Food Flavor Chapter 11 in your textbook * * Sensitivity or

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Food Flavor

• Chapter 11 in your textbook

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• Flavor Chemistry
• Flavor is a combination of taste and aroma
• Taste
• Sweet, sour, bitter, salty
• Sensed on the tongue (protein receptors)
• Nerves sense metallic and astringent flavors
• Aroma
• Volatiles released directly from the food
• Volatiles that are released in the mouth, then
  sensed in the nasal cavity (retro-nasal).

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Food flavors Mixtures of natural and/or
artificial aromatic compounds designed to impart
a flavor, modify a flavor, or mask an
undesirable flavor Natural versus
Artificial Natural - concentrated flavoring
constituents derived from plant or animal
sources Artificial - substances used to impart
flavor that are not derived from plant or animal
sources
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• Most natural flavors are concentrated from
  botanicals
• plants, trees, fruits, and vegetables
• Most artificial flavors are synthesized with high
  purity
• - pharmaceutical flavors

Isolation techniques - Steam distillation - mint
and herbal oils - Solvent extraction - vanilla
oleoresins - Expression - citrus oils -
Supercritical fluid extraction targeted
extractions
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Sour
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SOURNESS and sour taste is often thought of as
acid However there is not a simple
relationship between acid concentration (pH) and
sourness Organic acids differ in
sourness CITRIC ACID (0.05 N solution) fresh
taste sensation LACTIC ACID (0.05 N solution)
sour, tart PROPIONIC ACID (0.05 N solution)
sour, cheesy ACETIC ACID (0.05 N solution)
vinegar PHOSPHORIC ACID (0.05 N solution)
intense MALIC ACID (0.05 N solution)
green TARTARIC ACID (0.05 N solution) hard
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Bitter
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BITTERNESS cqn be attributed to several
inorganics and organics KI CsCl
MgSO4 Certain amino acids and peptides (dipeptide
leucine-leucine) Alkaloids derived from pyridine
(N-containing 6-membered ring) and purines
A caffeine (1, 3, 7 trimethylxanthine) B
theobromine (from cacao)
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Alpha Acids

• Hop cones
• Humulus lupulus
• Beer flavor (essential oils) and stability
  (anti-micro)
• Beer bitterness (lupulone, colupulone,
  adlupulone)
• Alpha-acids isomerize during boiling, increasing
  bitterness.

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GYCOSIDES are sugars that have been added to a
natural compound. Grapefruits generally have a
bitter taste to them. This is due to the
flavonoid compound Naringin. Naringin actually
has 2 sugars (both glucose) as part of its
structure. Compound is still intensely
bitter. Removal of these sugars with
naringinase, will render the compound
tasteless. Naringin is then converted to
Naringinin. The de-bittering of grapefruit
juice can be done, if desired.
Where rutinoside is the sugar
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Salty
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SALTY depends on the nature of the cation and
anion in the ionic salt crystal structure high
molecular weight salts may be bitter some
salts may even exhibit sweetness
Examples NaCl NaBr NaI KCl LiBr
NaNO3 salty KBr salty bitter Lead
acetate (toxic) sweet
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Trigeminal Response
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HOTNESS (pungency) is characteristic of
piperine in black pepper and capsicum in red
pepper and gingerols in ginger
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Cool is a characteristic of menthol Peppermint
or mint oils
Spicy is a characteristic of eugenol Clove,
nutmeg, cinnamon, bay leaf
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Aromas
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Sources of Aromas in Food

• Natural flavors
• Herbs and spices (some enzymatic rxns)
• Fruits (biosynthesis during ripening)
• Process flavors
• Browning and Maillard
• Lipid oxidation
• Fermentation
• Artificial flavors
• Single compounds with character impact
• Isoamyl acetate bananna

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Allium sp.(onions, garlic, shallots, leeks)

