Wiki: Semi-Sealing Rind Development

Gouda With Natural Rind & Natural Protective Geotrichum candidum Mold Development - CheeseForum.org

This wiki article discusses semi-sealing traditional natural rind development of pressed cheeses during aging. These encompass a range of rind development methods commonly used by cheese makers of old and still very common. This article does not cover high sealing and often more modern cheese protection systems such as:

  • Wax Coating (common on Gouda and Edam cheeses for protection during shipping).
  • Sealed Vacuum Plastic (common on many cheeses).
  • Cheesecloth wrapping and larding (common on some cheddars).
  • Milk based edible casein based bag or cloth wrapping cheese as common with large Gouda wheels. This is the same material used for modern labels on large cheeses.

Rind’s Function

Gouda With  Natural Rind & Natural Protective Geotrichum candidum Mold Development - CheeseForum.org
Gouda With Natural Rind & Natural Protective Geotrichum candidum Mold Development - CheeseForum.org

Rinds of cheeses are started to be formed during the pressing stage of making cheese, they are a critical component of cheese during aging as it protects the interior of the cheese to allow it to ripen harmoniously by acting as a barrier to unwanted micro-organisms and to dehydration. Its presence thus affects the final flavor of the cheese.

Salting plays an important role in natural rind formation. Heavily surface salted cheeses develop a thick, tough outer rind, typified by the Swiss range of cheeses. Cheddar, another natural rind cheese, is less salted than the Swiss varieties, and consequently has a much thinner rind.

Different natural rind developments are discussed below:

Clean Natural Rind

To create a truly hygienically clean natural rind with no induced microorganisms is very hard to do due to high chance of airborne wild contaminants and thus this method is almost never done.

Brine & Salt Rubbed Rind

Cheeses can be intermittantly once per week washed with saturated brine and then rubbed with coarse salt to build a hard thick neutral pH natural rind. It is important to keep the humidity of the aging environment down after rubbing the salt on as the resultant moisture on the rind as the salt is absorbed as brine can cause areas of unwanted yeast infection. Cheese makers often oil their cheeses after several weeks of brining and salting.

Oiled Rind

Gouda At 25 Days, Natural Rind With Natural Protective Geotrichum candidum Mold Development (Finger mark on left) - CheeseForum.org
Gouda At 25 Days, Natural Rind With Natural Protective Geotrichum candidum Mold Development (Finger mark on left) - CheeseForum.org

Oiling rinds with food grade oil is very common and discussed in the Wiki: Oiling Rinds article.

Benign Microorganism Rinds – Added During Pressing/Brining Phase

A protective rind is preferred from ????bugs.

Benign Microorganism Rinds – Added After Pressing/Brining Phase

Many cheeses have their natural rind coated with a permeable barrier to control unwanted microorganisms during aging. Examples are washing the rind with a fluid with live microorganisms such as beer, cider, wine.

Wiki: Microorganisms & Cheese Making

This Wiki Article provides an introduction to microorganisms common in cheese making. Microorganisms are organisms that are unicellular or live in a colony of cellular organisms such as bacteria, fungi, archaea, and protists; microscopic plants (green algae); and animals such as plankton and the planarian. Microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago, the study of microorganisms is called microbiology.

Microorganisms live in all parts of the earth’s biosphere where there is liquid water, including soil, hot springs, on the ocean floor, high in the atmosphere and deep inside rocks within the Earth’s crust. Microorganisms are critical to nutrient recycling in ecosystems as they act as decomposers. Microorganisms are present in raw milk and are used in controlling the fermentation process in making cheese, either natively or by additionally applying, and are critical in developing different cheese types flavours and aromas, and in inhibiting undesirable organisms. Microorganisms are also used in brewing, winemaking, baking, pickling and other food making processes. Historically and in many cases currently cheese has been made in very rustic facilities with many ambient/wild microorganisms, which does not necessarily mean unsanitary, but does result in cheese quality that is too inconsistent for modern cheese factories but good for home and artisan cheese making.

The main types of microorganisms used in making cheese are shown below.

Bacteria

Bacteria are a biological kingdom of simple single-celled, prokaryote (lacking a cell nucleus) microorganisms. They are typically a few micrometres in length and have a wide range of shapes ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat, growing in water, soil, acidic hot springs, as well as in organic matter and the live bodies of plants and animals including humans. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; and in total form a bacteria with a biomass which exceeds that of all plants and animals. There are approximately ten times as many bacterial cells in the human flora as there are cells in the human body, large numbers of bacteria are on the skin and in the intestines. Bacteria are vital in recycling nutrients, however most bacteria have not been characterised, the study of bacteria is known as bacteriology, a branch of microbiology.

