Oil Waste due to high FFA Values

Hello,

I need some help.  The plant I work out changed to a different way of testing FFA values in our oil.  Since then we've been throwing away a lot of oil due to high FFA values.  I've listed our previous method and current method. Any thoughts as to why the new method is giving such higher values.  Our cut-off is 0.4%.  Is that a common cut off?

Old:

Frequency: Every 2 hours

Procedure:

Apparatus:      Digital Scale

                        Burette – 50 ml set-up in 0.1 ml divisions

                        250 ml Erlenmeyer flask

Reagents:        Reagent alcohol

                        Phenolphthalein Indicator

1. N NaOH

1. Collect a representative sample of the oil from the fryer.
2. Carefully weigh out 28.2 g of oil into a tared 250ml Erlenmeyer flask.
3. Add 50ml of Reagent alcohol to the Erlenmeyer flask. Gently swirl to mix.
4. Add 3 drops of phenolphthalein indicator to the oil/alcohol mixture. Gently swirl to mix.
5. Titrate to the phenolphthalein endpoint (pink color) with 0.1 N NaOH.
6. Allow mixture to sit for 20 seconds; if pink color fades to clear, continue titrating until pink color persists.
7. Read the ml directly off the burette to get the FFA value.

Corrective Action Limits:

Standards:       Aim – 0.2

                        Control Limits – 0.4

                        Reject Level - >0.4%

New:

Frequency:Every 2 hours

Procedure:

Apparatus:      Digital Scale

                        Burette – 50 mL set-up in 0.1 mL divisions

                        2 x 250 mL Erlenmeyer flasks

                        50 mL graduated cylinder

Reagents:        Isopropanol 99%

                        Phenolphthalein Indicator 1% (w/v) in 95% (v/v) Alcohol

                       .1N NaOH

1. Measure 50mL of Isopropyl alcohol to an Erlenmeyer flask.  Add 2mL of Phenolphthalein Indicator. Gently mix.
2. Titrate using .1N NaOH in the zeroed Burette until a faint pink color persists for 15 to 30 seconds.  This will be the neutralized alcohol.
3. Collect a representative sample of the oil from the fryer.
4. Carefully weigh out 28.2 ± .2 g of oil into a tared 250mL Erlenmeyer flask.
5. Add 50 mL of the neutralized alcohol to the oil filled Erlenmeyer flask. Gently swirl to mix.
6. Add 2 mL of phenolphthalein indicator to the oil/alcohol mixture. Gently swirl to mix.
7. Titrate with 0.1 N NaOH in the zeroed Burette, shaking vigorously until the appearance of the first permanent pink color of the same intensity as that of the neutralized alcohol before the addition of the sample.   The color must persist for 30 seconds, if pink color fades to clear, continue titrating until pink color persists.
8. Read the ml directly off the burette and multiply by .1 to get the FFA value.

Corrective Action Limits:

Standards:       Aim – 0.2

                        Control Limits – 0.4

                        Reject Level - >0.4%

Hi Snissley,

I assume this is for a frying process.

The cut-off may relate to yr specific process/product specification/frying conditions. However IMEX 0.4% max is very low.,

I’m curious as to how the alcohol reagent solutions are prepared. As this can have a large impact on the results. I note in the new method it does note to use neutralised alcohol. Did you use or neutralise the alcohol (ethanol) in the first method?

Methods are near identical with the exception of the alcohols.

The FFA method we use is the same as your initial method, but we’d use half the sample amount and multiply the burette result by 0.2. Typically, anything over 0.4 was a fail.

Why the change in methodology?  There is an ISO standard for the dertermination of FFA in oils and that would be the best way to go to ensure standardisation of the test method and results.