|MadSci Network: Biochemistry|
Hi Alex, I received the following from the Mad Scientist Subject: What would be a safe liquid to use to reproduce stomach acids? Message ID Number: 920383802.Bc "I would like to do an experiment on how long it takes certain foods to break down. I'd like to use some liquid as my 'stomach acid' and place different foods into the liquid. Thanks so much for your help!" The short answer: Hydrochloric acid (HCL) also know as Muriatic acid is the acid in the stomach check out the following URLs for more info: http://www.exclamedia.com/dHCl.htm http://www.exclamedia.com/dmur.htm BUT!!! - - - it's not just the acid that digests the food. There are enzymes (e.g. pepsin and rennin) and the mechanical stirring you stomach does. See one of the URLs below. I did a quick web search for more info (because after 30 + years, I couldn't remember the names of the stomach enzymes, just the intestinal ones -- I work mostly with bacteria now) Here's how and some of what I found: Using AltaVista (my fav search engine for science stuff) http://www.altavista.com/ I entered: +"stomach acid" +enzyme +digest and got the following URLs -- & a bunch of antacid commercials ;^( These all contain the same info -- word for word -- without citing their source (sigh) But, it's still excellent information that you could use as background material for your experiment. Do cite your sources of information. http://www.nutristrategy.com/digestion.htm http://www.wnygastro.com/gastroenterology/digestive_system.html http://www.niddk.nih.gov/health/digest/pubs/digesyst/newdiges.htm I went back to Alta Vista and entered +stomach +Hydrochloric The first URL: http://www.campus.bt.com/public/ScienceNet/database/Biology/Food/b00206c.html contained the following: Hydrochloric acid in the stomach The hydrochloric acid in gastric fluid has several functions: 1)It provides the optimum pH for pepsin and rennin (an enzyme which digests milk proteins). 2) it begins the digestion of some carbohydrates and lipids through the chemical reaction of hydrolysis. 3) it denatures proteins and helps to soften tough connective tissue in meat. 4) it is a strong bactericide (it kills bacteria) and so protects the body from some of the harmful microbes which might enter the body in food. Interesting (to me any way) stuff: 1) HCl as a bactericide: Don't count on it. Escherichia coli O157:H7 (the "hamburger disease" bug) is very acid resistant; that's why it takes so few of these bacteria to cause disease because most of them survive the stomach acid. Shigella is another acid resistant bacterial pathogen. Also, acid-sensitive pathogens such as Salmonella have proven to be infective in small doses -- if they are protected from the stomach acid by being covered by the food, especially fatty food, such as chocolate, cheese, and even hamburger (good reason to chew your food well). 2) Safety of HCL: Do heed the warnings at: http://www.exclamedia.com/dHCl.htm but, HCl is unique from other strong acids in that it doesn't readily attack skin. I used to illustrate this by holding a steel nail in my palm and spooning a little HCl over it. The HCL would attack the nail, give off bubbles of hydrogen gas and not harm my hand -- BUT -- the chemical reaction would get pretty hot so I would have a cold water tap handy and a safe place to dump the acid (it eats the heck out of clothes and you may not notice where the droplets landed until your clothes are washed) 3) Rennin: Renin is an enzyme that used to be commonly found in the grocery store as "rennet". Rennet is used to make "rennet pudding" and cheese. References for additional reading: Facts and Fallacies About Digestive Diseases. 1991. This fact sheet discusses commonly held beliefs about digestive diseases. Available from the National Digestive Diseases Information Clearinghouse, 2 INFORMATION WAY, BETHESDA, MD 20892-3570. (301) 654-3810. Larson DE, Editor-in-chief. Mayo Clinic Family Health Book. New York: William Morrow and Company, Inc., 1990. General medical guide with section on the digestive system and how it works. Available in libraries and bookstores. Tapley DF, et al., eds. The Columbia University College of Physicians and Surgeons Complete Home Medical Guide, revised edition. New York: Crown Publishers, Inc., 1990. General medical guide with section on the digestive system and how it works. Available in libraries and bookstores.
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