咖啡： flavor profile and caffeine content：

Roast Level and Flavor Profile

The longer and hotter coffee beans are roasted, the more their inherent flavors change and new flavors develop due to chemical reactions (like Maillard reactions and caramelization).

Heres a general guide to how roast level impacts flavor:

• Light Roasts (e.g., Cinnamon, New England, Blonde):
  
  
  • Appearance: Light brown, often no oil on the surface.
    
    
  • Flavor: These roasts retain most of the beans original characteristics, showcasing its terroir (the influence of its origin, climate, and processing). They are often described as:
    
    
    
    
    
    • Bright, vibrant, and acidic (in a pleasant, sparkling way).
      
      
      
      
      
    • Fruity (citrus, berries, stone fruit), floral (jasmine, bergamot), and sometimes grassy or herbaceous.
      
      
      
      
      
    • Lighter body.
      
      
  • Best for: Highlighting nuanced, delicate flavors, often enjoyed in pour-over or AeroPress.
    
    
    
    
    
• Medium Roasts (e.g., American, City, Breakfast):
  
  
  • Appearance: Medium brown, sometimes with a slight sheen as oils begin to emerge.
    
    
  • Flavor: A balance between the beans origin flavors and the flavors developed during roasting. They are generally:
    
    
    • Well-balanced in acidity and sweetness.
      
      
    • Nutty, caramel, chocolate, and sometimes toasty notes.
      
      
    • Medium body.
      
      
  • Best for: A versatile, everyday cup, suitable for most brewing methods.
    
    
    
    
    
• Medium-Dark Roasts (e.g., Full City, Vienna):
  
  
  
  
  
  • Appearance: Darker brown, with more visible oil on the surface.
    
    
  • Flavor: The roast flavors start to dominate more. Youll find:
    
    
    • Richer, bolder flavors.
      
      
    • Sweet, often with notes of dark chocolate, toasted nuts, and deeper caramel.
      
      
      
      
      
    • Lower acidity and a heavier body.
      
      
    • A bittersweet aftertaste can be present.
      
      
      
      
      
• Dark Roasts (e.g., French, Italian, Espresso, Continental):
  
  
  • Appearance: Very dark brown, often almost black, with a prominent oily sheen.
    
    
    
    
    
  • Flavor: The roast character is paramount, often overshadowing the original bean flavors. They are characterized by:
    
    
    • Intense, robust, and often smoky flavors.
      
      
    • Pronounced notes of dark chocolate, burnt caramel, molasses, and sometimes an ashy or charred taste.
      
      
      
      
      
    • Very low acidity.
      
      
    • Very full body.
      
      
    • Noticeable bitterness (though a good dark roast should still have a pleasant, complex bitterness, not just burnt).
      
      
      
      
      
  • Best for: Espresso, French press, or for those who prefer a very strong, bold cup.