve 1.1-V; maximum: 1,100,000 CFU).
Test 4.2 (temperature TP = 15 °C in advance line 3)
Test 4.2 (figure 2; label: the curve at 4.2-V; listed in the legend as 4.2-advance line - non-deaerated) ran for a total of 9 hours and was operated over the entire test time with non-deaerated skimmed milk M. Over the entire test period the non-deaerated skimmed milk M passed from a plate heat exchanger to advance line 3 at a process temperature TP of approximately 15 °C.
The curve 4.2-V shows the initial bacterial contamination (bacterial count CFU/ml) of the nondeaerated milk M passing into advance line 3 under the aforementioned conditions. The measuring results are from the first sample Pl of the first sample collection point 14 in advance line 3. The measured values stagnate at 100 (minimum) to 240 CFU/ml (maximum) with the exception of an outlier at t = 7 h at 1,700 CFU/ml.
The non-deaerated skimmed milk M in accordance with the aforementioned curve 4.2-V is heated in the first heat exchanger 1 to an outlet temperature of approximately 62 °C. A second sample P2 of this non-deaerated skimmed milk M is taken at the second sample collection point 15. The assigned measuring results are shown in the curve 4.2-62 °C in figure 2 (label: listed in the legend as 4.262 °C- non-deaerated).
With the exception of an outlier at t = 2 h at 3500 CFU/ml, until the time t = 6 h there is a significant increase in the thermophilic bacterial count in the curve 4.2-62 °C, namely from 17,000 (minimum) to 280,000 CFU/ml (maximum). This increase, in turn, correlates with the start of the biofilm in the first heat exchanger 1. From time t = 6 h the portion of thermophilic bacteria remains at a high level, i.e. between 110,000 CFU/ml (minimum) and 950,000 CFU/ml (maximum) and is thereby always two to three to the power of ten higher than the portion in advance line 3 (curve 4.2-V; maximum: 240 CFU).
Test 4.1 (Deaeration at TD = 55 °C; temperature approximately 8 to 15 °C in the advance line 3)
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018
Test 4.1 (figure 2; label: the curve with 4.1-V; listed in the legend as 4.1-advance - deaerated) ran for a total of 13 hours with deaerated skimmed milk M* over the entire test period. This deaerated skimmed milk M* was very effectively deaerated at approximately 55 °C and then cooled down to approximately 8 °C to 15 °C. Until approximately the time t = 5 h (first test section) the deaerated skimmed milk M* passed from a plate heat exchanger to the advance line 3. From approximately the time t = 5 h (second test section) the deaerated skimmed milk M* passed from a tank storage to the advance line 3.
The curve 4.1-V shows the initial bacterial contamination (bacterial count CFU/ml) of the deaerated skimmedmilk M* passing into the advance line 3 under the aforementioned conditions. The measuring results are from the first sample Pl taken at the first sample collection point 14 in the advance line 3. The measured values approximately stagnate at very low levels of 100 (minimum) to 350 CFU/ml (maximum) in the time range t = 0 to 5 h.
The deaerated skimmed milk M* from the tank storage added from approximately the time t = 5 h to t = 13 h has much higher levels of contamination according to the curve 4.1-V in the time t = 5 to t = 11 h at 6,800 (maximum) and 1,200 CFU/ml (minimum) than the deaerated skimmed milk M* added in the first test section of the test 4.1.
The deaerated skimmed milk M* is heated in the first heat exchanger 1 to an outlet temperature of approximately 62 °C, according to the aforementioned curve 4.1-V. A second sample P2 is taken of this deaerated skimmed milk M* at the second sample collection point 15. The assigned measuring values are shown in curve 4.1-62 °C in figure 2 (label: listed in the legend as 4.1-62 °C - deaerated).
Until the time t = 5 h there is no visible increase in the thermophilic bacterial count in the curve 4.162 °C with levels at 100 (minimum) to 360 CFU/ml (maximum), assuming a value of 4,200 CFU/ml is an outlier at the time t = 4 h. The deaerated skimmed milk M* does not cause a measurable biofilm in the first heat exchanger 1.
