NL2021412B1 - Safe and stable nitrite free meat products - Google Patents
Safe and stable nitrite free meat products Download PDFInfo
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- NL2021412B1 NL2021412B1 NL2021412A NL2021412A NL2021412B1 NL 2021412 B1 NL2021412 B1 NL 2021412B1 NL 2021412 A NL2021412 A NL 2021412A NL 2021412 A NL2021412 A NL 2021412A NL 2021412 B1 NL2021412 B1 NL 2021412B1
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L13/00—Meat products; Meat meal; Preparation or treatment thereof
- A23L13/60—Comminuted or emulsified meat products, e.g. sausages; Reformed meat from comminuted meat product
- A23L13/65—Sausages
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B4/00—General methods for preserving meat, sausages, fish or fish products
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L13/00—Meat products; Meat meal; Preparation or treatment thereof
- A23L13/40—Meat products; Meat meal; Preparation or treatment thereof containing additives
- A23L13/42—Additives other than enzymes or microorganisms in meat products or meat meals
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- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
- A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
- A23L3/015—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with pressure variation, shock, acceleration or shear stress or cavitation
- A23L3/0155—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with pressure variation, shock, acceleration or shear stress or cavitation using sub- or super-atmospheric pressures, or pressure variations transmitted by a liquid or gas
Abstract
The invention relates to a method for producing a safe non-cured meat product, wherein the meat product has a shelf life at a storage temperature of equal to or less than 7 °C of at least 18 days, wherein the method comprises a mixing stage and a high pressure processing stage; wherein the mixing stage comprises: combining raw meat material and additives to provide a mixture of meat material and additives, wherein the additives comprise one or more ingredients selected from the group consisting of herbs, spices, salt, and vegetables, a total weight of the raw meat material relative to a total weight of the additives is selected from the range of 70:30 — 99.505, the raw meat material comprises less than 0.1 cfu C. botulinum and less than 0.1 cfu B. cereus spores per gram of raw meat material, the additives comprise equal to or less than 50 cfu C. botulinum and equal to or less than 50 cfu B cereus spores per gram of additives, and the raw meat material and the additives are selected to provide the mixture of meat material and additive at a pH equal to or smaller than 5.9 and to provide the meat product having a water activity equal to or smaller than 0.980.
Description
FIELD OF THE INVENTION
The invention relates to a method for producing a safe and stable noncured meat product and a safe and stable non-cured meat product obtainable with the method.
BACKGROUND OF THE INVENTION
Ordinarily, (shelf stable) meat products (or meats) that are stored in the refrigerator (for e.g. 10-14 days or more) are preserved using nitrite (salts) or curing salts to inhibit or retard germination and growth of pathogenic microorganisms. The nitrites, however, may form nitrosamines in combination with meat. Since nitrosamines are known carcinogenic compounds, the use and presence of nitrite in meat products has given rise (especially in the past years) to negative consumer feelings.
At present, meat products without nitrite (or with a reduced amount of nitrite) are already available on the market. The solutions that are found may use celery (extract) or Swiss chard as a source of natural nitrite. These products are, e.g., sold in the USA under the name ‘uncured’ meat products. These products, though, still contain nitrite.
SUMMARY OF THE INVENTION
Nitrites are often used to inhibit or retard germination and growth of Clostridium botulinum and Bacillus cereus\ both capable of producing endospores. C. botulinum can produce botulinum toxin in food in general, and especially in meat products. Botulinum toxin is the most acutely lethal toxin known. At very low doses, the toxin may already cause food poisoning (botulism). Botulism neurotoxins prevent neurotransmitters from functioning properly and inhibit motor control. As botulism progresses, the patient experiences paralysis from top to bottom, starting with the eyes and face and moving to the throat, chest, and extremities. Finally, the paralysis may reach the chest, which may lead to death from the inability to breathe. Especially, inhibiting non-proteolytic C. botulinum may be relevant, because the bacteria may grow in refrigerated conditions e.g. at temperatures in the range of 0-7°, especially at temperatures in the range of 2-7 °C. B. cereus toxins may cause vomiting, while a second type of toxins produced by B cereus gives diarrhea.
To prevent microbiological problems with meat product, meat product on the one hand may be fermented (and dried) to provide a pH of below 4.5 that may prevent growth of harmful microorganism. Cooked meat product normally found on the market may have a pH of over 6.0, wherein nitrite (by nitrite containing salts and/or nitrite containing natural products are added) to prevent outgrowth of the harmful microorganisms.
The growth of these bacteria are retarded or inhi bited by the addition of curing salts during the production of the meat products. Meat products having a water activity (aw) of at least 0.97 or higher and a pH of 5.7 or more (especially a pH higher than 5.9) especially require inhibition of these pathogenic bacteria. The nitrite, however, may form nitrosamines in combination with meat. Moreover, nitrosamines are known carcinogenic compounds. Meat processing companies, therefore, may have the ambition to produce meat products without nitrite and other E-numbers.
Products, without nitrite (or with a reduced amount of nitrite) may use a natural source of nitrate/nitrite such as celery or Swiss chard as a source of nitrite. Further, sometimes combinations with other ‘smart’ ingredients are made, in order to control fat oxidation and enhance color. At present, several companies adopted this concept in the production of commercial products. Moreover, several suppliers are available that offer celery products, e.g., containing 15.000 ppm nitrite.
Natural flavorings or spices, and celery juice or celery powder are therefore frequently listed as ingredients. Celery and chard are natural sources of nitrate with concentrations of 1500-2800 ppm. Celery juice and celery powder have mild flavor and little vegetable pigment, so they may not affect the product flavor and color and seem compatible with processed meat products. Celery is accounted as an allergen. Herein, the term “chard” may especially relate to Swiss chard.
Addition of celery powder/juice in meat products requires the presence of a nitrate-reducing bacterial culture (such as Staphylococcus xylosus, Staphylococcus carnosus}, which reduces the nitrate in the celery to nitrite. This incubation step (38-42 °C) is needed before cooking. Since the nitrate has to be converted in the meat product into nitrite, it is difficult to determine the exact dose into the product. Therefore, often overdoses of celery are used, to make sure enough nitrite is available in the final meat product. Nowadays, also pre-incubated or pre-converted celery juice or powder is available on the market. This celery juice has already been fermented, wherein the nitrate has been converted to nitrite before drying into powder. This may allow for adding the more exact required dose of nitrite.
Studies, though, show that the nitrite levels are higher in the “nitrite free” products that contain celery as a nitrite source, than in “regular” cured products. The fact that the “nitrite free” meat products still contain nitrite (possibly at even higher levels than regular meat products), has given rise to consumer concerns. This has been demonstrated in “the Applegate case”. In this case, Applegate has requested the FDA to be allowed to use clear terminology, so that consumers understand that ‘non-cured’ meat products still contain nitrite, but that this nitrite is obtained from natural sources. These products, though, still may contain the carcinogenic nitrosamines.
