PACKAGING OF CULTURED TISSUE

Abstract

The invention is in the field of cultured meat. In particular the invention is related to a method for aseptic packaging of cultured tissue and a system suitable for this method. The method comprises the steps of producing the cultured tissue, harvesting the cultured tissue, transferring the cultured tissue to a sterile package and sealing the sterile package, wherein all steps are executed under aseptic conditions.

Claims

1-22. (canceled)

23. A method for aseptic packaging of cultured tissue comprising the steps of: producing cultured tissue in a sterilized bioreactor; harvesting cultured tissue from said sterilized bioreactor; transferring cultured tissue to a sterile package; sealing said sterile package; wherein the steps are executed under aseptic conditions, and wherein the cultured tissue is cultured meat for consumption.

24. The method according to claim 23, further comprising one or more processing steps which are also carried out under aseptic conditions.

25. The method according to claim 23, wherein all steps are performed in the same sterile enclosure.

26. The method according to claim 23, wherein at least some of the steps are performed in separate sterile enclosures and wherein transferring cultured tissue between the separate enclosures is performed under aseptic conditions.

27. The method according to claim 23 further comprising the steps of: transferring cultured tissue to a sterilized connecting piece; transferring cultured tissue from said sterilized connecting piece to said sterile package; wherein the steps are executed under aseptic conditions and wherein said sterilized connecting piece connects said sterile package with said sterilized bioreactor of cultured tissue.

28. The method according to claim 23 wherein the steps are executed in said sterilized bioreactor.

29. The method according to claim 23 wherein the one or more enclosures comprise a grade A isolator capable of self-sterilizing.

30. The method according to claim 25 wherein said enclosure is a grade A isolator capable of self-sterilizing.

31. The method according to claim 26 wherein said separate sterile enclosures are grade A isolators capable of self-sterilizing.

32. The method according to claim 23 wherein said method further comprises an integrity test of the sterile package.

33. The method according to claim 23 wherein the process pressure in said sterilized bioreactor is between 0 to 11 bar absolute pressure.

34. The method according to claim 23 wherein the process temperature in said sterilized bioreactor is between 0 to 50° C.

35. The method according to claim 23 wherein cultured tissue is transferred to said sterile package at a temperature between 0 to 50° C.

36. The method according to claim 23 wherein cultured tissue is transferred to said sterile package at a pressure between 0 to 4 bar absolute pressure.

37. The method according to claim 23 wherein the sealing of said sterile package is hermetic.

38. The method according to claim 23 wherein the sterile package comprises a sterile chamber.

39. The method according to claim 23 wherein said sterile package is suitable for storage between −20 to 50° C.

40. The method according to claim 23 wherein said sterile package, said sterilized connecting piece and said sterilized bioreactor of cultured tissue are easily sterilized by conventional sterilization methods.

41. The method according to claim 23 wherein the bioreactor comprises a medium suitable for the formation of cultured tissue.

42. The method according to claim 41 wherein the medium is a hydrogel.

43. The method according to claim 23 wherein cultured tissue is fresh cultured tissue.

44. The aseptic packaged cultured meat obtainable by the method according to claim 23.

45. The aseptic packaged cultured meat according to claim 44 having a shelf-life of up to 60 days.

46. An aseptic packaging system for aseptic packaging of cultured tissue according to claim 23, wherein the cultured tissue is cultured meat for consumption, said aseptic packaging system comprising a sterilized bioreactor for producing cultured tissue, a sterile package and a means for sealing said sterile package, wherein the system operates under aseptic conditions.

Description

[0033] In another preferred embodiment, the steps of the method are executed in the bioreactor under aseptic conditions. This may be in the form that the sterile package is introduced into the bioreactor. Preferably the medium is introduced in the sterile package. The medium may be removed before sealing of the sterile package. Removal may be achieved by enzymatic degradation or washing with a sterile post processing solution. The post processing solution may be flavored.

[0034] By executing the steps in the bioreactor, the risk of contamination may be reduced. Moreover, by providing a single process it may be energetically more favorable and less time consuming.

