Course:FNH200/Projects/2022/Artisan Blue Cheese

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Introduction

Blue cheese is a kind of semi-soft cheese that has a bluish or greenish vein caused by the growth of penicillium, which has a strong salty flavour[1][2][3]. Blue cheese originated in a cave outside the village of Roquefort in France in the 7th century[4]. It is said that a shepherd forgot his cheese in that cave[4]. When he came back a few months later, the cheese was infected with penicillium, which formed the blue cheese[4].

Cheese in a cave

Preparation

First, penicillium roqueforti inoculum should be prepared[3]. Penicillium roqueforti could be commercially grown or extracted from soil, decaying organic substances and plant parts [3][5]. Although, It is more common for cheese producers to use commercially grown penicillium roqueforti inoculum for practical reasons[3]. The next thing to prepare is the pasteurized milk. Milk is pasteurized by heating its temperature to 71.67°C by passing between heated stainless steel and holding that temperature for 15 seconds before cooling back to 3.89°C[6]. This step is vital because it can prevent potential competition between the microorganisms inoculated and those originally from the milk[7]. Furthermore, starter culture predominately consisting of lactic acid bacteria helps to start the fermentation process of the blue cheese mainly by converting lactose to lactic acid[8]. Since starter culture can be commercially produced and packed by large companies, cheese makers only need to buy the starter culture packages[9]. Last but not least, rennet is also necessary to coagulate the milk in the preparation of blue cheese. Rennet is the commercial form of rennin, which is extracted from the fourth stomach of calves[10][11]. Rennet consists of rennin and other constituents and is available in the market in the form of powder, liquid and paste[9][11][12]. As mentioned above, these products reduce a lot of work for cheese makers.

Production

Cheese production

The first step in the production of blue cheese is the mixing and pasteurizing of raw milk[3][13][14]. Then, to acidify the milk, a starter culture is added[3][13][14]. This converts lactose into lactic acid, which acidifies the milk and turns it into a solid before the addition of rennet, which further solidifies the milk[3][13][14]. Then, the curds are cut to allow whey to be released[3][13][14]. After this, the curds are placed into containers so that they can be drained and a full wheel of cheese can be formed[3]. At this point, the Penicillium roqueforti inoculum and Brevibacterium linens are added to the curds of cheese. Then, loaves of cheese are created after the curd granules are knit in molds and whey is drained for several hours[3]. Salt is then added for flavour and to prevent the cheese from spoiling[3]. Next, small holes are created in the loaves to allow air to flow and further the growth of Penicillium roqueforti cultures.[3][13][14] The cheese is then aged for about 60-90 days, during which time the temperature and humidity is closely controlled to prevent the cheese from going bad.[3] The total ketone level is also monitored since methyl ketones, which are a product of Penicillium roqueforti, are responsible for the distinctive flavour and aroma attributed with blue cheese[3]. The cheese is sterilized at ultra high temperatures for a short time after a reasonable level of ketone production is reached[3]. This sterilization also prevents any further fermentation by inactivating Penicillium roqueforti[3].

Chemical properties

Chemical Changes

pH Level, Oxygen and Carbon Dioxide Concentration

Cabrales blue cheese

Several chemical changes occur in the process of ripening blue cheese, including changes in the concentration of oxygen and carbon dioxide, as well as changes in the pH level[15]. The pH level in Stilton, Mycella, and Danablu blue cheese ranges from 4.6-4.7 before the ripening stage[16][17]. However, for Cabrales, Picon Bejes-Tresviso, Gorgonzola, and Valdeon blue cheese, the pH level ranges from 5.0-5.3 before the ripening stage[18][19][20][21]. During ripening, the pH level of all types of blue cheese increases to a range of 6.5-7.0, as a result of the metabolism of lactic acid to carbon dioxide by yeasts and molds[22]. The metabolism of lactic acid is essential in the cheese making process. Thus, a pH level below the 6.5-7.0 range for blue cheese may be an indicator of a disruption in the fermentation process and may result in a different flavour from the typical tangy and sharp taste of blue cheese[15]. The concentration of oxygen changes during the ripening stage across all types of blue cheese by 50%, resulting in a final concentration of only 3% oxygen out of the 21% in the air[23]. On the other hand, the concentration of carbon dioxide increases as a result of the metabolism of lactic acid[22].

