Course:FNH200/Projects/2023/Fermented Milk
Introduction
Fermented Milk refers to the milk that has been allowed to ferment with lactic acid bacteria.[1] The process of fermentation breaks down milk proteins and lactose.[1] Consequently, this will benefit individuals living with milk protein allergies or lactose intolerance.[1] In addition, this process of fermentation extends the shelf-life of milk products.[1]Fermented milk is commonly used during instances of the common cold, diarrhea, eczema, high blood pressure, high cholesterol, irritable bowel syndrome (IBS), and lactose intolerance.[1]
Common Fermented Milk Products
Cultured Buttermilk
Commonly misinterpreted to have a high fat content, the name of buttermilk is derived from the fact that it is the watery end-product of butter making.[2] The production of cultured buttermilk begins with the pasteurization of skim or low-fat milk at 82 to 88 °C (180 to 190 °F) for 30 minutes, or at 90 °C (195 °F) for 2-3 minutes.[2] In doing so, the heating process destroys all naturally occurring bacteria and denatures the protein to minimize wheying off.[2] The milk is then cooled to a temperature of 22 °C (72 °F) and desirable bacteria is added to develop the acidity and contribute a unique flavor. These bacteria include: Leuconostoc citrovorum, Leuconostoc mesenteroides, Streptococcus cremoris, and Streptococcus lactic.[2] The ripening process occurs over 12 to 14 hours, at which the product is gently stored and cooled to 7.2 °C (45 °F) to stop fermentation.[2] The cultured buttermilk is then packaged and refrigerated, and ready to be transported.
Sour Cream
The process of creating sour cream follows the same temperature and culture methods described in buttermilk. The main difference is that the starting input is light 18 percent cream.[2]
Yogurt
Similar to buttermilk and sour cream, the only difference in yogurt is the difference in bacteria and temperatures.[2] The initial mixture is composed of low-fat, skim, or whole milk that is fortified with condensed skim milk or nonfat dry milk.[2] The mixture is then heat-treated the same as buttermilk, then cooled 45.6 to 46.7 °C (114 to 116 °F).[2] After cooling, equal parts of lactobacillus bulgaricus and Streptococcus thermophiles is added to the milk.[2] Depending on the style of yogurt, cups containing fruit at the bottom have the cultured mixture poured in.[2] After a short period, approximately 4 hours to allow for coagulation, the product is then moved to a refrigerated room.[2] For Swiss or French-style yogurt that has fruits or other flavors blended in, the milk is initially incubated in large heat tanks. After coagulation, the mixture is cooled and any fruits and flavoring is added.[2] The product is then placed into the appropriate containers and is ready for consumption or sale.
Cheese
A product which its variations were rarely deliberately developed, cheese is the product of specific conditions of air temperature, humidity, mold, and milk source.[3] Due to its early origin, the lack of understanding in fields of microbiology and chemistry at the time resulted in increased challenges to duplicate cheese.[3] As such, cheese making was known as an art, and its process was often passed down from one generation to the next.[3]
The cheese-making process begins with the removal of water from fresh fluid milk. As storage life increases as water content decreases, the process of removing water is also considered to be a form of food preservation.[3] The milk used in cheese making is often pasteurized in an effort to slow spoilage, eliminate defects induced by pre-existing bacteria, and destroy pathogenetic microorganisms.[3]
The milk is then fermented with microorganisms to carry out the anaerobic conversion of lactose to lactic acid.[3] The types of microorganisms added will influence the variety of cheese and on the overall production process. some cheese are produced by acid coagulation alone.[3] However, in other cheeses the presences of lactic acid, or added rennet, will cause the casein protein within the milk to clump together in a process known as curdling.[3]
