Homemade ice cream is a special summertime treat. However, for hundreds of consumers each year, it also can become a threat because of salmonellosis.
According to a report by the U.S. Centers for Disease Control and Prevention, or CDC, between 1996 and 2000, 17 outbreaks in the U.S. involving more than 500 people were traced to salmonella bacteria in homemade ice cream. Even commercially prepared ice cream can become plagued with salmonella, as evidenced by the recent nationwide recall of "Cake Batter" ice cream from Cold Stone Creamery stores in the U.S.
The Cold Stone Creamery outbreak was discovered when multiple cases of salmonella typhimurium infection were reported in Minnesota, Washington, Oregon and Ohio with the common pattern of consuming "cake batter" ice cream shortly before onset of illness. In homemade ice cream, salmonella enteritidis, which can be transmitted from the hen to the egg yolk before the shell forms, is the more common culprit. Because of this, it’s no longer safe to assume that a clean, uncracked raw egg is safe to eat.
Salmonella infection is characterized by fever, diarrhea and abdominal cramps usually beginning 12 hours to 72 hours after eating or drinking a contaminated food item and lasting up to a week. Although most people require no medical treatment, it can be life threatening for those at high risk for foodborne illness, including infants, older people, pregnant women and people with weakened immune systems.
While commercially manufactured ice cream is typically made with pasteurized eggs or egg products, recipes for homemade ice cream often use raw eggs in the base mixture. Here are some suggestions for safe alternatives to using raw eggs in your homemade ice cream:
– Find a recipe that is eggless. An easy one calls for 2 cups milk, 1 cup sugar, 2 cups whipping cream or half-and-half and 2 teaspoons vanilla. Combine and stir until sugar is dissolved, then pour into a 1-gallon ice cream freezer and freeze according to manufacturer’s directions.
– Use pasteurized shell eggs or pasteurized egg substitutes in recipes calling for raw eggs. These can be found in the dairy case near the regular eggs. The FDA requires that pasteurized shell eggs be individually marked or specially packaged to prevent intermingling with unpasteurized eggs. Although pasteurized eggs may cost a few cents more, the pasteurization process destroys salmonella bacteria.
– Use a recipe that contains a cooked custard base. The custard base must reach 160o F, measured with a food thermometer, to kill the salmonella bacteria. This is also the point at which the mixture will coat a metal spoon. Resist the temptation to taste-test it during preparation when the custard isn’t fully cooked. After cooking, chill the custard thoroughly before freezing. A recipe for homemade ice cream using a cooked egg base is available on the American Egg Board’s Web site, www.aeb.org, along with recipes for other foods traditionally made with raw or undercooked eggs, such as mayonnaise, Caesar salad dressing and eggnog.
– Even when using pasteurized eggs, the FDA and the USDA advise consumers to start with a cooked base for optimal safety, especially if serving people at high risk for foodborne illness. Additionally, it’s important to only used pasteurized milk and cream products in making your homemade ice cream.
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by Pat Kendall, Ph.D., R.D., Food Science and Human Nutrition Specialist, Colorado State University, Cooperative Extension