[0035] In a preferred embodiment the individual elements involved in the method are easily sterilized. It may be required to sterilize the sterile package, sterilized connecting piece and sterilized bioreactor. Preferably conventional sterilization methods such as heat, irradiation, chemical treatment and combinations thereof are sufficient to sterilize the individual elements. Furthermore, the ingredients of the growth medium are preferably sterilized. Sterilization may be achieved through e.g. sterilization filtration.

[0036] The cultured tissue is preferably cultured meat. The cultured tissue may be grown in such a manner to provide muscle cell tissue, that is preferably suitable to be aseptically packaged. More preferably the cultured meat is suitable for consumption. As used herein, “suitable for consumption” refers to the suitability for consumption by humans and/or animals, preferably by humans. It may be suitable for consumption if the myosatellite cell originates from cows, sheep, pigs, poultry, fish or the like, and combinations thereof. The combination of cultured meat and packaging under aseptic conditions may extend shelf life and reduces or may even eliminate over-code products. This extends to retailers but also to consumers.

[0037] In a preferred embodiment the process pressure within the bioreactor is between 0 to 11 bar absolute pressure. The process pressure relates to the pressure present during the process, this process may comprise all the steps of the method or may comprise one or more steps. The pressure influences the aseptic conditions in combination with the temperature. Depending on the temperature the pressure is at the lower or higher end of the range. Pressure alone cannot sterilize a product. The pressure may be sufficient for correct growing of the cultured tissue. Furthermore, the pressure may be sufficient to maintain aseptic conditions.

[0038] Preferably the process temperature in the bioreactor is between 0 to 50° C. The process temperature relates to the temperature present during the process, this process may comprise all the steps of the method or may comprise one or more steps. The process temperature may be dependent on the pressure. The temperature range is well below temperatures for sterilizing conditions. It may be preferred to have a process temperature of 20 to 40° C. in case the step comprises production of the cultured tissue. The temperature is of importance for the sufficient growing conditions for the cultured tissue. Furthermore, the temperature may be sufficient to maintain aseptic conditions.

[0039] In another preferred embodiment the cultured tissue is transferred to the sterile package at a temperature between 0 to 50° C. The temperature may be chosen dependent on the material. A higher temperature may influence the tissue. At higher temperatures the tissue may be partly cooked, and the structural features may change. Irreversibly altering the integrity of the tissue is then inevitable. Moreover, a higher temperature may damage the physical integrity of the packaging material. The physical integrity of the packaging material may also be influenced by a lower temperature. The temperature furthermore is significantly lower than needed for common sterilization conditions.

[0040] Preferably the sterile package is impermeable to oxygen. This sterile package may be in the form of a blister package with a recyclable barrier film, or it may be a reusable glass or metal container.

[0041] The cultured tissue is preferably transferred to the sterile package at a pressure between 0 to 5 bar absolute pressure. The pressure may be sufficient for time effective transfer. Moreover, the pressure may be sufficient to correctly fill the sterile package. It may be preferred to use protective atmosphere during the transferring of the cultured tissue to the sterile package.

[0042] Preferably the sterile package is suitable for storage between −20 to 50° C. A higher temperature may alter the shelf life as well as the taste. The package may be suitable for storage under refrigerated conditions as well as ambient conditions, thereby still needing to fulfill all requirements for aseptic packaging. At lower temperatures, the structural integrity of the material may be compromised.

[0043] An aseptic packaging system may be designed for the aseptic packaging of cultured tissue. This system comprises a sterilized bioreactor for producing cultured tissue, a sterile package and a means for sealing the sterile package. The system preferably can operate under aseptic conditions. In a preferred embodiment the system comprises a grade A isolator capable of self-sterilization. The aseptic system packaging system is preferably suitable for aseptic packaging of fresh cultured tissue.

[0044] In accordance with the invention it is possible to produce fresh mincemeat or fresh (viz. uncooked) hamburgers with a shelf life of up to 60 days.