After curdling, the cheese is cut with fine wires and gently heated to reduce the size and induce shrinking.[3] The last step involves the ripening of the cheese which involves the activity of different enzymes, microorganisms and the physical conditions in the curing room.[3] Lactose is fermented to lactic acid in most cheese, and then hydrolyzed to form other sugars.[3] Proteins and lipids are also broken down during ripening, which will affect the flavour and consistency of the final product.[3] The ripening time for different cheeses vary, and can be as short as one month, Brie, or exceed a year, in cases of cheddar. Interesting, not all cheese require ripening.[3] These include common cheeses such as Cottage, ricotta, and most mozzarella.[3]
Kefir
Typically tangy and slightly sour, Kefir is a fermented milk drink with a similar consistence to cultured buttermilk.[4] Kefir is created by fermenting milk with special microbial cultures known as kefir grains, which are composed of symbiotic colonies of bacteria and yeasts.[4] These yeasts include but are not limited to, Saccharomyces kefir and Torula kefir.[4] Unique to its mesophilic properties, fermentation of kefir does not require high temperatures such as in yogurt production.[4] At room temperature, the lactic-acid bacteria as well as the yeasts are able to reproduce rapidly, approximately doubling their population every 20 minutes.[4] The flavor of kefir is a result of the by-products of many metabolic processes.[4] These include the production of alcohol and carbon dioxide from the yeasts.[4] A second round of fermentation is often performed to reduce lactose content, boost probiotic content, or add additional flavoring.[4]
Packaging
The packaging of coagulated and fermented dairy products is an important aspect to the preservation of physical, chemical, and bacteriological properties of fermented milk.[5] Commonly used materials include glass, polyethylene, low-density polyethylene (LDPE), high-density polyethylene (HDPE), Ethylene vinyl alcohol, polyvinylidene chloride (PVDC) and tetrapak.[5]
Special considerations are necessary for different types of fermented dairy products.[5] For yogurt, the aroma of fruit can have influence the brittleness of polystyrene packaging.[5] However, fruit acids used can result in the formation of small holes or depressions (pitting) on the surface of aluminum lids that have not been treated with a protective lacquer coating.[5] Thus, we see the use of polystyrene tubs as the main method of yogurt packaging due to its economical and practical application.[5]
In the case of buttermilk and sour cream, LDPE sachets, wax coated paper cups, polystyrene cups, and polypropylene cups are used.[5] The preference for these, and the deference from using high impact polystyrene (HIPS) packaging is due to the risk free fatty acids pose on cracking of the material.[5]
For cheese, the packaging must prevent moisture loss, provide general protection, protect against microorganisms and prevent oxygen transmission.[5] With cheese being a product of high moisture content and fat, packaging must prevent mold growth and oxidation.[5] Creating an oxygen-sealed environment is usually performed through the use of sealed containers in a vacuum or inert gas atmosphere.[5] Processed cheeses are typically packaged using aluminum foil.[5] For other cheeses, PVDC coated plastic films provide effective moisture and oxygen barrier properties.[5] Kefir, containing active microbes found in its kefir grains, requires special consideration for packaging as well. In a study examining the acidification activity of the lyophilized Kefir grains when packaged in low-density polyethylene (LDPE), oriented polyester film (OPET), and methallized oriented polyester film (MOPET), MOPET was found to be most effective.[6] This is hypothesized to be due to MOPET functioning better as a barrier for oxygen and moisture.[6] However, due to the added preparation and labor costs required to prepare, and consumer complications to consuming freeze-dried kefir preparation, freeze-dried kefir is not as marketable or profitable. Thus, polyethylene film packaging is the dominant method for packaging of kefir due to its superior economical and practical application.
