FLAVOR OBJECTIVES 1 Flavor significance 2 Food taste

FLAVOR OBJECTIVES 1. Flavor – significance; 2. Food taste; 3. Food aroma.

FLAVOR Major flavor-forming processes in foodstuffs 1

FLAVOR PERCEPTION 3

FLAVOR 4 Perception of flavor – taste, aroma, texture Trigeminal nerve - texture V 1 – ophthalmic nerve V 2 – maxillary nerve V 3 – mandibular nerve Chorda tympani and facial nerve- taste

FLAVOR 5 Perception of flavor – taste, aroma, texture Olfactory system – around 100 millions receptors. Olfactory nerve Bulbs 1. Olfactory bulb 2. Mitral cells 3. Bone 4. Nasal epithelium 5. Glomerulus 6. Olfactory receptor cells Ortonasal detection – directly through the nasal cavity Retronasal detection – through the mouth (mastication) and then nasal cavity

! FLAVOR PERCEPTION Flavor perception. Relation between structure and flavor 1. Taste perception – 4 (5) major tastes: salty, sweet, bitter, sour + umami also some sensations – cooling effect, metallic taste, pungent, astringency 25 milliseconds – response time 6

FLAVOR PERCEPTION Flavor perception. Relation between structure and flavor 7

FLAVOR PERCEPTION 8 Tastes 1. 1. Salty – presence of ions (principally Na. Cl but Li. Cl also is percepts as salty substance); passing of the ions through specific membrane channels Cations – reason for the salty taste; Anions – modifying and sometimes masking it. ornithine taurine

FLAVOR PERCEPTION G protein-coupled receptors T 1 R 2+3 and T 1 R 3 Tastes Sweet receptors 1. 2. Sweet – formation of с. АМР after activation; AH/B theory 9 g- intensity of sweetness Relation of the sweet taste of cyclamate and it’s structure

FLAVOR PERCEPTION Tastes 1. 2. Sweet – relation between sweet taste and structure of saccharin and derivatives 10

FLAVOR PERCEPTION 1. 2. Sweet – relation between sweet taste and structure of substances 11

FLAVOR PERCEPTION Tastes 1. 3. Sour – due to presence of H+ (H 3 O+); receptors – potassium ion channels on the taste cells; Organic acids – more profound effect on sour taste than inorganic 12

FLAVOR PERCEPTION 13 Tastes 1. 4. Bitter taste – characteristic for great number compounds (many of them without any physical or chemical similarities in the structure) - existence of several theories – presence of more receptors for bitter taste; lack of receptors for the bitter taste Detected at concentrations 0. 0016% (4. 10 -5 mol) quinine Sour tatse – 0. 007% HCl Salty – 0. 25% Na. Cl Sweet – 0. 5% sucrose (but perception for saccharine – second after quinine) naringin rutinose hesperidin

FLAVOR PERCEPTION 14 Tastes 1. 5. Umami (“delicious”) taste – MSG (mono sodium glutamate) and glutamates Kikunae Ikeda – 1908 was the first to discover it (brown seaweeds, Laminaria japonica) (umai – delicious; mi – taste) Tricholomic acid Ibotenic acid Produced by some fungi Nucleotides with flavor activity IMP – inosine monophosphate; GMP - guanosine monophosphate XMP – Xanthosine monophosphate Synergistic effect between the two groups

FLAVOR PERCEPTION Perceptions and feelings 1. 6. Other sensations – cooling effect (-) menthol (1 R, 2 S, 5 R) Transient receptor potential cation channel subfamily M 8 (TRPM 8) – cold feeling 15

FLAVOR PERCEPTION 16 Perceptions and feelings 1. 6. Other sensations – pungency, hotness myrosinase sinigrin transient receptor potential cation channel subfamily V member 1 (Trp. V 1) Allyl isothiocyanate (horseradish)

FLAVOR PERCEPTION Perceptions and feelings 1. 6. Other sensations – taste modifications 1). Leaves of a tropical plant Gymnema sylvestre (gymnemagenin) – suppress the ability to taste sweetness (several hours); sugar seems like sand in the mouth. 2). The berries of a West African shrub (Synsepalum dulcificum) – miracle fruit had a protein, a substance which changes the sour taste into sweet. 17

FLAVOR 18 Food aroma Aroma substances; key odorants Around 7100 compounds (data from 1999) found in 450 foodstuffs; Around 7 -8% from them – key odorants; H. Maarse and R. Belz (1983) give approximate number of flavor substances in: beef (boiled, cooked)- 486; beer-562; butter-257; coffee-790; grape-466; orange-203; tea-541; tomato- 387 and wine (white)-644. Special attention is paid to aroma substances present in higher concentration and to those which give the specific aroma (key odorants). Isolation, Separation and Identification of Volatile Compounds in Aroma Research Hardcover – Nov 30 1982 by H. Maarse, R. Belz, 1983, Berlin, Springer.

