This is a paper I wrote about the scientific process of making blue cheese.

1. JoAnna Brown
Blue Cheese Development
Blue cheese is thought to have been one of the earliest cheeses produced by allowing moldy bread
to come in contact with the cheese. Blue cheese is a soft cheese and different varieties are made with
either sheep’s or cow’s milk (Anonymous 2010). The cheese is made by pasteurizing the milk product,
cutting and stirring the clumps that form to separate the curds from the whey, adding emulsifiers, and
pressing the curds into blocks (Heiman and Torkelson 2011).Next, the cheese needs to develop its
characteristic clue veins. This is done by either allowing the mold to naturally come in contact with the
cheese in the caves where it’s aged, or by introducing the mold from a culture. Cultures are grown and
allowed to ferment in sterilized milk-based mediums with high osmotic pressure, then high heat is added
to inactivate the mold (Nelson 1970).High pressure has also been shown to reduce the microbial load of
the cheese and may inhibit further undesirable ripening of the cheese (Voigtand others 2010).
When adding the mold to the cheese, needles are used to introduce the mold throughout the
cheese and not just on the outside (Fernandez-Salguero 2004). Normally seeing mold on food doesn’t
entice us to eat it, but the spoilage molds found on cheese are of the Pseudomonas genus of bacteria such
as Pseudomonas fluorescens (Martin and others 2011). The mold typically used to make blue cheese is
PenicilliumRoqueforti. The synergy of P. Roqueforti and YarrowiaLypolytica helps to produce the
distinct blue cheese odor (Gkatzionis and others 2013). Short chain ketones are also responsible for the
distinct aroma of blue cheese. Fatty acids present in the cheese undergo beta-oxidation to form these
ketones (Patton 1950). Different sections of the cheese contain different organic molecules that give them
different scents. The blue and the outer crust of the cheese contain high amounts of ketones whereas the
white is high in alcohols and aldehydes (Gkatzionis 2009).
Along with hydrocarbons and mold, yeasts also contribute to the unique flavor, texture, and
appearance of blue-veined cheeses. In tests, over 74 types of yeasts were found present in blue cheese.
These yeast are the microbiota of blue cheese and contribute to the mold growth as well as taste and

2. aroma (Alvarez-Martin and others 2007). Geotrichumcandidumis a fungal species that has been
characterized as a yeast that consumes lactate and produces enzymes that break down fats and proteins;
this aids in the softening of the cheese and helps develop the texture (Belen-Florez and others 2007).
Different types of bacteria also contribute to flavor, scent, and texture. Almost 95% of the aerobic
mesophile bacteria present in blue cheese is lactic acid bacteria ( - 2000).
In the finished product, the amount and color of the veins determine desirability of the product for
the consumer. A large amount of dark blue veins would produce a strong flavor, where as fewer/lighter
veins would have a weaker flavor. Typically, if the mold is greenish or brownish, consumers will view it
as over-ripened or old. This can happen as a result of improper packaging. If the cheese is allowed to
ripen in a closed package, it will produce CO2. As the carbon dioxide concentration increases, conidial
pigmentation of the PenicilliumRoqueforti was affected and caused it to turn greenish brown (Fairclough
and others 2011).
Salt and fat content of the finished product are also important factors to take into account.
Reduced fat content can be linked to increased flavor perception as well as aroma intensity. An increase
in salt content can lead to a lack of cohesiveness in the cheese because the salt leads to an increase in
protein-water interactions and a decrease in protein-protein interactions which would cause a less firm
cheese (Saint-Eve and others 2009). Diethyl succinate can also be added to blue cheese to change the
intensity of its flavors. When present in 500 ppm, a fruity note is brought out in the blue cheese. This
diethyl succinate also can deepen, enhance, and round out the cheese flavors (Wright 2012). Studies
have allowed the production of blue cheese a long way from leaving it by moldy bread, and all of these
factors play a huge part in the preparation of a blue cheese consumers will love.

