Welcome to City-Data.com Forum!
U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > General Forums > Food and Drink
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
Reply Start New Thread
 
Old 04-25-2014, 06:23 AM
 
Location: Northern Virginia
1,474 posts, read 2,283,017 times
Reputation: 3289

Advertisements

Some comments at this thread about keeping milk from spoiling made me wonder why spoiled milk tastes so bad and is not something we care to ingest, but yogurt (which is apparently spoiled milk?) is edible.
Reply With Quote Quick reply to this message

 
Old 04-25-2014, 09:28 AM
 
1,830 posts, read 1,342,379 times
Reputation: 2986
Raw milk contains many kinds of microbes, with more being introduced depending on its storage and handling practices. Pasteurization dramatically decreases many of these microbes, but not all, thus extending its shelf-life but not indefinitely.

Whether milk spoils, or is converted to a beneficial product like yogurt, depends on the growth of the predominant microbe. This is influenced by growth conditions such as temp, nutrient content, water availability, oxygen content, acidity and concentrations of competitors. By outcompeting its rivals for nutrients, microbes (in the initial stages certain bacteria) alter the composition of the milk due to its production of by-products of growth (acids, enzymes) that can inhibit the ability of other microbes to grow. For example, the produced acids lower the milk pH, which inhibits the growth of other microbes that grow best in more basic (vs. acidic) conditions.

Store bought yogurt is artificially inoculated with high levels of specific bacteria responsible for the conversion of milk to yogurt. Additionally, they are grown in conditions that allows for fermentation, because most of these specific bacteria grow best, or are capable of growth, at very low to zero levels of oxygen. These bacteria feed on the milk sugars and produce acids responsible for the tart taste of yogurt. Historically, yogurt was produced accidentally by storing raw milk in animal stomachs, which contained the right conditions for its formation. In the absence of artificial inoculation or historical milk storing practices, normally stored milk will eventually spoil due to the serial aerobic (presence of oxygen) growth of bacteria and other microbes (mold, yeast), which metabolize the sugars, proteins and fats. The metabolism of the latter two produce by-products mainly responsible for the offensive off-odors and tastes associated with milk spoilage.

Last edited by mingna; 04-25-2014 at 10:49 AM..
Reply With Quote Quick reply to this message
 
Old 04-25-2014, 11:22 AM
 
1,830 posts, read 1,342,379 times
Reputation: 2986
ETA: The specific bacteria (and their by-products) responsible for yogurt formation do not make you ill when ingested; rather, they become beneficial members of your microflora. Other bacteria and microbes (and their by-products) that cause milk spoilage, on the other hand, often also cause gastrointestinal illness. And the offensive off-odors and other visual cues they produce from protein and fat metabolism serve to instinctively prevent one from ingesting it, and possibly getting ill.
Reply With Quote Quick reply to this message
 
Old 04-25-2014, 11:58 AM
 
726 posts, read 1,350,593 times
Reputation: 687
In the United States, for a product to be labeled "yogurt," it must be cultured with Lactobacillus bulgaricus and Streptococcus thermophilus. These are sometimes labeled L. bulgaricus and S. thermophilus respectively. Products in the U.S. labeled as yogurt may also contain other cultures if considered safe to consume but many of the commercial yogurts will only contain the two required ones. Almost all of them will only contain 4-5 in total.

Products labeled as yogurt are made with pasteurized milk, i.e. raw milk that has been heated to very high temps to kill all the bacteria contained in it. Unfortunately, this means all the good bacteria are killed in the process as well as the living enzymes. It is estimated that raw milk contains 50-100 different beneficial species of bacteria. Contrary to popular belief, this started because of the modern mass production of milk where the milk was often contaminated with pathogens. However, in smaller organic or organic-like dairies, pasteurization is not necessary (I could write on a book on this subject but I will resist). The health benefits of raw milk over pasteurized milk are MANY.