Presently used systems, do not seem to be able to solve the problems. Hence, it is an aspect of the invention to provide an alternative method for producing a safe (non-cured) meat product, that preferably further at least partly obviate(s) one or more of the above-described drawbacks. It is a further aspect of the invention to provide a safe (and non-cured) meat product that preferably further at least partly obviate one or more of the above-described drawbacks.
The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
In a first aspect, the invention provides a method for producing a safe (non-cured) meat product, wherein the meat product has a shelf life (when stored at a storage temperature of equal to or lower than 7 °C) of at least 18 days. The method comprises a mixing stage and a high pressure processing stage. The mixing stage comprises combining raw meat material and additives to provide a mixture of meat material and additives. The high pressure processing stage comprises subjecting the mixture (of meat material and additives) to a treatment pressure during a treatment period to provide the meat product, especially wherein the treatment period comprises at least 1 minute, The treatment pressure is especially selected equal to or larger than 500 MPa, such as selected from the range of 500 MPa - 800 MPa.
The additives may (at least) comprise one or more ingredients selected from the group consisting of herbs, spices, salt, and vegetables. The mixture may comprise at least 50 wt% raw meat material relative to a total of raw meat material and additives. In embodiments, a total weight of the raw meat material relative to a total weight of the additives is selected from the range of 70:30 (w/w) - 99.5:0.5 (w/w).
The ingredients, especially the raw meat material and additives, may be selected to provide the mixture of meat material and additives for comprising less than 0.1 cfu C. botulinum, especially non-proteolytic C. botulinum strains, and less than 0.1 cfu B. cereus spores per gram of mixture (of meat material and additives). In further embodiments, the raw meat material (is selected to) comprise(s) less than 0.1 cfu C. botulinum and less than 0.1 cfu B. cereus spores per gram of raw meat material and especially the additives (are selected to) comprise equal to or less than 50 cfu C. botulinum and equal to or less than 50 cfu B cereus spores per gram of additives.
The raw meat material and the additives are (further) especially selected to provide the meat product, especially the mixture of meat material and additive, at a pH equal to or less than 5.9. The raw meat material and the additives are (further) (also) especially selected to provide the meat product having a water activity equal to or smaller than 0.980.
Herein the terms “the mixture” and “the mixture of meat material and additives” may be used interchangeably. Furthermore, the term “meat material” especially relates to the raw meat material.
The method may provide a meat product that is safe and especially substantially does not comprise nitrite and or nitrate. The meat product may be a “nitrite-free” meat product. The meat product (herein also referred to as the “product”) may be appreciated by the consumer for not comprising carcinogenic nitrosamines. The product may further be juicy and and/or tender, and may be less dry relative products sold at the market nowadays. The product may be an “all natural product”, especially not comprising any E-numbers. The product may not comprise “synthetic” and/or “chemical” additives. The product may comprise a taste desired by the consumer. The taste may be more meat-like than presently market meat products. The taste may be like the taste of meat prepared at home without using any nitrite salts.
Hence, in a further aspect, the invention provides a meat product obtainable by the method described herein. The meat product may be a non-cured and especially clean label meat product. The meat product may have a shelf life of at least 18 days, especially at least 24 days at a storage temperature of equal to or less than 7 °C (see further below).
Herein the term “non-cured meat product” is used, referring to a meat product that is not cured by the addition of combinations of salt (sodium chloride), nitrates, and/or nitrites. This combination of salt with nitrates and/or nitrites is also called curing salt.
The ingredients of the meat products and/or used in the method, are especially all natural ingredients. The ingredients comprise the raw meat material and the additives. In embodiments, the additives comprise herbs and/or spices and/or vegetables. Herbs and spices may be distinguished from vegetables in that they are used in small amounts and provide flavor rather than substance to food (the meat product). Many different kinds of spices and/or herbs may be used. Some examples of herbs are basil, chives, coriander, lavender, lemon balm, oregano, parsley, peppermint, rosemary, sage, tarragon, and thyme. Examples of spices are (cayenne) pepper, chili powder, cinnamon, cumin, curry powder, ground ginger, nutmeg, paprika, and vanilla. Yet, the invention also provides for other spices and/or herbs. A non limiting list of vegetables may comprise cabbage, (red) beet, celery root, kale, legumes, onions, peppers, (water)cress. The additives may (also) comprise other vegetables. The terms “vegetables”, “herbs”, and “spices” may relate to a plurality of vegetables, herbs and spices, respectively.
In embodiments, the additives may (further) comprise salt. In embodiments, the additives further comprise (further) additives for improving the sensorial and textural properties of the food product, such as taste enhancers, stabilizers, antioxidants, oxygen scavengers, et cetera.
The additives and the raw meat material are combined in the mixing stage. Herein, combining may at least comprise adding the additives to the raw meat material. In embodiments, the additives are, e.g., rubbed in the raw meat material. In further embodiments, the raw meat material is marinated with the additives. Yet, combining may further comprise mixing and/or tumbling. The mixing stage may further comprise providing a vacuum to the raw meat material and the additive before, during, and/or after combining the raw meat material and the additives. In further embodiments, the raw meat material is chopped, ground, minced, and/or comminuted before and/or during combining with the additives. Hence, combining may comprise chopping, grinding, mincing, and/or comminuting of the raw meat material. Furthermore, the raw meat material may comprise ground, mince, chopped, etc., raw meat material.
Herein the term “raw meat material” may relate to more than one (different) raw meat material. In the method, e.g., a part of the raw meat material may be comminuted, while another part of the raw meat material comprises larger meat parts, such as a muscle and/or a combination of muscles, or part of the muscle, especially still showing a distinct intact muscle structure, such as chopped (muscle) meat. Moreover, the raw meat material may comprise a combination of different types of meat, such as a combination of pork and beef
The term “raw” as in “raw meat material” and the like relate to a “raw material” as used like a “(natural) resource” and a “base material”. The meat material may (also) be raw, i.e. not cooked or heated prior to mixing. Yet, in embodiments, the raw meat material may at least partly have been heated and/or cooked prior to mixing.
The term “meat material” may relate to any kind of material of animal origin. Examples of animal material are animal muscle, animal fat, but also animal soft tissue such as organs, for example the heart. The meat material may (further) comprise mechanically separated meat. The raw meat material may (already) comprise a minced, ground, chopped or cut raw meat material. Furthermore, the term “animal” may relate to all kinds of animals, including mammals, fish, birds, reptiles, amphibians, and invertebrates.
Herein the phrase “subjecting the mixture (or product) to a treatment pressure during a treatment period” especially relates to “providing a high pressure process treatment to the mixture (or product)”, “high pressure process treating the mixture (or product)”, and “high pressure processing the mixture (or product)”, and the like. These terms may be used interchangeably. The terms “high pressure process” and “high pressure processing” are known to the skilled person and may also be called “high hydrostatic pressure processing”, “ultra high pressure processing”, “pascalization” and is commonly abbreviated to “hpp” or “HPP”. HPP is a cold pasteurization technique in which a product, especially packaged in a flexible container, is introduced into a vessel and subjected to a high level of isostatic pressure (such as 100-1000 MPa). During HPP, the pressure is transmitted to the product by a pressurized liquid, especially by water. In a typical process, a (treatment) liquid comprising an initial temperature is provided to the product. Successively, the pressure of the (treatment) liquid is increased from atmospheric pressure to the treatment pressure. Next, the treatment pressure is maintained during the treatment period. Finally, the pressure is released again, and the treated product is provided.
