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Kansas Value Added Foods Lab

Kansas Value Added Foods Lab
Kansas State University
203 Call Hall
1530 Mid-Campus Drive North
Manhattan, KS 66506

785-532-3295 fax


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Chemical Properties

pH meterCommon chemical properties analyzed in foods include the following:

  • pH - Acidity
  • Fat and oil quality
  • Fat content
  • Protein analysis

pH -Acidity

The pH is an indicator of the amount of acid or base present in a food. For canned foods, a pH of 4.6 or lower would prevent microorganisms such as Clostridium botulinum to grow if proper sterilization time and temperature are used. The pH also affects flavor, color and texture. The pH is measured using a pH meter. Here are some examples of the pH range for different food products.

pH for Various Food Products
DescriptionpH RangeExample of Products
Alkaline7.0-9.6Egg white
Neutral7.0-6.5Milk, chicken
Low Acid6.5-5.3Bacon, canned vegetables, fresh meat
Medium Acid5.3-4.5Canned soup, soft cheese, pickled cucumbers
Acid4.5-3.7Mayonnaise, yogurt, orange juice
High Acid<3.7Pickles, canned sauerkraut
The pH scale ranges from 0-14. A pH of 0 is extremely acid. A pH of 14 is extremely alkaline.

Fat and oil quality

This depends on the composition of the product, size of the product, type of processing and type of oil used. Higher fat products are more susceptible to rancidity. This defect is defined as the amount of free radicals that can cause an off-odor or off-flavor in foods. Rancidity is measured by the peroxide value, TBA test, Schaal test, or smoke point.

Fat content

This is measured using equipment that can evaluate solid and semisolid foods. An example is the Foss-Let instrument. Analysis can take 5-8 minutes to complete.

Protein analysis

Protein is typically measured using the Kjeldahl method. There are more rapid analyses to measure protein. These instruments can also measure oil, moisture, starch, fiber and sugar content.