Beef with reasonable marbling and juicy taste is preferred among consumers, and industry leaders continue to monitor how to consistently produce a product with these traits. A recent research article addresses the biology and biochemistry of beef marbling and its effects on production systems, carcass and fat quality.
“We need fat in beef to improve the eating experience,” said Dr. Stephen Smith, a Texas A&M AgriLife Research scientist and Regents Professor in the department of animal science at Texas A&M University. “We can increase the fat and marbling throughout the production cycle, but for many years there’s been this perception among consumers that too much fat in ground beef isn’t a good thing. Against conventional wisdom, ground beef of all kinds actually is healthy for you.”
Smith teamed with Dr. Brad Johnson, Gordon W. Davis Regent’s Chair in the department of animal and food science at Texas Tech University, to co-author a paper, “Marbling: Management of cattle to maximize the deposition of intramuscular adipose tissue.”
The research was funded by the National Cattlemen’s Beef Association Beef Checkoff Program and can be found online at http://bit.ly/1EwH8x6.
“In our research, we examined young cattle just before they marbled, and were primarily looking at genes related to fatty acid composition,” Smith said. “We’ve always had a strong interest in the monounsaturated fatty acid, oleic acid, which is abundant in olive oil and is a healthful fatty acid. We start out the marbling article relating how increasing the amount of fat in beef is definitely related to palatability. So we want to increase the fat content to a certain level to provide a good eating experience.”
In the research article, Smith and Johnson discuss how as more cattle fatten and put down marbling, the fat becomes healthier because there is a replacement of saturated fats with oleic acid.
“We are very interested in that,” Smith said. “What are the cellular processes that regulate this very natural increase in oleic acid in beef?”
Smith said Johnson looked at gene expression associated with fat development. In general terms in transitioning from pasture or grass feeding, to feedlot feeding there is profound increase in genes associated with fat development and making more oleic acid, Smith said.
“You can barely detect expression of genes related to marbling and fat composition in cattle on pasture, but much more so when cattle are fed grain,” he said. “The longer they are on feed the more oleic acid they deposit. If you take Korean Hanwoo or Japanese Waygu, which are fed up to 30 months of age, they have an extraordinary amount of marbling and oleic acid. Hanwoo and Wagyu beef marbling fat is very soft, which provides a juicy mouth feel.”
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Smith said within the article they describe the published ground-beef studies and how ground beef affects cholesterol in humans.
“In most studies, ground beef increased high-density lipoprotein (HDL) cholesterol – the good cholesterol – in men and women,” he said.
According to the research, the relationship between fat and overall palatability “underscores the importance of grain feeding and intramuscular lipid in beef quality.”
As fat increases, it is accompanied by a decrease in the proportion of saturated fatty acids and trans-fatty acids with a corresponding increase in oleic acid and other monounsaturated fatty acids.
“The more cattle fatten, (the more) they put down more marbling and the more healthful the beef is,” Smith said.
Both Smith and Johnson said they wondered why. Randomized, controlled studies evaluated individuals who consumed ground beef formulated from long-fed, grain-fed steers for five weeks (five patties per week), compared to consumption of regular ground beef – lower in oleic acid. HDL cholesterol increased significantly in normocholesterolemic men and postmenopausal women fed the high-oleic acid ground beef. In these studies, the men consumed ground beef containing 24 percent fat and the women consumed ground beef containing 20 percent fat.
The conclusions were that, even at these high levels of fat intake, ground beef had no negative effects on lipoprotein cholesterol metabolism in men and women, and ground beef naturally enriched in oleic acid had positive health benefits.
“We hope to convince everyone in the beef production chain, all the way from producers to retailers, that healthy fat in beef not only improves flavor, but you can modify the animal naturally so that the beef contains more oleic acid,” Smith said. “This provides a very palatable product that, even though it contains a relatively high level of fat, is not going to have a negative impact on cholesterol metabolism in humans.”