Using a pH meter to test cottage foods

Quick facts

The final (equilibrium) of canned or bottled acidic and acidified foods must be 4.60 or less.
Always calibrate your pH meter before testing foods.
Prepare and test at least 3 samples to ensure an accurate pH value.

The Minnesota Cottage Food Exemption law does not require testing of your cottage food product. However, as a cottage food producer, you are responsible for ensuring the safety of your food. Using a pH meter at home or in your cottage foods business is a best practice for verifying the safety of acidic and acidified food products.

What is pH and why is it important?

The pH scale is from 0 to 14 and is divided into acidic (pH less than 7), neutral (pH equal to 7) and alkaline (pH greater than 7). Research has shown that many foodborne illness-causing microorganisms (pathogens) are either inactivated or are unable to grow in acidic environments.Specifically, a pH of 4.6 or less is key to stopping the growth and toxin production of Clostridium botulinum, the pathogen that causes botulism.

A pH meter is a good investment if you can or bottle foods at home. Examples of foods that should be tested include:

Selecting a pH meter

There are a variety of pH meters that are suitable for use in your cottage foods business. Consider these factors when selecting a pH meter.

Intended for food

Select a pH meter that is intended for food testing, not soil or pure water.

Costing about $100 to $250

A reliable at-home food pH meter typically costs $100 to $250, depending on the model. Avoid very low-cost options, as they may lack the accuracy and durability needed for safe food testing.

(+/-) 0.01 accuracy or better

The accuracy of the device will be listed as a range of plus or minus (+/-) 0.XX. This is referred to as the resolution. Select a pH meter with an accuracy of plus or minus (+/-) 0.01 or better. A pH meter with an accuracy of 0.10 is less accurate than a device that has an accuracy of 0.01 pH.

Example 1
A meter with ±0.10 accuracy reads a food at pH 4.55. The true pH could be 4.45 to 4.65, meaning the food may exceed the safety limit of 4.6.
Example 2
A meter with ±0.01 accuracy reads the same food at pH 4.55. The true pH would be 4.54 to 4.56, providing confidence that the product meets safety requirements.

Replaceable electrode

The electrode is the part of the device that is submerged in the food sample. Choose a model with a replaceable electrode. A useful feature if it is damaged or improperly stored.

Temperature reading

A meter with built-in temperature measurement can help determine if the sample needs to be warmed or cooled (pH should be measured at 65 to 70 degrees Fahrenheit (room temperature)).

2-point calibration

Select a meter that supports at least 2-point calibration, which is key for accuracy.

2-point calibration: uses pH 7.0 (neutral) and pH 4.0 (acidic) buffers.
3-point calibration: uses pH 7.0 (neutral), pH 4.0 (acidic), and pH 10.0 (basic) buffers.

Calibrating your pH meter

Always refer to the device manufacturer's instructions for details on how to calibrate your specific pH meter. Calibrate your pH meter before each use, or once per day if you will be testing multiple samples throughout the day.

Remember these best practices when calibrating any device:

Check the electrode before calibrating to ensure it has not dried out. If it is dry, soak the electrode in a storage solution for 1 hour or as directed by the manufacturer.
Verify that the buffer solutions are not expired. Replace any buffering solutions past their expiration date.
Ensure the temperature of the buffer solutions is between 60 and 75 degrees Fahrenheit (room temperature), as temperature affects calibration accuracy.
Follow the manufacturer’s required calibration order. For example, many 2-point systems require calibrating with the neutral buffer (pH 7.0) first, followed by the acidic buffer (pH 4.0).
Rinse the electrode with distilled water between each buffer solution.

Using a pH meter

Before testing a food sample, read your specific device manufacturer's instructions. The general testing process is:

Preparing sample

Equilibrium pH is the final pH of a food after acidic ingredients have been added. An equilibrium pH is typically reached within 24 hours.
From each batch, select one jar (container) and prepare at least 3 samples of the food in separate dishes.
Use enough to fully cover the electrode. Your device may have minimum and maximum lines on the outside for guidance.
Do not submerge the device directly into the original jar (container).
Ensure the temperature of the food sample is room temperature (60 to 75 degrees Fahrenheit).

Testing procedure

Once calibrated, insert the electrode into the sample.
Allow the meter sufficient time to stabilize and display an accurate reading. Follow the manufacturer’s instructions.
Record all results in a testing log. Good record keeping is essential if questions arise about the safety of your cottage food products.
Download our sample testing log.
Rinse the electrode with distilled water between each measurement.
Calculate the average pH for the batch.

Special instructions by food type

Liquid foods (e.g., grape juice)

Gently shake or stir the contents in the original jar (container) to evenly distribute all ingredients before preparing the samples.

Chunky, mixed foods (e.g. salsas or relishes)

Blend each sample to a smooth, uniform consistency before testing. If the mixture is too thick, add a small amount of distilled water to achieve a measurable consistency. Add a very small amount of distilled water if the sample is too thick.

Solid foods (e.g. pickled or fermented produce)

Test the pH of the solid food and the liquid separately..

Separate the solids from the liquid.
Rinse the solids with distilled water to remove acidic liquid from the surface. This ensures the reading reflects whether the solids have been properly acidified.
Blend the solid ingredients until smooth (add a little distilled water if needed).
Measure the pH of the blended solids.
Measure the pH of the liquid brine.

Cleaning and storing a pH meter

When you are finished using your pH meter, it is important to thoroughly rinse the electrode and the outside of the device with distilled water. Refer to the device manufacturer's instructions for storage recommendations. It may be recommended to use a storage solution.

pH testing strips

pH test strips may be used to measure the pH of certain ingredients or to check pH during processing. However, pH test strips are not recommended for testing the pH of finished cottage foods. Instead, a pH meter should be used, as it is more accurate and easier to interpret.

pH test strips may give inaccurate results when:

The food has a pH above 4.0, because the strips are not as sensitive or precise as a pH meter.
The food is dark in color, which can make it difficult to clearly match the test strip to the color chart.

Reviewed by Amy Johnston and Autumn Stoll, Extension Educators, Food Safety

Reviewed in 2026