New Device Detects Adulteration Using Fluorescence Spectroscopy

The sensor uses a combination of laser diodes and computer-constructed algorithms to measure light emissions from samples of olive oils to determine whether they are correctly labeled.

By Daniel Dawson
Jan. 2, 2019 11:25 UTC

Using laser diodes and algo­rithms, researchers from the Complutense University of Madrid (CUM) and the Scintillon Institute have designed a sen­sor that could be used to detect fraud­u­lently labeled olive oil bot­tles.

The tech­nol­ogy is based on flu­o­res­cence spec­troscopy,” John Cancilla, a post­doc at the Scintillon Institute who col­lab­o­rated on the project, told Olive Oil Times. After irra­di­at­ing the olive oil sam­ples with the laser diode, emis­sion spec­tra are col­lected.”

These emis­sions, which are light given off by the olive oil mol­e­cules after they have been excited by the laser diode, are unique and reflect the dif­fer­ent con­cen­tra­tions of pig­ments that com­pose each of the mol­e­cules. Adulterated oils have dif­fer­ent emis­sion spec­tra than pure extra vir­gin olive oils.

The researchers car­ried out the study by mix­ing three PDO extra vir­gin olive oils with expired olive oils. One hun­dred and fifty-four blends con­tain­ing between one per­cent and 17 per­cent of the pure PDO extra vir­gin olive oil were then mea­sured along with the pure sam­ples.

After the emis­sion spec­tra had been col­lected, they were ana­lyzed by the algo­rithms. Once the data had been ana­lyzed, researchers could dif­fer­en­ti­ate the wave­lengths emit­ted by the three sam­ples of PDO extra vir­gin olive oil both from each other as well as the 154 adul­ter­ated olive oil sam­ples.

Through data analy­sis and mod­el­ing, we reach math­e­mat­i­cal tools that can dis­tin­guish, in this case, pure fresh extra vir­gin olive oil from sam­ples mixed with old olive oil,” Cancilla, who worked on the algo­rithms for the project, said.

In a blind test, the researchers were also able to deter­mine how much adul­ter­ant had been added to the PDO olive oils within a small mar­gin of error.

From the results of this thor­ough val­i­da­tion pro­ce­dure it can be seen that a tool based on an intel­li­gent ANNs [the algo­rithms] has been devel­oped and opti­mized to be able to dis­tin­guish among dif­fer­ent PDO extra vir­gin olive oils as well as quan­tify the amount of old extra vir­gin olive oils with which they have been mixed,” José S Torrecilla, a senior lec­turer at CUM who worked on the project, wrote in the report.

According to Torrecilla, the sen­sor presents an unprece­dented oppor­tu­nity for olive oil pro­duc­ers to pro­tect the value of their prod­uct and for retail­ers to ensure what they are buy­ing is authen­tic.

The com­bi­na­tion of a laser diode and cog­ni­tive mod­el­ing leads to a fast and cost-effec­tive tool able to authen­ti­cate PDO labels of extra vir­gin olive oils and esti­mate the amount of poten­tial adul­ter­at­ing agents such as olive oils from old har­vests,” he wrote in the report, which is set to be pub­lished in the upcom­ing issue of Talanta.

The sen­sors are made using 3D print­ers and can be repro­duced at a low cost, mak­ing them afford­able for most com­mer­cial pro­duc­ers.

Other clear advan­tages of our tool include the pos­si­bil­ity of con­duct­ing on-site analy­ses, because the equip­ment is the size of a brief­case and there­fore portable, and of gen­er­at­ing results in real time,” Torrecilla said.

This tech­nique is avail­able for use at any time, and only requires oils prior to pack­ag­ing for qual­ity con­trol or after pack­ag­ing to detect fraud­u­lent brands and/or pro­duc­ers,” he added.

The sen­sors have not yet been used com­mer­cially, with the pro­to­type still being tested in Spain. However, there is opti­mism among the researchers that the sen­sor will soon be ready for com­mer­cial use.


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