• S-(1-propenyl)-L-cysteine sulfoxide
• Allinase
• 1-propenyl sulfenic acid

Chemical Rearrangement w/heat
Chemical rearrangement
Mercaptans (thios) Disulfides
Thiopropanal S-oxide (Tear maker)
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Lipoxygenase Generated Flavors
green
melon, cucumber
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Vanilla- an extracted flavor
Vanillin
Seed pods of Planifolia (a tropical orchid)
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Flavor Protection
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Sunlight Flavor
Sunlight will induce oxidized flavor and sunlight
flavor and hay-like flavor. Oxidized
flavor Sunlight flavor burnt and / or
cabbage
Riboflavin (B2) Effect on Sunlight Flavor

• Riboflavin is a catalyst for production of the
  sunlight flavor.
• Milk protein and riboflavin sunlight
  sunlight flavor
• 2) Riboflavin increase in milk will increase the
  sunlight flavor
• 3) Riboflavin removal prevent the sunlight flavor

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According to the TG Lee Website

• Studies at the Silliker Laboratories in Illinois,
  the University of Michigan, and other leading
  labs and universities concluded that both
  sunlight and the fluorescent lighting in stores
  could decrease the freshness and flavor of milk
  and the potency of vital vitamins in it. But this
  research also showed that the majority of natural
  and artificial light could be blocked by
  containers that were yellow instead of white.

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Riboflavin Effect on Sunlight Flavor

• Riboflavin is a catalyst for production of the
  sunlight flavor.
• Milk protein and riboflavin sunlight
  sunlight flavor
• 2) Riboflavin increase in milk will increase the
  sunlight flavor
• 3) Riboflavin removal prevent the sunlight flavor

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Food Toxicology
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Food Toxicology

• The study of the nature, properties, effects, and
  detection of toxic substances in food, and their
  impact on humans.
• Early on, people were aware that some plants are
  poisonous and should be avoided as food.
• Other plants were found to contain chemicals that
  have medicinal, stimulatory, hallucinatory, or
  narcotic effects.

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The Dose Makes the Poison

• Attributed to Pericles
• -a Greek statesman.

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Toxic to One.not to Another

• Food Allergens
• Cows milk
• Crustacea
• Eggs
• Fish
• Peanuts
• Soybean
• Tree nut
• Wheat

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Celiac Disease

• Ingestion of wheat, barley, rye
• Proline-rich protein - gliadins
• Triggers immune damage to small intestine
• Impairs absorption of nutrients
• Diarrhea, bloating, weight loss, bone pain,
  anemia, chronic fatigue, weakness, muscle cramps

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Scombroid Poisoning

• Anaphylactic shock
• Eating fish with high histamine levels
• Tuna, mackerel, other pellagic fish species
• Histamine from spoilage bacteria in fish
• Also from putrecine and cadaverine
• Everyone is susceptible
• Some more sensitive (allergy?) than others.

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Sensitivity or Allergy to

• Lactose
• Sulfites
• Strawberries (internal histamine release)
• Fava beans (enzyme deficiency)
• Asparagus (sulfur compounds)
• Red wine (low levels of histamine)
• Fructose intolerance
• Aspartame
• Tartarazine (FDC Yellow 5)

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Mycotoxins

• Substances produced by fungi that are harmful to
  animals and humans
• gt 100,000 species of fungi
• gt 300 mycotoxins isolated 30 with food issues
• Plant specific
• Environmental
• Temperature
• Humidity
• Moisture
• Oxygen

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Claviceps purpurea

• Grows in wet and over-wintered grains
• rye, barley, wheat
• Sclerotia or ergots (Hard-packed mycelium)
• Ergotism
• Convulsions and gastrointestinal symptoms
• Ergotamine is an analogue of lysergic acid (LSD)
• Vasoconstrictor that may cause hallucinations
• St. Anthonys fire
• Potential cause of Salem, MA witch trials, 1692.

