Free Fatty Acid Testing

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 SafTest^TM 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

Free fatty acid testing