TOTAL POLYPHENOLIC CONTENT MEASUREMENT USING POLYPHENOL SENSORS - PowerPoint PPT Presentation

TOTAL POLYPHENOLIC CONTENT MEASUREMENT USING POLYPHENOL SENSORS

GRUPO 19

Cristina Ruiz Martínez

Sara Ugarte Cerrato

• 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

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

• CLASSICAL METHODS
• spectrophotometry
• gas chromatography
• liquid chromatography
• capillary electrophoresis
• Folin-Ciocalteau

• RECENT METHODS
• Biosensors: basedonenzymes
• Advantages:
• rapid response
• cost-effectiveness
• simplicity of operation and manufacturing, minimal sample pretreatment and solvent requirements.

Introduction

• Mechanisms
• Samples
• Red wine
• Olive oil
• Other vegetable extracts
• A new biosensor

• 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

• 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.

• 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

• Twosensors:
• 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

Tyrosinase

Pre-actived membrane

Amperometric Gas Diffuse Electrode

Gas permeable membrane

Dialysis membrane

Sensor

Teflon O-ring

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

• Electrode

Introduction

• Mechanisms
• Samples
• Red wine
• Olive oil
• Other vegetable extracts
• A new biosensor

• Enzyme: horseradish peroxidase.
• Inmmobilization: silica-titanium.
• Material with high chemical stability.
• Improvement of the amperometric detection.
• No significant influence of the matrix was observed.

• Mechanism: double displacement or ping-pong.

Introduction

• Mechanisms
• Samples
• Red wine
• Olive oil
• Other vegetable extracts
• A new 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