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Aspergillus flavus and A. paraciticus

• Universal food contaminant
• Corn, peanuts, wheat, rice, pecans, walnuts, etc
• Animal carcinogen at 5 ppb
• Human liver carcinogen
• Problem in food industry and grain handling
• Harvesting, transport, storage
• 4 main aflatoxins B1, B2, G1, G2
• In animal feed, B1 and B2 can be converted to M1
  and M2 and secreted in milk (ie. cow or human)

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Toxins formed during Food Processing

• We previously covered the Maillard reaction
• Polycyclic aromatic hydrocarbons (benzo(a)pyrine)
• Carcinogenic agents in almost every model tested
• Nitrite used in curing meat and fish
• Antimicrobial agent
• Reacts with myoglobin and hemoglobin to form red
  nitrosyl compounds
• Nitrite may also react with amines to form
  nitrosoamines.
• Carcinogenic, mutagenic..but really harmful??

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Toxins formed during Food Processing

• Acrylamide in foods
• In 2000-2002 Swedish researchers identified
  acrylamide in foods and residues from human
  samples.
• Acrylamide is a neurotoxin and carcinogen.
• Used as
• Cement binder, plastic manufacture, waste water
  treatment agent, soil conditioner, thickening
  agent for pesticides, cosmetics, laboratory gels,
  etc)
• Broad range of foods with significant levels of
  acrylamide.
• Foods prepared at high temperatures.
• Fried and baked, but not boiled.
• Higher in high carbohydrate foods.

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Acrylamide in Potatoes

• Acrylamide derived from asparagine in the
  presence of sugar.
• Carbonyl carbon in glucose facilitates the
  reaction
• Asparagine Sugar Heat Acrylamide

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Natural Food Toxins in Plants
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Metabolism and Plant Primary Compounds

• Plant metabolism
• Used to describe the chemical reactions and
  interactions that take place in a biological
  system.
• Includes reactions that cause a plant to shift
  its leaves towards a light source
• Cause chloroplasts to produce photosynthetic
  sugars from sunlight, carbon dioxide, and water,
  ect
• Includes the production of plant primary and
  secondary compounds.
• Plant Primary Compounds
• Those compounds which are formed as a part of the
  normal anabolic and catabolic processes.

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Plant Secondary Compounds

• Secondary Compounds
• Those compounds that are not primary compounds.
• A compound that does not seem to directly
  function in the processes of growth and
  development.
• Some regarded these substances as waste products
  of a cell.
• At least one major benefit a plant gains from
  producing secondary compounds was later
  discovered protection from certain types of
  herbivory.
• The most obvious way to discourage this was to
  synthesize a substance to make the plant taste
  bad.
• The bitter taste of tea is due to the secondary
  compounds found in the tea leaves

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Other Mean Tricks

• Secondary Compounds
• Another way to hinder herbivory was to synthesize
  compounds that would cause temporary or permanent
  physiological changes in the herbivore (Toxins)
• Caffeine and morphine are good examples.
• Isoflavonoids affect reproduction in mammals.
  Found in alfalfa and some clover species, it
  mimics the hormone progesterone and may cause
  infertility, reduced lactation, or difficulties
  in labor.
• These types of secondary compounds make an animal
  "think twice" about eating off the same plant
  again.
• Not so coincidentally, this same type of
  physiological effect is what people refer to as
  the "high" after consuming certain plants
  (mushrooms, nutmeg, weed, coffee, etc)

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Do plants experience stress the way humans do?
Hypericum perforatun
Lycopersicum esculentun
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Causes of Plant Stress (Elicitors)

• Insects (US est. at 100M annum)
• Weather (drought, flood, wind, hail)
• Ethylene (ppb levels)
• Post-harvest storage
• UV light
• Physical wounds (harvest, transport)
• Microbial contamination (polysaccharides)

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Results of Plant Stress

• Phytoalexins (Phyto plant and alexin to
  ward off)
• Low MW organic metabolites produced by plants in
  response to stress
• Self-made antibiotics
• We consume 10,000 times more natural chemicals
  than man-made chemicals
• 150 true phytoalexins known

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What? Toxic Chemicals in My Food!!