Bacteria reproduce asexually by simple division of the cell and its contents, called fission. The doubling time can be as short as 20 min, and as each cell grows and divides at the same rate as the parent cell, this could under favourable conditions translate to an increase from one to 10 million cells in 11 hours. However, bacterial growth in reality is limited by lack of nutrients, accumulation of toxins and metabolic wastes, unfavourable temperatures and dessication. Bacterial populations are expressed as colony forming units (CFU) per gram or millilitre.

Bacterial growth generally has several phases:

  • Lag Phase: Time for bacteria to become accustomed to their new environment. There is little or no growth during this phase.
  • Log Phase: Bacteria exponential growth begins; the rate of multiplication is the most rapid and constant.
  • Stationary Phase: Rate of multiplication slows down due to lack of nutrients and build-up of toxins. At the same time, bacteria are constantly dying so the numbers actually remain constant.
  • Death Phase: Cell numbers decrease as growth stops and existing cells die off.

Milk is sterile at secretion into the udder but is contaminated by bacteria before it leaves the udder. Except in the case of mastitis, the natural microflora of bacteria at this point are harmless and few in number. Further infection of the milk by microorganisms can take place during milking, handling, storage, and other pre-processing activities. If significant lactic acid producing bacteria are in raw milk, it will, with time and warmer temperatures, multiply, acidify and curdle the milk (commonly called clabber) after which whey can be drained. However, depending on bacteria amount and types this can result in either inefficient, uncontrollable, and unpredictable and thus variable results and if lactic acid producing bacteria are minimal, an environment for unwanted/unhealthy bacteria to reproduce. Thus to extend shelf life, milk is commonly pasteurized to kill off most of the bacteria, both good and bad types. Commonly in cheese making, wanted lactic acid producing bacteria are added (inoculation) to the milk, to out-compete unwanted native bacteria, these are called starter cultures.

Common bacteria used in making cheese are:

  • Lactic Acid Producing Bacteria: Commonly called starter cultures, naturally in milk but commonly added to milk to ferment lactose in milk to lactic acid causing coagulation and release of whey to condense remaining milk ingredients into cheese for longer shelf life.
  • Brevibacterium linens which is ubiquitously present on the human skin where it causes foot odor and applied to give cheese rinds an orange colour and a very pungent aroma, examples are Limburger and Port-du-Salut.

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Fungi

In biological terms, Fungi are a Kingdom and thus different from other Kingdoms such as plants, animals, and bacteria. Fungi are made up of yeasts, molds (spelt moulds in Britain) and mushrooms. The discipline of the study of fungi is called mycology, a branch of microbiology. Fungi are abundant worldwide but most are inconspicuous because of the small size of their structures. They may become noticeable when fruiting, either as mushrooms or molds. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange. Fungi have long been used as a direct source of food, such as mushrooms and truffles as a leavening agent for bread, and in fermentation of various food products, such as wine, beer, soy sauce, and cheese.

Little is known of the true biodiversity of the Fungi Kingdom, which has been estimated at around 1.5 million species, with about 5% of these having been formally classified. Most fungi grow in cylindrical, thread-like structures 2–10 µm in diameter and up to several centimeters in length called hyphae. From these they grow by a combination of apical growth and branching/forking resulting in mycelium, an interconnected network of hyphae which is normally more visible to the naked eye, (ie fuzzy mold on damp walls, spoiled food such as bread, or on cheese where used to provide flavour and aroma.

Yeast Fungi

Currently yeasts are thought to be about 1% of all fungal species, about 500 have been described by mycologists. Yeasts ferment carbohydrates to carbon dioxide and alcohols, and are common in baking such as bread making for their carbon dioxide forming attributes and in for their alcohol making attributes in alcoholic beverage making such as beer and wine.

Yeasts are intentionally used in making some cheese types to enable rind development and are also a source of unwanted “infections” resulting in rising bread/beer yeasty smells and swelling. Note that Swiss types cheeses with eyes (Emmenthaler, Leerdammer) are not made with yeast but with Propionibacterium freudenreichii, a bacteria.

Mold Fungi

Molds grow like mushrooms, they have a surface component and send down roots called mycelia into the insides of the cheese where they break down the fats and proteins and create different flavors and textures, some penetrate just cheese rinds, some penetrate the whole paste (for example Brie or Camembert.

Common molds used in making cheese are

  • Geotrichum.
  • Penicillium white strains used in making the fluffy coating on Brie/Camembert.
  • Penicillium blue strains used in giving blue cheeses such as Roquefort and Stilton their distinctive blue to blue-green veins.

