Edit: Thanks so much for the silver kind stranger!
Edit 2: And the others! You’ve made my day! Glad I dropped my biscuit in my tea and decided I needed answers
In: Chemistry
Answer: molecule speed.
I saw an interesting documentary that showed a graph over how fast the impacts was happening in room temperature. And then overlayed fridge temperature. You could not tell the difference.
Until he zoomed in on the high temperature area. Like thousands of degrees hot. There it was. A minute difference.
And that is all the energy needed to break down what we would consider food into nasty organic pulp.
Bacteria and fungus be all like: what’s the problem?
Molecules move faster when hot. So imagine each molecule is the size of a marble and you put them inside a container like a pringles tube. Now suspend a biscuit in that tube while gently agitating the tube enough to make the marbles vibrate ever so slightly, vs throwing the marbles around inside the tube violently. Which one is likely to cause more damage to the biscuit? The violently moving marbles. Thats hot liquid.
Its the same reason its easier to dissolve sugar in hot tea than cold tea.
Clunky explanation, but hopefully you get an idea.
There is a lot of fat in pastry. Butter mostly. When you melt the fat you lose structural integrity. Heat melts fat.
Short answer: Heat
Slightly longer answer: It is the heat.
Long answer: The heat from the hot liquid in witch the biscuit/cookie is put in, breaks the structural integrity of the biacuit/cookie, more quicker than the liquid that is not heated.
There.
Glad I helped.
A cookie is a composite of 3 things: Carbohydrates (sugar and starch), Fat, and Protein. The carbohydrates are water soluble to varying degrees, and will dissolve faster in hotter water, because the faster-moving molecules are better able to rip the molecules of the carbohydrates apart. Fats are not water soluble, but warm liquids will soften them, making the cookie softer. Protein (from the egg and to a lesser extent, the gluten in from the flour) isn’t super water soluble, but it doesn’t contribute as much to the overall structure of the cookie as the fat and carbs do. So, hot liquids can compromise 2/3 elements of the cookie’s structure a lot faster than cold ones.
The fat (butter usually) in a biscuit or cookie melt with hot water, unsticking the other ingredients from each other
I am not sure if its right, but since a good portion of the structural integrity of these treats comes from fat (butter or whatever oil uses) and they melt quickly in hot tea or coffee…
Because the fats within the cookie / biscuit (butter, oils, etc.) loosen with heat and create a melting affect. The cold water hardens the fat instead of melting, making it harder for the cookie to dissolve.
By hot liquid, you probably mean hot water. Water dissolves simple carbohydrates (sucrose being the most common sugar in a cookie; sucrose is a disaccharide, formed of two different sugar molecules joined together in a solid, covalent bond), which help the cookie stick together. Hot water dissolves them more readily (quicker) and at higher concentration (more sugar dissolved in a given volume of water) than does cold water. Keep in mind that this is not melting, which is a common misconception. Sugars do not melt in water – they dissolve. People think they melt because a higher temperature allows the sugar to dissolve faster and in greater amounts. Again, this is not melting.
Thinking of non-aqueous liquids, hot vegetable oil would probably cause a cookie to fall apart faster than cold vegetable oil as well, but because in this case the oil is dissolving the fats, which would be congealed and sticky in the cookie, helping it hold together as well. It’s a general rule that the solubility (amount you can dissolve, per volume of liquid) of a solid increases in a liquid as the temperature is increased, although some solids are not soluble in certain liquids at all. For example, table salt is not soluble in vegetable oil or mineral oil at all.
By hot liquid, you probably mean hot water. Water dissolves simple carbohydrates (sucrose being the most common sugar in a cookie; sucrose is a disaccharide, formed of two different sugar molecules joined together in a solid, covalent bond), which help the cookie stick together. Hot water dissolves them more readily (quicker) and at higher concentration (more sugar dissolved in a given volume of water) than does cold water. Keep in mind that this is not melting, which is a common misconception. Sugars do not melt in water – they dissolve. People think they melt because a higher temperature allows the sugar to dissolve faster and in greater amounts. Again, this is not melting.
Thinking of non-aqueous liquids, hot vegetable oil would probably cause a cookie to fall apart faster than cold vegetable oil as well, but because in this case the oil is dissolving the fats, which would be congealed and sticky in the cookie, helping it hold together as well. It’s a general rule that the solubility (amount you can dissolve, per volume of liquid) of a solid increases in a liquid as the temperature is increased, although some solids are not soluble in certain liquids at all. For example, table salt is not soluble in vegetable oil or mineral oil at all.
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