TOTAL POLYPHENOLIC CONTENT MEASUREMENT USING POLYPHENOL SENSORS

GRUPO 19 Cristina Ruiz Martínez Sara Ugarte Cerrato

INDEX

 Introduction  Mechanisms  Samples    Red wine Olive oil Other vegetable extracts  A new biosensor

 Introduction  Mechanisms  Samples    Red wine Olive oil Other vegetable extracts  A new biosensor

I

NTRODUCTION POLYPHENOL COMPOUNDS malvidin quercetin - Natural antioxidants widely distributed in the plant kingdom - Important determination - physiological effects - employment as markers in taxonomic studies - their properties to food quality control

 Introduction  Mechanisms  Samples    Red wine Olive oil Other vegetable extracts  A new biosensor

M

ECHANISM  CLASSICAL METHODS    spectrophotometry gas chromatography liquid chromatography   capillary electrophoresis

Folin-Ciocalteau

 RECENT METHODS  Biosensors: based on enzymes  Advantages: • • • rapid response cost-effectiveness simplicity of operation and manufacturing, minimal sample pretreatment and solvent requirements.

B

IOSENSORS FOR POLYPHENOLS DETERMINATION

 Introduction  Mechanisms  Samples    Red wine Olive oil Other vegetable extracts  A new biosensor

SAMPLES RED WINE

    Enzyme: laccase Product of its oxidation: 1,2 benzoquinone reduced at the electrode. Actual mechanism of reaction still unclear.

From spectroscopic and electron paramagnetic resonance (EPR) studies: 1º enzyme completely reduced 2º oxygen reduced to water

WINE SAMPLE

 Immobilization in polyethersulfone membranes:  1º Washings containing an excess of enzyme with acetate buffer.

 2º A quantity deposited on polyethersulfone membrane cut in the form of discs.

 3º Application to the electrode.

 4º The biosensor is dipped in the buffer.

 5º Injections of the sample or standard under magnetic stirring.

WINE SAMPLE

 Conclusion: able to discriminate between catechin and caffeic acid but negligible responses when using with wine.

 The complex matrix of the red wine samples interference in the response.  More research to overcome the deviations.

 Introduction  Mechanisms  Samples    Red wine Olive oil Other vegetable extracts  A new biosensor

OLIVE OIL SAMPLE

 Two sensors:  Biosensor based on the catalytic activity of the tyrosinase.

Main advantages: -prior extraction pre-treatment analysis time not necessary eliminated decreased - Flow injection analysis - saving time - Semiautomization of - minimization of the entire procedure exposure to solvent vapors

OLIVE OIL SAMPLE

Tyrosinase Pre-actived membrane Amperometric Gas Diffuse Electrode Gas permeable membrane Dialysis membrane Sensor Teflon O-ring

OLIVE OIL SAMPLE



Voltammetric sensor

    Prior extraction Using a disposable screen-printed sensor (SPE) Reference compound: oleuropein A calibration curve of oleuropein

OLIVE OIL SAMPLE

 Electrode

 Introduction  Mechanisms  Samples    Red wine Olive oil Other vegetable extracts  A new biosensor

VEGETABLE EXTRACTS

   Enzyme: horseradish peroxidase.

Inmmobilization: silica-titanium.

  Material with high chemical stability. Improvement of the amperometric detection.

No significant influence of the matrix was observed.

VEGETABLE EXTRACTS

 Mechanism: double displacement or ping-pong.

 Introduction  Mechanisms  Samples    Red wine Olive oil Other vegetable extracts  A new biosensor

N

EW BIOSENSOR  Based on laccase immobilized onto silver nanoparticles/multiwalled carbon nanotube/polyaniline gold electrode.

 Immobilization on AgNPs/PANI/MWCNT/Au (gold) electrode through covalent coupling to construct an enzyme electrode for determination of polyphenols.

 Employed for amperometric determination of total phenolic content in beverages and pharmaceutical formulation.  Conclusion: good biosensor, likely to overcome the problem of leakage of enzyme.

THE END