3. Blue Cheese
References
Alvarez-Martin P, Florez AB, Lopez-Diaz TM, Mayo B. 2007. Phenotypic and molecular identification of
yeast species associated with Spanish blue-veined Cabrales cheese. Int.Dairy J. 17(8):961-7.
Concepts: Yeasts are microbiota for blue-veined cheeses; Yeast growth tolerances; Yeasts
contribute to mold growth; Metabolic capabilities aid in taste and aroma; Yeast classification tests;
Cabrales; 74 yeasts; Role in dairy
Anonymous 2010. Choosing cheese. Prep.Foods 179(4):39, 41-44.
Concepts: Cheese categorization strategies; History of blue cheese; Modern production; Different
types of blue-veined cheeses; Roquefort vs. Gorganzola
Belen-Florez A, Alvarez-Martin P, Lopez-Diaz TM, Mayo B. 2007. Morphotypic and molecular
identification of filamentous fungi from Spanish blue-veined Cabrales cheese, and typing of
Penicilliumroqueforti and Geotrichumcandidum isolates. Int.Dairy J. 17(4):350-7.
Concepts: 35 white and blue-green filamentous fungi in Cabrales; Use of mold in cheese
characteristics; Geotrichumcandidum function; no P. Roquefortispores added to Cabrales; Cultures
Fairclough AC, Cliffe DE, Knapper S. 2011. Factors affecting Penicilliumroquefortii(
Penicilliumglaucum) in internally mould ripened cheeses: implications for pre-packed blue cheeses.
Int.J.FoodSci.Tech. 46(8):1586-90.
Concepts: Desirable cheese characteristics; Lactose main carbon source; Optimum growth
conditions; Relationship of veins and flavor; Mold changes atmosphere within packaging causing
discoloration
Fernandez-Salguero J. 2004. Internal mould-ripened cheeses: characteristics, composition and proteolysis
of the main European blue vein varieties. Italian Journal of Food Science 16(4):437-45.
Concepts: Characteristics of blue cheese; Fatty acids vs. flavor; Openness in texture using
Lactococcuslactis; Bacteria present in caves and commercially; Poking with needles allows for mold
growth throughout cheese; Manufacturing process of different types of blue cheese
Gkatzionis K, Hewson L, Hollowood T, Hort J, Dodd CER, Linforth RST. 2013. Effect of
Yarrowialipolytica on blue cheese odour development: flash profile sensory evaluation of microbiological
models and cheeses. Int.Dairy J. 30(1):8-13.
Concepts: Synergy of P. roqueforti and Y. Lipolytica produce cheese odor
Gkatzionis K, Linforth RST, Dodd CER. 2009. Volatile profile of Stilton cheeses: Differences between
zones within a cheese and dairies. Food Chem. 113(2):506-12.
Concepts: Different sections of cheese (blue veins, white core, and outer crust); Blue and outer crust
high in ketones, White high in alcohols and aldehydes; Sporulation and vein formation; Different
aromas
Heiman KF, Torkelson TS, inventors; Anonymous 2011 Blue cheese product and process for preparing
same.
Concepts: Process for making blue cheese

4. - -López ML, Moreno B. 2000. Lactic acid bacteria isolated
from a hand-made blue cheese. Food Microbiol. 17(1):23-32.
Concepts: Nearly 95% of aerobic mesophiles found in cheese are lactic acid bacteria; Lactococci
and enterococci predominantly found at beginning stages of processing, enterococci and lactobacilli
and leuconostoc present from drying to time of consumption
Martin NH, Murphy SC, Ralyea RD, Wiedmann M, Boor KJ. 2011. When cheese gets the blues:
Pseudomonas fluorescens as the causative agent of cheese spoilage. J.Dairy Sci. 94(6):3176-83.
Concepts: Microbial spoilage in cheese; Pseudomonas genus bacteria commonly cause spoilage;
Pseudomonas fluorescens, L. lactic, Klebsiella, Pantoea, and Bacillus cereus are blue molds causing
spoilage
Nelson, J. 1970. Production of Blue cheese flavor via submerged fermentation by Penicilliumroqueforti.
J. Agric. Food Chem. (4): 567.
Concepts: Submerged fermentation process; Mold cultured in sterile milk-based medium with high
osmotic pressure; Enzymaticall hydrolyzed milkfat added; Allowed to ferment, then high heat
added to inactivate mold
Patton S. 1950. The Methyl Ketones of Blue Cheese and their Relation to its Flavor. J.Dairy Sci.
33(9):680-4.
Concepts: Fatty acids in cheese undergo beta-oxidation to form ketones associated with aroma of
cheese; Methyl ketones are the constituents that give mold-ripened cheeses their distinct taste
Saint-Eve A, Lauverjat C, Magnan C, Deleris I, Souchon I. 2009. Reducing salt and fat content: Impact of
composition, texture and cognitive interactions on the perception of flavoured model cheeses. Food
Chem. 116(1):167-75.
Concepts: Salt content effects cheese properties; Fat content effects cheese properties; Sensory
properties are the result of physiochemical characteristics
Voigt DD, Chevalier F, Qian MC, Kelly AL. 2010. Effect of high-pressure treatment on microbiology,
proteolysis, lipolysis and levels of flavour compounds in mature blue-veined cheese. Innovative Food
Science and Emerging Technologies 11(1):68-77.
Concepts: Bacterial cells sensitive to high pressure; High pressure has antimicrobial effect; Flavor
compounds derived from metabolic pathways; High pressure causes lower pH; High pressure may
possibly stop undesirable further ripening
Wright J. 2012. Diethyl succinate. Perfum.Flavor. 37(4):22-3.
Concepts: Chemical characteristics of diethyl succinate; Deepens, enhances, and rounds out taste
effects; Adds subtly to fruity taste