From approximately the time t = 5 h the bacterial count increases in the deaerated skimmed milk M* to 3600 (minimum) to 7000 CFU/ml (maximum), whereby at the time t = 6 h and t = 9 h the measurements 86,000 or 500,000 CFU/ml were probably outliers. However, the portion of thermophilic bacteria in the sufficiently deaerated skimmed milk M* is approximately two to the power of ten lower than test 4.2 (non-deaerated skimmed milk M) and approximately three to the power of ten lower than in test 1.1 (also non-deaerated skimmed milk M).
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018
This demonstrates that a sufficient deaeration of the skimmed milk significantly lowers the thermophilic bacterial count in recuperative heat exchangers operating in a temperature range of approximately 50 °C to 70 °C, and therefore leads to a reduced growth of a biofilm on the surfaces of the heat exchanger in contact with the product. This in turn means that the service life of the heat exchanger is extended and therefore the interval between necessary adjacent cleaning cycles is extended.
It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.
REFERENCE LIST OF ABBREVIATIONS USED
100 Unit of a processing plant
First heat exchanger
Second heat exchanger
Advance line
First advance line section
Second advance line section
First return line section
Second return line section
Return line
First heating circuit line
Second heating circuit line
First pump
Second pump
Third pump
First sample collection point
Second sample collection point
Control valve
VP First heat transfer medium (e.g. vapours)
M Skimmed milk (non-deaerated)
M* Skimmed milk (deaerated)
SMC Second heat transfer medium (e.g. skimmed milk concentrate SMC)
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018
| SR | Source (skimmed milk Μ, M*) |
| SI | First sample (advance line, TI) |
| S2 | Second sample (T2 = 62 °C) |
| TI | First sample temperature (advance line) |
| T2 | Second sample temperature (T2 = 62 °C) |
| TD | Deaeration temperature |
| TS | Storage temperature |
| TP | Process temperature |
| Top | Optimum temperature (optimum bacterial growth) |
| Z | TR |
10190280_1 (GHMatters) P103617.AU
2015208412 19 Apr 2018
Claims (6)
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102014001037.6 | 2014-01-25 | ||
| DE102014001037.6A DE102014001037A1 (en) | 2014-01-25 | 2014-01-25 | Method and apparatus for reducing the growth of thermophilic bacteria in skimmed milk |
| PCT/EP2015/000097 WO2015110258A1 (en) | 2014-01-25 | 2015-01-20 | Method and device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2015208412A1 AU2015208412A1 (en) | 2016-10-13 |
| AU2015208412B2 true AU2015208412B2 (en) | 2018-05-10 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2015208412A Active AU2015208412B2 (en) | 2014-01-25 | 2015-01-20 | Method and device for reducing the growth of thermophilic bacteria in heat exchangers of dairy processing plants |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP3096626B1 (en) |
| JP (1) | JP6450770B2 (en) |
| AU (1) | AU2015208412B2 (en) |
| CA (1) | CA2937703C (en) |
| CL (1) | CL2016001872A1 (en) |
| DE (1) | DE102014001037A1 (en) |
| MX (1) | MX2016009446A (en) |
| PH (1) | PH12016501467A1 (en) |
| PL (1) | PL3096626T3 (en) |
| RU (1) | RU2016131854A (en) |
| WO (1) | WO2015110258A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL2019128B1 (en) * | 2017-06-27 | 2019-01-07 | Lely Patent Nv | Milk system |
| RU2706090C1 (en) * | 2018-09-04 | 2019-11-13 | федеральное государственное бюджетное образовательное учреждение высшего образования "Вологодская государственная молочнохозяйственная академия имени Н.В. Верещагина" (ФГБОУ ВО Вологодская ГМХА) | Method for milk bactericides reduction during milking |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR887000A (en) * | 1941-08-04 | 1943-10-29 | Westfalia Separator Ag | Installation for the treatment of milk, comprising a centrifuge or skimmer without foam and behind which is mounted a heater |
