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How do I measure the pH of brine used in canned food testing?

Brine is used in canned foods to inhibit the growth of food poisoning organisms like Clostridium botulinum, the most heat resistant of all pathogens.

Clostridium botulinum can flourish in badly prepared canned foods and cause severe illness and even death. The seals on cans provides an oxygen free environment that will allow C.botulinum spores to grow in high acid foods with pH greater than 4.6. The appropriate pH in the cans is obtained by the use of brines with known acid concentrations.

The contents of the cans must be then conveniently stirred to ensure that the pH is below 4.6 in the center of all food particles. Acids used in canning to lower the pH to 4.6 are usually citric, lactic and malic, but also glucono-delta-lactone.
The LAQUAtwin pH meter can be used by food processors or home canning to measure the pH of brine in canned foods. There are three new  LAQUAtwin pH meter models available
pH 11, 22, and 33. These light, pocket sized meters allow two to five calibration points using either NIST or USA pH buffers. The pH 33 meter has built in temperature sensor that measures
and displays temperature and automatic temperature compensation feature (ATC) that performs automatic calibration to the exact pH of the buffer at the measured temperature.

Refer to the specifications of each meter model for more information.

Horiba PH-22 meter
Horiba PH-22 meter

Calibrate the LAQUAtwin pH meter using pH 4.01 and 7.00 (or 6.86) buffers according to manufacturer’s instructions.
Sample Measurement
Using the pipette that comes with the meter, take an aliquot of the brine sample and place some drops into the sensor. Record the pH and temperature once stabilized. After testing each brine sample, rinse the sensor with water and blot dry with soft tissue.
To obtain accurate results, a uniform temperature should be maintained for the standard buffer solutions and brine samples. The test should be made at a temperature between 20-30°C, the optimum is 25°C.
Some pH Values of Common Foods

Vinegar 2.5, Lemon Juice 2.6, Jelly 3.1, Ketchup 3.6, Mayonnaise 3.7,  Canned peaches 3.9, Canned Tomatoes 4.0

Replacement sensors are available for Horiba LAQUAtwin pH meters and standard solutions to make sure the meter perform optimally.