• Phytochemical Paradox
• Dangerous pesticide or antioxidant wonder??
• For the plant
• UV light protection (Natures sun-screen)
• Oxidative protection
• Anti-microbial (Anti-Herbivores?)
• For the consumer (us)
• ROS quencher
• Bitter, astringent and sour flavors

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DEFENSE MECHANISMS
Pre-existing defenses Induced/Biochemical
defenses Hypersensitive responses
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PRODUCTION OF PHYTOALEXINS

• Production of phytoalexins may be stimulated by
  certain compounds called elicitors.
• High molecular weight substances found in the
  cell wall such as glucans, glycoprotein, or other
  polysaccharides.
• Gases such as ethylene (C2H4)

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PRODUCTION OF PHYTOALEXINS

• In susceptible plants, a pathogen may prevent the
  formation of phytoalexins, by the action of
  suppressors produced by the pathogen.
• The suppressor also can be a glucan, a
  glycoprotein, or a toxin produced by the pathogen

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Chemical and Sensory Properties of Food Toxins

• Metal chelator
• Antioxidant (-OH groups)
• Free radical terminators
• ROO. AH ROH A.
• Resonance stability

• Aromatic
• Sour
• Bitter
• Astringent
• Sulfurous
• Medicinal
• Smoky
• Animal-like

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Phytoalexic Toxins In Our Food
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Potato

• Stress Metabolites
• Cinnamates, scopolin, quinic acid,
  sesquiterpenoids, solanine, chaconine
• Solanine (Glycoalkaloid)
• Sunburned spuds or growth shoots (periderm)
• 10-50 ppm is normal, increases 7-fold during
  stress
• Natural pesticide (cholinesterase inhibitor)
• Acetylcholine is a neurotransmitter
• Extremely bitter, not soluble in water
• Heat stable

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Tomato

• Stress Metabolites
• Cinnamates, rishitin, falcarindiol, tomatine
• Tomatine (Alkaloid)
• High in immature fruit
• Ripe tomato contains 30-40 ppm
• Natural pesticide
• Heat labile

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Carrot

• Stress Metabolites
• Cinnamates, falcarinol, falcarindiol, isocoumarin
• Isocoumarin (neutral phenolic)
• Anti-microbial (10 ppm)
• Extremely bitter, not soluble in water
• Heat stable
• Ethylene sensitive synthesis

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Stressed Induced Methylation
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Natural Carcinogens in Coffee

• Ethylbenzene
• Formaldehyde
• Furan
• Furfural
• Hydrogen peroxide
• Hydroquinone
• Limonine
• Styrene
• Toluene
• Xylene

• Acetaldehyde
• Benzaldehyde
• Benzene
• Benzofuran
• Benzoapyrene
• Caffeic acid
• Catechol
• 1,2,5,6 Dibenzanthracene
• Ethanol

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Other Commodities

• Peppers- Capsidiol
• Sweet potato- Ipomeamarone
• Celery, parsnips, parsley- Psoralens
  (furanocoumarins)
• Grapes- Resveratrol, stilbene
• Alfalfa- Medicarpin (Isoflavonoid)
• Soybean roots- Glyceollin
• Peas- Pisatin
• Bean pods- Phaseollin

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Plant Vs Man Xenobiotic Metabolism

• Cytochrome P-450 system
• In body liver, lung, skin, nasal mucosa, GI
  tract
• Enzyme system to solubilize chemicals
• Substrate (xenobiotic) must be somewhat
  lipophilic to reach active sites
• Unfortunately, plants did not want to become food
  for people or animals.but we can fight back !!

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Antioxidant Enzyme Systems

• Active Oxygen Detoxification Enzymes
• SOD (superoxide dismutase)
• GSH (glutathione)
• POD (peroxidase)
• CAT (catalase)

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Cytochrome P-450 systemInduction of Phase I and
Phase II Enzymes
Phase I Oxidation/Reduction Add/Remove O,
Add/Remove H. ie. alcohol dehydrogenase Hydrolys
is. Add water
Phase II Conjugation reactions. -Enzyme catalyzed
reactions. -Tend to increase size and polarity
for excretion.