At any rate, if pasteurized milk is left out (heated up), it will "SPOIL" because the bacteria that will get a foothold are not the good kind. On the other hand, if raw milk is left out, it will "CLABBER" which is a word for milk fermentation. This basically means the good bacteria will proliferate and culture the milk. The bad bacteria are kept at bay by the good bacteria (mostly Lactobacillus species) and the conditions they create. Clabbered milk is delicious and is like yogurt in consistency, only with about 50-100 beneficial species instead of only two and tastes better than most commercial yogurts. However, it can't technically be called yogurt because it doesn't meet the definition set forth by the FDA.

The temperature does play a part in how well milk of any kind cultures and it depends on which bacterial species are doing the culturing. Some can culture at lower temps while other require a much higher temp. Those who make homemade yogurt sometimes buy expensive incubators to keep the milk at a precise temperature. Lactobacillus bulgaricus and Streptococcus thermophilus both require high temps to culture (110 degrees F I think and higher to begin with). However, raw milk will clabber at a lower temp, often room temp, or by sitting the milk in a slightly warmer spot such as in an oven with a pilot light on or inside an ice chest with a heating pad on low.

Note too: L. bulgaricus is sometimes considered a subspecies of Lactobacillus delbrueckii.
Reply With Quote Quick reply to this message
 
Old 04-25-2014, 08:32 PM
 
Location: Western Oregon
1,379 posts, read 1,537,691 times
Reputation: 1278
Sauerkraut is rotten cabbage. Beer is rotten barley syrup. Wine is rotten grape juice ... whether it's god or bad depends on what microorganisms acted on it, in what environment, and with other variables. Most cheeses depend on the same kind of thing.

Carefully controlled "rotting" is responsible for some of our best foods. Yogurt is the same whey.
Reply With Quote Quick reply to this message
 
Old 04-25-2014, 08:48 PM
 
Location: Illinois
4,751 posts, read 5,406,098 times
Reputation: 12999
Quote:
Originally Posted by WoodstockSchool1980 View Post
Sauerkraut is rotten cabbage. Beer is rotten barley syrup. Wine is rotten grape juice ... whether it's god or bad depends on what microorganisms acted on it, in what environment, and with other variables. Most cheeses depend on the same kind of thing.

Carefully controlled "rotting" is responsible for some of our best foods. Yogurt is the same whey.
Not rotten, fermented. There is a difference.
Reply With Quote Quick reply to this message
 
Old 04-25-2014, 08:53 PM
 
Location: Western Oregon
1,379 posts, read 1,537,691 times
Reputation: 1278
Quote:
Originally Posted by MoonBeam33 View Post
Not rotten, fermented. There is a difference.
My point is that rotting and fermenting are the same thing, in a sense. We use one word if it's seen as a good thing and another if it's seen as bad. I love yogurt, beer, wine and cheese.
Reply With Quote Quick reply to this message
 
Old 04-25-2014, 11:02 PM
 
726 posts, read 1,350,593 times
Reputation: 687
I'd like to add that traditionally sauerkraut, beer, and wine were all fermented with the microogranisms already on the cabbage, barley, and grapes.... much like raw milk clabbers... not by pasteurizing/killing the product first and then adding a few select microorganisms back in...
Reply With Quote Quick reply to this message
 
Old 04-26-2014, 08:27 AM
 
16,174 posts, read 32,332,373 times
Reputation: 20577
Stay on topic of the original post please.
Reply With Quote Quick reply to this message
 
Old 04-26-2014, 09:47 AM
 
Location: Chicago W Suburbs
487 posts, read 743,252 times
Reputation: 619
I think this topic is more a matter of semantics than of yogurt. The dictionary definition of both rotten and rancid explains that both words mean tainted, or unpleasant. Since yogurt (in my opinion) is neither, then no, yogurt is not rancid or rotten milk!
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:

Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > General Forums > Food and Drink
Similar Threads

All times are GMT -6.

© 2005-2024, Advameg, Inc. · Please obey Forum Rules · Terms of Use and Privacy Policy · Bug Bounty

City-Data.com - Contact Us - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 - Top