FSFS 3

• Sources of Flavor


  • Ripening: Enzymes and cell metabolism break down precursors to release aroma compounds (e.g., in fruits and vegetables)
  • Fermentation: Microorganisms like bacteria convert various compounds into flavor components (e.g., in cheese and tea)
  • Thermal Reactions: High temperatures trigger reactions like Maillard browning and caramelization to create new flavor molecules (e.g., roasted coffee, smoked foods)
• Natural flavors


  Come from natural sources like fruits, vegetables, and spices
• Artificial flavors


  Synthetically created in labs to mimic natural flavors
• Flavor Formation in Vegetables

  • Enzymes break down fatty acids during ripening, releasing volatile flavor compounds
• Flavor Formation in Fruits

  • Ripening involves both enzyme action and cellular metabolism to produce volatile flavor molecules like esters from fatty acids and amino acids
  • Climacteric fruits (triggered by ethylene) require controlled storage to manage flavor development
• Flavor Formation in Cheese


  • Flavor comes from fermentation of lactose (by lactic acid bacteria), proteolysis (protein breakdown), and lipolysis (fat breakdown)
  • Specific microorganisms contribute distinct flavors (e.g., strong blue cheese flavor)
• Flavor Formation in Tea


  • Withering and maceration of leaves allow enzymes to react with phenolics and phytochemicals
  • Fermentation at elevated temperatures produces additional flavors
• Flavor Formation in Roasted Coffee

  • Maillard reactions between sugars and proteins during roasting create hundreds of flavor compounds, including pyrazines and 2-furfurylthiol
  • Lighter roasts are fruitier, while darker roasts are more bitter
• Flavor Formation in Smoked Foods

  • Smoke from different woods (hickory, maple, etc.) contains phenols like guaiacol, contributing unique smoky flavors
  • Thermal degradation of wood components like lignin also plays a role
• Caramelization


  Heating sugars above 100°C leads to a series of reactions, ultimately forming caramelized flavors like furfural derivatives, carbonyls, alcohols, and hydrocarbons
• Important Takeaways


  • Understanding flavor formation helps optimize food processing and product development in the food industry
  • Many flavor precursors are found naturally in plants
  • Maillard reactions and caramelization are key thermal processes for flavor generation
• Flavor formation in vegetables involving endogenous enzymes


  1. Enzymes act on various precursors (sugars, amino acids) before cellular breakdown, breaking them into simpler molecules with more aroma potential

  2. Enzymes can also create new aroma compounds not present before (e.g., converting amino acids -> aldehydes & alcohols with diverse aromas)

  3. During cellular disruption (chopping, cooking), enzymes and precursors are released

  4. The lipoxygenase pathway contributes to flavor by oxidizing polyunsaturated fatty acids into hydroperoxides, then breaking down hydroperoxides to form aldehydes, alcohols, and esters, contributing to specific aroma profiles (e.g., grassy, green)
• Trapping of Flavor Precursors: The breakdown of complex molecules (lipids, proteins) during ripening and fermentation likely releases odorless precursors that can get trapped within the food matrix (fruits, vegetables, cheese)
• Cellular Disruption: Ripening and processing (chopping, grinding) can disrupt cell walls, allowing flavor precursors to come into contact with enzymes and react to form volatile aroma compounds
• Fat Solubility: Flavor compounds are often fat-soluble. The presence of fats in the food matrix can dissolve and hold these flavor compounds, influencing their release and perception during consumption
• Heat and Mass Transfer: Thermal processes like cooking and roasting can influence how flavor precursors migrate within the food and how volatile flavor compounds are released into the air