Chemistry of chocolate

One of my favorite chocolate

Not long ago, I posted an article regarding comfort food. Well, I sometimes eat chocolate when I am feeling sad.

What is so special about chocolate? First of all different cocoa varieties have different characteristics: Forastero, for example, has strong aroma, while Nacional has more aromatic and floral notes. More than 600 molecules are involved in the complexity of chocolate aroma and flavor.

Chocolate makes us feeling better because of tryptophan, a molecule involved in the production of serotonin. Serotonin is a neurotransmitter, contributing to our sense of well-being.

Another important molecule is theobromine. It is a stimulant, similar to caffeine, and its concentration is higher in dark chocolate. That is why if we eat dark chocolate during a mental activity (studying, thesis writing…) we feel more energetic. You need to be careful if you have cats and dogs. Because of theobromine, 50 gr of dark chocolate can be fatal for your little pets.

Vanillin is one of the aroma of chocolate, but it is not naturally found in cocoa beans, but it is often added to milk chocolate.

Butyric acid is also often added by chocolate producers. This molecule is responsible for the sour notes.

White chocolate is white because it does not contain any cocoa solid, but only milk, sugar and cocoa butter. Cocoa butter is composed by various fats, among them stearic acid and palmitic acid.

As usual, here some good reasons to eat chocolate (in a moderate way).

  • It has antioxidant properties (thanks to polyphenols and flavonoids).
  • Its consumption lower the risk of stroke, atherosclerosis and coronary artery disease.
  • It decreases blood pressure and the risk of developing hypertension (thanks to procyanidins).
  • It reduces the level of LDL (aka bad cholesterol).
  • It has anti-inflamatory effects (polyphenols, thank you again!).
  • It has anticarcinogenic properties (thanks to… our beloved polyphenols).
  • It has a protective effect against neurodegenerative disease (polyphenols, I am talking about you!).


Aprotosoaie et al., “Flavor Chemistry of Cocoa and Cocoa Products—An Overview”, (2015),

Barisisic et al., “The Chemistry behind Chocolate Production”, (2019), doi:10.3390/molecules24173163

Tannenbaum, “Chocolate: A Marvelous Natural Product of Chemistry”, (2004),

Women in STEM: dr. Carla

dr. Carla, in the lab

Forth episode of Women in STEM. Today, I have the pleasure to host dr. Carla. A scientist working on Hepatitis Delta Virus, a dear friend of mine and creator of Virus&Co.

Hi Carla, welcome! First of all, would you like to tell us something about you?

Hi Martina, hello everyone and thank you for inviting me.  I am 32 years old and I am currently a post-doctoral researcher at the Blizard Institute, Queen Mary University of London. I hold a Master’s Degree in Industrial Biotechnology, and I am a Ph.D. in Biomedical Research. I am also a serial reader and I am learning the basics of photography. I like writing, and one of my projects for 2020 is to be more active in science communication and public engagement.

When did you start your Instagram and Twitter accounts? How did you get the idea? 

I have an Instagram account (@carltyl) since 2014, it is a personal account not related to science. I sometimes post a pic about lab life or the congresses that I attend, but it is just because science is a big and important part of my life; I do not use my account for educational purposes, it’s just a collection of things that I like (books, travel, food, landscapes, family events). My Twitter account (@CarlaBiotech) is more recent. I started it about one year ago while I was attending a course about science communication at the Univeristy of Navarra: the lectures were held by speakers that communicate science in different ways, with different styles and by different means, but all of them have also a Twitter account. I was not really aware of how people in general, and scientists in particular, took advantage of it, it was a completely unknown world for me. Now I use Twitter to keep up with literature, get in touch with other scientists in my field, but also to have a better idea of what kind of scientific content the general audience is interested it.

Can you tell us something about how you balance work and private life?  

Honestly, I haven’t been very good at work-life balance, it is something that I have learnt –and I am still learning – with time. It is much easier now that I am a post doc than when I was a Ph.D. student. As a Ph.D. student in a foreign country, living in a small town which did not offer many recreational activities and where, especially at the beginning, I did not know many people, I often found myself working during the weekends, reading papers or analysing data, just because I had nothing better to do. But something that I learned quite early during my 1st year, and that I still do nowadays, is not to check my email during weekends or holidays unless it is necessary (approaching deadlines, an important experiment to finish). I have learned that resting properly is key for boosting productivity and that mental health is as important as physical health. Now I know that, especially for someone working in a foreign country or in a city that is not their own, it is very important to not confine ourselves to the work environment, to try to meet people with different backgrounds and cultivate a hobby. In my case, Latin dance is my “relief valve”, something that I enjoy, that allows me to switch off from work and to meet nice people.

During your experience in academia how many women were in your course? Why in your opinion? 