Chemical structure and Varieties

Microstructure

The structure of blue cheese is categorized as very heterogenous with blue and yellow/white areas containing sporelized mold and with pronounced gradients of salt, pH, and water activity [24]. The considerable structural differences influence the levels and distribution of oxygen and carbon dioxide, which have a great impact on the growth and biochemical activity of the various microorganisms present in blue mold cheese [25]. These groups of microorganisms that make up the complex microflora of blue mold cheeses contribute at different levels to ripening[24].

Spoilage

Microorganisms other than P. roqueforti and lab starter cultures can colonize and grow well on Blue cheeses, especially on the surface[8]. Spoilage of cheese due to fungal growth is caused by formation of off-flavours[26], mycotoxins, and possible discolouration of the cheese[15][27].

Factors enabling fungi to cause spoilage of cheese include the ability to grow at refrigeration temperature, growth at low oxygen tensions, lipolytic activity and resistance to weak acid preservatives[28]. A number of different species of Penicillium possess these properties, and Penicillium species are the major cause of cheese spoilage[28]. P. caseifulvum is sensitive to carbon dioxide, and therefore only grows on the surface of the cheese, where it can cause discolouration in the form of brown spots [28]. P. commune is the most common cause of spoilage in European cheeses[27]. This species produces dull green colonies on CYA and MEA, measuring 30–37 and 23–30 mm in diameter on CYA and MEA respectively, with clear or pale yellow exudate, no soluble pigment and a pale or light brown reverse[29].

Varieties

The most common types of commercially produced blue cheese are:

Varieties of Blue Cheese
Roquefort Blue Cheese
Gorgonzola Blue Cheese
Stilton blue cheese
Danablu Blue Cheese
File:Saint Agur L'intense.png
Saint Agur Blue Cheese

Storage and Packaging

Blue cheese is tightly wrapped by either foil, plastic, cheese paper, or bee's wrap in a high-humidity environment, which prevents it from growing bad or ugly bacteria[30][31]. Though, It is important to avoid wrapping blue cheese too tightly, as this can cause rapid degradation[30]. People can also periodically change the wrapper on blue cheese to keep it fresh[32].

Blue cheese can be either kept on the counter, which allows you to instantly consume it rather than thawing it for an hour, and stored in the fridge to increase preservation[30]. If blue cheese is left out on the counter, it should be placed in an area where fresh air can reach it, to increase preservation[30]. However, storing blue cheese in the fridge can keep it fresh for as long as possible, by slowing down the rate of fermentation[30]. If blue cheese is stored in the fridge, it should be left in a more humid section, such as a vegetable drawer, to prevent it from drying out[30][32].

Blue cheese package

See also

Potential Exam Question

The pH level of blue cheese ranges from 4.6--5.3 prior to beginning the ripening stage to a pH range of 6.5-7.0 during ripening. This happens as a result of the metabolism of lactic acid to carbon dioxide by

a) yeasts and molds

b) yeasts and acetic acid bacteria

c) molds and lactic acid bacteria

d) yeasts and lactic acid bacteria

Correct answer = yeasts and molds

We chose to do this question since it draws on the information we learnt in lesson 9, regarding the use of yeasts and molds in the production of blue cheese. Also in our lessons, we did not cover the pH change during ripening, therefore this question builds on our knowledge of the information we previously learnt.

