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| DETERMINATION OF SOAPS IN FATS AND OILS USING FOODLAB |
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Soaps are fatty acid salts obtained by the reaction of the free fatty acids with soda. Thanks to their solubility in water and insolubility in oil, they can then be separated from the fat using suitable procedures. Food industries use this procedure to lower acidity of alimentary fats, seed oils and olive oil and improve their organoleptic characteristics.
With the FoodLab system it is possible to determine in just a few seconds the concentration of soaps in alimentary fats using micro quantities of sample. Oil can be used directly raw, while solid fat must be melted at a temperature of approx. 60°C.
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.
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| MATERIALS AND CORRELATION METHODS |
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The FoodLab method is based on a colorimetric reaction in which the soaps, under certain pH conditions, with the bromophenol, give a blue coloration. The intensity of the color, measured at 600 nm, is directly proportional to the concentration of soaps, expressed in ppM of sodium oleate.
Alimentary fat samples were analyzed with the NGD system and with FoodLab, at the same time, in the reference laboratory. |
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| RESULTS AND DISCUSSION |
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The values obtained with the NGD system and with FoodLab on alimentary 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 fat samples are shown in the Tab.1.
The tests were carried out in the CDR laboratories.
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| Fig.1: Correlation between FoodLab and NGD methods |
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| Tab.1: Repeatability tests. |
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Ref
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Grasso¹ |
Grasso¹ |
Grasso¹ |
Grasso¹ |
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11,2 |
58,2 |
117,2 |
545 |
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11,9 |
57,3 |
115,2 |
534 |
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11,0 |
56,8 |
114,5 |
530 |
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10,8 |
54,8 |
110,3 |
539 |
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11,7 |
55,2 |
111,2 |
532 |
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MEAN |
11,4 |
56,3 |
114,0 |
537 |
SD |
0,43 |
1,37 |
2,71 |
6,11 |
CV,% |
3,77% |
2,44% |
2,38% |
1,14% |
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1 raw oil
2 fat melted at 60°C in a double boiler |
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| SHORT TABLE |
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Linearity |
Accuracy |
Repeat. |
R2 |
Sensitivity |
Total
analysis
time |
Test/hour |
1200 ppM |
±5% |
CV < 5% |
r > 0,99 |
5 ppM |
5- 8 min |
70 |
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