Question: We are using a lot of crème fraîche, but want to make our own. Can you help?

J.G., via e-mail

Answer: To make crème fraîche, you need heavy cream that is not ultra-pasteurized and buttermilk with active cultures. Heat 1 gal. of heavy cream to about 100°F, remove it from heat and stir in 8 ozs. of buttermilk. Cover the mixture loosely and store for about 24 hours in a warm place or until it thickens. Refrigerate thoroughly before using. Crème fraîche will last for about one week when kept chilled.

Question: We are using a lot of aluminum foil containers in the bakery. Can we use them in the microwave oven to heat ingredients?

D.S., Hingham, Mass.

Answer: Yes, you can use aluminum foil containers in the microwave if the microwave oven was manufactured after 1980. Food heats more thoroughly in aluminum containers than in plastic and retains more of its original texture and flavor.

Question: We produce and sell a lot of éclairs, however, the chocolate coating falls off after several hours. Why does this occur and what can we do to prevent it?

P.B., Huntington Beach, Calif.

Answer: Heat the chocolate coating to about 128°F (53°C), and allow it to cool to about 105°F (40°C) before you apply it to the éclairs. This will avoid variations in how quickly the chocolate sets. If the chocolate sets too quickly, it will shrink and fall off. Also, make sure that the surface of the éclairs is dry, as moisture on the surface could cause lack of adhesion.

Question: We cover a lot of wedding cakes with marzipan, but the marzipan hardens after a short period of time. How can we avoid this problem?

M.B., Hudson, Wis.

Answer: Adding additional moisture to the marzipan in the form of equal parts water and glucose is a good start to prevent moisture loss. I'm also very successful with a solution of 32 ozs. of water, 32 ozs. of granulated sugar and 8 ozs. of glucose, which is boiled and cooled before adding to the marzipan. Be careful not to add too much liquid, or the marzipan can become unmanageable.

Question: Our apple pies are great, but the shelf life is only two days. What can we do to extend the shelf life?

S.S., Fairfield, N.J.

Answer: Mix a large 10 kg batch of granulated sugar at slow speed with 10 g of potassium sorbate (100 ppm). Add the normal amount of sugar to your apple pie formula. The preservative potassium sorbate will increase the shelf life of the apple pie to about seven to eight days. Potassium sorbate is the potassium salt of sorbic acid. Potassium is the most widely used food preservative in the world. Potassium sorbate is effective against yeasts, molds, and certain bacteria, and it is widely used in bread, cakes, pies and fillings, baking mixes, doughs, icings, fudges, toppings, and confections. The maximum level allowable by law is 0.1%. If preservatives are used in a food, they must be declared in the list of ingredients on the label, along with a short explanation of intended use, such as "preservative," "mold inhibitor," or "to retard spoilage," etc.

Question: What temperature do you recommend for cake batters and why?

B.H., Easton, Pa.

Answer: By keeping the ingredients at an even temperature of 72°F (22°C), better aeration and a more thorough dispersion and hydration of ingredients is achieved, resulting in a finished product with great appearance, volume and texture when baked.

Question: Why are eggs so important in the production of baked products?

D.R., Minneapolis

Answer: Eggs have three primary attributes:

• Foaming: incorporating of air into the batter.
• Emulsification: stabilizing the suspension of one liquid in another.
• Coagulation: converting the liquid egg to a solid state, which binds together other ingredients.

Question: What is the optimal amount of sugar needed to sweeten heavy whipping cream?

Michael, via e-mail

Answer: I always add 10 percent of confectioners' sugar to the whipping cream, resulting in a nicely balanced, sweetened whipping cream.

KLAUS TENBERGEN is a B‰ckermeister ( Germany), Certified Master Baker (USA), Master Baker (South Africa) and Chef Instructor at Kendall College-"The School of Culinary Arts" in Chicago. For more information about Kendall College, call toll free 877/588-8860. You can contact Chef Klaus Tenbergen via e-mail at: btenbergen@wi.rr.com. DO YOU HAVE A QUESTION about formulation, make-up procedure, equipment application or other technical point? E-MAIL your question to modernbakingedit@penton.com or FAX it to 847/296-1968.