Biocatalytic biobots brew beer better (Chemistry World)

1 minute read

Beer-brewing ‘biobots’ could boost the drinks industry by speeding up fermentation. Researchers in Czechia encapsulated yeast and iron oxide nanoparticles in a biocompatible polymer to create self-propelling biobots, which can be retrieved from beer samples magnetically – eliminating the need for filtration steps.

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The Edible Insect Revolution Is Not for Those With Shellfish Allergies (McGill OSS)

5 minute read

Even if it might gross us out now, experts predict that edible insects will play a significant role in our future diets. Not only are these bugs rich in protein and nutrients, but they can also be farmed more sustainably. For example, farmed crickets have a water footprint roughly 1/3 the size of beef cattle, require 50-90% less land, and emit 100 times less greenhouse gas during the farming process. In addition, where most of a cow is inedible to humans, roughly 80% of a cricket can be eaten, meaning less waste.

All things considered, it is in our best interest to get comfortable with eating insects. Unless you’re allergic to shellfish, that is.

Shellfish allergies are highly prevalent throughout the world, particularly in places where consumption is high. It’s estimated that 2% of people worldwide show immune responses to shellfish. In the U.S., roughly 6.5 million individuals have a shellfish allergy, making it twice as common as a peanut allergy. Shellfish plus seven other common allergens (milk, eggs, fish, tree nuts, peanuts, wheat and soy) make up 90% of food allergies in the U.S. that are not outgrown after childhood.

It’s not only through eating shellfish that one can have an allergic reaction. Occupational exposure at shellfish processing plants can cause reactions, often just through inhaling the airborne particles of crustaceans.

Unfortunately, the edible-insect revolution is not very welcoming for the many affected by a shellfish allergy. Upon consumption of crickets, mealworms or other insects, individuals with shellfish allergies have a good chance of having an allergic reaction. This is even true for the occupational exposure route, with reports of cricket farm or pet store workers sensitive to shellfish having reactions.

The high potential for cross-allergic reactions between insects and shellfish might only make sense once you look at their phylogenetic tree. Shellfish is a colloquial term encompassing any ocean-dwelling animal with an exoskeleton. Almost none of them are actually fish. Bearers of the shellfish moniker come from three different phyla: Mollusca, containing mollusks like snails, clams, and octopi; Echinodermata, containing echinoderms like sea urchins and sea cucumbers; and crustaceans like shrimp and lobster, which are actually a subset of the phylum Arthropoda.

phylogenetic tree for shellfish and insects

Photo source:

You might know arthropods as all the things we typically call “bugs,” like spiders, millipedes, and all sorts of insects. Crustaceans like crayfish or prawns are, quite literally, just the bugs of the sea. With this evolutionary relationship in mind, it’s easier to imagine how immune systems often fail to differentiate between bugs of the land and the ocean.

diagram of phylum arthropoda

Photo source: 

Most shellfish allergies are due to the immune system reacting to proteins. There are a few different proteins in shellfish responsible (around 34), including arginine kinase and sarcoplasmic calcium-binding protein, but the overwhelming majority of those with shellfish allergies show sensitivity to the protein tropomyosin.

As Dr. Zachary Rubin, pediatric allergist, wrote to me, “The majority of people allergic to shellfish are allergic to a protein called tropomyosin, which is also found in many insects, so it’s not usually a good idea to consume insect-containing foods if you have a shellfish allergy.”

If you’ve studied biology or seen the famous “The Inner Life of the Cell” animation, you might recognize tropomyosin as one of the proteins integral to our muscles contracting. Without tropomyosin, I couldn’t move my fingers to type this article. But if tropomyosin is found in the proteins of most animals, why are so many people allergic to shellfish tropomyosins but not other animal tropomyosins?

It comes down to the sequence of amino acids that make up a tropomyosin protein. You can think of a protein as a chain, with each individual link being an amino acid. A protein chain can be constructed of many different combinations of amino acids in various orders to create countless distinct proteins with unique properties.

All tropomyosin proteins are similar to a certain degree—otherwise, they wouldn’t be tropomyosin proteins—but even working within these bounds, tropomyosin is afforded significant variation in its amino acid sequence between different animals. Some animals are more similar to others. Across various crustacean species such as prawns, crabs, and lobsters, amino acid identities can reach 95–100% similarity. The tropomyosin amino acid sequence is well preserved across shellfish, even though they belong to two different genetic phyla: Arthropoda and Mollusca.

Tropomyosin is the culprit allergen for cross-reactions between those allergic to shellfish and insects like crickets, fruit flies, grasshoppers, cockroacheslocusts, and dust mites.

