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    Principles of free fatty acid testing

    Free fatty acids (FFA) are a key indicator of hydrolytic degradation associated with off flavor and textual changes. MP Bio’s Free Fatty Acid Test Kit is designed to measure free fatty acid content in any raw material or finished product containing oil and deliver results within 30 minutes.

    Here’s how it works:

    Liquid or solid samples are solubilized in a stabilizing reagent (i.e. stabilized isopropanol) and exposed to mechanical mixing and warming techniques to release lipids from the sample. Then the samples go through a membrane separation pack and get analyzed by an optical reader at 400 nm-500 nm. The resulting absorbance values are logarithmically related to free fatty acid concentration and decrease with increasing free fatty acid concentration. Important to note is that the calibrant concentrations are based on a % oleic acid equivalent.

    Correlation with AOCS method

    We’ve developed our rancidity tests to be accurate and reproducible. MP Bio’s Free Fatty Acid Test Kit is in alignment with AOAC and is designed to replace AOCS extraction and titration testing methods.

    Compared to conventional FFA testing methods, the Free Fatty Acid Test Kit requires less volume of organic solvents, smaller sample aliquots, and eliminates a lengthy titration process and extraction that can take up to eighteen hours.

     

    Free fatty acid testing samples

    There are several samples types you can test for free fatty acids, including:

    • Pet food
    • Feedstock
    • Milk, dairy, and creamer
    • Cookies, Crackers, Candy, Potato Chips, Chocolate and Peanut Butter
    • Frying Oil
    • Essential Oils and Cosmetics
    • Nut, Nut Meals and Seeds
    • Oils and fats (tallow), Vegetable Oils (olive, palm, avocado, etc.)
    • Biodiesel

    Sample Handling Guidelines:

    Calibration Range:

    0.04 – 2.06% oleic acid

    Optimal Working Range:

    0.1 – 30% oleic acid

    Sample Preparation Time Requirement:

    1 – 20 minutes

    Analysis Time:

    ~10 minutes

    Minimum sample size:

    >1mL or 4g

    Sample Preparation:
    • Liquid oils may require heating or dilution
    • Semi-solid, solid oils and solid samples require heating and mechanical disruption
    • Solid samples require membrane separation

    While we do have an optimal working range listed above, the limit of quantitation (LOQ)—the lowest concentration of a substance that can be determined—varies based on sample type and dilution factor.

    Sample Type

    Example

    Dilution Factor

    LOQ

    Refined oils

    Vegetable Oil
    Fish Oil

    Neat

    0.05% FFA

    Snack products

    Vegetable Oil
    Fish Oil

    1:4

    0.16% FFA

    Meat meals

    Lamb meal

    1:4

    0.16% FFA

    Animal fats

    Tallows

    1:10

    0.4% FFA

    Through comprehensive validation studies, we found some noteworthy considerations when it comes to the samples you are testing with the Free Fatty Acid Test Kit:

    • Inorganic acids in food matrices can cross react with the Free Fatty Acid Test method
    • Diluting intensely colored oils can eliminate color interference that we observed with the AOCS Ca 5a-40 method

    We suggest preparing your samples based on our Sample Preparation Quick Card and if you’re looking for a step-by-step guide on how to determine free fatty acid in oil, snacks, or other sample, check out this Protocol.

    Protips for generating calibration curves

    When you receive a new kit, you should first run a calibration curve. If it’s your first time setting up a calibration curve, or if you simply need a refresher, check out our Free Fatty Acid Test Kit Protocol to get a step-by-step guide on how to properly set up a calibration curve for free fatty acid testing.

    The SafTest™ analyzer will use the Calibrators to calculate the acid content as percent (%) oleic acid in the sample. Adjust the instrument results by taking into account the dilution factor. For example:

    Dilution Factor

    SafTest™ Results

    Dilution x Results

    Final Results

    1:10

    0.23%

    10 x 0.23%

    2.3%

    The final result can be calculated to % oleic acid on a fat basis by taking the percent fat into consideration when performing your calculation. For example, with a sample that is 15% fat and yields a final result of 2.3%:

    Final Result

    Result / (%Fat/100)

    Final Result

    2.3%

    2.3 / (15/100)

    15.3%

    Calibration Protips:

    • Use a new tip for each Calibrator and Control
    • The same tip can be used if running a duplicate
    • Remove all air bubbles from the tip before drawing the final sample

    Summary of Advantages of SafTestTM Test Kits

    • Six different reagent kits for the analysis of quality in human and pet foods, oils, cosmetics and biodiesel
    • Requires only small amount of the sample (10 – 50 μL)
    • Results that meet the standards set by AOCS and or ASTM
    • Obtain quality data in 20 – 30 minutes as opposed to traditional methods that take 8 hours
    • Designed for ease-of-use and convenience
    • Each kit contains up to 120 tests and comes pre-packaged with all the reagents, calibrators and controls
    • All reagents are non-toxic

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