Wiki: Milk Standardization

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This Wiki Article is about standardization of milks and creams used in making cheese. It is divided into the following sections:

General


Milk’s properties vary depending on many variables such as:

  1. Breed (i.e. for cows, Holstein-Friesian, Brown Swiss, Guernsey, & Jersey).
  2. The animals feed.
  3. Time of lactation cycle.
  4. Time since milking.

As cheese is a function of the milk’s characteristics, industrial cheese makers standardize their milk 1) to the type of cheese that milk is for and 2) in order to obtain a standard cheese product.

Standardization it is not normally performed by hobby or artisan cheese makers.

Process

Standardization is the process of standardizing the milk to the required specifications depending on the type of cheese being made. This can involve several parameters such as:

  1. % Milkfat
  2. % Solids
  3. Casein to fat ratio – Altering either the fat or casein will have significant effects on the FDM (fat in dry matter) of the cheese.

Standardization of milk is commonly done by removing cream from the milk or by adding non-fat dry milk, skim milk, or condensed skim milk.

Measurement

South Portugal Sheep Off Bridge - CheeseForum.org
South Portugal Sheep Off Bridge - CheeseForum.org

Measurement of % milkfat is often performed by a Babcock test or Gerber Method.

Measurement of casein is complicated, however one can estimate its percentage in milk as casein is approximately 78% of the total protein in milk. The casein level also varies with the fat content of milk. For milk with 3.6% fat, the casein content is about 2.5%. For every 1% change in fat content, the casein level will change about 0.4%. The casein content of Non-Fat Dry Milk averages 28%.

Wiki: Non-Fat Dry Milk

This Wiki Article discussed Non-Far Dry Milk. It is divided into the following sections:

General

Milk is commonly dried into a powder form to:

  1. Preserve it as milk powder has a significantly longer shelf life than liquid milk and as milk powder does not need to be refrigerated due to its low moisture content.
  2. Reduce its bulk for economy of transportation.
  3. Use it as an additive in food making such as cheese.

Common powdered milk and dairy products are:

  1. Non-Fat Dry Milk
  2. Dry Whole Milk
  3. Dry Buttermilk
  4. Dry Whey Products
  5. Dry Dairy Blends

Non-Fat Dry Milk (NDM) is the most common, it’s milk sources in decreasing manufacture are:

  1. Cow’s Milk
  2. Goat’s Milk
  3. Sheep’s Milk

NDM Use In Cheese Making

NDM & No Milk

Cheese is rarely made using NDM and no liquid milk. This is primarily because the protein is denatured (changed from its natural state), and thus it is really only useful for making yogurt and soft cheese. While feasible for making other cheeses, the quality of the curd and resultant cheese are very different, for example the cheese will not melt.

NDM & Hobby/Artisan Cheese Making

In hobby and artisanal cheese making, adding NDM is rare, except in yogurt making to result in a thicker consistency.

NDM & Industrial Cheese Manufacture

Conversely, in industrial cheese making, NDM is often added to milk to help standardize the milk before making cheese where it is called “Cheese Milk Extension”. There are several reasons NDM is added:

  1. Maintain consistent composition of cheese.
  2. Produce more pounds of cheese per pound of fat purchased.
  3. Increase the output per vat and daily plant production.
  4. Enable more efficient production of reduced fat cheeses.
  5. Enable the storage of non-fat milk solids from peak production periods for use during periods of low milk production.

However, using NDM in cheese making also alters the cheese body, texture, flavor, and keeping quality.

Most varieties of cheese can tolerate up to 2% solids added NDM in the cheese milk without experiencing problems in body or texture. Levels of addition above 2% NDM may lead to crumbly body and poor texture in the cheese.

Cottage cheese is often made by fortifying skim milk with up to 4% added low-heat NDM. For the best quality curd, it has been found that milk for medium and large size curd should be 10% to 12% solids, whereas milk for small curd size should contain 9.5% to 11% solids.

NDM should not be used in cheeses that are dependent on eye-formation, e.g., Swiss, Gouda, etc as the NDM may cause weak spots in the curd which would result in poor eye formation.

