Bread deserves a longer post

Those of you who know me know how much I love bread. Even if it’s not your favourite thing, you have to admit that it is rather fascinating how simple ingredients such as flour, water and yeast combine to give rise to a wonderfully textured and tasty food. The secret to a great loaf is in the yeast: the live, single-celled fungus (Saccharomyces cerevisiae) that makes bread dough rise. But how is it that those dried granules that come in the little paper packets you get at the supermarket come alive and make a mix of flour and water leaven? The best way to understand how flour + water + yeast = bread is to actually bake the stuff. I’m going to follow this very simple “No-Knead Bread” recipe. No kneading means you don’t have to spend two hours in the kitchen mixing, folding, pressing and stretching the dough. The yeast does all the hard work for you but it needs time – this recipe requires 14 to 20 hours for the bread to rise. Trust me, it’s worth the wait – and you’ll learn some exciting science along the way!  

So, let’s start with the ingredients (for 1½-pound loaf):

3 cups all-purpose or bread flour, more for dusting


¼ teaspoon instant yeast


1¼ teaspoons salt


Cornmeal or wheat bran [or more flour] as needed

And follow with effortless mixing:

1. In a large bowl combine flour, yeast and salt. Add 1 5/8 cups water, and stir until blended; dough will be shaggy and sticky. Cover bowl with plastic wrap. Let dough rest at least 12 hours, preferably about 18, at warm room temperature, about 70 degrees [ºF = 21 ºC].

In step 1 of bread making the dried yeast, which consists of dormant cells of Saccharomyces cerevisiae, is reactivated. The fungus awakens as it comes in contact with warm water. The slow process that follows is called fermentation. Once reactivated, the yeast starts converting the carbohydrates in the flour into the simple sugars it likes to feed on. This reaction releases carbon dioxide and alcohol into the bread mix. Most carbon dioxide gas does not disappear into the air: it gets trapped inside the dough because of the gluten in it, formed when water is mixed with two proteins in the flour, glutenin and gliadin. The long, slow rise also helps the gluten molecules become aligned in a way that gives the dough a strong, elastic texture. The gluten structure traps air bubbles inside it, which are filled with the carbon dioxide released by the yeast. The more gas is released, the more the air cells inflate making the dough rise.  

(If the mixture was less wet and the rising time faster, as in other bread-making processes, the dough would need to be kneaded to help the gluten molecules align and give it the right structure and elasticity.)

2. The dough is ready when its surface is dotted with bubbles. Lightly flour a work surface and place dough on it; sprinkle it with a little more flour and fold it over on itself once or twice. Cover loosely with plastic wrap and let rest about 15 minutes.

3. Using just enough flour to keep dough from sticking to work surface, or to your fingers, gently and quickly shape dough into a ball. Generously coat a cotton towel (not terry cloth) with flour, wheat bran or cornmeal; put dough seam side down on towel and dust with more flour, bran or cornmeal. Cover with another cotton towel and let rise for about 2 hours. When it is ready, dough will be more than double in size and will not readily spring back when poked with a finger.

When the dough is folded over and shaped into a ball, the air cells inside it are moved and get distributed more evenly. The yeast, now highly active, keeps releasing carbon dioxide making the dough rise much faster than before. At the end of steps 2 and 3, air cells are inflated and homogeneously distributed throughout the bread dough giving it the perfect consistency.

4. At least a half-hour before dough is ready, heat oven to 450 degrees. Put a 6- to 8-quart heavy covered pot (cast iron, enamel, Pyrex or ceramic) in oven as it heats. When dough is ready, carefully remove pot from oven. Slide your hand under towel and turn dough over into pot, seam side up; it may look like a mess, but that is O.K. Shake pan once or twice if dough is unevenly distributed; it will straighten out as it bakes. Cover with lid and bake 30 minutes, then remove lid and bake another 15 to 30 minutes, until loaf is beautifully browned. Cool on a rack.

Once the dough is in the oven, the heat will continue to make the mixture rise as more carbon dioxide is released and the air cells expand. The yeast is eventually killed as the temperature continues to increase. The mixture stops rising, the gluten hardens, and the dough becomes solid. The bread is ready! Enjoy!

The end result (topped with a tomato mix).

Dear Fault, could you please wait until October?

Earthquakes are a frequent topic of conversation here in Santa Barbara where I'm spending the summer months doing research. California is a region of high seismic risk and the San Andreas Fault, which runs through the state, is believed to have accumulated enough strain to produce the next big Californian earthquake (or “Big One” as people call it around here). As you can imagine, I wasn't at all amused to be reminded that a quake of magnitude 7 or more might be coming my way. At least today's lunchtime chat brought to mind all the interesting stuff I learnt about geology back in school.

