What good is added cultures in yogurt when its pasteurized?

Question

Any of the "so called" good bacteria would be killed in the pasteurzation. What gives?

Answer 1

Yogurt is made in various ways, and brands can sometimes differ a lot in what they're made with and what methods are used (homemade yogurt varies too).

Milk for most commercial yogurt is pastuerized (and homogenized) *before* the cultures are added, so what matters is what happens after that. As long as the temperature during fermentation doesn't go too high, the cultures should stay alive. However, some yogurts are heated to high enough temps to actually kill the cultures when preparing them for sale (those will often say "heat-treated after culturing," or more stealthily, "made with" live cultures rather than "contain" live cultures ). Many frozen yogurt products are pasteurized after culturing too?

I don't think the length of time of fermentation will matter for keeping the bacteria alive (as long as they're kept at less than about 120 F --though too low a temp, less than about 110, will slow down fermentation).

I do know that the longer the fermentation, the more sour the yogurt will become as the lactose is gradually eaten up by the bacteria (that's why even regular yogurt can usually be eaten by those who are lactose intolerant... but a full 24 hr. fermentation is supposedly better for those with Crohn's Disease, colitis, etc.)


Diane B.

P.S. Some people in the U.S. like to use organic milk when making yogurt because organic dairy cattle are fed differently (better) than regular dairy cattle, and there is a difference in taste between the milk produced by them. The same is true in Europe... or maybe there, milk is also heated to a lower temp, don't remember.

P.S.S. Although this doesn't affect whether the cultures are alive or not, another difference between yogurts is their texture and shelf-life. Most commercial yogurts add stabilizers to their milk (gelatin, starches, pectin, gums) which help thicken the yogurt, keep it from separating, and give it a longer shelf life, but they also give it a kind of gumminess and/or taste I really don't like (I couldn't really taste that too much before I'd made my own yogurt, but then I wasn't a big yogurt fan until I made my own --which tastes "fresh and clean" in a way I can't really describe ... now I'm hooked).


Diane B.

Answer 2

Take 1 quart of milk and 1 cup powered dry milk and simmer it until it reaches 180 degrees. let it cool to 100 degrees and add 1 big spoonful of plain yogurt. Let it sit covered in a warm place ( about 80-100) degrees for about 6-8 hours. Your milk has been pasturized in the factory, but along the way to the store proper handling might not have taken place. Bringing it up to 180 degrees kills anything that might be growing in there now. Adding the good bacteria after it has cooled is what "cultures"it, makes it into yogurt.

Answer 3

Ah, I might be wrong but...I would think that the ADDED means after the pasteurization is completed.