| DE102005015713A1 (en) * | 2005-04-06 | 2006-10-12 | Tuchenhagen Dairy Systems Gmbh | Method and device for degassing and maintaining a continuous volume flow of a milk to be treated in an ultra-high-temperature (UHT) system |
| DE102007037941A1 (en) * | 2007-08-11 | 2009-02-19 | Tuchenhagen Dairy Systems Gmbh | Degassing liquid food such as dairy milk, cream or ultra-high temperature milk, comprises supplying total flow of gas-loaded product to an inlet of distributing pipe, so that partial flow of gas-loaded product is converted and/or branched |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1017011B (en) * | 1956-01-05 | 1957-10-03 | Allgaeuer Alpenmilch | Method for monitoring the water balance in steam injection heating processes |
| DE1185464B (en) * | 1962-11-29 | 1965-01-14 | Holstein & Kappert Maschf | Device for pasteurizing milk |
| US5456924A (en) * | 1988-12-23 | 1995-10-10 | Immunotec Research Corporation Ltd. | Method of treatment of HIV-seropositive individuals with dietary whey proteins |
| IL106576A (en) * | 1992-08-13 | 2000-08-13 | Immunotec Res Corp Ltd | Anti-cancer therapeutic compositions for prophylaxis or for treatment of cancer |
| US6326038B1 (en) * | 2000-03-27 | 2001-12-04 | Kraft Foods, Inc. | Calcium fortification of cheese |
| NL1026755C2 (en) * | 2004-07-30 | 2006-02-02 | Friesland Brands Bv | Method for conditioning milk, as well as the products obtained and available with it. |
| JP6322363B2 (en) * | 2010-12-02 | 2018-05-09 | 株式会社明治 | Browning-suppressing dairy food and method for producing the same |
-
2014
- 2014-01-25 DE DE102014001037.6A patent/DE102014001037A1/en not_active Ceased
-
2015
- 2015-01-20 EP EP15702963.8A patent/EP3096626B1/en active Active
- 2015-01-20 AU AU2015208412A patent/AU2015208412B2/en active Active
- 2015-01-20 WO PCT/EP2015/000097 patent/WO2015110258A1/en active Application Filing
- 2015-01-20 MX MX2016009446A patent/MX2016009446A/en unknown
- 2015-01-20 PL PL15702963T patent/PL3096626T3/en unknown
- 2015-01-20 CA CA2937703A patent/CA2937703C/en active Active
- 2015-01-20 JP JP2016547140A patent/JP6450770B2/en active Active
- 2015-01-20 RU RU2016131854A patent/RU2016131854A/en not_active Application Discontinuation
-
2016
- 2016-07-22 CL CL2016001872A patent/CL2016001872A1/en unknown
- 2016-07-25 PH PH12016501467A patent/PH12016501467A1/en unknown
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR887000A (en) * | 1941-08-04 | 1943-10-29 | Westfalia Separator Ag | Installation for the treatment of milk, comprising a centrifuge or skimmer without foam and behind which is mounted a heater |
| DE102005015713A1 (en) * | 2005-04-06 | 2006-10-12 | Tuchenhagen Dairy Systems Gmbh | Method and device for degassing and maintaining a continuous volume flow of a milk to be treated in an ultra-high-temperature (UHT) system |
| DE102007037941A1 (en) * | 2007-08-11 | 2009-02-19 | Tuchenhagen Dairy Systems Gmbh | Degassing liquid food such as dairy milk, cream or ultra-high temperature milk, comprises supplying total flow of gas-loaded product to an inlet of distributing pipe, so that partial flow of gas-loaded product is converted and/or branched |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2015110258A1 (en) | 2015-07-30 |
| RU2016131854A3 (en) | 2018-03-14 |
| CA2937703A1 (en) | 2015-07-30 |
| DE102014001037A1 (en) | 2015-07-30 |
| PH12016501467A1 (en) | 2016-08-22 |
| PL3096626T3 (en) | 2019-04-30 |
| CA2937703C (en) | 2018-09-04 |
| EP3096626A1 (en) | 2016-11-30 |
| AU2015208412A1 (en) | 2016-10-13 |
| JP2017509320A (en) | 2017-04-06 |
| EP3096626B1 (en) | 2018-09-12 |
| CL2016001872A1 (en) | 2017-03-31 |
| RU2016131854A (en) | 2018-03-05 |
| MX2016009446A (en) | 2016-10-13 |
| JP6450770B2 (en) | 2019-01-09 |
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