Raw milk commonly ferments to a "clean sour" in primitive or modern conditions. Sourdough bread, olives, pickles, undergo fermentatios by the same or similar bacteria.
All mammals produce milk. Man has been drinking milk from many mammal species for a long time. In cool climates, like northern Europe, the milk is comonly drunk in the sweet, fresh state. In warm climates, like Africa, the milk sours so rapidly due to bacteria growth that usually only sour milk is available. Therefore, humans from the two regions have differing enzymes for digesting milk.
Sour milk separates into solid white curd and clear liquid whey. The curd is called cottage cheese, but if allowed to stand the curd may become dangerously contaminated or develop into a variety of fine cheeses. Most primitive societies learned to make one or more cheeses which they could store for varying periods for food. Properly made the cheeses were fairly safe to eat.
120a - Comparison of Human, Cow, and Goat milks.
Lactic Acid bacteria, cheese, etc, even in bread.
A list of cheeses and how they are made.
Descrivbe 22 speciesl of Lactbacillus. with key. use sub-subpages.
copy table 39-1 from pelczar PRC
-----material below is being edited.
The main concern about working with microbiology at home is the possibility that you will accidentally isolate a pathogen (disease causing) organism. The bacteria used in food processing and fermentation are interesting and safe because you normally eat them. However, these projects are not totally safe because you could isolate a contaminating organism. The best insurance against such an accident is to use suitable medium and isolating conditions, and select the majority organism, not a strange unusual colony. Therefore, you need to read about bacteria before you isolate them so that you are armed with much knowledge. For that reason, this website will have pages describing many safe common bacteria and lists and info about those that cause disease. It will take months or years to complete those pages. Meanwhile, read any bacteriology books you can find.
B120 - Milk Fermentations and projects and lactic acid bacteria
B122 - Isolating Brevibacterium linens from Limburger Cheese; first experiment for kids.
If a page is not clear, or the method is too difficult for you or you don't have the supplies and equipment, write me. I will try to make the page more useful to you.
Suggested Bacteria Projects (Someday, I will expand each of these to a full web page):
Revised 1998 Dec 6 - Draft 1
Revised 1997 MAR 13 (incomplete) Part of our home microbiology at home series.
Microbiology at Home Series
This page covers typical uses of bacteria culture in the kitchen via selective media: bread making, dairy products, pickles. Microbiologists usually work with pure cultures containing a single strain of the microbe they want. However, before 1850, pure culture methods were unknown. To obtain the desired microflora in a food process, cooks and food processors used conditions which were known to produce the desired result. I recall listening to my mother, during the 1940s, discuss with her friends the problems she was having keeping the sourdough "starter" alive and able to produce bread of the desired flavor and texture. There was folklore that boiling peach leaves affected by "peach leaf curl" would rejuvenate sourdough starter. Ladies who had cool earthen cellars often were more successful at keeping the starter alive and they gave regular portions to their neighbors. Maintaining a semipure culture by suitable conditions and food supply is called selective enrichment. In the next page of this series, we will again work with food processing microbes, but we will learn pure culture methods. How I wish I had some of my mother's sourdough starter for such studies.
============== below this line is notes for future writing =======================
This is a short course to help kids and adults begin some interesting experiments at home. Microbiology is the study of microscopic organisms including, algae, protozoa, fungi, yeasts, viruses, and bacteria. This series begins with yeasts and bacteria which are already used in food in most homes. Therefore, these experiments should be safe. There is nothing to buy except normal foods for the first two pages. Indiana Biolab offers some inexpensive kits which make nice gifts to the student having a proven interest in microbiology. A middle school or high school student can do some very facinating things 0in microbiology and genetics at home. Pages at this site will take to the research level if you have the interest.
xxxxxxxxxxxxxxxxxxxx below this is my notes