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Wiki: Brine Bathing Cheeses

Two 2 kg Gouda's bathing in whey based brine bath.

This Wiki Article discusses temporarily bathing or soaking formed and pressed cheeses. This is normally done after pressing with a high salt content brine. Once in the brine, the cheese begins to absorb the salt and the proteins on the surface of the cheese harden and form the start of the rind. Other Wiki articles on brine are Wiki: Making BrineWiki: Maintaining Brine, and Wiki: Brine For Ripening Cheese. Wiki articles on salt are: Wiki: Salt Types, and Wiki: Salt’s Function.

Brine Exposure

2 kg Havarti bathing in water based brine incorrectly using weight to submerge.
2 kg Havarti bathing in water based brine incorrectly using weight to submerge.

Ideally cheese should be evenly exposed to the same concentration brine on all sides to ensure even brining. In practice there are two obstacles to this:

  1. As cheese is less dense than brine, it is buoyant and will float (similar to an iceberg with 10% above and 90% below the ocean). The result is non-even brining of the cheese and air drying of the surface of the cheese above the brine. If unaddressed this will result in the surface above the brine retaining higher moisture and thus forming a softer poorer rind. To minimize this:
    • After placing cheese in brine, sprinkle exposed area of cheese above brine with salt.
    • Turn cheese once during brining time and sprinkle again with salt on the newly exposed surface.
    • Note, if re-using and thus maintaining brine this extra salt will partially make up for the salt that is absorbed by the cheese.
  2. Cheese that is touching another surface, either the brine tank wall or another cheese, will not evenly absorb salt as i) poor contact with brine and ii) the brine between the cheese and wall/another cheese will become reduced in salt saturation. Thus ensure enough surface-areal room for cheese(s) to float freely away from the brine tank walls and from each other.

Brine Volume

Sprinking dry salt on cheese surfaces above water based brine.
Sprinking dry salt on cheese surfaces above water based brine.

As brining cheese withdraws the salt from the brine, to maintain a reasonably stable % salt, amount of brine should be roughly 5 times the amount of cheese being brined.

Brine Temperature

Brining temperature should be kept constant and around 50-60°F/10-15°C as:

  1. Higher temperatures enable a wider range of spoilage and pathogen type microorganisms to flourish and will also increase salt uptake and moisture loss in the cheese.
  2. Lower temperatures will 1) restrict or kill many of the flavour producing organisms in your cheese, and 2) result in less salt uptake and higher moisture contents in the cheese, making it difficult to develop a rind.
  3. If not constant, salt uptake will be inconsistent and thus cheese making results vary due to a wide range of salt content and moisture levels. Note, in addition to a stable brine temperature, allow fresh cheese(s) to reach this temperature before bathing.
  4. Note, pasta filata (pulled) type cheeses like mozzarella need cold brining to quickly cool the cheese and minimize moisture loss.

Soaking Time

2 kg Havarti after brining, surface indentation from incorrectly using weight to submerge cheese in brine.
2 kg Havarti after brining, surface indentation from incorrectly using weight to submerge cheese in brine.

Normally cheese making procedure dependant and increases with cheese weight/volume, thickness, and density. For example a very hard Parmagiano will require longer than a semi-hard Havarti.

Moving Cheese

As cheese is young, it is fragile, place cheese in brine and remove from brine by lifting from bottom, not by holding/pinching cheese from top as this can result in stress on the cheese above it’s strength and fracturing of the cheese, see Wiki: Turning Cheeses for more information.

Brining Best Practices

To ensure consistent results and tailor your next cheese making batch, record:

  1. Brine volume, density, temperature, and pH before and after brining cheese.
  2. Weight and temperature of cheese before brining.
  3. Duration cheese was in brine bath and amount the cheese was turned to avoid dry areas and promote even brining.
  4. Cheese’s weight after brining.
Two 2 kg Gouda's bathing in whey based brine bath.
Two 2 kg Gouda's bathing in whey based brine bath.

Wiki: Maintaining Brine

Filtering used brine to remove fine curd particles.

This Wiki Article discusses maintaining and regenerating brine for extended use, versus building a brine for a one time use then disposing. Other wiki brine articles are Wiki: Making Brine, Wiki: Brine Bathing Cheeses, and Wiki: Brine For Preserving Cheese.  

Skimming off foam from reboiled maintained brine.
Skimming off foam from reboiled maintained brine.

If brines are maintained and re-used, they should have an appropriate % salt, be stored properly, and periodically be cleaned and rebuilt.  

