Conclusion and discussion:
In this research we performed a quantitative determination of piperine in three different pepper species, videlicet black, white and green pepper. We used HPLC with a 70% methanol-30%water eluent. The results are as follows:
Table 28: results piperine
| Sample | Percentage piperine (g/g) | 95% confidence (g/g) |
| Black pepper | 0,0202 | 0,0019 |
| White pepper | 0,0239 | 0,0021 |
| Green pepper | 0,0383 | 0,0032 |
From the organoleptic research we can conclude that capsaicin has a higher pungency compared to piperine. Of the three pepper species, piperine causes the most pungent taste in black pepper. From these results we can conclude that the degree of pungency not only depends on the amount of piperine in the sample, but also on other factors. Piperine in its pure solid state doesn’t cause the pungent taste, but it is piperine in its mother oil in the pepper that causes the burning. In different pepper species there is a matter of different mother-oils in which the piperine is solved. Therefore one pepper species can be more pungent than another in spite of the fact that they contain the same amount of piperine.
RP-HPLC is a good method for quantitative determination of piperine in pepper samples. For the determination of piperonal other conditions are required, since the piperonal peaks are surrounded by a lot of other UV-absorbing components. Another eluent or eluent-composition could be a solution for this problem.
We also tried to determine piperine and piperonal with CZE and MECC, but no results were found. We still think that the CZE method should give satisfying results, but for some reason we didn’t detect any of the compounds. For more information on these measurements we refer to "What went wrong and why".
Better results considering the extraction of piperine can be obtained by centrifuging for a longer time and using more methanol to as extractionmedium. However, a lower concentration would then be obtained which includes a less accurate result.
The organoleptic research can be improved in the following ways:
First of all, more subjects are needed to get a more accurate result.
The difference in two subsequent dilution factors has to be decreased to prevent big
differences in the measured and true values.
A better result is obtained if every subject is given the series in a different order.
Because there is a certain degree of habituation, this would prevent the results to be
influenced by this factor.
.