In relation to the invention, the product is essentially the mixture of meat material and additives, and the treated product is the meat product. Hence, in embodiments, the high pressure processing stage (also) (further) comprises packaging the mixture of meat material and additives in a flexible container before the mixture is subjected to the treatment pressure. The mixture is especially packaged in portions.
The treatment period is preferable not more than 10 minutes, such as 5 minutes at maximum. In embodiments, the treatment period is selected from the range of 1-10 minutes, such as from 1-5 minutes or 5-10 minutes or especially from the range of 2-4 min. The treatment period may e.g. be selected to be at least 3, such as at least 5 minutes in combination with a treatment pressure of 500-600 MPa, and the treatment period may be selected to be at least 1 minute in combination with a treatment pressure of 600-800 MPa. In embodiments, the stages of pressure increase, maintaining of the pressure (during a (partial) treatment time), and pressure release may be provided a number of consecutive treatments. In such embodiments, the (total) treatment time may be defined by a total of each (partial) treatment time of each of the number of consecutive treatments.
The initial temperature (of the (treatment) liquid) may in embodiments of the method of the invention be selected from the range of 0-20 °C, especially 0-15 °C, such as 0-7°C. Yet, the initial temperature may also be higher than room temperature. The temperature of the liquid during the treatment period may be higher than the initial temperature due to an increase in temperature of the liquid as a result of (adiabatic) compression of the liquid (and the mixture). Such temperature rise may be about 3-4 °C per 100 MPa. After reducing the pressure again, the temperature will decrease again too. Hence, during the HPP treatment, the temperature of the mixture may rise as a consequence of the increased pressure. The temperature of the liquid may e.g. rise with about 15-25 °C. The temperature of the mixture may also rise with about 15-25 °C during the treatment period.
Because the treatment pressure may provide the inactivation of the microorganism, a high temperature may not be required to inactivate the microorganism. Therefore, the initial temperature of the (treatment) liquid, and especially (also) of a processing equipment used for performing the HPP treatment, may be selected such that a maximum temperature of the mixture during the high pressure processing stage does not exceed 45 °C, especially does not exceed 30 °C. In an embodiment, a maximum temperature of the mixture during the high pressure processing stage is selected from the range of 10-32 °C. Yet, in embodiments, the maximum temperature of the mixture during high pressure processing may be higher than 45 °C, for instance to cook or heat treat the mixture during the high pressure treatment (see also below).
The shelflife of the meat products is affected by the presence and growth of spoilage and pathogenic microorganisms. Relevant spoilage bacteria in meat product may comprise Pseudomonas spp., Enterobacteriaceae, Bacillaceae, Lactobacillus spp., Brochothrix thermosphacta, Leuconostoc spp., and Streptococcus spp. Furthermore, other examples of spoilage especially relevant for fish are Shewanella spp., Pseudomonas spp, Moraxella spp., Acetinohacter spp., Vibrionaceae. Relevant pathogenic microorganisms in meat products may originate from the meat, herbs, spices, and vegetables, from the equipment and/or tools and/or from handling (by personnel). These pathogen especially comprise: Spore forming bacteria (Bacillus cereus, non-proteolytic Clostridium botulinum', proteolytic Clostridium botulinum, Clostridium perfringens)', Vegetative bacteria (Campylobacter spp. thermophilic, Escherichia coli (STEC/ EHEC and other pathogenic groups), Listeria monocytogenes, Salmonella enterica, Shigella spp., Staphylococcus aureus, Yersinia enterocolitica)', Parasites (Cryptosporidium parvum, Giardia duodenalis, Sarcocystis spp., Taenia spp., Toxoplasma gondii, Trichinella spp.); Viruses (Hepatitis E, Other foodborne viruses (e.g. hepatitis A, Norovirus)); and Prions (Bovine spongiform encephalopathy (BSE)).
In a risk study, it was determined that all listed microorganisms except the spore forming bacteria and the prions are e.g. inactivated by a HPP treatment at a pressure of 600 MPa. Furthermore, of the relevant pathogenic microorganisms only Bacillus cereus, Clostridium botulinum non-proteolytic, Salmonella spp., Shigella spp, and Yersinia enterocolitica may grow at a temperature equal to or below 7 °C. The remainder of the relevant microorganisms essentially may not grow in a meat product stored at or below 7° C. It is furthermore anticipated that e.g. Vibrionaceae, Aeromona spp., and Plesiomonas spp., relevant pathogenic microorganisms related to fish, may be inactivated by a high processing treatment.
When providing a HPP treatment to the mixture, a pathogenic microorganism (as well as a spoilage microorganism) may be considered a risk (and therefore may reduce or minimize the shelflife) if no or very limited inactivation occurs by HPP processing and if the pathogen can grow during chilled storage. By applying HPP, vegetative cells, parasites and viruses may be inactivated substantially. Using HPP, the spore formers and prions may form a risk because they are (substantially) not affected by the treatment. Since prions also may provide a risk in standard meat (heating) processes, the meat supply chain is organized to prevent any meat comprising prions to enter the (human) food chain. The raw meat material may thus normally not contain any harmful prions. Furthermore, by storing the meat products at or below 7 °C, a growth of C. perfringens and proteolytic C. botulinum may also be controlled. Hence, when using HPP processing and a refrigerated storage (< 7 °C), the relevant microorganisms especially are B. cercus and non-proteolytic C. botulinum.
To understand the growth and the risks of these organisms during chilled storage, the inventors have determined the growth based on different scenarios, such as recipe and alternative additives, storage temperature, pH and water activity, initial load of B. cereus and non-proteolytic C. botulinum and gas packaging of the final product, see also the section “Experimental”. The inventors have found that a determined shelf life may be provided by selecting the ingredients such that the initial load of B. cereus and non-proteolytic C. botulinum is controlled. Therefore, especially, the raw meat material and the additives are selected such that the mixture of meat material and additives comprises less than 0.1 cfu (non-proteolytic) C. botulinum and less than 0.1 cfii B. cereus spores per gram of the mixture. Furthermore, the inventors found that (also) the pH and the water activity of the product preferably are controlled to the values described herein. In combination with the process conditions of the high pressure process as described herein, a shell life of at least 18 days, especially at least 24 days, may be provided without using any curing salt in the mixture.