NDM Manufacture

Historically, NDM was produced by vacuum evaporation of skim milk and then spray-drying the skim milk concentrate. Current powder plants use a centrifugal dryer.

NDM Classification

Grades of NDM (extra, standard, and instant) are based on specifications for fat, moisture, titratable acidity, and solubility indices.

NDM is also classified on the basis of the heat treatments it receives during manufacture, for example low heat NDM is manufactured with a minimum pasteurization treatment and limited heating during concentration and spray-drying.

Quality of NDM is critical, NDM processed with higher heat treatments:

  1. Produces curd with a weaker body.
  2. Causes delays in rennet action.
  3. Produced some defects in cheese flavor and body.

Thus NDM processed with lower heat is preferred.

Retail NDM is often “instant” grade with no information on heat treating.

NDM Storage

To maintain the best flavor and functional properties in NDM for cheese making, NDM should not be stored more than nine months. Most retail packages have a “best by” date.

NDM Handling

NDM dust should be prevented because if wetted, it provides an opportunity for the growth of undesirable microorganisms.

NDM Addition To Milk

If milk is being pasteurized, NDM should be added to the cheese-milk prior to pasteurization so that the full pasteurization of the standardized cheese-milk can provide for protection against pathogenic bacteria.

If adding directly to the milk, ensure that all lumps of NDM have been properly dispersed or strained.

For reduced-fat and part-skim milk based cheeses, it is recommended that:

  1. The NDM be reconstituted with warm water as a concentrate prior to addition to the milk.
  2. The reconstituted NDM be allowed to properly hydrate several hours prior to cheese making to ensure that proteins are fully hydrated and functional in the cheese making process.

Wiki: Milk Products

US Pasteurized & Homogenized Manufactured Cow Milk - CheeseForm.org

US Pasteurized & Homogenized Manufactured Cow Milk - CheeseForm.org
US Pasteurized & Homogenized Manufactured Cow Milk - CheeseForm.org

This Wiki Article discusses common cow milk derived products such as butter, cream, half & half, semi-skimmed milk etc and their butterfat %’s. It is divided into the following sections:

General

Milk is made into a wide range of dairy products, the following is a listing of some of these and their butterfat contents.

The listing is meant primarily as a reference to the cheese maker who uses store bought manufactured cow’s milk products rather than raw cow’s milk to make cheese. Often different % fat milks are used and creams can be added to raise fat content (i.e. double or triple cream cheeses) of the resultant cheese.

Cow’s Milk Products, Fat Contents – USA

US Kroger Grocery Store Brand Fat Free Half & Half, Container - CheeseForum.org
US Kroger Grocery Store Brand Fat Free Half & Half, Container - CheeseForum.org
Type Butterfat Content
Butter >80%
Manufacturers Cream 40%
Heavy Whipping Cream >36%
Light Whipping Cream/Whipping Cream 30-36%
Medium Cream 25%
Light Cream/Coffee Cream/Sour Cream 18-30%
Half & Half (Blend of cream & milk) 10.5-18%
Whole Milk (Called Homogenized in Canada) >3.25%
Reduced Fat or 2% ~2.0%
Semi Skimmed Milk 1.5-1.8%
Low Fat or 1% Milk ~1.0%
Skim Milk ~0.1%
Fat Free Half & Half (Blend of skim milk & corn syrup) ~0.0%

Cow’s Milk Products, Fat Contents – UK

US Kroger Grocery Store Brand Fat Free Half & Half, Ingredients - CheeseForum.org
US Kroger Grocery Store Brand Fat Free Half & Half, Ingredients - CheeseForum.org
Type Butterfat Content
Breakfast Milk/Channel Island Milk 5.5%
Whole Milk/Full Fat Milk 3.5%
Semi Skimmed Milk 1.5-1.8%
1%/The One Milk 1%
Skimmed Milk <0.3%

Wiki: Milk Yield

Camembert, Unaged - CheeseForum.org

This Wiki Article provides guidelines of cheese weight yields from different volumes of milk. It is divided into the following sections:

General

Camembert, Unaged - CheeseForum.org
Camembert, Unaged - CheeseForum.org

In cheese making, yield is a term for the amount of cheese resulting from a certain volume of milk, it varies by type of milk, amount of fat in milk, and moisture-water content of the cheese.

