Lemon-Lime Essential "Exam" Cupcakes

The genus Citrus (family Rutaceae) comprises of about 140 genera and 1300 species (wow!). The characteristic citrus fruit fragnance is due to flavonoids and limonoids (terpenes) contained in the rind, and the juice which is rich in citric acid that is also responsible for the sharp flavour.  Citrus peel essential oils are a source of bioactive compounds, such as the aforementioned flavonoids or carotenes, coumarins and linalool. These oils are also known for their antioxidant and antimicrobial properties.

For this recipe I chose Citrus limon (lemon) and Citrus aurantifolia (lime)... and I made use not only of their juice, but also of their zest.

My friends from the lab, Veronika and Iva, had a big day on Friday - they have been defending their PhD research projects. Apparently, it is a tradition here in Slovakia that students taking an important exam prepare refreshements for the exam committee... so they are stressed, nevous, spend all their time revising and preparing their presentation and above that, they are supposed to take care of food for their examiners. I would not have problem with that, as cooking and baking relaxes me, brings me joy, and would probably calm me down and help me focus, but I can imagine it is not how the majority of students like to spend their time before an exam... So I offered my services... 
...and voilà - lemon-lime cupcakes!

(I also made some mocha cupcakes with espresso-mascarpone frosting (probably my next post).)

Lemon-Lime Cupcakes with Creamy Lemon Frosting

Ingredients (makes for about 18 medium cupcakes)
     Cupcakes
100g white sugar
1&1/2 cup plain flour
1/2 cup milk
6 tbsp. vegetable oil
2 tbsp. lemon zest
1 tbsp. lime zest
2 tbsp. lemon juice
1 tbsp. lime juice
1.5 tsp. baking powder
0.5 tsp. salt
2 large eggs

     Creamy Lemon Frosting
200 g mascarpone
2-4 tbsp. powdered sugar
lemon juice

Directions
      Cupcakes
1. Preheat oven to 180°C
2. Mix oil, sugar, lemon and lime zest and salt (medium speed, app. 2 min)
3. Mix in the lime and lemon juice and eggs (medium speed, app. 2 min)
4. Add flour and baking powder to the mixture, keep beating while adding the milk until the dough is smooth
5. Line a cupcake/muffin pan with cupcake cases and fill each one a bit over 3/4 full
6. Bake for about 20 minutes (toothpick inserted in the centre should come out clean)
     
      Frosting
1. Mix mascarpone with sugar
2. Add lemon juice and mix thoroughly (how much you add depends on how sharp you want the frosting to be, but be careful not to overdo it, as the frosting might become too runny - if this happens, either add more sugar, mascarpone, or both)