Furthermore, the shelf life may be increased by reducing the pH and/or the water activity and/or increasing the severity of the HPP treatment, i.e. by increasing the treatment period, the treatment pressure or e.g. the temperature of the (treatment) liquid. Alternatively or additionally the shelf life may be increased by (temporarily) lowering the storage temperature of the meat product, e.g. from 7 °C to 0-2 °C. The shelf life may e.g. be increased with at least 8 days, such as at least 10 days, or at least days or even more, when the meat product is stored at 0-2 °C directly after providing the meat product in the high pressure stage. The shelf life may especially increase 8-15 days when the meat product is stored at 0-2 °C directly after providing the meat product in the high pressure stage. Hence, the meat product may have a shelf life of at least 26 days when it is stored at a storage temperature of equal to or less than 7 °C, wherein the storage temperature during the initial 8 days of storage is selected from the range of 0-2 °C. In further embodiments, the shelflife may be over 30 days when the meat product is initially stored 12 days or more at a storage temperature of 0-2 °C. These initial (8) days of storage may advantageously be used for storing the meat product at a location of a producer of the meat product, especially for logistic flexibility.
As described above, the raw meat material and the additives are especially selected to provide the mixture at a pH equal to or less than 5.9. The mixture of meat material and additive, may be selected to provide the mixture, especially the meat product at a pH below 5.90. The raw meat material and the additives may be selected to provide the meat product, especially the mixture, at a pH selected from the range of 5.0-5.9, especially in the range of 5.6-5.9. The raw meat material and the additives are especially selected to provide the meat product, especially the mixture, at a pH larger than 4.0, especially larger than 4.5, such as equal to or larger than 4.6, even more especially equal to or larger than 4.8, such as equal to or larger than 5.0, such as equal to or larger than 5.6, especially equal to or larger than 5.7. In further embodiments, the raw meat material and the additives are selected to provide the mixture having a pH equal to or more than 4.5, especially more than 4.5.such as equal to or more than 4.6.
The treatment pressure is especially selected to be equal to or larger than 400 MPa, such as equal to or larger than 500 MPa. At present, commercial high pressure devices may be operated at a pressure equal to or lower than 900 MPa, especially equal to or smaller than 800 MPa. Hence, in embodiments, the treatment pressure is selected from the range of 500 MPa-800 MPa. Yet, in further embodiments, the treatment pressure is selected from the range of 500 MPa-700 MPa.
In specific embodiments, the pH of the mixture is selected from the range of 5.5-5.9, especially 5.7-5.9, and the treatment pressure is selected from the range of 500 MPa-700 MPa, especially in the range of 600 MPa-700 MPa.
The raw meat material and the additives are further especially selected for providing the meat product having a water activity equal to or smaller than 0,980, especially equal to or smaller than 0.975, such as equal to or smaller than 0.970. The raw meat material and the additives may especially be selected for providing the meat product having a water activity of at least 0.960. In embodiments, the raw meat material and the additives are selected for providing the meat product having a water activity equal selected from the range of 0.970-0.980. Lower values for the water activity may provide less desirable, i.e. too dry, meat products. Higher values of the water activity may provide meat products that may not comprise the desired shelflife (at 7 °C).
In embodiments, the raw meat material and the additives are selected to provide the meat product, especially the mixture, at a pH selected from the range of 5.65.7, and especially to provide the meat product to comprise a water activity equal to and smaller than 0.975. Especially, in such embodiment, the meat product may have a shelf life (at 7 °C) of at least 30 days. In a further embodiment, the meat product has a water activity equal to or smaller than 0.980 and a pH equal to or smaller than 5.6, wherein the product has a shelf life of at least 25 days, such as at least 30 days, at a storage temperature of 7 °C.
Different measures may be taken to provide the desired pH and/or water activity to the mixture and/or the meat product. Such options may be known to the person skilled in the art. Controlling the water activity and the pH may be part of a standard meat processing practice. For instance, the meat raw material that is used may be selected to comprise a determined pH resulting in the required pH of the mixture and/or the meat product. The pH may depend on the type of muscle used. The pH may be affected by a ripening process of the meat. Further, acidifying additives may be applied for (further) lowering the pH of the mixture and/or the meat product. For instance, the additives may comprise glucono-5-lactone to lower the pH. Alternatively or additionally, the additives may comprise an (organic) acid, such as citric acid, lactic acid, lemon juice or e.g. vinegar to lower the pH of the product and the mixture. Furthermore, an addition of acids may (also) decrease the water activity of the food product. Yet addition of a large amount of these additives to lower the pH may require a simultaneous addition of a sweetener. Especially, when lowering the pH to a pH of 5.4 or lower, such as 5.2 or lower, a sweetener may be required for masking the acidity.
An increase of salt may result in lowering the water activity of the meat product. Next to that, an amount of herbs and vegetables relative to an amount of meat in the mixture may, as well as the processing conditions, such as the treatment period and a temperature during the process, may affect the pH and the water activity of the 5 mixture and the meat product. An addition of phosphates may further reduce the water activity to a certain extent, and yet may increase the pH. In the table below, some possible parameters and their possible effect on the pH and water activity are depicted.
| controllable parameter | increase/ decrease | effect on pH | effect on aw |
| pH raw meat | ; | - | |
| Addition acids | ΐ | J, small effect | |
| Addition salt (e.g. NaCl, KC1) | ΐ | - | |
| Addition of sugars | ΐ | - | |
| Addition phosphates | ΐ | ΐ | J, very small effect |
| Amount vegetables (fresh) | ΐ | - | t small effect |
| Heating temperature | ΐ | - | J, small effect |
| Heating time | ΐ | - | f small effect |
| Ripening period of the raw meat material | ΐ | unknown | |
| Amount of raw meat material | ΐ | - | J, small effect |
| Amount of non-meat protein | ΐ | - | J, small effect |
| Amount herbs (fresh) | ΐ | - | t small effect |
| Amount spices (pepper) | ΐ | - | - |
| HPP conditions (pressure) | ΐ | - | - |
| HPP conditions (time) | ΐ | - | - |
Possible effects of determined parameters on the pH and water activity of the mixture and//or meat product.
In further embodiments, lactic acid, and/or acetic acid, and/or propionic acid and/or the salts thereof may be part of the additives to control the pH. These acids, especially a combination of these acids may further (also) retard the gemination and growth of C. botulinum and B. cereus, and may (further) increase the shelf life. Hence, in an embodiment, the additives further comprise one or more compounds selected from the group consisting of lactic acid, acetic acid, and propionic acid and salts of said acids, especially wherein the meat product has a shelf life at a storage temperature of 7 °C of at least 42 days.
As discussed above, in embodiments, the mixture of meat material and the additives especially comprises less than 0.1 cfu (non-proteolytic) C. botulinum spores per gram of the mixture, and less than 0.1 cfu B. cereus spores per gram of the mixture.
The additives comprise especially one or more ingredients selected from the group consisting of herbs, spices, salt, and vegetables, and the raw meat material. The total weight of the raw meat material relative to the total weight of the mixture is especially selected from the range of 65-99.9 (w/w), especially 70-99.5 (w/w). The raw meat material may comprise less than 0.1 cfu C. botulinum, especially non-proteolytic C. botulinum, and less than 0.1 cfu B. cereus spores per gram of raw meat material. The additives may comprise less than 10 cfu C. botulinum, especially non-proteolytic C. botulinum, and less than 10 cfu B cereus spores per gram of additives.