Role of Lactic Acid Bacteria
Different types of strains of lactic acid bacteria include but are not limited to: Lactobacillus, Lactococcus, Leuconostoc, Fructobacillus, Weissella, Pediococcus, Enterococcus, Streptococcus, Carnobacterium, and Oenococcus.[7]
Lactic acid bacteria are very resistant, and can tolerate low pH, heat treatments, and concentrations of salt.[7]
Flavor
The variety and difference in fermented milk products are often a result of difference in technologies and strain of lactic acid bacteria. In the production of cheese, starter cultures, involved in the initial phase of fermentation, are used to produce acid during manufacturing and contribute to the ripening process.[8] Non-starter cultures, live cultures that are involved in the secondary phase, are not responsible for the production of acid but contribute to the ripening process.[8] Thus, formation of flavor is a result of the activity of both starter and non-starter LAB during the ripening.[8] In particular, the metabolic pathways involving the metabolism of lactose, lactate, and citrate, as well as the release of free fatty acids through lipolysis play a role in dictating flavor profile.[8]
Texture Development
In yogurt, the role of lactic acid bacteria is essential to develop the desired texture. some LAB, depending on strain, produces the exopolysaccharides (EPS), a viscosifying agent that helps provide the soft and thicker texture found in yogurt.[8] In addition, the formation of acid by lactic acid bacteria contributes to coagulation through its neutralization effect on milk proteins.[8] The production of exopolysaccharides, acidification of milk, and proteolytic activities on milk proteins enables for the generation of flavor and texture.[8]
Preservation
The presence of lactic acid bacteria (LAB) in milk fermentation is important as it produces acid that function as preservative agents and contribute to flavor.[8] Milk and fermented milk products are very favorable substances for the growth of microorganisms.[8] The functional capability of lactic acid bacteria to produce acid functions as a preservative property, exhibiting antimicrobial activity.[8] Thus, acidification of milk defeats against proliferation of pathogens as well as spoilage microorganisms.[8]
[History?]
up to yall if you think this is necessary!
[Labelling Requirements for Dairy Products?]
if someone could help look at this link below and add (wherever you deem fit, or make your own header) any relevant information about labelling requirements for dairy products
https://www.inspection.gc.ca/en/food-labels/labelling/industry/dairy (link is from course content, module 4.3)
feel free to move text around, create/remove headers, do anything.
[Regulations?]
super broad but if we really wanted to, we could add the general "Food" regulatory practices in place from here https://laws-lois.justice.gc.ca/eng/acts/F-27/page-2.html#h-234067 (link is from course content, module 4.1)
[Health Benefits/Concerns?]
could discuss common health benefits/concerns
https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00846/full (this link [where I found the photo] promotes lactic acid bacteria to be beneficial for many different reasons)
like lactose intolerance or something idk
Exam Question(s)
the world is your oyster
References
- ↑ 1.0 1.1 1.2 1.3 1.4 "Fermented Milk - Uses, Side Effects, and More". WebMD. Retrieved July, 24, 2024. Check date values in:
|access-date=(help) - ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Paul Singh, R; Bandler, David. "Cultured dairy foods". Britannica. Retrieved July, 24, 2024. Check date values in:
|access-date=(help) - ↑ 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 Paul Singh, R. "Cheese". Britannica. Retrieved July, 24, 2024. Check date values in:
|access-date=(help) - ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Samie, August. "Kefir". Britannica. Retrieved July 24, 2024.
- ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 "Packaging of Dairy Products". Indian Agricultural Statistics Research Institute. Retrieved July, 24, 2024. Check date values in:
|access-date=(help) - ↑ 6.0 6.1 Witthuhn, R.C.; Schoeman, T.; Cilliers, A.; Britz, T.J. (August 2005). "Impact of preservation and different packaging conditions on the microbial community and activity of Kefir grains". Food Microbiology. Volume 22, Issue 4: 337–344 – via Elsevier Science Direct.
- ↑ 7.0 7.1 Dillon, V.M. (2014). "NATURAL ANTI-MICROBIAL SYSTEMS | Preservative Effects During Storage". Encyclopedia of Food Microbiology (Second Edition): 941–947 – via Elsevier Science Direct.
- ↑ 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 Widyastuti, Yantyati; Febrisiantosa, Andi (January 10, 2014). "The Role of Lactic Acid Bacteria in Milk Fermentation" (PDF). Scientific Research Publishing. Retrieved July 24, 2024.
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