FLAVOR 19 Substances giving a characteristic aroma (key odorants) geosmin 1 -p-menthene-8 -thiol geranial filbertone neral 2 -furfurylthiol Raspberry ketone

! FLAVOR 21 Major flavor-forming processes in foodstuffs Threshold value (odor threshold) – limit of detection – the lowest concentration, at which the characteristic aroma is recognized Aroma value (Ах) Ax = Cx / ax; - Cx – concentration - ax – odor threshold

FLAVOR 22 Major flavor-forming processes in foodstuffs Threshold value (odor threshold) – limit of detection – the lowest concentration, at which the characteristic aroma is recognized Variation of the threshold value depending from the matrix

FLAVOR Major flavor-forming processes in foodstuffs 23

FLAVOR 24 Major flavor-forming processes in foodstuffs – Maillard reaction From 1 to 5 (table – first column): key odorant and responsible for the smell of the French fries

FLAVOR Major flavor-forming processes in foodstuffs 25

FLAVOR 25 a Aroma compounds in bread

FLAVOR PERCEPTION Food aroma 2. Aroma perception - significance - Theories explaining perception of the aromas: chemical (adsorption-desorption processes); physical-chemical (effect of the dipole moments in the molecules); vibrational (oscillation, vibration of the bonds); enzymatic, etc. 26

FLAVOR Food aroma Spearmint Caraway 3 -hexenol (CH 2 OH-CH 2 -CH=CH-CH 2 CH 3) cis- green, some fresh aroma; trans- floral, chrysanthemums 27

FLAVOR PERCEPTION Food aroma 3. Relation between aroma and chemical structure - parameters influencing the specific food aroma Lipophilicity; Hydrogen bonds; Electronic factors – presence of electron pairs, π-bonds; Steric factors, etc. 28

FLAVOR PERCEPTION Food aroma. Relation between structure and aroma 3 major cases found: - Different structures having same (or resembling) aroma of fried foodstuffs aroma of cocoa 29

FLAVOR PERCEPTION Food aroma. Relation between structure and aroma 3 major cases found: - Similar structures having different aroma of cooked meat chemical aroma, hydrogen sulfide 30

FLAVOR PERCEPTION Food aroma. Relation between structure and aroma 3 major cases found: - Similar structures having same (or resembling) aroma of popcorn aroma of green peppers 31

FLAVOR PERCEPTION 32 Food aroma. Relation between structure and aroma - Smell of burnt – presence of polycarbonyl compounds (diacetyl, glyoxal etc. ) or α, β unsaturated aldehydes (acrolein etc. ) - Aroma of caramel

FLAVOR PERCEPTION Food aroma. Relation between structure and aroma - aroma of fresh tomatoes similar structure 33

FLAVOR PERCEPTION 33 Food aroma. Relation between structure and aroma similar structures – different thresholds Odor thresholds of alkyl pyrazines (according to Wagner et al. , 1999). The odor threshold in pmol / L air is given in brackets Dilution analyses suggested that compounds which appear with a high odor intensity are only P 7 and P 16 in addition to P 5, P 13 and P 17

FLAVOR Flavoring substances Natural, nature-identical and artificial (synthetic) Type Description Flavoring substances obtained from plant or animal raw materials, by Natural flavoring physical, microbiological or enzymatic processes. They can be either substances used in their natural state or processed for human consumption, but cannot contain any nature-identical or artificial flavoring substances. Nature-identical flavoring substances Flavoring substances that are obtained by synthesis or isolated through chemical processes, which are chemically and organoleptically identical to flavoring substances naturally present in products intended for human consumption. They cannot contain any artificial flavoring substances. Artificial flavoring substances Flavoring substances not identified in a natural product intended for human consumption, whether or not the product is processed. These are typically produced by fractional distillation and additional chemical manipulation of naturally sourced chemicals, crude oil or coal tar. Although they are chemically different, in sensory characteristics are the same as natural ones. 34

FLAVOR Flavoring substances - use Natural, nature-identical and artificial (synthetic) 35

FLAVOR 36 Flavoring substances - synthesis Acetyl pyrazines Alkyl and acetyl pyrazines

FLAVOR 38 Natural, nature-identical and artificial (synthetic) Substance Odor Diacetyl Isoamyl acetate Benzaldehyde Cinnamaldehyde Ethyl propionate Methyl anthranilate Limonene Ethyl decadienoate Allyl hexanoate Ethyl maltol Ethylvanillin Methyl salicylate Buttery Banana Bitter almond Cinnamon Fruity Grape Orange Pear Pineapple Sugar, Cotton candy Vanilla Wintergreen

Aroma of the Strecker aldehydes 39 Amino acid Strecker aldehyde Odor at 100 °C Odor at 180 °C Glycine HCHO formaldehyde Caramel-like, soft, ester-like Burnt sugar Alanine CH 3 CHO acetaldehyde Caramel-like, spicy, fruity Burnt sugar Threonine hydroxypropanal Chocolate Burnt Valine 2 -methyl propanal Straw, green, rye bread Chocolate, pungent Leucine 3 -methyl butanal Bread, malty, green Cream cheese Isoleucine 2 -methyl butanal Fruity, ester, green Cream cheese

Aroma of the Strecker aldehydes 40 Amino acid Strecker aldehyde Odor at 100 °C Odor at 180 °C Methionine Methional CH 3 SCH 2 CHO Fermented cabbage, sour, cabbage, sour unpleasent Phenyl alanine 2 -phenyl acetaldehyde Floral, violet, honey, Floral – violet, lilac Tyrosine 2 -(4 -hydroxyphenyl)acetaldehyde Caramel-like Serine Hydroxyacetaldehyde Maple syrup α-amino butyric acid Propanal CH 3 CH 2 CHO Caramel-like, Maple syrup Burnt sugar

Aroma of the Strecker aldehydes 41 Amino acid Strecker aldehyde Odor at 100 °C Odor at 180 °C Phenyl- glycine Benzaldehyde Almond Proline Burnt proteins Sweet smell Hydroxy proline Potatoes Histidine No specific Burnt sugar Arginine Burnt sugar

Aroma of the Strecker aldehydes Amino acid Strecker aldehyde Aspartic acid 42 Odor at 100 °C Odor at 180 °C Sweet, candy Burnt sugar Glutamic acid Butanal and propanal Caramel like Burnt sugar Glutamine Pyrrolidone Chocolate Hard caramel Cysteine Acetaldehyde, propanal Sulfide, smell of H 2 S, cooked H 2 S meat