Beam Me Up, Biscotti!

This week, Mia and I made biscotti: the hardest cookie.  I do not actually know if it is the hardest possible cookie; I just thought that was a cool subtitle for biscotti.  Anyway, in order to test how different fat sources changed the texture of the biscotti, some groups used butter while others used olive oil.  We used butter in ours.  Here is how we made the biscotti magic happen!

After preheating our oven to 350 degrees, we placed 1/2 cup of almonds on a baking sheet and toasted them for 15 minutes, then chopped them once they had cooled.

Next, we whisked together 1 large egg, the zest of 1 lemon, 1/2 cup of sugar, 4 tablespoon of melted unsalted butter, 1/2 teaspoon of almond extract, and 1/2 teaspoon of vanilla extract in a bowl.  In another bowl, we combined the almonds that we had toasted and chopped before, 1-1/4 cups of all-purpose flour, 1/2 teaspoon of baking powder, and 1/4 teaspoon of table salt.  We slowly added the dry mixture to the wet mixture, and stirred until the dough was stiff.  We had to add a little bit more flour to get our dough to stiffen up.

We then shaped the dough into a slab, and put said slab into a baking sheet lined with parchment paper.

We baked the slab for 14 minutes in our already preheated oven, then rotated it and baked for 14 more minutes.

After letting it cool for 15 minutes, we lowered the oven temperature to 250 degrees and cut the slab into logs using a serrated knife, put the logs on two baking sheets and baked them for 7 more minutes, then rotated and baked for 7 more.

And just like that, our biscotti was done!  Here’s how it turned out:

1. Why is butter a solid at room temperature while olive oil is a liquid?  Butter is a saturated fat while olive oil is a monounsaturated fat.
   1. A molecule is more fluid when it has more double bonds.  Since butter is a saturated fat, it contains no double bonds, and is therefore solid at room temperature.  Olive oil contains one double bond, and is therefore liquid at room temperature.
2. Butter is a fat that contains ~15% water, compared to olive oil (or shortening) which contains < 1% water. Read about the effects of this water content at this page (Water Activity and Cookie Softness) and then explain the textures of the two different types of biscotti.
   1. Since the biscotti made with olive oil contains no water, its texture is more dry and crumbly than the biscotti made with butter, because of the lower water activity.
3. When mixing the ingredients you added the flour mixture slowly to the fat/oil mixture. What effect does the fat/oil have on gluten formation in the dough? What about your biscotti supports your conclusion?
   1. The fat/oil inhibits the formation of gluten by coating the glutenin and gliadin in the flour.  This conclusion is supported by the fact that the interior of the biscotti does not appear to have many holes, which means that very little gluten was formed.