|
|
|||||||||
|
Pungency Analysis |
|||||||||
|
(based on the procedure Streamlining Onion Pungency Analyses) |
|||||||||
|
1.
A core sample or wedge is cut from the onion.
|
|||||||||
|
2. The sample is squeezed in the Randle/Bussard press.
|
|||||||||
| 3. 0.5 ml of the juice is put into a 40 ml test tube. | |||||||||
|
4. The slurry is allowed to sit for 10 minutes
|
|||||||||
| 5. 1.5 ml of 5% trichloroacetic acid is added to each test tube and vortexed. (To make 5% TCA: dissolve 50 g TCA in deionized water, fill to 1000 ml) | |||||||||
| 6. 18 ml of deionized water is added to each test tube, which is vortexed and capped. | |||||||||
| 7. 1 ml of the solution is added to a 20 ml test tube. | |||||||||
| 8. 1 ml of 2,4-Dinitrophenylhydrazine (Dissolve 0.125 g of 2,4-DNPH in 1000 ml 2 N HCL solution) and 1 ml of deionized water is added to each test tube and vortexed. | |||||||||
| 9. The test tubes are placed in a water bath at 37º C and allowed to incubate for 10 minutes. | |||||||||
|
10. 5 ml of 0.6 N sodium hydroxide (Dissolve 24 g NaOH in distilled water to make 1000 ml) is added to each test tube and vortexed.
|
|||||||||
| 11. The samples are run on a spectrophotometer set at 420 nanometers. Standards are made and run at the same conditions to create a standard curve. | |||||||||
|
|
|
|
|
|
|
|
|||
|
|
|||||||||
|
|
|||||||||