References

  1. ↑ "blue cheese". Britannica. Retrieved August 4, 2022.
  2. ↑ "Is It Safe to Eat Moldy Blue Cheese?". healthline. Retrieved August 4, 2022.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 "Blue cheese". Wikipedia. Retrieved August 4, 2022.
  4. ↑ 4.0 4.1 4.2 "Blue mould cheese". Castello. Retrieved August 4, 2022.
  5. ↑ "Attachment I-Final risk assessment penicillium roqueforti" (PDF). EPA. Retrieved August 5, 2022.
  6. ↑ "Milk Pasteurization Process: What Is Pasteurized Milk & Why". Undeniably Dairy. Retrieved August 5, 2022.
  7. ↑ "Microbial Interactions within the Cheese Ecosystem and Their Application to Improve Quality and Safety". foods. 25 February 2021.
  8. ↑ 8.0 8.1 Powell, I.B.; et al. (2011). "Cheese | starter cultures: General aspects". Encyclopedia of Dairy Sciences (Second Edition). 2: 2011 – via Science Direct. Explicit use of et al. in: |last= (help)
  9. ↑ 9.0 9.1 "What is starter culture for cheese and what does it do?". The Courtyard Dairy. Retrieved August 5, 2022.
  10. ↑ "rennin". Britannica. Retrieved August 5, 2022.
  11. ↑ 11.0 11.1 "What Is Rennet?". the spruce eats. Retrieved August 5, 2022.
  12. ↑ "Learn About Rennet: How to Use Rennet in Cheesemaking and Different Types of Rennet". MasterClass. Retrieved August 5, 2022.
  13. ↑ 13.0 13.1 13.2 13.3 13.4 "What Is Blue Cheese?".
  14. ↑ 14.0 14.1 14.2 14.3 14.4 "How is Blue Cheese Made?".
  15. ↑ 15.0 15.1 15.2 Cantor, Mette; et al. (2017). Cheese (Fourth edition). Science Direct. pp. 929-954 https://doi.org/10.1016/B978-0-12-417012-4.00037-5. Explicit use of et al. in: |last= (help)
  16. ↑ Llano, D.; et al. (1992). "Microbiological and physicochemical characteristics of gamonedo blue cheese during ripening". International Dairy Journal. 2: 121–135 – via Science Direct. Explicit use of et al. in: |last= (help)
  17. ↑ Madkor, Sabry; et al. (1987). "Studies on the ripening of stilton cheese: Proteolysis". Food Chemistry. 25: 13–29 – via Science Direct. Explicit use of et al. in: |last= (help)
  18. ↑ Diezhandinoa, l. (2015). "Microbiological, physico-chemical and proteolytic changes in a Spanish blue cheese during ripening (Valdeón cheese)". Food Chemistry. 168: 134–141 – via Science Direct.
  19. ↑ Cakmakci, Songül; et al. (2012). "Chemical and microbiological status and volatile profiles of mouldy civil cheese, a Turkish mould-ripened variety". International Journal of Food Science & Technology. 47: 2405–2412 – via IFST. Explicit use of et al. in: |last= (help)
  20. ↑ Gobbetti, M. (1997). "Microbiology and biochemistry of gorgonzola cheese during ripening". International Dairy Journal. 7: 519–529 – via Science Direct.
  21. ↑ Zarmpoutis, I. (1997). "Proteolysis in blue-veined cheese: An intervarietal study". Irish Journal of Agricultural and Food Research. 36: 219–229 – via JSTOR.
  22. ↑ 22.0 22.1 Tomasini, Araceli (1993). "Fat lipolyzed with a commercial lipase for the production of blue cheese flavour". International Dairy Journal. 3: 117–127 – via Science Direct.
  23. ↑ Tempel, Tatjana (2002). "The microdistribution of oxygen in danablu cheese measured by a microsensor during ripening". International Journal of Food Microbiology. 75: 157–161 – via Science Direct.
  24. ↑ 24.0 24.1 Ardö, Y. (2016). "Blue mold cheese". Reference Module in Food Science. 1: 767–772 – via Science Direct.
  25. ↑ Hayaloglu, A.A. (2022). "Microbiology of Cheese". Department of Food Engineering, Inonu University, Malatya, Turkey.
  26. ↑ Sensidoni, A. (1995). "Presence of an off-flavour associated with the use of sorbates in cheese and margarine". Food and Agriculture organization of the United Nations. 6: 237–242 – via AGRIS.
  27. ↑ 27.0 27.1 Lund, Flemming (1998). "Penicillium caseifulvum, a new species found on penicillium roqueforti fermented cheeses". Journal of Food Mycology. 1: 95–101 – via DTU Orbit.
  28. ↑ 28.0 28.1 28.2 Sørhaug, T. (2011). "Yeasts and molds | spoilage molds in dairy products". Encyclopedia of Dairy Sciences (Second Edition). 2: 780–784 – via Science Direct.
  29. ↑ Ardö, Y (2007). "Blue cheese". Cheese Problems Solved. 1: 284–288 – via Science Direct.
  30. ↑ 30.0 30.1 30.2 30.3 30.4 30.5 Sennett, Jessica (12/02/2020). "The Best Way to Store Blue Cheese". https://cheesegrotto.com/blogs/journal/the-best-way-to-store-blue-cheese. Check date values in: |date= (help); External link in |journal= (help)
  31. ↑ "How to store your artisan cheeses at home". MILK THE COW. Retrieved 07/08/2022. Check date values in: |access-date= (help)
  32. ↑ 32.0 32.1 Centoni, Danielle (14/04/2009). "Store artisan cheese properly, and enjoy it longer". Retrieved 07/08/2022. Check date values in: |access-date=, |date= (help)
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