A colony forming unit (cfu) is a unit used to express the number of viable bacteria in a sample. Viable is defined as the ability to multiply. Counting with colonyforming units requires culturing the microorganisms and counting only viable cells, in contrast with microscopic examination which counts all cells, living or dead. Determination of cfu is done by plate counting in which the visual appearance of a colony is observed under specific conditions of nutrient medium, temperature and time. When counting colonies it is uncertain if the colony arose from one cell or a group (cluster) of cells. Expressing the results as colony forming units reflects this uncertainty. It is noted that a number of colonies normally is a round number; therefore 0.1 cfu/gram product may also be indicated as 1 cfu/10 gram product.
In specific embodiments, an amount of the herbs in the mixture, relative to a total amount of the raw meat material and the additives in the mixture is selected from the range of 0-2 wt%, such as selected from the range of 1-1.5 wt%. The amount of herbs relative to the amount of the raw meat material and the additives may for instance be selected to be equal to or less than 1.5 wt%, such as equal to or less than 1.25 wt% (relative to the total amount of the raw material and the additives). The amount of herbs is especially selected to be larger than 0, such as at least 0.5 wt%, especially at least 1 wt% relative to the total amount of the raw meat material and the additives. Yet, in embodiments, the amount of herbs in the mixture is selected to be zero. The herbs may be selected to comprise less than 10 cfu (non-proteolytic) C. botulinum and less than 10 cfu B. cereus spores per gram of herbs.
Furthermore, an amount of the spices in the mixture, relative to the total amount of the raw meat material and the additives in the mixture may be selected to be equal to or smaller than 1 wt%, especially equal to or smaller than 0.5 wt%, such as selected from the range of 0-0.3 wt%. In further embodiments the amount of the spices in the mixture, relative to the total amount of the raw meat material and the additives in the mixture may be selected from the range of 0.1-0.2 wt%. The spices may be selected to comprise equal to or less than 50 cfu (non-proteolytic) C. botulinum and equal to or less than 50 cfu B. cereus spores per gram of spices,
An amount of the vegetables in the mixture, relative to the total amount of the raw meat material and the additives in the mixture may further be selected from the range of 0-30 wt%, such as 0-25 wt%. For instance, the mixture may comprise no vegetable. In further embodiments, mixture comprises 5-10 wt% or 6-25 wt% vegetables (relative to the total amount of the raw meat material and the additives). Especially, the mixture may comprise 9-25 wt% vegetables (relative to the total amount of the raw meat material and the additives). The vegetables are especially selected to comprise less than 1 cfu (non-proteolytic) C. botulinum and less than 1 cfu B. cereus spores per gram of vegetables.
The amount of raw meat material in the mixture relative to the total amount of the raw meat material and the additives in the mixture is especially selected from the range of 65-99.9 wt%, such as 70-99.5 wt%, even more especially 72-99 wt%. In embodiments, the amount of raw meat material in the mixture is selected to be at least 90 wt% relative to the total amount of the raw meat material and the additives.
Raw meat material may require proper handling, such as according to good manufacturing practice regulations to fulfill the requirement of less than 1 cfu per 10 gram of raw meat material. Also, for vegetables the less than 1 cfu/g level may be achieved by good manufacturing practice, since the incidence of spore formers in vegetables is low.
The amount of equal to or smaller than 50 cfu C. botulinum and equal to or smaller than 50 cfu B. cereus per gram of spices may not be met using untreated spices. For instance, for B. cereus of 500 cfu/g spices may normally be found. Furthermore, untreated herbs may (also) comprise over 10 cfu C. botulinum and 10 cfu
B. cereus per gram of herbs. Hence, specific spices and herbs may have to be selected to fulfill the requirement. The herbs and/or spices may have been treated to lower the microbial load. The herbs and/or spices may be steam processed to obtain such amount of cfu C. botulinum and B. cereus per gram of herbs and/or spices. The herbs and/or the spices may comprises steam treated herbs and/or spices (comprising said maximum cfii/gram).
The additives may comprise salt. Hence, the mixture may further comprise an amount of salt. The amount of salt may be (selected to be) equal to or less than 2.5 wt%, such as equal to or less than 2.0 wt%, or equal to or less than 1.5 wt% relative to the total amount of the raw meat material and the additives. In embodiments, the mixture substantially does not comprise salt. Yet in further embodiments, the mixture may comprise at least 0.5 wt% salt, such as at least 1.0 wt% relative to the total amount of the raw meat material and the additives. In further embodiments, the amount of salt relative to the amount of raw meat material and additives is selected from the range of 0-2 wt%, such as from the range of 1-1.5 wt%, especially 1.1-1.5 wt%. Salt may provide a reduced water activity to the meat product. For instance in an embodiment the mixture comprises 1.2 wt% salt, the water activity of the product may be equal to or less than 0.975. Furthermore, salt may provide an enhanced taste.
Herein, the term “salt” may relate to more than one (different type of) salt. The salt may comprise sodium chloride. Additionally or alternatively, the salt comprises potassium chloride. In embodiments, the salt comprises sea salt and/or mountain salt. The salt may be provided as a brine.
The mixture and especially also the meat product, substantially does not comprise nitrite, especially no nitrite provided by a nitrite and/or nitrate containing (curing) salt. The mixture, especially the meat product, may comprises less than 10 ppm, such as equal to or less than 8 ppm (of a total of nitrite and nitrate provided as a nitrite and/or nitrate containing salt to the mixture) (relative to a total weight of the mixture and/or the meat product).
As described herein, even without the addition of nitrites, a desirable shelflife may be obtained. Yet, in specific embodiments, the additives may comprise nitrate and/or nitrite containing natural resources or especially an extract (or fermented extract comprising nitrite) of such natural resources, especially allowing a further increase of the shelflife. Hence, in an embodiment, the additives comprise one or more additives selected from the group consisting of celery juice, celery powder, (swiss) chard juice, chard powder, wherein the meat product has a shelf life at a storage temperature of 7 °C of at least 42 days. Such meat product may comprise over 10 ppm such as 20-100 ppm nitrite. Especially, such meat product may comprise equal to or less than 50 ppm, such as equal to or less than 25 ppm, nitrite, (relative to the meat product).
In further embodiments, the mixture of meat material and additives is heated in a heating stage before high pressure processing. If the product is (only) treated by HPP, a safe product may be provided, having a juicy texture. Such product is less dry than a heat pasteurized product. Yet, the taste of such product may deviate from the taste and texture known to the consumer. Especially, such product is not a cooked product. Such product may be perceived as a raw product. Heating may provide a texture and taste common to the consumer. The heating stage may be performed at a lower temperature relative to normal heat treatment processes used in the production of meat products. The heating stage may comprise a mild heating process such as heating the mixture to a temperature selected from the range of 40-50 °C. Yet the temperature may also be selected from the range of 50-70 °C, such as 50-65 °C. The temperature may especially be selected for heating the mixture to a target core temperature. The target core temperature may e.g. be selected from the range of 45-70 °C, such as 50-65 °C. In embodiments, the target core temperature is selected from the range of 45-55 °C. The target core temperature may be selected based on the raw meat material. In a specific embodiment, the target core temperature is 62 °C ± 2 °C.
