pH

How it is used

Measured with a pH meter that must be calibrated with buffer solutions. pH 4.6 is a key safety limit: Clostridium botulinum cannot grow at or below it, so foods are classed as low-acid (above 4.6) or acid. Say 'a pH of 4.2' or 'at pH 4.2', and write it with a small p and a capital H.

Example sentences

1. The pH of the pickles must be below 4.0 before they leave the factory.

2. Calibrate the pH meter every morning with the 4.0 and 7.0 buffers.

Common collocations

• low pH
• measure the pH
• pH meter
• adjust the pH
• final pH

Related terms

• acidityThe amount of acid in a food, often measured by titration and expressed as a percentage of the main acid, such as lactic, citric or acetic acid.
• Clostridium botulinumA spore-forming bacterium that grows without oxygen and produces botulinum toxin, one of the strongest known poisons, which causes the rare but potentially fatal illness botulism.
• fermentationA process in which microorganisms such as bacteria, yeasts or molds change sugars and other components of food, producing acids, alcohol or gas and new flavors.
• water activityA measure from 0 to 1, written aw, of how much of the water in a food is free for microorganisms and chemical reactions; pure water has a value of 1.0.
• preservativeA food additive that slows down the growth of bacteria, yeasts and molds, helping the product stay safe and acceptable for longer.

This word in other fields

The same English word can have a different meaning in another field:

• pH · Chemistry

More terms: Food Chemistry and Composition

• moisture content
• protein
• carbohydrate
• lipid oxidation
• Maillard reaction
• enzymatic browning