One 2020 study found that certain insect species elicited less of an immune response from shrimp tropomyosin allergic patients. Mealworm larvae, waxworm larvae and superworm larvae may represent less allergenic insect options.

Another specific aspect of shellfish tropomyosins that may contribute to their allergenicity is their high thermostability. When proteins are heated, most will melt. Typically, this means that they are no longer active. Having lost their 3D structure, the proteins can’t be recognized by receptors or other important molecules and isn’t detectable by the immune system.

Treating proteins under high heat to denature them can be a strategy for making hypoallergenic products. The tricky thing is that the temperature needed to denature changes based on the protein. For example, tropomyosins happen to have very high melting points. This thermostability is thought to contribute to the highly allergenic nature of these proteins since treatment with heat, or even high pressure, isn’t sufficient to render them anallergenic.

Unfortunately, due mainly to tropomyosin and a handful of other allergenic proteins, the edible insect revolution is not for those with shellfish allergies. Given the popularity of alternative protein choices for pet foods, you may want to keep the shellfish-insect connection in mind when choosing kibble for your furry friends.

This article was written for the McGill Office of Science and Society. View the original here:

For a Pet with Allergies, Feathers May Be the Unexpected Solution (McGill OSS)

5 minute read

The difference between hypoallergenic and anallergenic pet foods is subtle but important. The Greek prefix hypo- means “lacking” or “less.” Hence, someone who is hypothermic is lacking in heat, and someone who is hypoglycemic has less blood glucose than they should. The prefix a- (or an- when it proceeds a word that starts with a vowel) is also Greek but means “no,” “not,” or “absence of.” We see this in terms like apolitical (not political) or anorexia (absence of appetite). Thus, hypoallergenic dog food contains fewer allergens, whereas anallergenic dog food contains none (or as close to none as possible).

What does that actually mean for pet food? Well, for most cats and dogs, proteins are the primary allergen, so hypoallergenic foods tend to use partially hydrolyzed proteins or proteins that have been broken down into smaller pieces and are therefore less likely to be recognized by an animal’s immune system, triggering a reaction. They tend to use a single source of protein instead of a blend and a single source of carbohydrates. Hypoallergenic pet foods often avoid the most common allergens for cats or dogs, sometimes employing specific parts of these animals—hydrolyzed chicken liver is common—or novel and “weird” protein sources like kangaroo, rabbit, or soybeans.

The problem is that roughly 25-50% of dogs will still have allergic reactions when fed hydrolyzed diets derived from proteins they’re allergic to. This may be due to incomplete hydrolyzation, leaving protein fragments still big enough to be recognized by the immune system, or even just cross-contamination from some part of the manufacturing process. For dogs like this, veterinarians often turn to anallergenic diets.

Proteins are long chains of amino acids. Their mass is measured in a unit called a Dalton (Da), or more commonly, a kilo-Dalton (kDa) because scientists prefer working with smaller numbers whenever possible. Protein masses can vary widely. For example, insulin has a mass of roughly 5.8 kDa, whereas ATP synthase, the enzyme responsible for powering everything we do, has a mass close to 600 kDa. Alcohol dehydrogenase, the enzyme that processes any alcohol we drink, weighs roughly 170 kDa.

There isn’t a consensus on how big a protein needs to be to potentially trigger an immune response, but we can confidently say that the smaller the protein, the lesser the chance. Hypoallergenic dog food tends to have proteins in the 3-15 kDa range. Conversely, Royal Canin’s Anallergenic food—debuted in 2012 after over a decade of research—was the first pet food considered to contain extensively hydrolyzed proteins. It contains proteins that are 95% less than 1 kDa and 88% broken down to the level of single amino acids!

In one randomized, double-blind crossover study of 10 dogs with cutaneous adverse food reactions, the Royal Canina Anallergenic diet did not trigger an allergy flare-up in a single participant. In contrast, a hydrolyzed chicken liver diet (a typical protein source for hypoallergenic dog foods) triggered a flare-up in 40%.

Despite being a feat of scientific engineering designed to help dogs and cats get relief from a condition without many other treatments, there remains a degree of controversy around Royal Canin’s Anallergenic food. Why? Because its protein source is hydrolyzed poultry feathers.

Pet food marketing has long relied on messages about feeding your dog as you would the other members of your family or avoiding “filler” ingredients. Unfortunately, this has resulted in demonizing ingredients like corn meal or hydrolyzed poultry feathers, even when all science supports their inclusion. Despite appeal-to-nature infused commercials referring to domestic dogs as “wolves” or “carnivores,” your Shih Tzu has evolved quite a bit from her wolf days and has different dietary requirements.