Hence, in embodiments, the method further comprises a heating stage configured between the mixing stage and the high pressure processing stage. The heating stage is especially a mild heating stage wherein the mixture of meat material and additives is heated to a target core temperature, especially selected from the range of range from 50-65 °C.
Heating to a target core temperature as described herein, will be understood by the skilled person as heating the mixture at a heating temperature until a core or center of the mixture reaches the target core temperature. Yet, in embodiments, heating may be continued after reaching the core temperature. If the heating temperature is substantially higher than the target core temperature, this may imply that the temperature in the core will further rise (relative to the target core temperature). This may provide overheating of the mixture. Therefore, in specific embodiments the heating temperature and the target core temperature are selected as being substantially the same temperature. As such, continuing heating may substantially not further increase the temperature in the core of the mixture. The heating may be continued for at a continue period of at least 1 hour, such as at least 2 hours, especially at least 6 hour. The continue period to continue heating may in embodiments be 48 hours. In further embodiments the heating may be continued for a continue period equal to or less than 36 hours, such as equal to or less than 24 hours, especially equal to or less than 12 hours. A difference between the determined external temperature and the target core temperature may e.g. be selected from the range of 1-10 5 °C, such as being equal to or less than 5 °C, especially equal to or less than 2 °C. Such process may especially be referred to as a mild heating process. In contrast to that, in prior art heating processes, the heating temperature (the temperature of the heating medium) may be substantially higher than the final core temperature. Before reaching the final core temperature, a substantial part (especially the major part) of the meat product is heated to a higher temperature than the required core temperature. Heating may e.g. be performed using steam as heating medium, or with a temperature of at least 20 °C, such as at least 30 °C higher than the required core temperature.
Hence, in embodiments, the heating stage comprises heating the mixture with a heating medium at a determined external temperature, wherein a difference between the determined external temperature and the target core temperature selected to be equal to or less than 5 °C, especially equal to or less than 2 °C, and especially wherein the heating is continued (at the determined external temperature) for a continue period after the mixture is heated to the target core temperature, especially wherein the continue period is selected from 1-48 hours.
In the heating stage, the mixture may set. The set mixture may further be sliced, and/or portioned before the high pressure processing. Hence, the method may further comprise portioning and/or slicing the (set) mixture of meat material and additives after heating the mixture and before the high pressure processing stage.
Alternatively or additionally heating the mixture of meat material and additives may also be configured during the pressure treatment. The method may e.g. be configured for providing the temperature of the treatment liquid during the treatment period at a determined temperature, such as equal to or, e.g., 10 °C larger than the target core temperature. The temperature of the treatment liquid may be controlled by the initial temperature of the treatment liquid, the temperature of the processing equipment used for performing the HPP treatment, and the treatment pressure. Furthermore, the temperature of the treatment liquid during the treatment period may control the temperature of the mixture. Hence, the method may further be configured for heating the mixture to the target core temperature in the high pressure processing stage during the treatment period.
Hence, the invention further provides a meat product obtainable by the method described herein, especially the meat product described herein. The meat product may be a non-cured and especially a clean label meat product. The meat product may have a shelf life of at least 18 days, such as at least 25 days, at a storage temperature of 7 °C. The meat product may in embodiments even have a shelf life of at least 42 days, especially at a storage temperature of 0-2 °C. The meat product may have a water activity equal to or smaller than 0.980 and a pH equal to or smaller than 5.9, especially smaller than 5.90. In embodiments, the meat product has a pH of equal to or lower than 5.6 and a shelf life of 30 days. In embodiments, the meat product comprise equal to or less than 50 ppm nitrite, such as equal to or less than 25 ppm nitrite, especially equal to or less than 10 ppm nitrite. The meat product especially has a pH equal to or more than 4.5, such as equal to or more than 4.6, even more especially equal to or more than 4.8, such as equal to or more than 5.0.
The terms ‘‘substantially” and “essentially” herein, such as in “substantially the same temperature” or in “substantially consists”, will be understood by the person skilled in the art. The terms “substantially” and “essentially may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjectives substantially and essentially may also be removed. Where applicable, the terms “substantially” and “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” includes also embodiments wherein the term “comprises” means “consists of’. The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term comprising may in an embodiment refer to consisting of' but may in another embodiment also refer to containing at least the defined species and optionally one or more other species.
Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.
The devices herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.
The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of a flow from the source of the flow, wherein relative to a first position within a flow flowing from the source, a second position in the flow closer to the source is “upstream”, and a third position within the flow further away from the source is “downstream”.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb to comprise and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article a or an preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.
Experimental
Growth of relevant microorganisms during chilled storage is modelled.
For that, several meat products have been prepared according to the recipes given in the next table and successively the pH and the water activity (aw) were monitored. 5 Successively, a risk assessment and different scenarios have been modelled in Combase to determine the shell life as a function of these parameters.
| Type of meat product | Ingredient | wt% |
| Pork chop | Meat | 98.7 |
| Salt | 1.3 | |
| Pork loin with cabbage | Meat | 88.8 |
| White cabbage | 10.0 | |
| Salt | 1.2 | |
| Pork cut off the shoulder with red beet | Meat | 89.9 |
| Beet juice | 9.0 | |
| Salt | 1.1 | |
| Bacon with red beet | Meat | 87.1 |
| Beet (sliced) | 11.8 | |
| Salt | 1.1 | |
| Pork neck cut | Meat | 98.5 |
| Salt | 1.5 | |
| Creamy bacon | Meat | 98.7 |
| Salt | 1.3 | |
| Fresh sausage with kale | Meat | 73.9 |
| Kale | 24.6 | |
| Pepper | 0.2 | |
| Salt | 1.3 | |
| Fresh sausage with celery root | Meat | 72.9 |
| Celery root | 24.3 | |
| Coriander | 1.5 | |
| Pepper | 0.1 | |
| Salt | 1.3 |
C omposition of the recipes; all meat products are pieces of pork except for the minced meat in the sausages, which is a mixture of pork and beef.
