Use double acting baking powder (this shouldn’t be a problem, as this is probably the only kind you will find at the store). Don’t keep baking powder or baking soda for more than a year.
Eggs All eggs are large. Brown or white makes no difference.
Nuts Nuts can turn rancid, even in the freezer. The best strategy is to roast them as soon as you get them; this will help their flavor and add to their shelf life. Spread them on a sheet pan and roast in a 350F oven for 15 minutes. Stir around once during the roasting. Once you have roasted them, store nuts in the freezer.
Nut oils Most nut oils are already rancid before you open the can or bottle. To avoid this, buy nut oils that have been made with roasted nuts, specifically Le Blanc brand. Store nut oils in the freezer.
Salt Regular fine salt or fine sea salt will do in all recipes.
Spirits Spirits used in baking are there to provide flavor, so, buy the best spirits you dare.
Eaux de vie, such as kirsch or framboise, should be French, German, or Swiss. Bourbon should be straight, not blended. Rum should be dark rum, preferably pot-stilled, from Martinique. Cognac should say Cognac on the bottle and not just brandy. (However, you don’t need to buy an old rare Cognac; a young fruity one will do.) When you add spirits to mixtures such as simple syrup, make sure that the mixture is cool, or the flavor and aroma of the spirits will volatilize and evaporate.
Vanilla Be sure to use real vanilla extract. Use real vanilla beans for infusing in custards and batters.
Vegetable oil Make sure vegetable oil is fresh, as it can go rancid in a few months. Canola or sunflower oil make good choices for baking.
Excerpted from Baking by James Peterson Copyright © 2009 by James Peterson. Excerpted by permission of Ten Speed Press, a division of Random House of Canada Limited. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.