[0045] Another advantage of aseptic packaging according to the invention is that less preservatives such as nitrites and nitrates have to be added to the meat. Preservatives such as nitrites and nitrates are typically added to certain meat products, such as ham, inter alia to prevent growth of bacteria such as Clostridium botulinum, which causes botulism. Because of the aseptic conditions during production and packaging of the cultured tissue, there will be much less chance of infection with these bacteria. Therefore, less or no preservatives have to be added. For example, the amount of sodium nitrite needed to prevent the occurrence of botulism may be less than 50 mg/kg meat, preferably less than 10 mg/kg. Still more preferably, the occurrence of botulism can be prevented when the meat is free or substantially free of sodium nitrite. Sodium nitrite also acts as a colorant, e.g. giving ham its pink color. If less or no sodium nitrite is used, other, less toxic colorants may be used instead.

[0046] Because of the aseptic conditions during production and packaging of the cultured tissue, ageing of the cultured tissue can be performed at elevated temperatures, because growth of unwanted micro-organisms at elevated temperatures is not a concern. This means that ageing does not have to be performed near freezing temperatures and/or in a refrigerated container. For instance, ageing can be performed at temperatures of 5° C. or higher, such as 10-50° C., for instance at room temperature. The cultured tissue can be aged before packaging and/or after packaging.

[0047] It is also possible to deliberately add certain micro-organisms to the cultured tissue. For instance, if fermentation or ageing of the cultured tissue under the influence of specific micro-organisms is desired, such micro-organisms can be added. The cultured tissue can for instance be fermented using micro-organisms before packaging. Because the aseptic conditions result in the absence of unwanted and harmful micro-organisms, the desired microbial process (such as fermentation) becomes predictable and controlled. In order to prevent these deliberately added micro-organisms to contaminate the bioreactor, a step of deliberately adding micro-organisms should not be performed in the same enclosure as the bioreactor. Despite the addition of micro-organisms, the steps of the method can still be considered to have been executed under aseptic conditions, because the only micro-organisms that will be present are deliberately added, and the introduction of unwanted and harmful micro-organisms is still prevented. An example of a meat product in which micro-organisms are deliberately added is salami.

[0048] An example of a method in which hamburgers made from cultured tissue suspensions are aseptically packaged is schematically shown in FIG. 1 and described below. However, the invention is not limited to hamburgers or other meat products that are made from tissue suspensions. It may also possible to produce larger (e.g. portion-sized) pieces of tissue in the bioreactor that can be packaged individually. Similar process steps may also apply to other products than hamburgers.

[0049] With reference to FIG. 1, muscle tissue is produced in muscle tissue bioreactor array (1), and fat tissue is produced in fat tissue bioreactor array (2). Muscle tissue suspension (21) and fat tissue suspension (22) are led to buffer tank (3), which provides a continuous feed for the subsequent steps. Mixed tissue suspension (23) is led to dewatering and spicing system (4), where the suspension is dewatered and where sterile spices and/or additives (27) can be added. After that, hamburger paste (24) is led to hamburger forming station (5), where it is formed into hamburger (25). Hamburger (25) is then packaged in packaging station (6) using sterile packaging material (28) and the package is sealed. Packaged hamburger (26) can then be removed from aseptic conditions and further processed on a standard packaging line.

[0050] The cultured tissue that is produced in bioreactor arrays (1) and (2) is free of micro-organisms, and the further processing and or packaging steps are carried out under aseptic conditions. Therefore, aseptically packaged cultured tissue can be obtained without the need for sterilizing the tissue. Items that are introduced from outside the aseptic environment, such as spices and/or additives (27) and packaging material (28) have to be sterilized when they are brought into the aseptic environment in order to avoid contamination.

[0051] In the example of FIG. 1, muscle tissue and fat tissue are produced as aseptic suspensions, meaning that fluid streams are obtained from the bioreactor arrays. The steps involving a fluid stream are performed under aseptic conditions in fluid zone (11). The units in this zone, such as process vessels (i.e., tanks) and fluid transfer lines can be cleaned and sterilized in a cleaning cycle. To this end, the equipment in fluid zone (11) may be equipped with clean-in-place (CIP) and sterilization-in-place (SIP) systems. The vessels and fluid transfer lines may for instance comprise several inlets and outlets through which cleaning liquids can introduced and removed from the system. After cleaning with a cleaning liquid, the process vessels and lines can be sterilized with e.g. steam. Therefore, the equipment in fluid zone (11) is preferably built from material that can withstand the conditions of the sterilization process, for instance high temperatures and pressures in case of sterilization with steam. The fluids can be transported using low shear stress pumps, that are preferably easily cleanable. For example, peristatic pumps or membrane pumps can be used.

