Pratica di Shadowing: How Onions ACTUALLY Make You Cry (And How to Stop Them) - Impara a parlare inglese con YouTube

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Onions. We love to hate them.
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Onions. We love to hate them.
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Or rather, our eyes hate  that we love them so much.
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They are one of the oldest recorded  vegetables in continuous use, with records dating back 4,000 years, and they’ve made their way into pretty  much every culinary tradition in the world.
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As amazing as they are, they’ve got one  really annoying flaw: all of the crying.
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Every time you cut into one, you can’t help but well up like you’re watching a sad dog movie.
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We actually know quite a  lot about what’s happening at the chemical and biological  levels to make this reaction happen.
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But a study published in October 2025  looks at the onion-crying problem from a new perspective: physics.
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They examined the droplets flung out of an onion being cut in various ways with a  precisely-tuned onion guillotine.
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And the results show us there is still  more to learn about how onions make us cry.
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[♪ INTRO] Now before we dive into the French  Revolution of onions, let’s recap the science behind the onion’s uncanny ability to  bring tears to even the toughest eyes.
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There’s a chemical that gets  released when you cut into an onion called syn-propanethial-S-oxide  which causes the glands in your eye that produce tears to work overtime to  attempt to flush the irritant of your eyes.
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The weird thing is, onions don’t  contain any propanethial-S-oxide.
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Instead, they contain the ingredients for it.
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First, when you cut into the onion, your  knife breaks open a lot of cell walls.
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And this is all the onion  needs to introduce the enzyme alliinase to air and produce  1-propenesulfenic acid.
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That chemical then reacts  further with another enzyme to make the tear-inducing propanethial-S-oxide.
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Given how long we’ve been tearing up at onions, you might be surprised at how  recent some of this science is.
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We only discovered that second step,  where 1-propenesulfenic acid reacts to another enzyme to make the actual  tear-jerker substance, in 2002.
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Which, to me, is like 5 years ago.
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So that’s the chemistry behind the effect.
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A weird side-note: onions get  their sulfur from the soil, and acid rain contains a lot of sulfur.
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So a strange consequence of the  success of tackling acid rain in many urban areas is that it  might actually make onions milder!
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It feels like it was worse when I was a kid.
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Maybe I’m just stronger now.
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This molecule is also pretty much  unstoppable once it gets to your eyes, so the only way to truly avoid tearing up is to prevent it from reaching  your eyes in the first place.
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So the chemistry and biology  are pretty much solved.
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But what hasn’t been addressed yet is the physics.
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As in, we don’t know exactly how this substance travels to your eyes in  order to be able to stop it.
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Enter: the onion guillotine, courtesy of  a research group at Cornell University.
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They also employed high-speed  cameras and an electron microscope to test which configurations of knife  sharpness, angle and speed of cutting, and temperature of onion resulted  in the worst onion-juice splashes.
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They found that the chemical  is carried in droplets, released in an initial burst when a blade  first punctures the onion’s surface, then more slowly as the blade travels through.
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In their tests, a more blunt  blade applied more pressure to the membrane before breaking it,  causing a bigger burst of droplets.
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And that reinforces the wisdom that you should always use a sharp knife in the kitchen.
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Keeping blades sharp also reduces  the chance of injuring yourself (which seems a little counterintuitive,  but it reduces the amount of pressure you need and the chance of the knife slipping).
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But this is another, brand new reason!
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The Cornell team also found  that cutting faster caused more droplets to be released,  so a cautious approach with a sharp knife might be the best  way to minimize tear production.
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As for the common “hack” of putting  your onions in the fridge to somehow limit their ability to hurt  your tear ducts’ feelings, the researchers did not find any support for this.
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In fact, chilled onions released  more droplets in their experiments.
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They thought that this might be because  the onion tissues get stiffer when cold, causing them to absorb more of the  knife’s pressure before breaking, then bursting with even more energy.
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There’s another solution running around out there, which is that you should put a damp towel or bowl of water near where you’re cutting.
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Given that the offending  chemical is water-soluble, if you could somehow get the onion droplets to hit the water before it hits your  eyes, that seems like it could work.
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It wasn’t part of the experiments in this paper, but if I’m allowed to make requests,  it might make for a good follow-up!
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Our speculation, though, is that  the Cornell’s team’s experiments show the droplets flying upwards, so water on the worktop can only  work to mop up splashes and bounces, and wouldn’t be in a position to stop  that first attack on your eyeballs.
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Outside of just stopping a  common kitchen annoyance, this research has implications  for food safety in general.
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Droplets sprayed from vegetables don’t  only carry tear-inducing chemicals, but also potentially foodborne pathogens as well.
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So, this research suggests that a  sharper knife keeps your kitchen safe in yet another way, by preventing potential  pathogens from being spread around.
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Armed with the knowledge from an onion guillotine and some fancy imaging equipment,  we can at least help you out if you really can’t stand that  stinging feeling in your eyes.
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The best way to limit the amount of  onion droplets spraying into your eyes seems to be to keep your  knife sharp and to cut slowly.
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Short of investing in goggles, anyway.
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Which I have heard from prep  cooks, is something they do.
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And wildly, that strategy might also keep  your whole kitchen safer at the same time.
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[♪ OUTRO]

