A French chemist, caramelization, and a summer galette

by Bonnie Sparrman

A highly anticipated miracle appears every springtime outside our dining room window on the south side of our house. Mind you, we live in Minnesota, where the earth thaws much later than I think is reasonable…but that’s another story. I’m grateful that sometime in April or May when the ice breaks up on the lakes, we peer out our window to spy the wrinkly sprouts of rhubarb bravely poking up to grab all the sunshine they can find. Occasionally a late snow hinders their progress, but we know the rhubarb will prevail.

It’s a happy day when I can pluck lovely red stalks, chop them into half-inch chunks and toss them along with berries into a fragrant summer tart. But what does dreaming of summer baking have to do with a French chemist and caramelization?

It is my penchant for flavor.

Whatever we bake or cook, coaxing maximum flavor out of ingredients is a worthwhile goal. Whether the food is savory fish, meat, fresh vegetables — or comes from a grain such as wheat, rye, barley, or oats — we aim for optimal taste.

Many variables influence the character of our food. Some variables we can control, and others we can’t. For example, if I’m handed a bushel of apples by a neighbor whose tree produced a bumper crop of B-grade Honeycrisps, how might I make something tasty from their bland flesh? I’d probably add a squeeze of fresh lemon juice, a generous shake of cinnamon and cook them into a sauce to concentrate their flavor. Additionally, I might throw a few pungent apples into the pot to intensify the appley taste, but ultimately I’d rather find perfectly ripe apples ready for the picking.

When it comes to veggies, fruit, cheese, meat, and fish, we’ve all heard it’s best to use the freshest ingredients possible. However, in addition to seeking out pristine produce, it’s what we do with raw food that matters. Enter French chemist and physician, Louis-Camille Maillard.

It is no surprise that cooking is science, and baking in particular is influenced by chemistry. Admittedly, I didn’t fully appreciate the organic or inorganic chemistry I studied in college, but when it comes to applying it to cooking and baking, my interest is piqued. I think it’s really cool that two different chemical reactions are responsible for the way food tastes when it is cooked. First we have the Maillard (my-YAR) reaction, aptly named for Louis-Camille Maillard, who in 1912 discovered the stunningly complicated reaction between reducing sugars and amino acids in protein in the presence of fat and heat. Secondly, caramelization takes a different route called pyrolysis. As its Greek etymology suggests, fire breaks molecules apart, which releases volatile chemicals and water, changing its chemical identity. While these reactions are as different as night and day, they both result in nutty caramel flavors that make us smack our lips and exclaim, “Yum!”

So, where do we see them at play in our cooking or baking? We caramelize onions when we patiently stir onion slices and olive oil in a medium-hot pan for about forty minutes. Stiff slices turn golden brown, limp, and best of all sweet as we encourage natural sugars to the surface. The Maillard reaction happens when we sear a steak or scallop, or roast hotdogs. When my husband heads to the backyard with chicken breasts to grill, I remind him, “Don’t forget Louis Camille!” Or “Make sure Maillard shows up on the salmon!” He knows I mean it’s best to place the pretty side of the food on the hottest part of the grill first and go for color before moving it to finish cooking by indirect heat.

In some cases both reactions work together. When baking, I constantly remind myself to not fear burning the bread, especially sourdough, but to let it develop a nice dark brown crust before removing it from the oven. Here both caramelization and Maillard create new flavors as they work in harmony. The same is true as we roast marshmallows and bake cookies.

I think I’ve mentioned before that if I choose a croissant at our local bakery, I look for a nice dark brown one in the case. It promises the deepest, most delightful nuttiness. The same goes for baking at home. I want to achieve deep tasty flavor that happens like magic beyond my shallow understanding of chemistry. Even with little knowledge of the rearrangement of oxygen and hydrogen molecules, we bakers are part of the process of encouraging flavor by simply applying common sense and patience.

