page_title: Cheese ripening
section_title: Eyes
hierarchical_section_title: Cheese ripening / Effect on features / Eyes
caption_attribution_description: Deutsch: Schweizer Emmentaler AOC, Block
context_page_description: Cheese ripening, alternatively cheese maturation or affinage, is a process in cheesemaking. It is responsible for the distinct flavour of cheese, and through the modification of "ripening agents", determines the features that define many different varieties of cheeses, such as taste, texture, and body. The process is "characterized by a series of complex physical, chemical and microbiological changes" that incorporates the agents of "bacteria and enzymes of the milk, lactic culture, rennet, lipases, added moulds or yeasts, and environmental contaminants". The majority of cheese is ripened, save for fresh cheese.
context_section_description: The round holes that are a characteristic feature of Swiss-type cheese (e.g. Emmentaler cheese) and some Dutch-type cheeses are called "eyes".  They are bubbles of carbon dioxide that is produced by bacteria in the cheese.
  In Swiss-type cheeses, the eyes form as a result of the activity of propionic acid bacteria (propionibacteria), notably Propionibacterium freudenreichii subsp. shermanii.  In Dutch-type cheeses, the CO₂ that forms the eyes results from the metabolisation of citrate by citrate-positive ("Cit+") strains of lactococci.
caption: Emmental with eyes.  Emmental tastes sweeter due to proline.
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