1 Preface

The free fatty acid value in animal fat refers to the number of milligrams of potassium hydroxide consumed to neutralize 1g of fat. Different fats have different amounts of free fatty acids. The content of fatty acid value is one of the indicators for measuring the quality of fat. This experiment determined the fatty acid value of chicken and duck by-product wastewater with the aim of understanding the rancidity conditions of the wastewater. This experiment refers to the national standard GB 5510

In 2011, the fatty acid value in oilseeds was determined. However, the extraction solution was changed according to different samples, and this application plan was formulated. The experimental process was simple to operate, minimizing the errors caused by manual titration as much as possible and avoiding the errors caused by color identification of the endpoint. The repeatability of the experimental results was good.

2. Instruments and equipment

2.1 Instruments

JH-T6 fully automatic potentiometric titrator, PH composite electrode.

2.2 Reagents

KOH- ethanol titrant (0.1 mol/L), anhydrous ethanol.

3 Experimental Methods

3.1 Experimental Procedures

(1) Pretreatment of the sample

Weigh approximately 25g of the sample, accurate to 0.001g, and place it in a 250mL conical flask. Use a pipette to accurately add 100mL of ethyl alcohol solution, add the stopper, shake for a few seconds, open the stopper to release the air, then tightly close the stopper and shake for about 15 minutes, or place it on an oscillator and shake for 15 minutes. Place filter paper in a short-necked glass funnel, filter the sample, and discard the first few drops of the filtrate. Collect the filtrate in another conical flask, cap it and set it aside for later use.

(2) Determination:

Accurately transfer 10mL of the sample prepared by filtration with a pipette into a titration cup, add 40ml of anhydrous ethanol solution (ensuring that the solution height covers the electrode), place it on the potentiometric titration stand, start stirring to ensure uniform mixing of the sample, insert the electrode and titration head, and wait for the potential to stabilize Titrate the potential crossing point with the potassium hydroxide - ethanol (0.100mol/L) standard solution, record the volume of sodium hydroxide standard solution consumed, and conduct a blank test simultaneously.

3.2 Parameter Settings

4. Results and Discussion

4.1 Experimental Results

Calculation formula

Ak = (V1 -V0) × c ×56.1 × Jiahang ×100

In the formula:

Ak is the fatty acid value, with the unit being milligrams per 100 grams (mg/100g).

V1 and V0 are respectively the volumes of titrant consumed for titrating the sample and the blank.

56.1 is the molar mass of potassium hydroxide;

100 and 10 are respectively the volume of the sample extract and the volume of the sample extract used for titration