Express analysis of full-fat soy

EXPRESS ANALYSIS OF FULL-FAT SOY EXTRUDATE TO DETERMINE THE UREASE ACTIVITY

After extrusion.

I. Initial components for the preparation of the indicator

1. The indicator is phenol-red.
2. Urea is chemically pure.
3. Standard titer of NaOH.
4. Distilled water.
5. Standard titer H2SO4

II. Indicator production

1. A 0.1-normal NaOH solution is prepared. For this, 1 ampoule of the standard titer of NaOH is poured into a flask with a capacity of 1 liter, the flask is \ “washed \” with distilled water and the volume is adjusted to 1 liter.
2. 210 g of urea is dissolved in 370 ml of distilled water. 70 ml of a 0.1-normal NaOH solution are poured into this solution, here we add 1.4 g of a phenol-red indicator and add 3 l of distilled water. It turns out a solution of bright red color.
3. Preparing a 0.1-normal solution of H2SO4. For this, 1 ampoule of the standard titer of H2SO4 is poured into a flask with a capacity of 1 liter, the flask is \ “washed \” with distilled water and the volume is adjusted to 1 liter.
4. A 0.1-normal solution of H2SO4 is poured into the burette.
5. Pour 25 ml of the prepared phenolic solution into a glass and titrate with a 0.1-normal solution of H2SO4 from the burette until the solution turns straw yellow.

III. Determination of urease activity

In a Petri dish, add 11 g of the finished soybean extrudate and fill with a previously prepared straw-yellow solution. We stand on the hourglass for 5 minutes.

Bright red dots appear:

1. individual points – urease activity of 0.05 pH;
2. points are 25% – urease activity 0.1 pH;
3. points are 50% – urease activity 0.1 – 0.15 pH;
4. points are 75% – urease activity 0.2 – 0.3 pH.

Notes:

• The standard activity of urease is 0.10-0.20 pH.
• The shelf life of the phenolic solution is 15 days.