So why is it that the ground beneath our feet shakes every now and then? The outermost layer of our planet is divided into pieces called tectonic plates that are in constant (but slow and imperceptible) movement. The boundaries of these blocks, made up of many faults, rub against and bump into each other. The edges of the plates are rough and tend to get stuck together while the plates themselves keep on moving. This builds up pressure at the faults where the energy that results from the deformation of the moving plates is stored. When two plates have moved far enough apart to overcome the friction between their boundaries, the stored energy is released and an earthquake occurs. As for the San Andreas Fault  – just a few miles east of where I'm currently living – it is “locked and loaded”, as the director of the Southern California Earthquake Center puts it. I can only hope that it doesn't decide to release its energy while I'm here.

photo: David K. Lynch

Cork, the natural choice

It was only when I moved to England that I realised wine bottles could have plastic stoppers or aluminium screw caps. Back in Portugal cork was always the natural choice.

The reason for the widespread use of cork stoppers in Portugal may be historic or economic, as the country produces over 50% of the cork harvested annually in the world. However, these days the preference for cork is also connected to sustainability, low carbon cost and biodiversity protection. Cork is a natural substance with amazing properties (buoyancy, elasticity and impermeability, to name a few) that make it ideal for use in wine bottles. It comes from the bark of cork oak trees which is sustainably extracted every nine years, the length of time required for the bare trunks to renew themselves after harvesting. The cork oak trees, endemic to the western Mediterranean, naturally sequester atmospheric carbon and can live for more than two centuries. It is therefore not hard to believe that the carbon cost associated to the production of cork stoppers is significantly lower than that linked to screw caps or plastic stoppers. But there is more to add to the list of environmental benefits of cork. As emphasised by WWF, choosing cork helps preserve the rich biodiversity of the western Mediterranean and reduces the risk of fire and desertification.

There is much environmental science (and more) to discuss over a glass of wine at your next dinner party. Just make sure the bottle has a cork stopper! 

photo: APCOR

Is the moon going to disappear?

I would like this blog to be about science in general so I wanted to resist the temptation of posting about Astronomy again so soon (fail!). Do forgive me but this is too cool not to comment on: “Did you know the moon is shrinking?”. Yes, the moon, the only celestial body humans have set foot on, that bright, big object in the night sky where satellites have been to so many times does not stop surprising us. New images from NASA’s Lunar Reconnaissance Orbiter show widespread wrinkle-like features in the moon’s surface. These scarps are interpreted as being due to global cooling and resultant contraction. The planets and their satellites formed in a violent environment: collisions (as well as radioactive decay) resulted in a hot primordial moon. If a hot object has no heat source to maintain its temperature it eventually cools down. That’s what is happening to the moon. What is surprising is that it is still happening even though the moon formed over 4 billion years ago! Indeed the scarps revealed by NASA’s spacecraft are relatively recent having originated in the past billion years or so showing that the moon has not stopped shrinking. Astronomers believe our satellite will keep on contracting until its interior is cool enough. But worry not, the moon is not going anywhere: since it formed it “lost” only about 200 metres of its 3476 km diameter.

photo: Luc Viatour

As if being ugly wasn’t bad enough

It wasn't until I saw this slide show that I found out about the blobfish. This funny-named fish is probably the most miserable looking animal that I have ever seen, with a “face” worse than that of a Cleveland worker with a bad case of the Mondays. The Psychrolutes marcidus, its scientific name, is a deep-sea creature that inhabits the southwest pacific waters off the coast of Australia. It lives at depths of up to 800 meters. Because the pressure at such depths is so high, normal fish would have to swim to exhaustion not to sink. Their internal gas-filled organs or gas bladders (the evolutionary equivalent of lungs if you wish) would not be efficient in helping them keep their buoyancy. The blobfish survives because the gelatinous material it is made of is slightly less dense than water. The creature has no muscle: it floats for a living and it feeds off drifting mollusks and other organic matter. Even though the blobfish is harmless and inedible it is in risk of becoming extinct due to over-fishing as it frequently gets caught in fishermen’s nets. 

photo: Caters

“Stars fall as rain”

If you looked at the night sky late last week you probably saw a few more shooting stars than normal. When “stars fall as rain” as Chinese astronomers reported in 902 AD, appearing to come from one point in the sky, a meteor shower is taking place. In events such as this stars don’t actually fall. What we see are meteors, fragments left behind by comets that burn up and glow as they pass through the Earth’s atmosphere. Comets are small bodies of the Solar System composed of icy gas and dust. When a comet passes close to the Sun and heats up, some of its dusty-icy material evaporates creating a stream scattered along the comet’s orbital path. Comets such as Swift-Tuttle – the responsible for last week’s meteor shower – leave a stream that intersects the Earth’s orbit. As our planet travels around the Sun, it encounters the debris left behind by the comet at regular and predictable times and a meteor shower happens.

photo: Mila Zinkova, Wikimedia Commons

Desbloqueador de conversa

This blog's inspiration is a Portuguese expression: "desbloqueador de conversa" (literally, conversation unblocker). Something you say at a dinner party when silence kicks in or when some of the people at the table are having a heated argument and ruining the atmosphere. A snappy way of changing the topic of conversation: "Did you know that the penis of the blue whale can be 8 feet long?". Go figure, my favourite ones are related to science. Actually, what I find interesting is the science behind the fact so that is what I plan to write about. Use it if you need it.