Spaghetti Science

Ever run out of soup noodles and relied on breaking up spaghetti into small 1 to 2 cm pieces? That’s what I just did, and I never realized how many 1-2 mm fragments are generated with each and every break. In fact some bits were even smaller than a millimeter. I realized it by fluke because I was breaking the spaghetti with my hands inside a strainer, and the “dust” trickled through the sieve’s 3 mm holes, decorating the counter top. Here’s what it looked like.

It turns out that this has been common knowledge. Scientists have looked into it as well. According to a Smithsonian article,

To break it requires bending it into a bow shape. Eventually the force of the bend snaps the rod in the middle where it is most curved. But the physics doesn’t end there. That break releases energy back down the pieces of spaghetti in a “snap-back” wave or vibration. There’s enough energy in those waves to break off smaller lengths of pasta.

Jason Daley August 16, 2018

If you first twist the spaghetti, apparently, the “twist wave” travels faster than the snap, dissipating its energy. And the spaghetti breaks cleanly. But it would have taken a lot of impractical twisting in my case, given that I broke each strand several times while clumping several strands together to break them faster.

What goes on when spaghetti cooks? The chemistry part.

There are basically two parts to the process occurring between 55 and 85 oC. Water moves into the starch granules, causing them to expand. But for the pasta to fully cook, its protein has to react. If you have egg noodles, an insoluble network of egg and flour proteins form, trapping the swelling starch granules. A pH of 6, according to molecular gastronomist, Herve This, helps the proteins bind the starch even more firmly. One year I had my students test this notion by acidifying the boiling water with a tablespoon of lemon juice. Surely, enough it prevented the pasta from becoming sticky.

What if you have regular noodles? The same thing happens to the starch. But heat converts the flour’s globular proteins into relaxed chains. If overcooked the chains don’t trap the expanding starch, and its amylopectin diffuses out. As it clings to the surface of different strands, it binds them together. You end up with messy lumps of spaghetti.

Oddly, it never takes me the 10 minutes of recommended cooking time. Five seem to be sufficient to create a slightly al dente spaghetti. What’s also noteworthy is how the same recipe but different shapes of pasta creates a different taste, probably because of the role that texture plays in taste and because different shapes have different surface to volume ratios. Thus varying amounts of sauce cling to each noodle.

Recent research (2021) at the University of Parma in Italy confirmed that pasta is a medium to low-GI food, (glycemic index = GI). That’s related to the fact that the starch granules remain trapped in the network, and so they are not completely hydrolyzed in the small intestine. The GI was lowest for those pastas that were enriched with legumes or other plant based products.

Sources:

Herve This. Molecular Gastronomy. Columbia University Press. 2006

Exploratorium. Soaking Pasta. https://www.exploratorium.edu/food/soaking-pasta

Jason Daley. Physics Reveals How to Break Spaghetti Cleanly In Two. Smithsonian. 16/08/2016

Giuseppe Di Pede and al. Glycemic Index Values of Pasta Products: An Overview. Foods 202110(11), 2541; https://doi.org/10.3390/foods10112541

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Expanding Birnbaum’s Observations

I was just making sure that my escarole (“scarola in Italian”) had enough water, early yesterday morning. But an unexpected surprise led me to learn more than a few things.

For starters, escarole is more closely related to chicory than to lettuce. Unlike the latter, escarole has toothed leaves and lacks the milky white sap characteristic of Lactuca plants. Escarole’s genus (a grouping of similar species) is Cichorium, which also includes endive and a cultivated variety of the same chicory species known as radicchio. Both the genera of lettuce and escarole are of the Asteraceae (aka Compositae aka sunflower) family, which has more than 13 000 species, most of which are not edible.

The fungus whose reproductive structures popped up and surprised me are a common flower pot mushroom originally from tropical zones. It’s known as Leucoprinus birnbaumii (the flowerpot parasol), named in 1839 after Birnbaum, a garden inspector. His observation made Corda, a mycologist, realize that it was an unrecognized species.

Less than 20 years ago, chemists decided to extract the toxic mushroom’s compounds with methanol. They separated the trio with inverted HPLC ( a form of chromatography used to separate polar organic compounds), and 2 of the 3 were unknown compounds. They first got the formulas ( C16H20N6O4 and C16H20N6O5 ) of the pair using mass spectrometry.

