Shelf Stability and Acid
In small food manufacturing pH is a critical factor enabling your product to be shelf stable.
The pH scale is a 14 point reference from 0 to 14, where 0 is the most acidic and 14 is the most alkaline.
It is measured with a pH meter. There are many of types of pH meters, but generally, a digital unit with a separate probe is more accurate. They can range from $250 and up. A good meter is worth the investment. The meter must be calabrated frequently to give accurate measurements and requires buffering liquid for this procedure. All of which can be purchased at the same tile from a reputable company such as Cole Parmer.
pH is important for food items as pathogenic bacteria cannot grow in a low pH environment.
Each bacteria has a differnet threshold. The most dangerous pathogen as far as shelf stability is concerned is clostridium botulinum (botulism) which cannot grow below a pH of 4.5.
As a reference, vinegar and lemon juice have an approximate pH of 2. Tomatoes have an approximate pH of 4 and most vegetables have a pH between 6 and 7, which is close to neutral. As a contrast, soapy water has a pH of approximately 12, which is alkaline.
To be safely packed, pH must be used in conjunction with temperature to prevent the possibility of mold growth.
When used together and evaluated by a recognized process authority, your product my be held at ambiaent temperatures and will be safe for an extended time for people to eat. This can be done with out the addition of dangerous chemicals. The process authority will write a scheduled process for you, which will outline the manufacturing requirements.
Ingredients with a low pH are sour and any additions of acid – lactic, malic, citric, vinegar, lemon juice or any other acids – will make your product more tart.
This type of control is essential to insure that your product is safely manufactured and will be safe to eat.