IES67884B2 - Process for tenderising meat - Google Patents

Abstract

A process for tenderising meat comprises injecting a proteolytic enzyme, preferably papain, into the interior of the meat from an array of injection needles so that the enzyme is substantially uniformly distributed throughout the meat. The enzyme may be dispersed in a briny curing solution to yield a cured, tenderised product. During cooking, the enzyme exerts its tenderising activity when the temperature at which it is active is reached. Cooking may be continued until the inactivation temperature of the enzyme is reached or alternatively, when a desired degree of tenderness is obtained, further proteolytic activity may be terminated by cooling the meat rapidly to a temperature at which no enzymatic activity occurs. The process enables uniform tenderisation of larger joints of meat to be achieved. Fig. 1

Description

PROCESS FOR TENDERISING MEAT The present invention relates to a process for tenderising meat and in particular to one in which enzymes are used to reduce the toughness of the meat.

Several factors contribute to the toughness of a cut of meat. These include the contractile state of the muscle at the time of development of rigor mortis, the function of the particular muscle and the age and history of the animal. Muscles tend to contract on death, contributing to toughness as contracted muscles are tougher than relaxed ones. This is often counteracted by hanging the carcass after slaughter to extend the muscles. Storing meat for a time also allows the tenderising action of naturally occurring proteolytic enzymes such as calciumactivated- factor to proceed.

Significant contributions to meat toughness arise from the connective tissue present in and about the muscle bundles and whole muscle. Meat derived from older animals and meat from active muscle such as leg (as opposed to support muscle such as loin) tends to contain relatively more connective tissue and therefore is tougher than meat with relatively less connective tissue.

Tougher cuts of meat can be tenderised by mechanical treatment to disrupt the connective tissue. As the connective tissue comprises primarily protein (collagen), tenderising can also be achieved by the application of proteolytic enzymes to meat. Proteolytic tenderisation is limited to smaller cuts of meat such as steaks and cubed meat as it is effective only insofar as the enzyme can be applied to the meat surface and diffuse throughout the meat. To assist the distribution of the enzyme, the 567884 surface of the meat can be needled prior to the application of enzyme (either dry or in solution). It will be appreciated that uneven distribution of applied enzyme in the meat will lead to a product having a relatively tender exterior but a relatively tough interior and that such products are commercially unacceptable.

Thus, in the past, it has not been possible adequately to tenderise larger cuts of meat such as roasting or boiling joints, as tenderising enzyme could not be reliably introduced to the interior part of the joint.

One approach to this problem was the introduction of tenderising enzyme into the bloodstream of the animal prior to slaughter, allowing the blood to carry the enzyme to the target muscles. However, such practice has been banned for some time.

Accordingly, there is a need for an efficient means of tenderising meat, especially meat joints and it is an object of the invention to provide such a method.

Accordingly, the present invention provides a process for tenderising meat comprising injecting a proteolytic enzyme into the interior of the meat from an array of hollow injection needles so that the enzyme is substantially uniformly distributed throughout the meat and cooking the meat for a sufficient time and at a sufficient temperature to enable the enzyme to exert a tenderising activity on the meat. The process of the invention is particularly suitable for tenderising larger joints of meat, the interiors of which cannot be tenderised by the application of proteolytic enzyme to the surface of the meat.

The enzyme, which is preferably delivered to the meat as a suspension or in solution, may be selected from any of the group comprising papain, ficin, bromelin, Neutrase (Trade Mark) and Alcalase (Trade Mark). Preferably, the proteolytic enzyme is papain and the meat is injected with between 2500 and 6000 USP - Units papain/Kilogram meat, most preferably between 3000 and 4000 USP - Units/Kilogram meat.

The cooking time is-preferably adjusted to ensure that it is sufficiently long to enable the internal temperature of the meat to rise at least to that at which the enzyme is inactivated. In the case of papain therefore, it is advantageous that the internal temperature should reach at least 82°C.

In a most preferred embodiment, the process is a combined process for curing and tenderising meat, the proteolytic enzyme being suspended or dissolved in a curing solution. The enzyme-containing curing solution is injected into the meat at an amount of between about 15% and 20% weight per weight meat.

The invention also extends to a fresh or cured meat prepared by the process of the invention.

Exemplary processes for tenderising joints of meat will now be described in the examples below. The process is suitable for tenderising tough joints such as collar meat and other joints whose toughness renders them unacceptable for human consumption as roasting or boiling joints.

Thus, the process renders marketable as table joints cuts of meat which would otherwise only be suitable for cooking by stewing and other long-cooking methods, or for animal feeds. It can be used for tenderising both fresh meat joints, for example pork, mutton and beef, and cured cuts, such as ham and bacon meats. Most advantageously, the process can be used as a combined tenderising and curing process, the curing solution (usually brine) being used as a vehicle for carrying the enzyme into the meat.

EXAMPLE 1 This example describes a combined process for curing and tenderising a pork lap joint to produce a ham joint.

A solution of brine, comprising 20% NaCl, 300 parts per million (ppm) NaN02 and 200 ppm NaNO^ was prepared. The purpose of the brine is to cure the meat.