Then the major part of the detective work known as structure elucidation started. They first broke up each of the molecules into smaller fragments, then carried out reactions and did more analyses.

They discovered that the pure substances were unusual indoles, not because they were N-hydroxyoxamidines, but because they were the two simplest versions of those compounds known to date. Indoles by the way are very common in nature. Examples in humans include skin pigment melatonin, the neurotransmitter serotonin, and the amino acid, tryptophan. Plants have important hormones, auxins, that feature the indole-building block and fungi make at least 140 indoles, including the drug psilocybin, the active ingredient of magic mushrooms.

Guess what they named the new indoles? More name-fame for the garden inspector: Birmaumin A and B.

The flowerpot parasol’s Birnbaumin A and B compounds are virtually identical, except that teh B-version has a hydroxyl group(OH) instead of a hydrogen as an “R’ group. In the figures below we see the indole group appearing in 7 different compounds found across life’s different kingdoms.

Sources:

Birnbaumin A and B: Two Unusual
1-Hydroxyindole Pigments from the “Flower Pot
Parasol” Leucocoprinus birnbaumii
Chem. Int. Ed. 2005, 44, 2957 –2959

Birdsfoot Trefoil Takes Over

Birdsfoot trefoil is an attractive relative of a familiar group of species of clovers known as Trifolium, which includes red, white, Swedish, Dutch and nearly 300 other species. Like clovers, it is a useful plant. While it grows on roadsides, it helps control erosion. It feeds both wild animals (geese, deer and elk) and domestic ones, without bloating the latter. The actual genus of birdsfoot trefoil is Lotus, which includes less members than Trifolium, some of which may need to be reclassified. The rest of its name which designates its species is corniculatus, and it’s very similar to other species with the birdsfoot name: slender, alpine and smallflower.

Why is it called birdsfoot? At first glance, the flower looks like that of a pea, another member of the Plant kingdom’s 3rd largest family, Leguminosae, which, of course, includes the pea-genus (Pisum) along with Lotus, Trifolium and about 750 others. But if you look at mature birdsfoot flowers, their seed pods spread out in a plane and resemble a bird’s foot.

The plant first caught my attention in the 1980s on northern stretches of the 87 interstate highway headed to New York City. In Montreal, I had never seen it. A few decades later it began to appear sporadically in small patches in parks and abandoned fields. This year in July it has become so dominant in parks and big lawns, that from a distance, one could mistake them for dandelions. Here is a field I photographed in 2011 when white clover dominated, and the same field nine years later when birdsfoot trefoil reigns.

Why the change? White clover is best suited to soils which have good moisture-holding ability. Birdsfoot trefoil does better in dry soils. Given that Montreal had unusually arid months of May and June this year ( 33.6 and 46.4 mm of rain instead of the usual 81 and 87 mm), this could have contributed to the boom in the growth of corniculatus.

Occasionally, one will notice birdsfoot trefoil flowers that are orange instead of yellow. Older flowers occasionally take on the latter color. I thought of a couple of explanations. They do contain lutein which appears yellow at low concentrations and orange to red at higher concentrations. Presumably, with age, lutein accumulates. But beta carotene is also found in the plant, so if its content builds up, it could also be responsible for the color change.

The highly conjugated structure of lutein, C40H56O2 , is responsible for the yellow color of birdsfoot trefoil flowers.
Beta carotene, C40H56, is very similar in structure to lutein. The former replaces a hydrogen on each end-ring with hydroxyl, and the ring on the right is conjugated with the rest of the structure. This means less energy is required to excite its electrons, leading to a higher blue maximum absorption peak for beta carotene. That in turn leads to a reflection of more orange than yellow. (see graph below)

Sources:

Fatty acids, α-tocopherol, β-carotene, and lutein contents in forage legumes, forbs, and a grass-clover mixture.Elgersma A, Søegaard K, Jensen SK.J Agric Food Chem. 2013 Dec 11

USDA Natural Resources Conservation Service. https://plants.sc.egov.usda.gov/java/

The Audubon Society Field Guide to North American Wildflowers. Richard Spellenberg. Knopf. New York. 1987