COLLEGE STATION Busy people want things that make life easier, and foods such as pre-cooked sausage biscuits and roast beef certainly fit the bill. But sometimes pre-cooked foods taste somewhat like warmed-over cardboard.
Lipid, or fat, oxidation creates these off-flavors in foods. Many processors try to avoid that by adding butylated hydroxy anisole (BHA) and butylated hydroxy tolvene (BHT) both of which are synthetic preservatives and antioxidants to foods.
Drs. Jimmy Keeton and Ki Soon Rhee with the department of animal science at Texas A&M University are studying plum products that may provide consumers with foods with less of that “warmed-over flavor” and give processors a natural alternatives to preservatives.
The Food and Drug Administration requires that antioxidants such as BHA and BHT be declared on food labels, but it does not consider them to be harmful at current levels in food.
“What we were trying to do is to find naturally-occurring substances that are equivalent to BHA and BHT,” said Keeton, professor of animal science. The research was funded in part by the California Dried Plum Board.
Antioxidants, especially in pre-cooked products, keep them from turning rancid, he said.
“When meats turn rancid, there is a characteristic flavor that called warmed-over flavor’. That’s a real problem with the pre-cooked foods we have today,” he said. “More products are being sold now as pre-cooked or ready-to-eat items. For convenience, they’ve already been cooked; all you have to do is reheat them.”
In the first study, researchers combined dried plum puree known otherwise as prune puree with fresh pork sausage. Pork sausage was used because it can contain from 30 percent to 50 percent fat and is susceptible to lipid oxidation. Dried plums have naturally-occurring antioxidants that may retard lipid oxidation.
“Because there’s an opportunity for lipid oxidation, that could cause off-flavors,” he said. “We wanted to evaluate the potential of this source of natural antioxidants.”
Dried plum puree was mixed into fresh pork sausage at levels of 3 percent and 6 percent.
Patties were pre-cooked, refrigerated and then reheated and served to a taste panel every few days to evaluate flavor stability. The patties also were analyzed to measure lipid oxidation or rancidity through chemical testing.
“What we found was…dried plum puree at 3 percent levels was as effective as BHA or BHT used in a product. It was as effective as the synthetic antioxidants were at retarding the lipid oxidation,” he said.
Adding dried plum puree did not change the taste dramatically; it only made it a little sweeter. It also decreased the salty and bitter taste, as well as what is sometimes called the “cooked pork taste,” Keeton said. And it tended to mask a little of the pepper and sage flavor.
“So all in all it performed very well,” he said.
The patties with 6 percent dried plum puree were a little sweeter, “probably a little too sweet,” he explained, but the puree was still effective at reducing oxidation.
An added benefit was that 3 percent of the meat volume was puree, so it actually reduced the total volume of meat and fat by that amount.
One of the biggest problems with using the dried plum puree is that it is stiff and sticky.
“It’s hard to use in the present form,” Keeton said.
“If we had it in a little different form, something that flows a little better, it may actually have more use. It can be difficult to get incorporated into the product.”
The dried plum industry wants to use the puree in its present form because it is already approved for use by the U.S. Department of Agriculture.
Keeton said, “So one of the things we need to look into is making it a little more adaptable, giving a little better flow’ properties.” Also, some companies already are looking at extracting the antioxidant properties of the dried plums for use commercially.
There was no dramatic increase in the amount of fiber in any of the meat nor was there any laxative effect, Keeton said. At least six to12 whole dried plums would have to be eaten to get any kind of laxative effect, he said.
In another study, fresh plum juice concentrate, dried plum juice concentrate, and spray- dried plum powder (fresh plum juice that has had the moisture removed), were added to brine- injected roast beef and hams. Brine is injected to enhance the flavor and texture of pre-cooked products, Keeton said.
For roast beef, the brine usually contains salt, phosphates and sugars. With ham, sodium nitrite and sodium erythorbate (a salt of vitamin C), both of which have antioxidant properties, are added to the other ingredients.
With the roast beef, injecting either the fresh plum juice concentrate or dried plum juice concentrate at 2.5 percent of the finished product weight did reduce rancidity in the product. It also increased the sweetness of the meat.
“We have another way of enhancing a product that is pre-cooked, ready-to-eat, and it is now more consumer-friendly, there’s less chance of oxidation occurring in that product as the result of storage,” he said.
With the ham, however, there was no difference in lipid oxidation levels.
The spray-dried plum powder with a maltodextrin carrier did not perform very well because it was diluted too much to have an antioxidant effect, he said.
The next step for the researchers is to test dried plum puree in irradiated ground beef.
“When you irradiate products, even at low dosages, you’re going to generate some free radicals, which, again cause oxidation and can cause color changes. What we’re interested in doing is finding out whether these antioxidants will also reduce or retard off-flavors or off- colors,” Keeton said.
Some results should be available by the end of the summer, he said.
Cooperating in the dried plum puree study were Keeton, Rhee, professor of animal science, and Randi Boleman and Maryuri Nunez, both doctoral candidates.
Participating in the study of plum products and juice concentrate were Keeton and Rhee; Brian Hafley, Nunez and Boleman, all doctoral candidates; and Iulia Movileanu, a master’s degree candidate.
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