A stock solution of papain (MERCK) containing 3.2 g/1 water was prepared. The activity of the papain was 30,000 USP - Units/mg. The stock solution of enzyme was then diluted with the brine at 0.22, 0.33 and 0.44 mis enzyme solution/litre brine. Each brine/enzyme solution was then used for injection into a joint of meat, namely lap muscle, using a Belam Injector M1602 machine. The machine carries an array of 230 hollow injection needles fed from a reservoir of the brine/enzyme solution. The needles were sunk throughout the full dept of the joint to either side of the bone, steadily injecting brine/enzyme solution into the muscle mass during their travel through it.

Thus, the enzyme solution was distributed substantially uniformly throughout the full thickness of the joint. The injection rate was regulated so that during this procedure, the joint took up 15% of its pre-treatment weight of brine/enzyme solution. On completion of the injection and withdrawal of the needles, the joint was tumbled to optimise the distribution of the enzyme throughout the meat, then transferred to a maturing tank containing the brine described above in this Example and held at 4°C for 2 days. The joint was then drained to remove excess fluid and vacuum packed. Joints were held for periods of between 1 and 5 weeks under refrigerated conditions, then cooked slowly at 70°C for 5 hours for a 5kg joint in an oven. The oven was not preheated. The tenderness of the cooked meat was measured on a Warner Bratzier Shear instrument. Control experiments omitting the papain were also conducted. The shear instrument measures tenderness as resistance to cutting, expressed in kilograms, using a blade speed of 100mm/min and a meat core size of 12mm. For the control sample a cutting force corresponding to 1.59kg was required. The figures for the sample injected with 0.22 mis enzyme solution/litre brine was 1.1kg and for the 0.44 ml enzyme solution/litre brine was 0.8kg.

On tasting, the meat which was injected with the brine solution containing 0.22 mis enzyme solution/litre brine was very acceptably tender after cooking. On the other hand, use of the 0.44 ml enzyme/I brine solution resulted in a product which after cooking was over-tender and of quite a mushy consistency.

There was no significant tenderness difference between the comparable meats held for 1 and 5 weeks after injection of enzyme. This is as expected as the papain is inactive at the refrigerated temperature at which the meat was held.

During the cooking process, as the temperature of the meat rises, the papain enzyme becomes increasingly active until its optimal activity is reached. As the optimum temperature is passed, the enzyme steadily loses activity.

Above about 82°C, papain is inactivated. In cooking the meat, it is important to avoid over-tenderisation of the meat by either (a) allowing the internal temperature of all part of the joint to rise to above 82°C to ensure that all the enzyme is inactivated or (b) rapidly chilling the meat after cooking so that the internal temperature falls back quickly to a temperature at which the enzyme has no proteolytic activity.

Example 2 50kgs collar meat was injected with the standard brine as used in Example 1 at an 18% take-up injection rate. At the same time 50kgs collar meat was injected with the brine plus 0.22ml papain solution/litre brine used in Example 1.

The injected meat was left to cure overnight at 4-6°C before being packed into plastic film on a Placenta machine and then cut into individual joints with a knife, vacuum packed, boxed and stored at 1-2°C for 19 days. The Placenta machine packs the meat into an open ended sleeve which serves to shape the meat and retain it in the given shape.

Some joints were removed from the chill cabinet for analysis.

The numbers of contaminants, salt content and sodium nitrite levels were assessed.

Total viable counts/gram Conforms/ gram Staphyloccus/ gram XSalt ppm NaNitrite Standard Joint 1 896000 40 3680 2.8 72 Standard Joint 2 92800 0 280 2.6 68 Tenderised Joint 1 24000 30 1680 2.5 70 Tenderised Joint 2 24000 0 580 2.7 72 1kg samples of both types of joints were removed from their outer packing, placed into boiling water and allowed to simmer for 2.5 hours before being sliced and tasted.

The enzyme treated product was selected by tasters as being more tender than the standard collar joint product. It was also noticed that the centre of the enzyme treated product was not as tender as the outside of the joint.

The penetration of the heat to the middle of the joint would take longer than to the external areas and thus the enzyme would have been more active on the external surfaces of the joints.

The shear test results were obtained as described in Example 1 and were as follows: Enzyme treated sample 1.8kg Control 1.9kg It is thought from this example that cooking the joint by immersion in boiling water is a less efficient way of achieving tenderisation.

EXAMPLE 3 A batch of collar joints were injected with the brine plus the papain of Example 1 (0.22 ml enzyme solution/litre brine) and left in the chill cabinet at 4°C overnight. A batch without the papain was prepared as a control.

The above injected collar joints were filled into plastic sleeves on the Placenta machine, cut into approximately 1kg joints, vacuum packed, boxed and sent to the chill cabinet for overnight storage.

Then, one of the enzyme treated joints and one of the untreated joints were weighed before being placed into a saucepan of cold water and left on the cooker at low heat. The joints were left in the vacuum bags with the vacuum bags pierced in a few places with a knife in order to allow the steam generated within the bags during cooking to escape. The water temperature and the product core temperature was measured by means of an alcohol thermometer every five minutes. The internal temperature of the meat compared to the cooking water temperature as a function of time is shown in Table 1 and Figure 1. The product was left cooking for 2.75 hours before being removed from the water, reweighed and tasted. Samples of the cooked products were tested on the Warner Bratzier Shear instrument as described in Example 1 .

