FoodFood preference preferences of vertebrates s of vertebrates and humansand humans

• food choice depends on tastetaste and smellsmell regardless its nutritive value

• lack of reliable experiments

• expensive research in domestic animals

• unreliable data in wild animals

• all vertebrates significantly prefer sweet taste

HumansHumans - - 55 basic types of tastebasic types of taste

• sweet (tip of tongue)• bitter (root of tongue)• sour (sides of tongue)• salty (tip and edge of tongue)• umami (meet taste)

• threshold for perception of salty taste - 0,05 %• bitter taste - 0,0001 %

Chemical basis of some aromaChemical basis of some aromaCH3

H3C CH3

OHCHO

Terpenes

thymol (mandarines)

citral (lemon)

CHO

OCH3

OH

OH

OCH3

CH2

Aromatics

vanillin (vanilla)

eugenol (banana)

O O O OLactones

-nonalactone(coconut)

undecalactone(peach)

SS

S

SS

SS

Sulfur-containing compounds

di-2-propenyldisulfide (garlic)

lenthionine(mushrooms)

Green leaf odourGreen leaf odourOH

OH

O

O

2- a 3-hexen-1-ol

fresh leaf odour

2- a 3-hexenal

intense grass odour

myrcenehops odour

Flower odourFlower odour

OH

OH

O

OH

O

COOH

1- and 2-fenylethanol, fenylacetaldehyde

rose hyacinth

geraniol

2- and 3-methylbifenylrose

methyl jasmonatejasmín odour

FruitFruit odourodourO

O

1,1-diethoxyethane

O(2E,6Z)-2,6-nonadienalmelon odour

OH

pent-1-en-3-olfresh fruits(strawberries, blackberries)

O

citronellallemon odour

aliphatic ketones - peach, bananaalkanes C11-C15 - light fatty fruit odour

Vegetable odourVegetable odour

CH3

H3C

CH3

CH3

humulenetomatoes

OH

oct-1-en-3-olmushrooms

(E)-2-hexenal ..... raw potatoes(E)-2-nonenal ..... fresh cucumber odourdimethylsulfide ... fresh cabbage

Nut odourNut odourOH O CN

benzylalcohollight almond

odour

2-methylbenzaldehydebitter almond odour

fenylacetonitrilhoney almond odour

O O-nonalactone

coconut

N

-picolinenut and rhum odour

Chemical basis of hot (spicy)Chemical basis of hot (spicy) tastetaste

OCH3

OH

O

OCH3

OH

O OH

zingerone (ginger) gingerol(artefact)

OCH3

OH

HN

O

N

OO

O

capsaicin (chilli peppers)

piperine (black and white pepper)

Chemical basis of sweet tasteChemical basis of sweet taste

O

HO

O

OH

CH2OH

HO O

OH HOCH2OH

CH2OH

OS

O NH

O-

NH

O

NH2

HOOC

O OCH3

O

HNS

O O

sucrosesweetness 1

cyclamatesweetness 30

aspartamesweetness 200

saccharinesweetness 500

DL-xylitolsweetness 1

HO

OH

OH

OH

OH

HO

OH

OH

OH

OH OH

D-glucitol (sorbitol)sweetness 0,6

Lapčík et al.: Chem. Listy 2007, 101, 44-54 (in Czech).

Natural sweetenersNatural sweeteners

H

H

CH3CH2

OHO

OH

O

OH

HO

OHO

OH

HO

O

OHO

OH

OH

HOCH3

O

O

stevioside(Stevia

rebaudiana)sweetness 300

proteinsproteins – from seeds of different plants; sweetness 103

amino acids derivatives:amino acids derivatives: terpenes:terpenes:

NH

OH

O

NH2OH

O OH

monatinroots of South African bush

sweetness 103

Natural sweetenersNatural sweeteners

H3C COOH

H

CH3CH3

O

H CH3

CH3

HHO

CH3H3C

O

OO

Oglycyrrhetinic acidCOOH

COOH

OH

HO

OH

OH

HO

glycyrrhetinnic acidglycyrrhizic acid

triterpentriterpeneses:liquorice

Bitter agentsBitter agents

• bitter plant products without further pharmacological activity

• common occurrence, limited use• different structural types (often glycosides)• in some of them, chemical structure is not

known• bitterness numberbitterness number – the lowest

concentration of a compound or extract that has a bitter taste

• used in the form of extracts, tincture, or wine

• bitter agents - amaraeamarae – in small doses increase the appetite, secretion of gastric juice and influence its acidity

• cholagoguescholagogues – stimulate secretion of bile or the gall bladder contraction to promote the bile flow

• used in food industry for production of liquors, aperitifs, and other bitter drinks

Bitter agentsBitter agents

• Gentiana luteaGentiana lutea (hořec žlutý) – perennial plants (up to 60 years old)

• roots harvested from 4th year• protected, grown for medicinal effects• dried roots• content - glykosidic bitter agents – pyrane

derivatives - gentiopicrin (bitterness number 12 000), amarogentin (bitterness number 58 millions), and gentiamarin, essential oil, tannins, and sugars (gentiobiose and sucrose)

• yellow pigment gentisin (xanthone derivative)

