Test for tenderness at the slaughterhouse

Janne Brodin (English translation Ane Skjelfjord)

If beef could be sorted for tenderness at the slaughterhouse, consumers could be spared a lot of tough steak. Achieving this is one of the goals of genetics scientist Laila Aass in the project “More and better beef”.

She is currently testing two instruments that may provide an easy, low-cost and efficient way of mass testing carcasses for tenderness.

Laila Aass Photo: Janne Brodin

Through testing each individual carcass for tenderness, and deciding its fate as either steak or hamburger, Norwegian beef could improve its reputation as steak material. There is large variation in tenderness between cattle families. The “toughest” sires have a large proportion of “tough” sons, and the “tender” sires have a large proportion of “tender” sons. But – since tenderness has not, up until now, been emphasized in the breeding program, whether the beef you buy is tender or tough is a toss-up.

- If we could weed out the “tough and chewy” sons, we could have spared consumers a lot of tough steak, says Laila Aass.

The work of mapping and measuring tenderness has been split into two projects, and is part of the research called “More and better beef”. Geno is project leader, with Tyr and Nortura as partners. The Research Council of Norway is a financing partner.

Mapping characteristics for tender meat
Mapping genetic variation in meat characteristics of Norwegian Red was carried out in a project in the period 2001 to 2007. 700 bulls from Geno’s test station at Øyer were examined for tenderness using Warner-Bratzler carving resistance, which is a method for mechanical measuring of tenderness that approximates human appreciation of tenderness very closely. The amount of intramuscular fat was mapped along with the activity of enzymes involved in the tenderizing process.

Clear variations in tenderness
Along with a clear genetic variation in tenderness between Norwegian Red families, Aass found genetic correlations between tenderness, colour and intramuscular fat or marbling, and the activity of the tenderizing enzymes.

What the enzymes do is they cut the muscle fibres. If the enzymes are really active during the tenderizing process, we experience the beef as more tender.

- The results from this basic project gave us the information we needed in order to evaluate whether this was worth pursuing, says Aass.

We need a simple, low cost, efficient measuring method
In order to address this in the breeding plans, we need to be able to measure tenderness in a low cost and efficient way on a large number of animals.

- The methods used in the basic project are laboratory methods, which are both too expensive and too comprehensive to be used in a large scale practice. It is necessary to find a simpler and cheaper method.

Testing measuring methods in traditional productions
To get a realistic product and results that can be used in traditional productions, the new project makes use of commercial slaughter bulls from ordinary livestock herds. Two NIR instruments are being tested. NIR are analysis methods that take advantage of the qualities of infrared light.

One of these is an American made measuring instrument (QualitySpec(R)BT) where the documentation shows that the equipment distinguishes between tender and tough carcasses with quite a high degree of accuracy. Photo: Janne Brodin

-This instrument has been developed for American carcasses. It remains to be seen how it will work with our animal material. American animal material is very different from ours. The carcasses have more marbling due to feeding regimes and the use of castrates rather than bulls, says Aass.

The second instrument is developed by Nofima Mat in cooperation among others with Sintef. The prototype measures meat in depth, whereas the American instrument measures reflections on the surface.

The results can be used both in the slaughterhouse and for breeding purposes
If the measuring methods work as expected, they can be used for routine measuring in the slaughterhouse, and Geno can use the information in their selection program.

The experiment is conducted using 600 bulls from 25 hand picked NFR (Norwegian Red) elite sires from 7 livestock herds. By individual recording and detailed relationship information, heritability and genetic correlations may be estimated. In addition to that, all the other parameters of the breeding work are included.

- As well as looking into the characteristics we have been examining in the basic project, we will relate the figures from the instrument to the meat quality parameters measured in the lab.

- Whether the instruments work well enough that we can really find variations, and whether they will actually distinguish between tough and tender carcasses we do not know as yet, says Aass, who awaits the results eagerly.

Intramuscular fat or marbling is highly inheritable, meaning that the characteristic is very likely to be inherited, and it is a parameter which is presumed to reveal quite a lot about meat tenderness. Therefore, marbling may be an efficient parameter in the breeding program.

- The more marbling, the more the meat seems to be perceived as tender. There is also a larger chance that the marbled than the non-marbled steak is tender, says Aass.

As yet no selection for tenderness
It is mainly milk yield and characteristics related to fertility and health that are being stressed in the selection program for cattle. Breeding for meat quality accounts for only six per cent of the total breeding goal, and is based on growth and carcass grading.

Large variations in tenderness is a good reason for selection
To be able to avoid “tough” sires, it is a prerequisite that there be variation in the animal material. In the first basic project, with 47 bull sires, it turned out that the “toughest” sires had 34 % “tough” sons, whereas among the “tender” sires only 14 % were “tough” sons.

Photo: Laila Aass

- If we had disregarded the other breeding parameters, concentrated solely on tenderness and used the “tender” sires for breeding, we could have reduced the share of tough and chewy meat coming on the market by a significant amount, says Aass.

As a consumer, there’s something you can do
When next you buy a beefsteak in your local shop, you would do well to choose a marbled cut. Do pay attention to the difference between connective tissue and marbling.

It’s not all one
Rule of thumb: Fat at the edges of the steak is “waste fat”, whereas marbled fat is “taste fat”.

According to genetics scientist Aass, the cut to the right is more likely to be tender, because it contains more marbled fat than the cut to the left. Photo: Janne Brodin

- We have been cooperating with the Americans on this project, and they shake their heads at the lean cuts we Norwegians pour litres of Béarnaise sauce over. They figure their beefsteaks are so juicy that they don’t need any sauce at all. A properly marbled steak doesn’t feel fat and is really tasty, concludes Aass, who has been paying close attention to her choice of meat cuts during the grilling season.

Updated: 20.08.10
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