TABLE 1 Cooking Profile Results: Time (Mins) Water Temp (°C) Meat Core Temp 0 25 5 5 35 5 10 45 5.5 25 15 56 7.5 20 66 10 25 73.5 12.5 30 80 14.5 35 84 17 30 40 88 20 45 91 .5 23.5 50 96 27 55 98.5 31 .5 60 100 35.5 35 65 100 40 TABLE 1 COntd.

Time (Mins) Water Temp (°C) Meat Core Temo (°C 5 70 100 44.5 75 100 48.5 80 100 52.5 85 100 56 90 100 60 10 95 100 63.5 100 100 66.5 105 100 69.5 110 100 72 115 100 74 15 120 100 76.5 125 100 78.5 130 100 80.5 135 100 82 140 100 83 20 145 100 84 150 100 85.5 155 100 86 160 100 87 165 100 88 25 Results:- Enzyme %Cooking Control Treated Loss 30 Weight before cooking (kgs) 1.155 .845 26.8 Weight after cooking (kgs) .956 .684 28.5 The enzyme treated product was found to be very tender when tasted by a number of regular product tasters as compared to the control product.

Shear Test Results:5 These results are the average of 10 samples in each case, sampled randomly throughout the joint. The resistance to the blade cutting the meat is measured and expressed in kgs Blade speed equals 10Omm/min, with a 12mm meat core size.

Enzyme treated sample Control sample 1.38kgs 1.809kgs This experiment demonstrates that a very acceptable, tender joint can be obtained when the meat is cooked gradually from cold, with the meat being immersed initially in cold water. The internal temperature of the meat is raised above 82°C after cooking for 140 minutes, ensuring that the papain is inactivated so that further enzyme activity which might result in over-tenderisation of the meat is avoided. Cooking could thus have been terminated after 140 minutes with no adverse affects on the quality of the meat. Once the internal temperature has reached about 70°C, the meat is cooked so as to be ready for human consumption. Accordingly, the cooking could also have been terminated after about 110 minutes, provided that the meat was then chilled rapidly so as to bring its temperature down to a level at which the papain enzyme is inactive.

Example 4 A joint of fresh beef was injected with a solution of papain in water, the enzyme concentration being adjusted to deliver 3000 USP - Units enzyme/kilogram beef at an injection rate of 3% weight per weight meat. A low injection volume was necessary to maintain the fresh character of the meat. The joint was then cooked from cold in a moderately cool oven, which was initially unheated, until the internal temperature of the meat exceeded 82°C. The so-cooked joint was found to be very acceptably tender and more tender than a similarly treated control sample.

While the invention has been described above in the 10 examples using papain as the tenderising enzyme it will be appreciated by those skilled in the art that any suitable enzyme for meat tenderising can be used in the process of the invention. Suitable such enzymes include ficin, bromelin, Neutrase (Trade Mark) and Alcalase (Trade Mark) (both supplied by Novo Industrie A/S).

If the meat is not to be cooked for long enough to allow the internal temperature to exceed the temperature of inactivation of the tenderising enzyme being used, then the meat should be left in the cooking environment at a temperature and for a time sufficient to allow the desired degree of tenderness to be developed, then removed and chilled rapidly to a temperature at which the enzyme has negligible proteolytic activity. This is to ensure that the meat does not become over-tender.

In the production of cured, tenderised joints, the meats will normally be prepared, injected with the enzyme/curing solution, packed, chilled for about two days at about 4°C, then dispatched for sale. The normal shelf life of such meats is usually given as 4 weeks after the packing date. As shown in Example 1 herein, negligible loss of papain activity occurs over this period.

It will of course be understood that the invention is not limited to the specific details described herein, which I are given by way of example only, and that various modifications and alterations are possible within the ♦ scope of the invention.

Claims (5)

CLAIMS :

1. A process for tenderising meat comprising injecting a proteolytic enzyme into the interior of the meat from an 5 array of injection needles so that the enzyme is substantially uniformly distributed throughout the meat and cooking the meat for a sufficient time and at a sufficient temperature to enable the enzyme to exert a tenderising activity on the meat.

2. A process according to claim 1 including continuing the cooking for a time sufficient to allow the internal temperature of the meat to rise to at least that at which the enzyme is inactivated.

3. A meat product comprising a meat joint into the interior of which is injected a proteolytic enzyme from an array of injection needles, the enzyme being substantially uniformly distributed throughout the meat so that on cooking the meat for a sufficient time and at a sufficient temperature, the enzyme is enabled to exert a tenderising activity on the meat.

4. The invention according to any of the preceding 25 claims in which the proteolytic enzyme is selected from one or more of papain, ficin, bromelin, Neutrase and Alcalase, and preferably comprises papain, and optionally in which the enzyme is suspended or dissolved in a curing solution.

5. A process for tenderising meat or a tenderised meat product, substantially as herein described in the Examples.