[Montegue]

Could someone please tell me the difference in process of fermentation between alcohol and vinegar?

[Arkcon]

You could try to work the answer out for yourself, you'll be better off during exam time.  Can you give us a definition, from your textbook or elsewhere, for the term: fermentation?

[Montegue]

I read in my book about respiration. It says that in the absent of oxygen, facilitative bacteria use other substance to substitute oxygen. The example was fermentation of wine. Then I do my experiment by two methods.

Method 1: I added water to wheat flour in cooking pot and covered it with a lid (not air tight). After 4 days, it smells sour, and I tasted it. It's slightly sour, but others in the family said that it smells like vomit. So I thought oxygen must be the cause.

Method 2: I added water to wheat flour and kept it in an air tight container. After 4 days, it smells very good. Someone said it smells like Roses. Others said it smells like alcohol. So this must be how alcohol is fermented.

Looked all over in the book, but can't find it. I have Microbiology by Prescott.

Just curious. I drank the liquid from Method 1 three hours ago, and I am still not sick or drunk yet.

[Arkcon]

Do try to search harder, look up expected products and see how they differ.  And please don't consume anything you produce until you're sure of what you're making.

[Montegue]

Found it. Fermentation is not respiration. Book says wine vinegar is oxidized wine. The method 1 in my experiment turn sour because of oxygen, so I was right.

The wheat flour obvious has no botulinum strain; otherwise, the whole family would have been sick from the bread made from it.

Test kits tested negative for E-coli and listeria and salmonella.  Pasteurization can get rid of, not all, but practically all of it.

The sourness from Method 1 is products of natural yeast and lactobacillus species. I found the fermentation by soaking flour in water found to be as old as ancient history.

I am sure something else could have made me sick from the liquid. I would like to hear about other possible harmful microbes-- not including those that cannot be killed by pasteurization or cooking at 220 Fahrenheit.

If soaking flour in clean drinking water can turn into poisonous chemical, I would like to know what they are from experts.

[Babcock_Hall]

I think you may be drawing a wrong inference.  It has been many years since I attempted to make beer, but I will draw upon my experiences there, as well as general knowledge of biochemistry.  Fermentation is anaerobic catabolism, usually of glucose, the most common monosaccharide.  Fermentation of glucose by yeast makes ethanol (ethyl alcohol) and carbon dioxide.  But fermentation of glucose by certain bacteria produces lactic acid, which might impart a sour taste.  When making beer, I would occasionally get a sour batch, which may be because we did not rid ourselves of bacteria that competed with the yeast for sugar.  Oxidation of ethanol (possibly by O₂ itself) could produce acetic acid (basically white vinegar).

There are many anaerobic bacteria, and some, like Clostridium botulinum, are potentially very harmful.  Offhand I don't know all of its products of its fermentation of glucose, but they include butyric acid and acetic acid.
http://www.fsis.usda.gov/factsheets/Clostridium_botulinum/index.asp
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC291715/pdf/aem00242-0045.pdf

[Montegue]

Thanks. You taught me something.

Both samples turned sour after 3 days, like you said. I poured both into a cloth bag and hung it over kitchen counter and let it drip over night. The liquid made good ice tea. The dough from inside the bag raised and increased in size more than double. I got a very delicious sourdough bread for breakfast.

Always learn, but never get to use all of them to make money, but this? I get to eat after learning.