• the drug stimulates secretion of gastric juice and digestion of nutrients, division of blood cells

• gentiopicrin,  erythaurin and its aglycone erythrocentaurin are present in Centaurium Centaurium erythraea erythraea (zeměžluč menší), annual or biannual herb (harvest of flowering aerial parts)

OO

O

GlcOCH=CH2

gentiopikrin

• Absinthe wormwoodAbsinthe wormwood (Artemisia absinthium, pelyněk pravý) - perennial (South and Middle Europe)

• harvest of flowering aerial parts in full sun

Absinthe wormwoodAbsinthe wormwood

• content - 2 % essential oil (more than 20 components)

• main component - β-thujone (60 %)

• toxic, causes irreversible neurodegenerative damage (overestimated earlier)

• other components – bitter agents absinthin and artabsin, bitterness number 10 mil.

O

-thujon

O

O

O CH3

CH3

OH

CH3O

CH3

H

CH3OH

H

HH H

absinthin

O

HCH3

CH3

OH

H

CH3O

artabsin

CH3

CH3

CH3

chamazulen

Components of absinthe wormwoodComponents of absinthe wormwood

Essential oil of absinthe wormwoodEssential oil of absinthe wormwood

• hydrodistillation – decomposition chamazulencarboxylic acid decarboxylation, the final product is chamazulene (blue colour)

• drug stimulates secretion of gastric juice (digestive)

• essential oil is toxic, causes nausea, dizziness, spasm, heady state, congestion of organs in pelvis (misused for illegal abortions)

• in low concentration additive in absinth or vermouth (nowadays prohibited in almost all countries)

• Achillea millefoliumAchillea millefolium (řebříček obecný) – flowering aerial part contains 0,3 % essential oil (40 % chamazulene)

O

O

O

achillin

Bitter agent achillin oxidizes on air to chamazulencarboxylic acid that decarboxylizes to blue chamazulene

Achillea millefoliumAchillea millefolium

• use - amarum, stomachikum and cholagogue

• in traditional medicine as anti-inflammatory agent

Acidic bitter agentsAcidic bitter agents

• HopsHops (Humulus lupulus, chmel otáčivý)

• drug - female burs, source of lupulin

• essential oil (1-3 %) consists of myrcene, caryophyllene, farnesene, humulene, and other components

HopsHops• resin forms up to 80 % mass, contains mainly

bitter agents (50 %), α- and β-bitter acids• humulone (2–6 %) and lupulone (8–12 %)

R

O

O OHOH

OH

-kyseliny

O

R

O

OHOH

OH

humulon

kohumulon

adhumulon

R

CH2-CH(CH3)2CH(CH3)2

CH(CH3)CH2CH3

R

O

O OH

OH

-kyseliny

O

R

O

OH

OH

lupulon

kolupulon

R

CH2-CH(CH3)2CH(CH3)2

Bitter acidsBitter acids

• chemically instable, degradation in light and air (storage max. 1 year)

• taste and bacteriostatic effect - isocompounds arise from bitter acids in brewing process

• sedative effect, sleepiness, aphrodisiacs, amarum and stomachics

• hops extract has antibiotic and estrogenic effect

• Acorus calamusAcorus calamus (puškvorec obecný) spread from Asia to Europe; grows in wetlands, harvest of rhizome

• content – essential oil (2–4 %)• β-asarone and minor α-asarone

OCH3

H3CO

OCH3

CH3

H

H

OCH3

H3CO

OCH3 H

H

CH3

-Asarone -Asarone

• Acorus calamusAcorus calamus

• bitter agents acorine and acoretine; choline

• stimulates metabolism

• used for production of stomachic liquor (Acorus +Gentiana+Angelica+ Centaurium+fennel+caraway)

• asarone is suspected cancerogene, prohibited use in USA

• Juniper Juniper (Juniperus communis, jalovec obecný) – evergreen bush occurring in all Northen temperate zone, protected in CR

• drug – dried fruits, contains essential oil (2 %, terpenes - pinenes, cadinene, terpineol), up to 30 % invert sugar, inositol, 9 % resin, phytoncides, and bitter agent glycoside juniperin

CH2

H3C CH3

CH3

longifolene (juniperene)

JuniperJuniper• effect - diuretics, stimulates metabolism,

external application – skin congestion

• use in food industry (liquors, spice)

• DandelionDandelion, , Taraxacum officinale (smetanka lékařská – pampeliška)

• flowers - honey

• leaves – spring salad

• drug – root, leaves and unopened flowers; strong bitter taste – bitter agent taraxin (taraxacin), complex of water-soluble compounds

• other compounds - lactucopicrin (sequiterpenic lactone, guajanolide), bitter, sedative effect

OH OHtaraxasterin taraxasterol

OH

OH

O

O

OO

laktukopikrin

DandelionDandelion

DandelionDandelion• other compounds - phytosterols, terpenic

alcohols (taraxasterin, taraxasterol), organic acids and fatty acids

• leave – high content of vitamin C

• flowers - vitamin B2

• cations - sodium, potassium, manganese

• drug stimulates digestion, heals urinary tract inflammations, kidney stones, liver and metabolic issues

• supporting drug in diabetes