I don’t remember a great difference in number between male and female students at University, while women outnumbered men in my group during the doctorate: only 3 men in a group of 15 people! In my current group, there are only 4 of us: two men (including the PI) and two women, perfectly balanced. What I have noticed is that even though I see more female researchers or technicians in the labs, the number of female and male PIs is similar, but then when we look at heads of departments or higher positions in Universities, the situation is exactly the opposite. It took me a while to become aware of this phenomenon because I have had more female supervisors than male ones, and I do not have any real explanation for that. I don’t think that is something intentional, is not a “strategy against women”. Maybe, most of the women themselves prefer to step back when they have the opportunity of getting a promotion in career, for example because they have children and have to split their time between their family and their job. However, the same would apply also to men: if both parents are involved in raising their children and one of them receives a promotion, or gets a more demanding job, and is forced to spend more time at work, this needs to be compensated by the other parent spending more time at home. It doesn’t matter if it is a woman or a man; at least, this is my opinion of how a family should work.

Have you ever felt harassed or being kept apart as a scholar because you are a woman? 

No, I did not. There was a time at the very beginning of my career in which the guys of the lab used to do sexist jokes to the girls almost on a daily basis, but I don’t think it was something related to their position in science: I think that those guys used to behave the same way in any other circumstances. Actually, I believe that this is the very origin of the problem: unfortunately, our society is still sexist itself, it is not a problem circumscribed to STEM. And for this same reason sometime there is a tendency to underestimate it because we are somehow used to see women belittled or in less important jobs.

How did you become passionate about science?  

I was one of those hardworking students that have good grades in all the subjects. I enjoyed studying, and even though I had some less favorite subjects, I was not able to identify something that really excited me. When I started studying Chemistry and Physics during high school, I realized that those where the things that I really enjoy studying: I was attracted by the infinitely small and the microscopic world! I was interested in the biology of the cell, the DNA was fascinating and trendy with the Human Genome Project just declared completed in 2003. This is why in 2005 I decided to study Biotechnology at the University of Padova, and I am very happy with that decision!

Would you like to talk briefly about your job? 

I study a virus called Hepatitis Delta Virus (HDV), it is the smallest among the viruses that can infect humans, and it can cause a very severe liver disease for which there is not a cure yet; HDV infection can lead to fulminant hepatitis and also liver cancer. In the worst scenario, the only therapy for these patients is liver transplantation. There are still many things about this infection that are not completely understood, and this is why the treatments currently available are only partially effective. I started to work on HDV during my Ph.D., developing a mouse model that has allowed us to unveil some aspects of the innate immune response, while my project as a post doc is focused on the immune response against this virus in patients. Hopefully, combining the knowledge from the model and data from patients we will able to put together more pieces of the puzzle.

Thank you so much for your time. Lastly, can you give any advice to girls interested in stem? 

Don’t let anyone tell you that you can’t do it. Be assertive and proactive, work hard and don’t compare yourself to anyone: just do your best. If possible, look for role models. I was very lucky to have as a supervisor during my Ph.D. a very smart and successful woman, which is still to me a great example both as a scientist and as a person. Also, in my family science is a “girls’ thing”: my mother is a pharmacist and my sister is a medical doctor, so I have had role models literally all my life.

Speaking of this, I am very happy to be able to do something more than giving a piece of advice: I have recently joined a committee in my university that supports equality in STEM and runs events to engage girls of every age and also their families to give more visibility to our work. From 2020 I will be the social media manager of this group, so I invite you to check on our Twitter and Instagram accounts (@wiseqmul) if you want to know more about our initiatives!

What happens to a woman when she is pregnant

Me, when I was pregnant

Pregnancy is that period of time in which a new life develops inside a woman’s body.

As all mothers know, pregnancy is characterized by A LOT of changes in our body, both anatomical and physiological.

Here is a (partial) list of changes which women experience during pregnancy.

  • Plasma volume. It increases of about 1.5 L during the whole pregnancy. The number of red blood cell increases at a lower rate than plasma volume, causing a fall in hemoglobin concentration.
  • Micro-nutrients necessity. During pregnancy the requirement for iron and vitamin B12 increases 2 to 3 times and for folic acid (vitamin B9) 10 to 20 times.
  • Cardiac changes. Hearth is put under stress during gestation. At 8 weeks the cardiac output is increased by 20%. The supine position causes a reduction in venous return, therefore pregnant women should lay in the left or right position.
  • Respiratory changes. The demand of oxygen increases greatly during pregnancy due both to the increase in the metabolic rate and in the consumption of oxygen.
  • Renal function. Kidneys increase of about 1.5 cm. Changes of the sympathetic nervous system cause sodium and water retention (aka cellulite and swollen feet).
  • Alimentary trait. Nausea and vomiting typical of the first trimester could be an evolutionary mechanism preventing women from eating teratogenic food. Glucose metabolism changes causes in some women pregnancy diabetes. Lipid metabolism changes and the body accumulate fat as storage for mother’s energy.
  • Progesterone. It is the most important hormone during gestation. It reduces urethral tone and peristalsis (aka we pee ourselves when we sneeze), can cause teeth pain and gastroesophageal reflux.


Soma-Pillay et al., “Physiological changes in pregnancy”, (2016), 10.5830/CVJA-2016-021

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