Dogs are not carnivores and haven’t been for thousands of years. They can digest grains quite well and benefit significantly from modern advancements in food processing, just like humans. Raw diets are dangerous for a multitude of reasons, and just because you wouldn’t want to eat an ingredient like hydrolyzed poultry feathers doesn’t mean it isn’t perfectly beneficial to your pet. Not to mention, as the poultry feathers are so extensively broken down before being included in kibble, it makes about as much sense to consider them feathers as you’d consider a single brick a cathedral.

All of the dogs in the above-mentioned crossover study readily ate the feather-based food, and such diets seem acceptable even for the more traditionally discerning cats. Despite claims to the contrary, hydrolyzed poultry feathers are well-digested by both cats and dogs.

Other attempts to demonize poultry feathers as a source of protein rely on characterizing them as a “waste product” of human meat processing—as if that’s a bad thing. For sustainability purposes, utilizing every part of an animal is far preferable to disposing of a perfectly functional ingredient. Claims that Royal Canin is only using feathers to benefit their own pockets are equally nonsensical, given how expensive the extensive hydrolyzation process is, the extensive research and development funding that went into perfecting it, and how much cheaper it would be to continue to use the conventional protein sources they already have.

Anallergenic food is a powerful tool for veterinarians and pet owners to diagnose and treat severe pet allergies that, prior to its invention, often had no great treatments. The demonization of by-products, highly processed ingredients, or whatever else you want to call hydrolyzed poultry feathers is unscientific rubbish that will almost certainly lead to pets who would benefit from this food not getting it. It’s high time we overcame our fear of the unknown and instead marvelled at how science can find unique new solutions to age-old problems.

This article was written for the McGill Office of Science and Society. View the original here:

Should you add milk to tea, or tea to milk? (McGill OSS)

2 minute read

Everyone seems to have an opinion on making the best cup of tea. People who have weighed in on this topic range from royal butlers to George Orwell, but despite many claims of it being definitively settled—often by science—the debate rages on.

From the ideal water temperature to the source of the tea leaves, the best material for a pot (china, earthenware, or pewter, according to Orwell, never silver!), the best shape of a cup, or whether it is sacrilege to add sugar, there are a lot of variables in brewing tea. However, one of the most hotly contested ones is not whether to add milk or not, but in what order.

Adding milk to tea has a few benefits, according to the experts. It can help counteract the tannin’s astringent or bitter aspects and adds a few calories and nutrients to an otherwise nutritionally bereft beverage. Modern research also shows that adding milk can decrease the staining effects of tea on teeth and, presumably, mugs and pots as well.

A commonly circulated theory posits that first pouring milk into a china teacup helps avoid the heat shock of directly filling it with hot fresh tea and stops low-quality china from cracking. Some sources claim that the practice of pouring tea into a cup before milk, therefore, became a subtle way to brag about the quality of your china. While it’s hard to validate this theory, tea before milk is the preferred pouring order of the British Royal Family, who are likely to take an opportunity to boast their riches.

Regardless of its origins, almost all guides and sources now agree that tea should be poured into a cup first and milk (if desired) second. As for the claims that science has somehow settled this debate, besides a few industry-funded “studies” (really more like PR stunts) and a press release from the Royal Society of Chemistry based on research that was either never done or never published, I can’t find any actual scientific discussion of whether it’s better to add your milk or tea to your mug first.

Although, if a research group wants to study this in the future, they’ll likely benefit from ISO 3103, a publication from the International Organization for Standardization (ISO) that details standardized steps with which to brew a cup of tea for the purposes of comparison. The ISO is a non-governmental organization that exists for the express purpose of developing standards that are applicable across all 167 member countries for technical and manufacturing purposes. ISO 3103 was approved by all member countries, with the exception of Ireland, which objected on technical grounds due to the omission of a teapot warming step.

As I said, almost everyone seems to have strong opinions on this topic. I think I’ll be keeping my tea-brewing method to myself.

This article was written for the McGill Office of Science and Society. View the original here:

Why is poop brown? (McGill OSS)

1 minute read

A certain amount of the muddy colour can be attributed to the different colours of food we eat. Like mixing all the paint colours together, the result is a dull brown. But, much bigger factors for humans’ brown poop are bilirubin and bile. Bilirubin is a yellow substance found in the liver, the product of the breakdown of old red blood cells. Bile is dark brown or green and is produced by the liver to help digest fats. Both of these substances are secreted into the small intestine during digestion, and slowly make their way into poop, bringing with them a dark brown hue.

