Science Buddies: "Ask an Expert"

In a debate with a friend I need help to prove my point. My friend insists that her juicer and all jucers cannot destroy the enzymes contained in the fruit or food being juiced because the fruit or food is not being heated as in heating over a stove which is the only way she insists enzymes can be distroyed. (At what temperature are enzymes destroyed when the fruit or food is heated this way?) I told her that enzymes are distroyed in the juicing process of most juicers through the energy imparted to the fruit or food through the high rate of speed that the fruit or food is moved and the grinding/chopping process. She will not believe me unless I can provide solid scientific research or reliable scientific information that will prove what I am saying is correct. Please provde me with this information. P.S. The "juicer" that I have presses the fruit or food thus separating out the juice from the substance of the fruit or food which comes out of the "juicer" through a spigot.

Hi

This Science Buddies experiment writeup may be germane to your debate:

https://www.sciencebuddies.org/science- ... p011.shtml

Particularly note this paragraph:

“Because enzymes are proteins, they are somewhat fragile. They can be denatured by heat, and can easily be broken down by proteases when cells are homogenized. To preserve activity of proteins in solution, it is important to keep the solutions on ice until you are ready to use them. Denaturing conditions, such as boiling, can also be used as evidence to show that an enzyme-based reaction is protein-dependent.”

You may be interested in this page discussing enzyme denaturation in food:

http://class.fst.ohio-state.edu/FST822/ ... /Denat.htm

Here are paper abstracts discussing shear denaturation of enzymes:

http://onlinelibrary.wiley.com/doi/10.1 ... 7/abstract

http://onlinelibrary.wiley.com/doi/10.1 ... 8/abstract

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1614479/

Enzymes vary widely in their stability against various denaturation methods, so your debate may be extremely difficult unless you narrow it down to a specific enzyme and environment.

Good luck!

Barrett L. Tomlinson

I doubt that there is any ONE correct answer as the question is too broad. When you burst cell walls, you mix chemicals outside the cell wall with chemicals inside the cell wall and chemical reactions can occur. Some enxymes will oxidize and denature. If you juice mixed things like apples and oranges together, you get even more complex situations.