[0052] After dewatering of the mixed tissue suspension, further steps take place in an aseptic environment outside the fluid zone, for instance in grade A isolator (12). The boundary between fluid zone (11) and grade A isolator (12) can for instance be formed by a three-way valve. Such a three-way valve can also be used as inlet and/or outlet for a CIP process.

[0053] Grade A isolators are hermetically sealed isolators that circulate air through HEPA filters to keep the environment sterile. Any operator contact with the systems in such an isolator is done with gloves. In addition, Grade A isolators are typically kept under overpressure with respect to the surrounding atmosphere, to prevent gas and microorganisms from the surrounding atmosphere from entering the isolator. Before production runs the isolator can be flooded with ca. 150 ppm of vaporized hydrogen peroxide. This kills all microorganisms and sterilizes the isolator. In this way it provides a contamination free workspace for aseptic processing. Afterwards, the vaporized peroxide is removed, typically using a catalytic filter. Production is only started if the peroxide levels fall below levels which are safe for the product, thereby preventing contamination and degradation of the food product by hydrogen peroxide.

[0054] Because the output of tissue bioreactors is typically periodic, arrays of bioreactors, such as muscle tissue bioreactor array (1) and fat tissue bioreactor array (2) can advantageously be used to provide a continuous feed for the subsequent steps.

[0055] Buffer tank (3) can be a simple stirred tank that acts as a buffer for the output of the bioreactors. Its purpose is to provide a continuous feed for the packaging line. In addition, muscle tissue suspension (21) and fat tissue suspension (22) can be mixed in the buffer tank.

[0056] Dewatering and spicing system (4) can be implemented as a two-stage process in which the mixed tissue suspension is continually dewatered using, for example, a belt filter press which feeds into a mixing auger. Sterile spices and/or additives (27) can be added in the mixing auger, and the tissue spice mixture is treated to get the desired texture.

[0057] The output of dewatering and spicing system (4) is hamburger paste (24). This paste can be transported by the mixing auger to the hamburger forming station (5), which for instance comprises a forming wheel in which the hamburgers are formed. The formed hamburger (25) can then be fed onto a belt, from where it can be placed into packaging station (6) by a pick-and-place machine.

[0058] Packaging station (6) can for instance be a blister machine which seals hamburgers into thermoformed packages under a protective atmosphere. To this end, sterile packaging material (28), for instance a stiff thermoformable film and a flexible sealing film, can be brought into the isolator through a sterilizing inlet. Sterilization of the packaging material (for example UV sterilization) is used to ensure that no contamination can enter the isolator. The stiff film is then heated, and vacuum formed into the desired container shape. Hamburger (25) can be placed inside the formed product cavities. The container is then sealed in a sealing step and the sealed container is cut from the packaging material and brought out of the isolator in a controlled manner without contaminating the isolator, for instance using an aseptic airlock. From this point, since the products are aseptically packaged and the package is hermetically sealed, the packaged product can be further processed in a standard packaging line without measures to maintain aseptic conditions.

[0059] All devices and parts in the isolator should be designed in such a way that they can be easily disassembled and cleaned in between packaging runs. The disassembled parts should then be placed in positions in which good contact with the sterilization vapors, e.g. vaporized hydrogen peroxide (VHP), can be ensured. An operator can then reinstall all parts before a packaging run without opening the isolator and breaking sterility.

[0060] There are several ways in which the quality of the packaged products can be checked. Periodic samples can be taken to confirm the absence of microbes. Packaged products can be stored for several days and checked for signs of contamination. Chemical indicators that can detect undesired microbiological growth can be included in the packaging. Yearly runs with an indicator product can be performed in order to confirm that the process can be run without introducing contamination.

[0061] For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combination of all or some of the features described.