Bird poop, on the other hand, is not brown but white. That is because—unlike mammals—birds don’t pee!

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Do We Actually Need To Eat More Calories When Menstruating? (Skeptical Inquirer)

4 minute read

Shark week, moon time, the crimson tide, a visit from Auntie Flo: whatever you call it menstruation is the roughly monthly interval during which the uterus sheds its lining. For the uterus owner, it is not generally a super fun time; cramping, bloating, headaches, and fatigue are just a few of the symptoms associated with “that time of the month.”

The symptom I want to focus on today, though, is hunger. Whether for chocolate, pizza, or any food really, an increased hunger is a commonly reported phenomenon during, or right before, menstruation. Although we know that periodic (get it?) changes in appetite can be influenced by fluctuations in hormones such as estrogen and progesterone, I became curious whether this increase in hunger also correlated with an actual increased need for energy from food. Just like our bodies produce the sensation of thirst when they require more hydration, maybe they produce the sensation of hunger during menstruation in part because of an increased caloric need.

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The Science of Cold Brew (McGill OSS)

2 minute read

A few weeks ago I finally had enough of the cold brew trend and decided to see what all the hype was about. I followed this recipe (because $5 at Starbucks is just too much for me), and was surprised to find cold brew wonderfully smooth, sweet and mild. I love coffee, and though I drink it with milk and sugar, I’ve never especially been bothered by the bitterness or acidity of traditionally brewed coffee. None the less, cold brew is quite amazing, and it left me wondering what the chemistry behind it was. 

It turns out that hot water (about 93 ℃ in most drip coffee makers ) accelerates the extraction of molecules and chemicals that, once mixed with water, form the coffee we know and love. Once brewed, the coffee continues to react with air and water molecules. This is why coffee goes stale. Heat accelerates these reactions (as it does most), so coffee left on a burner, or in your car, all day goes staler more rapidly. 

In cold brew, however, there is no heat to help extract these molecules and to cause the break down of others. The time the cold brew is left brewing allows the chemicals to be extracted from the coffee grounds much like the heat does, but you do get different amounts of different chemicals, leading to a different taste. Notably, many molecules that taste bitter are not extracted in large amounts in the absence of heat, which explains cold brew’s sweetness. You may have also seen cold brew being sold pre-packaged in stores, a possibility that is afforded to it due to the cold water not accelerating the ‘staling’ process.

So for once it seems like the hype was justified, though I’ll stick to making my cold brew at home. 

Originally posted here:

Bananas are Berries. Raspberries are Not. (McGill OSS)

2 minute read
All images created by Cassandra Lee

It turns out berry is actually a botanical term, not a common English one. It turns out that blackberries, mulberries, and raspberries are not berries at all,  but bananas, pumpkins, avocados and cucumbers are. So what makes a berry?

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You Don’t Need To Bleach, X-Ray, Or Inspect Your Kids’ Candy This Halloween (But You Do Need To Wear A Mask) (Skeptical Inquirer)

7 minute read

I haven’t gone trick or treating in over a decade, but I still vividly remember my fear and anxiety around Halloween candy. I remember double-checking every piece to make sure it was sealed and throwing away anything that wasn’t. I remember that the neighbors who gave cans of soda were my favorite to visit, not only because I loved pop but also because it was nearly impossible for a can to be opened or tampered with and maintain its pressure.

Halloween sadism is the idea that a stranger would try to hurt trick or treaters by adding poisons or sharp objects to their candy. I remember the first time my mom told me about it. I was around six years old, and as she was tucking me into bed we got to talking about Halloween and razor blades in apples. I was instantly terrified, and when I expressed this, my mom tried to backtrack and explain that it was just a story; it didn’t really happen.

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Will Wearing A Hat Make Me Go Bald? (Skeptical Inquirer)

10 minute read

While losing the hair on our heads doesn’t have any serious medical implications on its own, it can be seriously damaging to our psyches. Studies have shown that both women and men with alopecia, or hair loss, experience increased stress, diminished self-esteem, and other negative psychological effects.

Some of us live in fear of our part widening or our hairlines receding. Others have made peace with their eventual journey to becoming a Patrick Stewart lookalike. Either way, you’ve likely heard a lot of unsubstantiated claims about behaviors that can cause baldness. As usual, some can be dismissed outright (no, masturbating won’t make you go bald), but some bear further investigation.

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