Flavour Chemistry

NAME OF THE COURSE Flavour Chemistry

Code

KTM213

Year of study

2.

Course teacher

Prof Igor Jerković

Credits (ECTS)

4.0

Associate teachers

Type of instruction (number of hours)

P S V T

30

0

15

0

Status of the course

Mandatory

Percentage of application of e-learning

0 %

COURSE DESCRIPTION

Course objectives

Acquisition of basic knowledge of flavour chemistry, understanding of the activation of receptors of smell and taste, knowledge of the structure of organic compounds of the typical flavours and their division, knowledge of the basic mechanisms of flavour formation and the flavour isolation methods.

Course enrolment requirements and entry competences required for the course

 

Learning outcomes expected at the level of the course (4 to 10 learning outcomes)

After passing the course, students will be able to:
- describe the basic concepts, types of flavours, gustatory active molecule, legal regulations related to the flavour toxicological assessment and allowed concentration of biologically active substances
- illustrate ways of flavour perception (smell and taste), the mechanisms of development of natural flavour, the division of flavouring substances based on the chemical structure
- demonstrate basic procedures of flavour isolation from solid and liquid samples (headspace, volatile, semivolatile and nonvolatile substances)
- identify appropriate mechanisms of flavour origin by specific patterns, particularly flavourings derived from carbohydrates and proteins and lipid oxidation flavours
- propose appropriate methods of the sample processing taking into account the fundamental principles of distillation and extraction and the possibility of artefacts formation, structural linkage between aromatic compounds and suitable mechanism for their origin
- choose the correct chemical approach to solving problems in the field of flavour chemistry, starting from the acquired knowledge in organic chemistry and biochemistry

Course content broken down in detail by weekly class schedule (syllabus)

1st week: Introduction to the chemistry of flavour. Classification of flavours. Natural, natural identical and artificial flavouring substances. Flavouring preparations. Thermal process flavourings. Smoke flavour. Blends of flavours. Review of the quality of flavour.
2nd week: A short overview of the development of flavour chemistry. Legal regulations. Natural, natural identical and artificial flavours – differences between the United States and the EU. New EU legislation.
3rd week: Croatian law on flavourings (NN) with emphasis on chemical specifications of flavours and maximum allowed values of biologically active substances in flavoured food. Croatian regulations on food additives (NN). Sweetening agents. Flavour enhancers.
4th week: The sense of smell. Activating receptors of smell. The sense of taste - basic taste qualities. Activation of taste receptors. Example of aromagram.
5th week: Molecules with sensory effects - examples of chemical structures: stinging molecules; molecules for cooling; strong, sharp molecules with heating and hot stimuli, the molecules with the contraction, shrinkage. The taste active molecule - examples of structures: sweeteners (nutritive, nonnutritious sweeteners, natural carbohydrates, noncarbohydrates, artificial sweeteners), salt, acid, bitter and umami substances (monosodium glutamate, inosine monophosphate).
6th week: The division of the flavour substances according to the chemical structure: flavouring substances I (C, H, O compounds: alcohols, phenols, acids, ketones, carotenoids, ionones and related compounds, hydrocarbons) - examples; the flavouring substances II (heterocyclic compounds with oxygen: oxiranes, furans, hydrofurans, pyrans and oxepines; heterocyclic compounds with nitrogen and/or sulphur) - examples, flavouring compounds III (compounds containing sulphur: thiols, thioethers, sulphides, heterocyclic compounds with sulphur) - examples
7th week: Mechanisms of flavour formation from the starting compounds. Terpenes (biosynthesis through MVA and DXP). Norisoprenoids (the mechanism of degradation of carotenoids). Phenylpropanoic derivatives (shikimate biogenetic pathway).
8th week: Flavours derived from carbohydrates and proteins. Maillard reactions. Aldol reactions and retro-aldol reactions. Strecker degradations (cysteine, methionine). Comparison of Strecker degradation and Amadori rearrangement.
9th week: Independent pathways occurrence of Strecker aldehydes. Amadori rearrangement by transamination and Strecker aldehydes formation by decarboxylation of α-oxocarboxylic acids. Strecker degradation and Amadori modelling in the development of flavour and colour.
10th week: Heterocyclization (formation of furfural, hydroxymethylfurfural, 5-methyl-4-hydroxy-3(2H)-furanone, formyl furol, isomaltol, pyrazine, oxazole and thiazole). Flavours of thermal degradation of vitamin B1.
11th week: Flavours of lipid oxidation. Triplet and singlet oxygen. Lipid oxidation by radicals (initiation, propagation and termination). Hydroperoxides and hydroperoxides breakup. Lactones.
12th week: Non-radical lipid oxidation. Enzymatic lipid oxidation (lipoxygenation). Flavours caused by enzymatic reactions and by microorganisms (diacetyl from lactose, the flavours of onion and garlic).
13th week: Isolation methods for flavourings. Solvent extraction. Accelerated solvent extraction. Supercritical fluid extraction. The fractionation of the extracts. Concentration of the extracts.
14th week: Distillation methods. Headspace isolation techniques (static, dynamic). Thermal desorption. Sorption techniques: headspace solid-phase microextraction; headspace extraction and extraction from the stirring stick.
15th week: Examples of chemical flavour profiles of selected food products: Honey flavour. Flavour of roasted coffee. Flavour of wine. Flavour of meat products. Cheese flavour.

Format of instruction:

Student responsibilities

Students are required to attend classes (lectures and seminars) and actively participate in the teaching process, which will be evaluated in the final assessment by the weight coefficient of 5%.

Screening student work (name the proportion of ECTS credits for eachactivity so that the total number of ECTS credits is equal to the ECTS value of the course):

Class attendance

1.0

Research

0.0

Practical training

0.0

Experimental work

0.0

Report

0.0

 

 

Essay

0.0

Seminar essay

0.0

 

 

Tests

0.0

Oral exam

0.0

 

 

Written exam

3.0

Project

0.0

 

 

Grading and evaluating student work in class and at the final exam

Students can take two partial tests during the lectures. If not pass partial tests, students will be evaluated by written exam. Rating at partial tests and the final examination is formed as follows: 51-60% sufficient (2); 61-75% good (3); 76-88% very good (4); 89-100% excellent (5). The total score is formed by summing all activities (for each activity % success multiply weigh coefficient): 5% x the presence and activity in lectures and seminars + 10% x success in experimental work + 40% x performance on the first test + 45% x performance on the second test.

Required literature (available in the library and via other media)

Title

Number of copies in the library

Availability via other media

I. Jerković: Kemija aroma (recenzirana interna skripta), KTF-Split, 2011.

0

Web

D. Rowe: Chemistry and Technology of Flavours and Fragrances, Blackwell, 2005.

2

C. Fisher, T. R. Scott: Food Flavours: Biology and Chemistry, Royal Chemical Society, 1997.

1

Optional literature (at the time of submission of study programme proposal)

K. A. Smith: Advances in Flavours and Fragrances, Royal Chemical Society, 2001.

Quality assurance methods that ensure the acquisition of exit competences

Quality assurance will be performed at three levels:
(1) University Level;
(2) Faculty Level by Quality Control Committee;
(3) Lecturer’s Level.

Other (as the proposer wishes to add)