|
|
 |
|
|
|
| DETERMINATION OF PEROXIDES IN FATS AND OILS USING FOODLAB |
|
The peroxide content present in a alimentary fat or oil attests to its state of primary oxidation and thus its tendency to go rancid. Unsaturated fatty acids, in fact, react with oxygen forming peroxides, which determine a series of chain reactions whose end result is volatile substances having the characteristic smell of rancidness. These reactions are accelerated by high temperatures and by exposure to light and oxygen. The lower the peroxides values, the better the quality of the alimentary oil and its state of preservation.
With the FoodLab system it is possible to determine in just a few minutes the concentration of peroxides in alimentary fats, seed oils, olive oil and dried fruit using micro quantities of sample. Oil can be used directly raw, while solid fat must be melted at a temperature of approx. 60°C.
Furthermore CDR has also designed an innovative system for the cold extraction by means of pressure of the oil contained in dried fruit. The system is practical, fast and uses small quantities of dried fruit given the micro quantities required for analysis, without using solvents to extract the oil.
The reagents are composed exclusively of low toxicity substances, easily disposable, which allow the test to be carried out in any environment. The method's reliability and precision are guaranteed by a calibration system that allows alignment of the instrument using known standards.
|
|
| MATERIALS AND CORRELATION METHODS |
|
The FoodLab method is based on a colorimetric reaction in which peroxides R-O-O-R oxidize the Fe++ ions. These ions are complexed, forming a red color whose intensity, measured at 505 nm, is directly proportional to the concentration of peroxides in the sample, expressed as mEO2/Kg.
Alimentary fat and oil samples were analyzed with the NGD system and with FoodLab, at the same time, in the reference laboratory. |
|
| RESULTS AND DISCUSSION |
|
The values obtained with the NGD system and with FoodLab on alimentary oil and fat samples are shown in Fig.1. The regression line correlation coefficient (r>0.99) indicates that the FoodLab system is perfectly aligned with the reference method.
Some repeatability tests carried out on the FoodLab system with oil and fat samples are shown in the Tab.1. The tests were carried out in the CDR laboratories. |
|
| Fig.1: Correlation between FoodLab and NGD methods |
|
 |
|
| Tab.1: Repeatability tests. |
|
Ref
|
Olio¹ |
Olio¹ |
Grasso² |
Grasso² |
| |
6,84 |
9,03 |
3,40 |
0,49 |
| |
6,64 |
8,72 |
3,25 |
0,48 |
| |
6,63 |
8,58 |
3,29 |
0,48 |
| |
6,54 |
8,29 |
3,27 |
0,49 |
| |
6,84 |
8,85 |
3,25 |
0,50 |
|
|
|
|
|
MEAN |
6,68 |
8,71 |
3,29 |
0,49 |
SD |
0,12 |
0,26 |
0,06 |
0,01 |
CV,% |
1,87% |
2,93% |
1,69% |
2,16% |
| |
1 raw oil
2 fat melted at 60°C in a double boiler |
|
|
| SHORT TABLE |
|
Linearity |
Accuracy |
Repeat. |
R2 |
Sensitivity |
Total
analysis
time |
Test/hour |
150 mEO/Kg |
± 5% |
CV < 6% |
r > 0,99 |
0,2 mEO/Kg |
5 - 8 min |
70 |
|
|
| |
|
|
 |
|
|
