Tiramisu is a layered dessert of Italian origin. It combines the creamy texture of zabaglione custard and mascarpone cheese with the firmness of ladyfinger cookies. The eggs in the custard and the mascarpone cheese make tiramisu highly perishable at room temperature. Refrigeration will slow down spoilage and help prevent sogginess.
Store Tiramisu Safely
Store tiramisu in the refrigerator for up to three days. According to the U.S. Department of Health and Human Services, egg custards such as zabaglione can be stored safely in the refrigerator for three to four days, but the combination of soaked ladyfingers and custard will become soupy and unappetizing after two or three days.
Do not store tiramisu at room temperature. The eggs in the zabaglione will spoil and put you and your family at risk for food poisoning, and the texture of the dessert will deteriorate, making the dish unappetizing.
You can leave tiramisu out of the refrigerator for up to two hours during serving before it will begin to spoil. If your party will last longer than two hours, keep the tiramisu in the refrigerator until just before dessert.
Use Pasteurized Eggs
Zabaglione is a cooked egg custard that is essential to a traditional tiramisu. This custard gives tiramisu its creaminess and cuts the sharp bitterness of the coffee. When you make tiramisu, use pasteurized eggs or check the temperature of your zabaglione when it is finished cooking. If it has reached 160 degrees Fahrenheit, you can be confident that illness-causing bacteria such as salmonella have been eliminated. This step does not eliminate the need to refrigerate tiramisu, however. If the dessert is left out, additional bacteria can grow, and the custard will lose its firmness.
Pasteurization Is Not Enough
Mascarpone is a soft, fresh cheese similar to cream cheese. It adds body and firmness when mixed with the zabaglione. Like all cheeses sold in the United States, it is made from pasteurized milk, which eliminates the bacteria that cause many food-borne illnesses. Pasteurization does not prevent the cheese from going bad when left at room temperature, however, especially on a hot day. Refrigeration will help the mascarpone maintain its texture in the tiramisu.
Alcohol Cannot Preserve Tiramisu
Tiramisu includes several non-dairy ingredients, including ladyfinger cookies, coffee, brandy or coffee liqueur and vanilla. While alcohol can effectively sterilize egg dishes such as eggnog, there is not enough alcohol in tiramisu to combat the bacterial growth that can occur on a hot day.