I have an NMNF Starter that is 20 weeks old, but PH is 4.0. The starter has an extremely acidic smell. And it has made some great bread.
This is how I ran the PH test. I thoroughly mixed equal parts of starter and distilled water. Then I wet the PH strip with it. It appears to be exactly 4.0 to me.
I would have expected a lower PH.
I am interested to know your thoughts. I want to learn.
Dan
I have fish tanks and when the pH gets around 6, I freak so 4 is way way down there!
...my rye based nmnf starter often resides in the fridge for several weeks but the bread it makes tastes quite mild.
Danni, I was thinking more in the range of 3.5. I was my understanding that 4.0 was the PH of a healthy “sweet” (non-sour) starter.
Aroma, the breads made with this starter are very sour. I love the taste. The smell is very strong. The starter could almost be used in the place of smelling salts :-) . Kidding, but just a little bit.
Debra told me that testing the starter’s PH was not necessary. I’ll have to go back to my correspondence to see exactly why. I tested out of curiosity.
And curiosity led to this post. What should be the PH on an extremely sour smelling and sour tasting 20 week old NMNF starter?
Dan
”inquiring minds want to know”
From Debra Wink; (published with her permission)
”When it comes to measuring the pH of your starter, adding water (even distilled) will change the reading because you're diluting everything, including the acid. It's possible that the pH was as low as 3.5. Clearly, it would be better if you can get a reading straight off the starter, provided it's wet enough.
You should get used to smelling your starter, but it won't help you determine pH; the primary acid in sourdough -- lactic -- has very little aroma. There are other aromas generated by fermentation, and your starter will smell different at various stages. Get familiar with how it smells beginning, middle, and when ripe or even beyond. The pH won't tell you when it is ripe. It only tells you what the pH is, and ripeness doesn't depend on pH. It could be useful to know for high-percentage rye breads, but even then not a necessity. Personally I don't recommend spending the money on a pH meter unless you plan to conduct some sort of science project.
If you want to know the sourness, your tongue is probably a better gauge anyway. The scale that measures pH is a logarithmic one, meaning that each whole number represents a 10-fold change. The free part of the acid molecule measured by pH (H+) is not the part responsible for the flavor. pH 4 represents 10 times more free hydrogen ions than 5, and 100 times more than 6. The various acids have different strengths, which means they each have a different impact on the pH at different pH's and ratios to each other. So pH isn't an indicator of concentration either. And concentration is how the tongue gauges sourness. You can easily taste a 10-fold change in acid concentration. Imagine the difference between vinegar straight from the bottle, and 1 part vinegar diluted in 9 parts water. The pH doesn't change nearly as much as the perceived sourness does.”