As we cook and bake, let’s remember to engage our senses. Listen for sizzling, smell for toastiness, watch for browning, feel for firmness as proteins coagulate, and certainly keep a tasting spoon handy. I find it best to consider the time and temperature settings in recipes as mere suggestions. Our home ovens aren’t going to behave the same as a test-kitchen’s, or for that matter, the same as each other’s. Also, the temperature of ingredients when they’re placed in the oven influences timing. Hopefully they begin at room temperature, yes, even meat. (The one exception is when cold butter is required for pastry or scones.) Rather than reading a recipe’s temperature and time as gospel truth, watch and smell what’s going on. Is the front of the pie crust pale and the backside brown? Turn that baby around! Is the turkey darkening on top but colorless on its sides? Tent the top with foil and let the lower parts catch up. Get to know the hot spots in your oven and let Maillard and caramelization happen on every side of your cake, on all of your muffins, plus on the tops and bottoms of loaves of bread.

I’m grateful for Louis-Camille Maillard for brilliantly uncovering the genius of the reaction that bears his name, but I am even more thankful for many great cooks whose example of common sense taught me to go for brown, because brown equals flavor. This does not mean it’s okay to burn garlic or nuts, which when burnt become bitter and must be tossed. Rather, as one chef I know tells his students, “When toasting nuts or coconut in the oven, when the fragrance hits your nose; pull them out.” Good advice indeed, since the momentum of cooking doesn’t stop the second the nuts are retrieved from the heat. Best of all, my grandmothers taught me to be less fearful of burnt buns and more cautious of pale pie.

This rustic summer galette cries out for a deep brown golden crust. The crispy texture and caramel flavor of the pastry and almonds, the result of sugars doing an intricate dance in the heat of the oven, plays nicely with the tart/sweetness of the rhubarb and berries. A dollop of softly whipped cream on top unites the flavors and textures so beautifully you too will exclaim, “Yum!”

Summer Rhubarb and Berry Galette

Serves eight

Crust (pâte brisée)

4 oz. unsalted butter, chilled and cut into about 16 pats
1¼ c. all-purpose flour (156 gm)
1 T. sugar
¼ t. salt
¼ c. ice water

Place dry ingredients in mixing bowl. Stir with pastry blender or fingers. Add butter. Cut in until bits of butter are no larger than tiny peas. Add ice water 1 T. at a time. Mix with hands until it forms a ball. Knead dough on counter very briefly. (Five turns maximum.) Form into a 7-inch disk, wrap and refrigerate. Chill for at least 1 hour.

Streusel Topping

3 T. unsalted butter, chilled and cut into small pieces
⅓ c. flour (41 gm)
6 T. brown sugar (75 gm)
⅓ c. sliced almonds, plus a few more for sprinkling on galette
pinch salt

Combine flour, sugar, ⅓ cup almonds, and salt. Add butter pieces. Using your fingers, rub the butter into the dry ingredients until the mixture appears uniform and crumbly. Set aside.

Strawberry-Raspberry-Rhubarb Filling

10 oz. rhubarb, trimmed and cut into a ½-inch dice (about 2 cups) 1 heaping pint combination of strawberries, hulled and quartered, and raspberries (about 12 oz. total berries)
¼ c. sugar
3 T. corn starch
1 oz. almond paste, grated
1 egg for egg wash

In a large bowl, combine rhubarb, strawberries, raspberries, sugar, and corn starch. Set aside. Place disk of dough in the center of a large square of baking parchment, sprinkled lightly with flour. Roll dough from center to outside, frequently rotating parchment a quarter turn, forming a 14-inch circle. Slide parchment and circle of dough onto a baking sheet.

Grate almond paste over an 8-inch circle in the center of the dough, avoiding a three-inch perimeter around the outside. Add fruit on top of the almond paste, and sprinkle the streusel over the fruit. Fold edges of dough up and over filling, pleating it about every two inches. Arrange reserved almond slices on the surface of the streusel. Chill tart for 15 minutes. Beat egg with a fork, and brush crust with egg wash. Sprinkle with sugar. Begin baking galette at 450 degrees F. After ten minutes reduce oven temperature to 400-425. Bake 25-30 more minutes or until the crust and the edges of the almonds are nice and brown. If any juices ooze from tart they should be clear and bubble slowly, indicating doneness. Cool tart for one hour.

Just before serving, dust lightly with confectioners’ sugar. Serve with whipped cream or vanilla ice cream.

Cook’s Note: I have made this galette gluten free by substituting Bob’s Red Mill, “1 to 1” Baking Flour.