The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Starter Ph remained at 5.6-5.8 after matured

sonorvinh's picture

Starter Ph remained at 5.6-5.8 after matured

Hi All, I'm new to this group, i have a question and would like to see if anyone can help..

i have this starter for a couple of year.. and recently i noticed the starter doesnt smell "soury" or "vinegery" but instead, it's "sweet" smelling....

so, the curiosity mode kicked in and i measure the PH of it... and it's around 5.6-5.8 after feeding and leave in fridge (5-9'C) even after a week.... i even tested it fed and leave it at 28-30'C for a couple of hours and after couple of hour.. it triple in size (high hydration though)... but the PH still at 5.6-5.8... i remmber it was 3.8-4.3 back in the day.... so, someone suggested me this starter has been contaminated... could be pathogen OR comercial yeast...

anyone can shed me some light?

franbaker's picture

I couldn’t get pH paper to work for me, so I’m just curious.'s picture

My starter has consistently measured pH 5 - 5.5, regardless of time since maturation.  pH 3 sounds too acidic for a starter.  That'll take the stains off your tea cups.  But I'm sure there's a way to achieve that if you really like it that way.  My only direct experience with increasing starter and bread acidity is to include more whole grains in the starter feed. Perhaps specific grains (I'm thinking rye) will nudge the pH down.  But I haven't been there.  Let's see what others have to say.

I love it when my starter smells sweet -- twist off the cap and get a whiff of ripe apples.  Mmmm.  Just right.  For us at least.

@franbaker: I've always used EMD Millipore pH paper with good results (in the lab and in the kitchen).


dabrownman's picture

on the counter  It should be in the low 4's or high 3's if a whole grain rye one.  Whole grains act as a buffer and allow the AB to continue to make Acid at lower pH's than they normally would.  Low pH;'s shut the LAB down from making acid of any kind.

The reading at the 12 hour mark on the counter will be about as low as your starter will get based on the flour you use!

It isn't contaminated more than  usual with Wee beasties.

Mini Oven's picture
Mini Oven

probably not, but it could have lost a key bacteria or yeast strain.  One that sinks the pH (raises acidity)  hard to track down without a laboratory.  Got any old archived backup starter you could use to start up a new starter?

No mention of the feeding details, that might help us.  What's the water pH?

I might try moving some mature starter to a separate jar for a few days, starve and stir it for a while until the pH test drops low enaough.  Then give it a small feeding.  I compare it to the last step in getting a starter "started."

Abe's picture

...with the taste of your bread?

I'd also like to point out what makes a sourdough starter so is the lactic acid producing bacteria present, not the yeasts, which is lacking in bakers' yeast. It's very common that the natural yeasts in a sourdough starter will be the very same Saccharomyces cerevisiae cultivated for commercial yeast. Sourdough starters will have many different yeasts and bacteria in varying percentages and won't necessarily have Saccharomyces cerevisiae as the main yeast strain whereas bakers' yeast will be only one strain being Saccharomyces cerevisiae. Starters are made up of wild yeasts and bacteria and are symbiotic but bakers' yeast is a single cultivated strain of yeast.

While we are careful of cross contamination in reality your starter should be fine even if you have made a mistake. In other words the bacteria shouldn't have gone anywhere. While your starter is symbiotic there will be one dominant strain of each. This can change depending on certain factors. Other strains can become more dominant. But as far as "getting rid of" all bacteria I'd think this will be very difficult to do.

I'd concentrate on finding ways on how to maintain your starter to restore it's flavour profile.

barryvabeach's picture

sonorvinh ,   what tester are you using to test the ph?  

sonorvinh's picture

I'm using PH meter