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Research – for Feb. 14, 2011

Tenderness is one of the key factors affecting beef eating quality. A 10 per cent improvement in tenderness will increase eating quality by more than a 10 per cent improvement in either flavour or juiciness. Youthful beef is more tender than cow beef, but there is no easy way to know whether one youthful carcass will be better than another.

Canada’s National Checkoff has supported two Canadian Retail Beef Satisfaction surveys. In each study, over 1,000 consumers were given a top sirloin, strip loin, boneless cross rib or inside round steak to cook and eat at home. As expected, more consumers were satisfied with the tenderness of the top sirloin and strip loin than with the boneless cross rib and inside round. Overall consumer satisfaction with beef tenderness increased from 68 per cent in 2001 to 75 per cent in 2009, but the fact that a quarter of consumers are not satisfied indicates that there is still considerable room for improvement.

Differences in consumer satisfaction among different cuts of beef are largely explained by two components of muscle. One is the muscle fibres, and the other is the gristle (connective tissue, primarily collagen).

Like ropes, muscles are made up of many long, fine strands. Ropes weaken when the individual strands are stretched and begin to tear apart. This also happens in a hanging carcass; the weight of the carcass pulling on the muscles helps to stretch and weaken the muscle fibres. As a carcass ages, natural enzymes further degrade the muscle, and make beef still more tender.

But if some of the fibres in our rope are elastic, the rope will have higher tensile strength, and the stretching will be reversible. A similar thing happens in muscles with high collagen content. Even if the muscle fibres are weakened by stretching and enzymatic action, much of the collagen will still be intact when aging is complete.

The challenge is that every carcass has muscles with both high and low collagen content. Muscles that work harder have more collagen. For example, the muscles in the neck and shoulder are carrying the head around whenever the animal is awake. The high collagen content of these muscles makes their job easier, but also makes the beef tougher. An interesting exception to this is the infraspinatus muscle (flat iron steak) that lies just underneath the shoulder blade. It escapes the heavy lifting, has very little collagen, and is one of the most tender muscles in the beef carcass. Hind leg muscles work when the animal moves, but not when the animal is resting. So they have an intermediate collagen content and intermediate tenderness. The ribeye and loin muscles mainly keep the spine aligned and help the animal turn corners, so they have still less collagen and are usually tender.

Collagen levels determine how beef should be cooked. Low-collagen strip loins and sirloins can be fried, grilled, broiled or roasted. The higher-collagen boneless cross rib and inside rounds need to be marinated or slow cooked. Marinades with natural acids or plant enzymes can degrade collagen, and slow cooking with moist heat converts collagen to softer gelatin. The challenge is that many people don’t like to read instructions. In the 2009 Canadian Retail Beef Satisfaction study, consumers followed recommended methods for cooking the boneless cross rib and inside round less than 10 per cent of the time, then blamed the beef (not the cook) 80 per cent of the time for not turning out perfectly.

So how can we provide consumers with a product that is more cook-proof? Aging is one approach, but it doesn’t help every cut. This has been shown by industry supported research carried out by at Agriculture and Agri-Food Canada’s Lacombe research station. These studies were published in 2004 and 2010, and reported that aging for three weeks instead of one week improved the tenderness of the ribeye (striploin and top sirloin) by 10 to 15 per cent, but did not improve the tenderness of the higher-collagen cuts from the round and chuck. A 2006 study done by Gruber and others also reported that aging select-grade beef for three weeks instead of one week was of more value for the ribeye (24 per cent improvement) than the inside round (18 per cent improvement) or chuck muscles (12 per cent improvement).

This means that other approaches are needed to improve the tenderness of tougher cuts from the chuck and round. Grinding is an obvious approach. Tough hamburger is hard to find, but ground beef is not a premium product. Blade or needle tenderization is another approach. In this technique, small blades or needles are used to pierce the steak or roast. This improves tenderness by making small cuts through the muscle fibres and connective tissue. A Beef Science Cluster project at the University of Alberta will examine whether needle tenderization can be combined with naturally occurring collagen-specifienzymes. If successful, processors and retailers could sell consumers a pre-tenderized and pre-marinated product that the consumer is more likely to cook properly.

ReynoldBergenisthesciencedirectorofBeefCattleResearch Council.

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Overall consumer satisfaction with beef tenderness increased from 68 per cent in 2001 to 75 per cent in 2009

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Dr. Reynold Bergen is the science director of the Beef Cattle Research Council.

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