Yield in cheese making is normally given in weight of final cheese after salting and aging, per weight of milk used (thus ignoring non-cheese additives such as peppers & nuts and coatings if used such as wax or lard bandaging). Weight is used rather than volume as weight of final cheese is an easier measure than volume.

While commercial cheesemakers use weight of milk in their cheese making batches, for small home or artisan sized cheese making batches, most people use volume of milk.

Thus for people new to cheese making, the following tables convert i) volume of milk to weight of milk (assuming specific gravity of 1.033, the average S.G. for raw-whole cow’s milk, the most common milk used in cheese making) and ii) using the % Yield to calculate the resulting weight of the cheese, after salting and aging. Note, these final weight of cheese tables are a guide only, for example higher fat milks will have a lower S.G., and milk at warm temperatures will also have a lower S.G., thus it is good practice to weight your final cheese to determine your yield for future reference and to determine if it is the approximate right moisture content.

Yield Table – Metric

Type Yield  Weight For 3 Liters Milk
(kg)
 Weight For 5 Liters Milk
(kg)
 Weight For 10 Liters Milk
(kg)
 Weight For 20 Liters Milk
(kg)
Cream Cheese 20% 0.62 1.03 2.07 4.13
Feta 13% 0.40 0.67 1.34 2.69
Camembert 12-14% 0.37-0.43 0.62-0.72 1.24-1.45 2.48-2.89
Gouda & Cheddar 10% 0.31 0.52 1.03 2.07
Parmesan & Romano 7-8% 0.22-0.25 0.36-0.41 0.72-0.83 1.45-1.65

Yield Table – USA

Type Yield  Weight For 1 Gallon Milk
(pound)
 Weight For 2 Gallon Milk
(pound)
 Weight For 4 Gallon Milk
(pound)
 Weight For 6 Gallon Milk
(pound)
Cream Cheese 20% 1.7 3.3 6.6 9.9
Feta 13% 1.1 2.2 4.3 6.5
Camembert 12-14% 1.0-1.2 2.0-2.3 4.0-4.6 6.0-6.9
Gouda & Cheddar 10% 0.8 1.7 3.3 5.0
Parmesan & Romano 7-8% 0.6-0.7 1.2-1.3 2.3-2.6 3.5-4.0

Wiki: Milk Processing

9 US Gallons, 34 Liters Pasteurized & Homogenized USA Store Bought Whole Cow's Milk - CheeseForum.org
9 US Gallons, 34 Liters Pasteurized & Homogenized USA Store Bought Whole Cow's Milk - CheeseForum.org
9 US Gallons, 34 Liters Pasteurized & Homogenized USA Store Bought Whole Cow's Milk - CheeseForum.org

This Wiki Article discusses the different forms of milk processing. Milk straight from the cow, goat, or ewe is often referred to as “raw” milk. there are five processes commonly applied to raw milk, depending on if home dairy or mass manufactured milk that is bought in stores:

  1. Filtration to remove any foreign bodies.
  2. Pasteurization to kill any harmful bacteria and increase the milk’s shelf life.
  3. Cooling either after pasteurization or after milking to increase the milk’s shelf life.
  4. Ultrafiltration, where butterfat is removed from the raw milk.
  5. Homogenization to provide a more stable uniform product.

Filtration

Filtration of milk is to remove any foreign bodies that may have entered the milk during the milking and collection process.

For a home dairy this may be as simple as a very fine mesh kitchen strainer. For larger quantities, a purpose made milk filtration unit is often used.

Cooling

If the milk is to be pasteurized or used in cheese a making immediately, then this step is omitted. If not then the milk must be cooled immediately to slow natural bacteria from multiplying and reducing the milk’s like.

For small home dairies, the easiest way is to place the milk in bottles of stainless steel containers with lids and stand the containers in a sink of running cold water. For larger quantities, an in-churn milk cooler is often used.

Once cooled the milk should be placed in a refrigerator until at 4C / 40F or below.

