Question about final PH

[Xilli]

So I've been reading topics about fermentation and have a couple batches going to try my hand at it.
 
My question is, what is the relevance of the finished product PH?
 
I see people stating that it should be below 4, which would be acidic obviously, but why is this so important?
 
If it above 4 is it still safe to eat?
Will it just not be safe to store for very long?
 
What is the significance of the finished PH level?

 

[Al-from-Chile]

you need to be aware that the ph-scale is logarithmic ...
 
e.g. ph5 is 10 times more acid than ph6 ... ph4 is 10 times more acid than ph5 (and 100 times as acid as ph6) ... and so on ...
 
the more acid your product the less likely is it that "bad" bacteria can survive there.
 
cheers, Al

 

[salsalady]

The purpose it to prevent Nasties from growing in the product.  That is generally achieved by getting the sauce to 4.0 or below (either by using fermentation or by adding acids [vinegars] to the sauce) or by pressure canning the product.
 
Generally, a product with pH over 4.0 can only be safely stored for long term either in the refrigerator or if it's been PRESSURE CANNED.  If it's pressure canned, it can be considered shelf stable and stored unrefrigerated.  Nasties can still grow in a product that is 4.0 and has not been pressure canned.
 
Most people don't pressure can their products, so it's strongly encouraged to be at least pH4.0 or lower, preferably pH 3.5 or below.  Sauces in that pH range can be safely processed using regular canning jars and a Hot Water Bath or using the typical sauce wozzy bottles and using the Hot Fill-Hold method. 
 
All of those methods and more are discussed Here-

 

[The Hot Pepper]

Most people don't pressure can their products, so it's strongly encouraged to be at least pH4.0 or lower, preferably pH 3.5 or below.  Sauces in that pH range can be safely processed using regular canning jars and a Hot Water Bath or using the typical sauce wozzy bottles and using the Hot Fill-Hold method. 

 
4.0 is the highest not the lowest it should be. Quoted for clarification. I know what you meant.