The production process started with the preparation of the products. All the products for the larger pieces were marinated/tumbled under vacuum for 24 hours. After that, they were heated in a water bath of 62 °C to a core temperature of about 6162 °C. Then they were placed at 7 °C to cool. They were HPP-treated (3 min at 600 MPa) and stored chilled (7°C), according to the next process steps:
1. Adding the additive including salt to the meat and vacuum packing the mixture; the salt is rubbed in the pieces; the raw meat material of the sausages are minced and mixed with the additives and stuffed in a natural casing and (only) vacuum packed after heating;
2. Marinating (resting), optionally tumbling for 24h at 4 °C of the larger pieces;
3. Heating at 62 °C during a heating time as depicted in the next table.
4. Cooling at 7 °C;
5. Repack in small portions;
6. 3 min HPP treatment at 600 MPa;
7. Storage at 7 °C
| Type of meat product | Heating time (hours) at 62 °C |
| Pork chop | 3 hours |
| Pork loin with white cabbage | 3.5 hours |
| Pork cut off the shoulder with red beet | 3.5 hours |
| Creamy bacon | 48 hours |
| Bacon with red beet | 48 hours |
| Pork cut neck | 3.5 hours |
| Sausages (cooked in the skin) | 1 hour |
Heating times to a core temperature of 60-62°C in the water bath of 62 °C pH and waler activity measurements
The measured values of pH and water activity during storage are shown in the next table. All values are an average of two measurements.
| Meat product | Day 0 | Day 14 | Day 30 | |||
| pH | aw | pH | aw | pH | a„ | |
| Pork chop | 5.75 | 0.978 | 5.82 | 0.983 | 5.92 | 0.977 |
| Pork loin (back) | 5.73 | 0.974 | 5.90 | 0.979 | 5.92 | 0.978 |
| White cabbage | 5.90 | 0.977 | 6.03 | 0.978 | 5.64 | 0.978 |
| Pork cut off the shoulder with red beet | 5.85 | 0.981 | 6.06 | 0.980 | 6.07 | 0.981 |
| Bacon | 6.00 | 0.980 | 6.15 | 0.984 | 6.32 | 0.979 |
| Bacon with red beet | 6.12 | 0.976 | 6.32 | 0.983 | 6.34 | 0.977 |
| Pork neck cut | 6.52 | 0.975 | 6.62 | 0.982 | 6.62 | 0.979 |
| Creamy bacon | 6.00 | 0.974 | 6.18 | 0.982 | 6.10 | 0.979 |
| Fresh sausage kale | 6.10 | 0.976 | 6.27 | 0.974 | 6.33 | 0.978 |
| Fresh sausage celery root | 6.01 | 0.967 | 6.22 | 0.975 | 6.25 | 0.979 |
Since growth of microorganisms is faster with higher pH and higher aw, for each type of meat product the highest pH and aw were selected for further modelling; which is a realistic but worst case scenario. In this risk inventory and evaluation, the microbial risks of the developed products are evaluated and possible control measurements are discussed.
The relevant microorganisms are B. cereus and non-proteolytic C. botulinum (see also above). Growth of these organisms during chilled storage is modelled and discussed below. For the modelling, the assumed start amount of pathogens in the products is 1 cfu/g (log 0.1 cfu/g). The number of days until the product is not safe for consumption anymore (Minimum Infective Dose) is calculated Growth during shelflife at 7 °C of the originally produced meat products.
The modelling shows that in the products pork neck and bacon with red beet dangerous levels are reached first. B. cereus leads to potentially dangerous products before non-proteolytic C. botulinum leads to potentially dangerous products, which means that growth of B. cereus is limiting for the shelf life. A 13-14 days’ shelf life can be achieved for the potentially most dangerous product (the product in which the minimum infective dose - MID- is reached first), i.e. the pork neck cut, without any adjustments in processing or ingredients. Other product, like the fresh sausages may have a shelf life of about 17 days without any adjustments. For the data, see the table given below in the section “Growth in the product by controlling the quantity of spores in the raw material”. Since there is little temperature control in the chilled chain at the consumer, this strategy is risky.
Growth in the original meat products, stored at a different temperature.
A minimum of 21-22 days’ shelf life can be achieved without any adjustments in processing or ingredients when the products are stored the first 8 days at 5 0-2 °C (for internal storage at the producer) and successively at 7 °C. Since there is little temperature control in the chilled chain at the consumer, this strategy is still risky.
Growth in the product wherein the pH of the original products is lowered.
The effect of lowering the pH with 0.3 units on the shelf life may increase the shelf life with at least 1 day. Lowering the pH with 0.2 units has no effect on the shelf life. The combination of lowering the pH to <5.90 and the water activity <0,980 may gain 3 days of shelflife.
Growth in the product by controlling the quantity of spores in the raw material.
The initial growth calculations are based on an initial concentration of 1 cfu/g (0.1 log cfu/g) of either B. cereus or C. botulinum spores in the newly produced meat products. Modeling the growth of the spores based on a reduction of the initial amount of pathogens in the products by a factor ten to 1 cfu/10 gram is shown that an extra 2 days (for the most risky products) to 6 days of shelflife may be gained.
| Product | Microorganisms | Time to MID (day) | Gain of shelf life (day) | |
| with 1 cfu/g | with 1 cfu/10 g | |||
| Pork chop | B. cereus | 16.2 | 18.2 | 2 |
| C. botulinum (non-prot.) | 21.2 | 25.5 | 4.3 | |
| Loin (pork) | B. cereus | 18.5 | 20.8 | 2.3 |
| C. botulinum (non-prot.) | 31.3 | 37.7 | 6.4 | |
| Cabbage | B. cereus | 18.6 | 20.9 | 2.3 |
| C. botulinum (non-prot.) | 32 | 38.5 | 6.5 | |
| Pork cut off the shoulder w. red beet | B. cereus | 16.3 | 18.4 | 2.1 |
| C. botulinum (non-prot.) | 22.2 | 26.6 | 4.4 | |
| Bacon | B. cereus | 14.1 | 15.9 | 1.8 |
| C. botulinum (non-prot.) | 14.9 | 17.9 | 3 |
| Red beet | B. cereus | 14.5 | 16.3 | 1.8 |
| C. botulinum (non-prot.) | 16.4 | 19.7 | 3.3 | |
| Pork neck cut | B. cereus | 13.8 | 15.5 | 1.7 |
| C. botulinum (non-prot.) | 16.5 | 19.9 | 3.4 | |
| Creamy bacon | B. cereus | 15.4 | 17.3 | 1.9 |
| C. botulinum (non-prot.) | 18.9 | 22.8 | 3.9 | |
| Fresh sausage Kale | B. cereus | 17 | 19.1 | 2.1 |
| C. botulinum (non-prot.) | 26.9 | 32.3 | 5.4 | |
| Fresh sausage Celery root | B. cereus | 16.9 | 19.1 | 2.2 |
| C. botulinum (non-prot.) | 24.3 | 29.2 | 4.9 |
Number of days storage at 7°C until the MID is reached for 1 cfu/g and 1 cfu/10 g start load and the gain in shelf life with a lower start load.
Growth during shelf life of the product packaged under a controlled atmosphere.
C. botulinum is an anaerobic microorganism that in general only grows when oxygen is absent. The germination of spores is generally less susceptible to oxygen inhibition than subsequent outgrowth. Spores of non-proteolytic C. botulinum type B germinated similarly under aerobic and anaerobic conditions. The presence of oxygen does not affect germination of C. botulinum, but it adversely affects subsequent stages that require active metabolism. Several studies report that toxin formation by C. botulinum can be as rapid or even more rapid in foods packed in air as under vacuum packaging or low-oxygen Modified Atmosphere Packaging (presumably because there is no oxygen in the food). Packaging under air or a similar oxygen-containing atmosphere therefore does not guarantee to slow or prevent toxin formation by nonproteolytic C. botulinum.