Note, even if making cheese immediately, the milk temperature after milking may still be too high and thus cooling required.

Pasteurization

Half US Gallon, 1.8 Liters Ultra-Pasteurized & Homogenized USA Store Bought Half Cow's Milk & Half Cow's Cream - CheeseForum.org
Half US Gallon, 1.8 Liters Ultra-Pasteurized & Homogenized USA Store Bought Half Cow's Milk & Half Cow's Cream - CheeseForum.org
Pasteurization is named after its creator, French chemist and microbiologist Louis Pasteuris and it involves the heating of milk for short time periods to kill bacteria and thereby reduce health risks to its consumers. A secondary benefit of this process is to increase its shelf life. This process kills both wanted and unwanted bacteria.

Pasteurization can be at different temperature and time, with generally the higher the temperature, the less time. There is no global standard for pasteurization, but in general the temperature and time are grouped into 3 levels:

  • Pasteurized: Milk is heated to ~66C / 150F and held for ~30 seconds before cooling. This is the most common and kills the least bacteria. Milk normally requires refrigeration to prolong its life.
  • Ultra-Pasteurized: Milk is heated to ~72C / 162F and held for ~15 seconds before cooling. Higher temperature and shorter time, the second most common, kills more bacteria than Pasteurized. Thus enables longer refrigerated shelf life and is common on products that are consumed or sold slower such as creams and organic milks.
  • Ultra Heat Treated or UHT: Milk is heated to ~82C / 180F and cooled immediately. Highest temperature and shortest time, the least common method, kills the most bacteria. Results in shelf life of years even without refrigeration. Commonly used where milk is not common or logistics of getting Pasteurized milk or other products is problematic.

After heating cooling is performed rapidly, normally via cold water and on larger equipment through heat exchangers.

Note, often manufactured milk (and products derived from it) are labeled Pasteurized or Ultra-Pasteurized or UHT, this may not describe the level of pasteurization.

In general, good bacteria in the milk makes a better cheese. Thus, hygiene issues aside, raw milk is the best for making cheese, followed by Pasteurized, then Ultra-Pasteurized, and the UHT (almost completely dead) milk. Unless you know the source and the hygiene conditions of the source of your milk, Pasteurized is always best. Check local laws at your location as to the use of unpasteurized milk in cheese making.

Note, many people new to cheese making if using store-bought milk assume organic milk is the best, this is normally not true as it is often Ultra-Pasteurized to provide longer shelf life but also making it poorer for cheese-making than cheaper Pasteurized milk.

There are considerable arguments about the merits or advantages of pasteurization versus the disadvantages of also killing off the good bacteria in milk. For more information, see the International Dairy Foods Association’s website on pasteurization, go to Resource Center > Industry Facts > Milk > Pasteurization pdf.

For counter arguments to pasteurization, see the US-based Campaign for Real Milk’s website.

Ultrafiltration

One US Quart, 0.9 Liters Ultra-Pasteurized & Homogenized USA Store Bought Goat's Milk - CheeseForum.org
One US Quart, 0.9 Liters Ultra-Pasteurized & Homogenized USA Store Bought Goat's Milk - CheeseForum.org
To reduce fat content of cow’s milk, butterfat is removed from the raw milk to make lower % fat milks and the high fat milk used for making butter, heavy creams, and other high fat milk products including cheese.

For small home dairies this is normally done via skimming the cream off the top of cow’s milk after it has separated or by using a hand crank or electric centrifuge which separates the lighter cream. Industrial large dairies use a process known as Ultrafiltration where milk under high pressure is pumped through a semi-permeable membrane  to remove the fat and other high molecular weight components. UF milk is low-cost to manufacture as i) the permeate (leftovers) can be sold for whey protein, ii) labor is reduced, and iii) if using UF to make cheese you use less milk to make the same volume as you are binding more of the lost fat and protein up front rather than losing it in the whey and lower shipping cost to transport the concentrate.

