King Arthur Flour had a very intriguing blog post recently about the steps necessary to create brownies with a shiny and flakey crust. They had some outstanding follow-up questions which we decided to investigate. Keep reading for more brownie science!

Initial observation: 

Fellow food blogger over at King Arthur flour did an interesting experiment on shiny brownies, and determined that the addition of chocolate chips was vitally important to the finished brownie characteristics.

Question: 

What aspect of the chocolate chips is most important for changing the spectral characteristics of the finished brownies – the sugar or the fat (or something else)?

Expectation:

We really were not sure if it was the sugar or fat on this one, but we expected one would make a difference somehow!

Equipment & Materials:

• two 8×8″ pans
• aluminum foil to divide pans
• Thermapen (optional)
• scale (our current standard is the AMW-2000)
• ingredients for single batch of this recipe (we used the weight-based, gram, version of the recipe to avoid the volume-based measurement issues with ingredients like flour)
• extra sugar and butter equivalent to the amounts that would be in 85 grams of chocolate chips
  • 48g sugar
  • 24g butter (butter seemed to have the same ratio of saturated:unsaturated fat as the chocolate chips)

Procedure:

1. Use foil to partition the pans. Spray foil with cooking spray
   

   Prepping brownie partitions. Left: one partition built, Right: pan with two completed partitions.

2. Make the brownie batter as directed, except do not add the chocolate chips
   • use the thermapen during the butter melting and sugar stage to hit the target temperature of 110-120°F
   • note this temp is hit surprisingly fast and our attempt reached 135°F
     

     Checking the temperature of the butter and sugar mixture… a tad higher than the 120°F target (oops).

3. Mass the batter and divide into fourths
4. Leave one 1/4 as is (non-shiny control)
5. Add 85 grams chocolate chips to one 1/4 (shiny control)
6. Add 48g granulated sugar to one 1/4
7. Add 24g melted butter to one 1/4
8. Label foil in some manner to keep all batches straight
   

   Labeled brownies in partitioned pans. V1: original recipe – chips, V2: recipe (with chips), V3: recipe – chips + sugar, V4: recipe – chips + butter.

9. Bake at 350°F for ~25 minutes – we swapped pan locations in oven half way through
10. Place pans on wire rack and cool completely

Data: 

The control recipes (as directed and without chocolate chips), behaved in a similar manner to the results obtained by King Arthur flour (whew!). In the image below, it can be seen that the brownie batter with the extra sugar looks similar to the recipe that includes chocolate chips, while simply adding butter resulted in a dull/matte crust.

Finished brownies. From left to right: V1, V2, V3, V4 (see previous image).

Surprise Results: Even though the extra sugar was simply mixed in, and not dissolved in the melted butter as some of the recipes tested by King Arthur suggested was critical, the crust was very similar to the batch with the added chocolate chips.

Conclusion: Based on our small trial, it appears that it is the sugar in the chocolate chips that is critical component for the shine, and not the additional fat.

Taste test results indicated that the batch with the chocolate chips was the tastiest, followed by the one with the extra sugar, extra butter, and the plain recipe minus chocolate chips was the least favorite (although, all in all, none would be rejected by our taste testers).

Future Questions: Can you replace the sugar with a flavored liquor (e.g. orange liquor) and still get a shiny crust? How important is the temperature of the butter and sugar mixture really? How many other experiments can we come up with before people suspect we just want an excuse to make brownies?

Related Works:

Hamel, P.J. 2015. “How to make brownies with shiny crust: the surprising secret ingredient.” Flourish – King Arthur Flour blog. Web. Accessed July 4, 2015.