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Informazioni su Questa Lezione

In questa lezione, esplorerai il mondo delle cipolle e il motivo per cui ci fanno piangere. Imparerai i termini chiave e le frasi utilizzate nel contesto scientifico per spiegare il meccanismo chimico che causa la lacrimazione. Attraverso la pratica di shadow speech, avrai l'opportunità di migliorare la tua pronuncia in inglese, seguendo il tono e la velocità del video. Questa lezione è ideale per chiunque voglia affinare le proprie abilità di shadow speaking e comprendere meglio l'inglese parlato.

Vocabolario e Frasi Chiave

  • Cipolle - Onions
  • Chimica - Chemistry
  • Reazione - Reaction
  • Tear-jerker - Che fa piangere
  • Melma - Mucus
  • Enzimi - Enzymes
  • Uso di un coltello affilato - Using a sharp knife
  • Fase della ricerca - Research phase

Consigli per la Pratica

Quando pratichi il tuo shadowing, prova a seguire il ritmo del video prestando attenzione alla pronuncia degli esperti. La velocità del discorso può variare, quindi inizia con tre ascolti: il primo per comprendere il contesto, il secondo per riprodurre i suoni e il terzo per affinare la tua intonazione. Non esitare a ripetere frasi o sezioni che trovi particolarmente difficili. Utilizza le tecniche di shadowspeaks per sincronizzare la tua voce con quella nel video; queste tecniche ti aiuteranno a migliorare la tua pronuncia inglese in un modo dinamico e pratico. Inoltre, fai attenzione ai suoni delle consonanti e delle vocali mentre parli per trasformare il tuo parlato in qualcosa di più naturale e fluente.

Cos'è la tecnica dello Shadowing?

Shadowing è una tecnica di apprendimento delle lingue supportata da studi scientifici, originariamente sviluppata per la formazione dei traduttori professionisti e resa popolare dal poliglotta Dr. Alexander Arguelles. Il metodo è semplice ma potente: ascolti un audio in inglese di madrelingua e lo ripeti immediatamente ad alta voce — come un'ombra che segue il parlante con un ritardo di solo 1–2 secondi. A differenza dell'ascolto passivo o degli esercizi di grammatica, lo shadowing costringe il tuo cervello e i muscoli della bocca a elaborare e riprodurre simultaneamente i modelli di discorso reale. La ricerca dimostra che migliora significativamente la precisione della pronuncia, l'intonazione, il ritmo, il discorso connesso, la comprensione dell'ascolto e la fluidità del parlato — rendendolo uno dei metodi più efficaci per la preparazione alla prova di speaking dell'IELTS e per la comunicazione reale in inglese.

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