Ultrafiltration was applied to industrial cheese making in France in the late 70’s to significantly lower costs in making Camembert and Brie cheeses. Since then it has been applied to many industrially made high moisture cheeses around the world such as Cream Cheese, Chevre, and Feta where you simply filter the milk to give you your final moisture, fat and protein content. Most industrial milk processing plants use UF and industrial cheese making dairies order their milk to a specified concentration which is used to make almost instant cheese by spraying rennet into it as the molds are filled. If the cheese is retailed in plastic containers then often that is the mold. As the material is already de-wheyed, there is no draining or drying. UF cheeses generally have very-creamy texture but none of the flavour of traditional artisan made cheese and the high moisture leads to poor shelf life. To add flavour, often manufactured artificial cheese flavours are added which depending on the country and labeling requirements, may not explicitly be disclosed in the list of ingredients.

Homogenization

Homogenization is the process where milk is (in general) pumped at high pressure through small orifices which breaks up the fat globules in milk into smaller sizes so that they have significantly less tendency to coagulate. Before mass homogenization of milk, the fat in milk, or butterfat as it is called in the industry, would coagulate and as lighter than the water part of milk, float to the top of the milk and was known as the cream. Homogenization thus prevents or delays this natural separation.

Homogenization is common with processing of cow’s milk but not with goat’s or ewe’s milk as the fat globules are already small.

Wiki: Milk & Cream Types

South Portugal Sheep Crossing Bridge - CheeseForum.org

This Wiki Article discusses milk and cream and cream types commonly used in making cheese. Dairy animals have been kept by mankind for the provision of milk since before history was recorded. Raw or unprocessed milk has a very short shelf life and thus it was historically commonly made into cheese to provide as a method of food storage. As such, milk is the largest building block of cheese making.

Types

South Portugal Sheep Crossing Bridge - CheeseForum.org
South Portugal Sheep Crossing Bridge - CheeseForum.org

Dairy animals include but are not limited to:

  • Cows
  • Goats
  • Sheep/Ewes
  • Buffaloes
  • Asses/Donkeys
  • Mares/Horses

Most cheese is made from cow’s, goat’s, and sheep’s milk.

Colours

  • Cow’s milk ranges from bluish-white to cream depending on amount of fats and non-fat solids and amount of carotene which increases the yellowish colour.
  • Goat’s milk is slightly opaque white as no carotene even when fed grass.

pH

  • Cow’s milk when fresh normally has a pH of 6.7.
  • Goat’s milk when fresh normally has a pH of 6.4 which is slightly more acidic than cow’s milk as higher content of acids and can cause more rapid souring.

Butterfat

Fat in milk is called butterfat and is suspended in the milk in a water external emulsion (fat particles in a matrix of water) as water is by far the high % of milk.

Raw, unprocessed cow’s milk’s butterfat are large particles which when left undisturbed will via gravity as fat is lighter than water, rise to the top of the milk where it will form a layer, a process called creaming. Goat’s and ewe’s milk’s butterfat particles are generally smaller than in cow’s milk and thus less gravity versus emulsion forces and in general it will not separate and it will freeze better.

Components

Raw unprocessed milk is an extremely complex material, it’s makeup depends on animal type, breed, feed, and stage in it’s lactation cycle. Plus in general, higher fat milk’s are obtained at the end of a milking of stripping.

Raw Milk Major Components – Type:

  • Water.
  • Triglyceride fats:
    • Saturated fatty acids.
    • Unsaturated fatty acids.
  • Proteins:
    • Casein, highest % and key in cheese making.
    • Albumin.
    • Lecithin.
    • Globulin.
    • Fibrin.
  • Carbohydrate
    • Lactose sugar.
  • Ash, the residual content of milk containing a range of minerals and vitamins.

Raw Milk Major Components – Content:

Solids
Type Fat % Protein % Lactose % Ash % Total Solids% Water %
Cow, Guernsey 5.0 3.8 4.9 0.7 14.4 85.6
Cow, Holstein 3.5 3.1 4.9 0.7 12.2 87.8
Cow, Jersey 5.5 3.9 4.9 0.7 15.0 85.0
Goat 3.5 3.1 4.6 0.79 12.0 88.0
Sheep 5.3 5.5 4.6 0.9 16.3 83.7