B. cereus is a facultative aerobic microorganism, i.e. it can germinate and grow under both aerobic and anaerobic conditions. Under anaerobic conditions, B. cereus displayed lower sporulation ability than under aerobic conditions. Spores produced under anaerobic conditions germinated more efficiently than spores produced under aerobic conditions. No data are available on the effect of oxygen level on the growth rate of B. cereus.
So, increasing the oxygen level in the packaging, by either increasing it during packaging or by using a packaging material with high oxygen transfer rate (OTR), may help to lower the growth rate of C. botulinum. It is not known what the effect is on the growth rate of B. cereus. Increasing the oxygen level in the packaging must always be combined with other measures to control the growth of C. botulinum.
By combining the different measures, shelf life may increase considerably. In the next table, a summary is given of shelf life extensions based on the different measures. The possible extension may depend on the product. Moreover, only the minimal modelled extensions are indicated. That means that the combination of all studied measures leads to a minimal shelflife of 26 days.
| Measure | Shelf life until the product is potentially unsafe and shelf life extensions (days) |
| No measures: unchanged products | 13 |
| Internal storage at 0-2 °C during 8 days | 8 |
| pH lowered to <5.90 and water activity <0.980 | 3 |
| 10-fold lower initial amount of pathogens | 2 |
| Total | 26 |
Summary of shelflife extension (calculated for products with shortest shelflife)
In order to achieve the low initial amount of pathogens in the meat products of 1 cell/10 g, the amount in the raw materials must be low. Based on the recipes and the modelling, the maximum allowable spore count in the raw material based on an initial concentration (1 cfu/g or 1 cfu/1 Og) of C. botulinum and B. cereus in 15 the end product (just after production) is depicted in the next tables:
| Ingredient | % of raw material in the recipe | Max allowed spore count for both B. cereus and non-proteolytic C. botulinum, to achieve | |
| 1 cfu/g in the product | 1 cfu/10 g in the product | ||
| Meat | 73-99* | <1 cfu/g | <0.1 cfu/g |
| Herbs | 1.5-24.5* | <100 cfu/g | <10 cfu/g |
| Spices | 0.1-0.2* | <500 cfu/g | <50 cfu/g |
| Vegetables | 9-12* | <10 cfu/g | <1 cfu/g |
| Maximum a | lowed amount of spores in raw material per ingredient, that achieve 1 cfu/ |
g or 1 cfu/10 g in the product; * Depending on the product recipe.
In herbs (coriander) and in vegetables (kale, red beet, celery root and cabbage) there are no literature data available on spore load. In meat, 1 cfu/g of 1 cfu/10 g of spores is the maximum load allowed based on calculations. There are no measured data on spore load in meat available. By heating at 62 °C and HPP treatment no inactivation of B. cereus spores occurs, so 1 cfu/g and 1 cfu/10 g are estimations for start concentration of spores.
Untreated herbs and spices do not meet the set specifications. In spices (black pepper), 500 cfu/g of spores are allowed (max). In literature the spore load of B. cereus found is <500 cfu/g and of C. botulinum is <1000 cfu/g. A 1 or 2 log inactivation may be obtained by steam treatment to meet the requirements mentioned in the table. Steam treatment as offered by herb and spices supplier can provide steam treated herbs and spices with a <100 cfu/g count for B. cereus spores. That is sufficient to fulfil the set raw material specifications.
Since the spore incidence in meat products is low, it can be assumed that the 1 cfu/ 10 g level can be achieved. It is assumed that the 1 cfu/g level in vegetables can be achieved by good manufacturing practice, since the incidence of spore formers in vegetables is low.
Based on the analysis it is concluded that in order to achieve 1 cfu/10 g final product it may be required to: meat: proper selection, no additional treatment necessary; vegetables: proper selection , no additional treatment necessary; herbs and spices: treatment is necessary. A steam treatment that may be offered commercially (or commercial treated herbs and spices) is sufficient.
Further experiments
A further series of products was produced using the ingredients listed in the following table:
| Ingredient / product | pH |
| Lean meat | 5.9 |
| Fatty meat | 5.7 |
| Dried bell pepper | 5.2 |
| Bell pepper with minced meat | 5.6 |
| Dried champignon mushroom | 6.0 |
| Mushroom with minced meat | 5.9 |
| Dried cabbage | 5.9 |
| Cabbage with minced meat | 5.9 |
Meat products and ingredients used in the further experiments, and their respective pH
From the ingredients, Bratwurst (based of minced meat) was produced in the variants Bratwurst Bell pepper, Bratwurst Cabbage and Bratwurst Mushroom. The microbial shelf life was studied by monitoring the total plate count, the aerobic spore count, and the Enterobacteriacea counts. Analysis were performed on days 2, 7 and 14 is in 3-fold. Analysis on days 20, 24 and 28 is in 5-fold.
The results show that total plate count is stable (at about 3 log cfu/g) for the bratwurst with bell pepper and with cabbage. Total plate count in bratwurst with mushroom increases over time but is still acceptable after 24 days (having a mean total plate count of about 4.5 log cfu/g). The aerobic spore counts range between log 1 and log 2 cfu/g in the products and do not change much over time. Enterobacteriacea counts were below detection limit in nearly all samples.
These results show that the developed three recipes with pH 5.6 may easily achieve 30 days of shelflife without microbial spoilage. Mushroom recipes with pH 5.9 are still acceptable after 28 days, but are near the end of their shelflife. Cabbage recipes may easily achieve 30 days. The difference may be caused by a difference in water activity of the product. No aw measurements have been performed. The aw of the cabbage sample may be lower than the one of the mushroom, causing the difference in growth speed of microorganisms.
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| US20130059037A1 (en) * | 2010-03-04 | 2013-03-07 | Deutsches Institut Fur Lebensmitteltechnik E.V. | Method for controlling product characteristics in the production of foodstuffs |
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| EP0668026A1 (en) * | 1994-02-17 | 1995-08-23 | Societe Des Produits Nestle S.A. | Low salt and/or low phosphate sausages manufacture |
| US20130059037A1 (en) * | 2010-03-04 | 2013-03-07 | Deutsches Institut Fur Lebensmitteltechnik E.V. | Method for controlling product characteristics in the production of foodstuffs |
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| BEGONYA MARCOS ET AL: "Evaluation of high pressure processing as an additional hurdle to control Listeria monocytogenes and Salmonella enteritica in low-acid fermented sausages", JOURNAL OF FOOD SCIENCE,, vol. 70, no. 7, 1 January 2005 (2005-01-01), pages M339 - M344, XP002555372, DOI: 10.1111/J.1365-2621.2005.TB11477.X * |
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