What is Flavor

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What is Flavor?

• A sensation produced by a material taken in
  the mouth, perceived principally by the senses of
  taste and smell, and also by the general pain,
  tactile, and temperature receptors in the mouth.
  Flavor also denotes the sum of the
  characteristics of the material which produces
  that sensation

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Sensory Properties
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Food Flavors

• Desirable flavor
• orange juice
• potato chips
• roast beef
• Undesirable flavor (off-flavor)
• oxidized
• stale
• rancid
• warmed-over

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Objectives of Flavor Chemistry

• To understand the chemical composition of natural
  flavors and the mechanism of their formation
• To retard or prevent the development of the
  off-flavors in foods
• To restore the fresh flavor to a processed food
• To improve the flavor of food by the addition of
  synthetic flavor
• To produce new foods with special flavor such as
  potato chip flavor
• To improve flavor by the acceleration of
  reactions which produce desirable flavor compound
• To assist geneticist to breed food raw material
  with improved flavor compounds or flavor
  precursors
• To specify raw material and to control quality of
  food products

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Classification of Flavors
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Compounds Responsible for Flavor
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Compounds Responsible for Flavor(continued)
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Flavors of Acids
Acid Flavor

• Formic
• Acetic
• Propionic
• Butyric
• Hexanoic
• Octanoic
• Decanoic
• Lauric
• Myristic
• Palmitic

• Acid, pungent
• Acid, vinegary
• Acid, rancid, cheesy
• Acid, rancid
• Sweaty, goaty
• Rancid
• Waxy
• Tallowy
• Soapy, cardboard
• Soapy

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Formation of Flavor Compounds

• Enzymatic
• Volatile flavors developed in most food plants
  mainly at the ripening stage
• Non-Enzymatic
• Raw meat must be heated (Maillard browning)
  before it develops any organoleptically
  acceptable flavor

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ISOLATION AND SEPARATION OF FLAVOR COMPOUNDS

• Selection of Good flavor sample
• Isolation of Volatile Flavor Compounds
• Extraction and Concentration
• Fractionation
• Preparation of pure compound
• Identification
• Synthesis
• Reconstitution of the flavor

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Fractionation of Flavor Compounds
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Final Fractionation of Flavor Compounds

• Gas-Liquid Chromatography (GC)
• Sample as concentrate as possible
• GC-Mass
• Use capillary column
• Identification of the important peaks by mass
  spectrometry

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Spectrometric Methods for Flavor Identification

• Ultra Violet Spectrometry
• Infrared Spectrometry
• Nuclear Magnetic Resonance Spectrometry
• Mass Spectrometry

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Pyrazine Formation(cocoa, coffee, french fries,
roast beef)
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Formation of Trimethyloxazole from Diacetyl,
Acetaldehyde, and Ammonia
(Found in beef stew)
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Trimethylthiazole Formation(nutty, sulfur )
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Formation of Furans
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Generation of Diacetyl in Butter
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Generation of Banana Flavor
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Physical and Chemical States of Flavor Compounds
in Foods

• Flavor compounds may be dissolved, adsorbed,
  absorbed, or entrapped in food components
  depending upon functional groups, molecular size,
  shape and volatility, and chemical properties of
  the components in the food.

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Effects of Selective Binding on Flavor Perception

• The selective binding of one flavor compound
  of a blend to food components or packaging
  material can markedly alter the overall flavor
  impact. Binding limits its volatilization and
  diffusion and hence impairs its immediate
  perception as a components of an overall flavor
  when food is taken into the mouth.

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Factors Affecting Partition Coefficients

• Temperature
• The presence of soluble solutes and nonsoluble
  materials
• Diffusion rates in the aqueous phase
• Physical retention of flavor compound

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Interactions of Flavor Compounds with Food
Components

• In lipid systems, solubilization and rates of
  partitioning control the interactions and
  partition coefficients, thus determines the rates
  of release
• In polysaccharide systems, polysaccharides
  interact with flavor compounds by nonspecific
  adsorption and formation of inclusion compounds
• In protein systems, protein involves adsorption,
  specific binding, entrapment, covalent binding
  and these mechanisms may account for the
  retention of flavor compounds
• Moisture affects diffusion and partition
  coefficients and macromolecular structures in the
  case of protein and polysaccharides and thereby
  affect the rate of release of flavor compound

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Interactions Between Flavor Compounds and Food
Components