ENOLOGICAL CHEMISTRY AND LABORATORY ANALYSES

Single discipline educational activity

Course Sheet

Academic Year of enrolment:

2018/2019

Type of Course:

Characterising

Optional/Mandatory:

Compulsory

Degree:

Bachelor's Degree Programme in VITICULTURAL, OENOLOGICAL AND FOOD TECHNOLOGIES

Disciplinary Sector:

Food Sciences

Language:

Italian

Credits:

Programme Year:

Professor and Collaborators:

PETROZZIELLO Maurizio

Hours of classroom activity:

Prerequisites:

General and inorganic chemistry, Organic chemistry and agricultural biochemistry.

AF code:

A000568

Assessment Methods

Verification of learning:

Students will be assessed through a final written exam of about 1 hours. The final evaluation will take into account the outcome of the laboratory sessions.

Teaching period

First semester

Objectives

The aim of the course is to acquire specific knowledge of chemical composition of grapes, musts and wines focusing to the main classes of compounds, their origin and their evolution. The related analytical techniques will also be illustrated.

On completion of the course, the student:
- demonstrates a good understanding of the chemical-physical composition of the wine products
- indicates the most appropriate analytical techniques for the evaluation of the major chemical and physical parameters of grapes, musts and wines
- identifies changes in composition related to tainted wines.

Contents

- The oenological chemistry and the progress of oenology.
- Nitrogen compounds of grapes: Ammonium, amino acids, peptides and proteins. Other nitrogen compounds.
- Grape acids. Acid-base equilibria. Measurement of total acid content and pH.
- Monosaccharides, disaccharides and polysaccharides. Physiological functions and technological implications. The glucose colloids of musts and wines. Quantification methods in enology
- Grape polyphenols. Classification and properties. The concept of phenolic maturity. The chemical equilibria of anthocyanins in aqueous solution.
- Varietal aromas and their precursors: Classification and main characteristics. The impact of climate, viticultural practices and maturity on the aromatic composition of the grapes. Overview of aromas analysis.
- Enzymes and enzymatic reactions in grapes. The enzymatic oxidation of musts.
- Sugars and fermentation. Glycolysis, the respiratory chain. Biochemistry of alcoholic fermentation. Metabolism of lactic bacteria of oenological interest. Metabolism of acetic bacteria and its consequences. Chemical analyzes during fermentation.
- Organic acids and mineral substances in wines. Changes in wine acid profile after fermentation. Buffering capacity of wines. Tartaric precipitation and acid equilibria in wines.
- Extraction of the polyphenolic fraction during fermentation. The composition and the polyphenolic evolution of wines. Reactions of anthocyanins and tannins. The color of the wines.
- Pre-fermentative volatile compounds. Fermentation aromas compounds in wine, alcohols and polyalcohols, esters and carbonyl compounds. Other fermentation compounds.
- The volatile substances released from the wood. Evolution of volatile aromatic compounds during bottle storage.
- Wines redox potential and oxido-reductive phenomena. Wine and oxygen
- The oenological antioxidants, sulfur dioxide in enology: chemical-physical and technological characteristics. Measurement of sulfur dioxide in wines: status quo and future perspectives.
- Colloids, colloidal phenomena and turbidity in wines. Protein precipitation and metal casse

Recommended Bibliography

Presentations/handouts will be provided during the course

- Suggested bibliography:
Handbook of Enology, Volume 1: The Microbiology of Wine and Vinifications. Pascal Ribéreau-Gayon, Denis Dubourdieu, B. Donèche, A. Lonvaud. John Wiley & Sons, 1 mag 2006 - 512 pp.
Handbook of Enology, Volume 2: The Chemistry of Wine - Stabilization and Treatments. Pascal Ribéreau-Gayon, Y. Glories, A. Maujean, Denis Dubourdieu. John Wiley & Sons, 1 maj 2006 - 450 pp
International Organization of Vine and Wine (OIV). Collection of international methods of analysis of wines and musts. Updated version available at http://www.oiv.int/
Waterhouse A.L., Sacks G.L., Jeffery D.W. Understanding Wine Chemistry. Wiley, 2016.

Methods of Provision

Conventional

Teaching Methods

- lectures supported by ppt slides
- laboratory practice sessions
- Numerical laboratory exercises, both individually and in groups

Contacts/More Information

ENOLOGICAL CHEMISTRY AND LABORATORY ANALYSES

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ENOLOGICAL CHEMISTRY AND LABORATORY ANALYSES