Older cheese makers say that you should not dispose of brine but rather just replenish the salt absorbed by the cheese. In today’s climate of higher hygiene, it is advisable to dispose and build a new brine solution periodically.  

Salt %

Re-used brines should be above 16% salt, the minimum for a hostile environment to bacteria. Brines below 16% will become contaminated with unwanted brine resistant bacteria.  

Storing Brine

  1. Store covered to avoid unwanted items falling in.
  2. Store at normal application temperature of -60°F/15.6°C or lower.
  3. Note, do not allow a smear of slime to develop on the sides of the bath above the water line, this will be fat and a habitat for bacterial growth.

Cleaning Brine

Filtering used brine to remove fine curd particles.
Filtering used brine to remove fine curd particles.
  1. Skim the surface of the brine for bits of cheese shortly after each use with a very fine mesh tool such as a plastic swimming pool skimmer or small kitchen sieve.
  2. If cloudy, to clarify, periodically pour or pump used brine through paper towel or cheesecloth lined strainer/colander, toss paper towel, clean cheesecloth. You can also use this as an opportunity to clean the tank and surrounding area.
  3. If in poor shape, then boil the brine to kill off any brine resistant microorganisms such as Listeria.

Rebuilding Brine

Maintained brine’s % salt will decline with time as it is absorbed by the cheeses and thus should be replenished to the % salt required.  

  1. For un-saturated brine, stir in additional non-iodized NaCl salt to bring you back to target % as measured by a salometer.
  2. For saturated brine, re-boil and stir in additional non-iodized NaCl salt until it no longer dissolves, cool to using temperature.
  3. Note, after using newly made brine, pH and calcium level should normally not need to be adjusted, assuming brine is used reasonably frequently.
Boiling old brine to kill any brine resistant micro-organisms, lots of foam.
Boiling old brine to kill any brine resistant micro-organisms, lots of foam.

Wiki: Brine For Ripening Cheese

Mediterranean Store, Vancouver Canada, barrel of Feta in brine without cover.

This Wiki Article discusses brines used for ripening “Aegean Sea” type cheeses such as φέτα/Feta/Fetta, Brinza, Halloumi, Domiati, Nabulsi, Gyptian, Gibna Bayda, Arabian Cheese, Akawi where depending upon recipe, they can be kept for up to 12 months. Brines for these cheeses are normally disposed after the cheese is consumed. There are separate Wiki Articles for making an maintaining brines.

Brine Concentration

Mediterranean Store, Vancouver Canada, barrel of Feta in brine without cover.
Mediterranean Store, Vancouver Canada, barrel of Feta in brine without cover.

Brines used to store these cheeses are normally 16% salt, the minimum for minimizing unwanted bacteria growth.

Higher % salt can be used, but is not required and will make the cheese taste very salty.

Lower % salt will result in a more immediately edible cheese but with shorter shelf life due to unwanted bacteria growth.

Base Fluid

Base fluid options for making brine for ripening cheese are water, a mixture of water and whey, or all whey from making cheese.

Using whey gives the brine a higher calcium component and a lower pH, reducing the need for the addition of CaCl2 and vinegar in newly made brine. The use of whey also makes the brine ripened cheese more flavourful.

Using Brine Ripened Cheese

Mediterranean Store, Vancouver Canada, several retail Feta brands in brine, covered.
Mediterranean Store, Vancouver Canada, several retail Feta brands in brine, covered.

Cheese ripened in 16% brine and used in cooking are fine, but if eaten directly are to most people, very salty to the taste. Methods to reduce the salty taste are:

  1. Remove cheese from brine and soak in fresh water or milk for up to 1 hour before consuming.
  2. Instead of all NaCl salt, use up to 50% KCl (Potassium Chloride) salt.
Feta cheese in water based brine.
Feta cheese in water based brine.
1 US gallon whole cow's milk Feta in water based brine.
1 US gallon whole cow's milk Feta in water based brine.

Wiki: Oiling Rinds

Two 4 pound Gouda's at 30 days age with oiled rinds, one cleaned of mold, second with blue surface mold due to improper aging humidity.

This Wiki Article discusses oiling formed cheese rinds, normally during aging. Fresh fresh formed and unformed cheeses are not oiled. Formed cheeses during aging are commonly either natural rinds, vacuum bag sealed rinds, or waxed rinds. Historically waxing was empoyed after aging to reduce damage during shipping (ie Dutch Gouda & Edam). Vacuum bag sealing is a modern invention.

The primary advantage to natural rinds is that the rind enables the cheese to breath during aging, which is good. However there are two disadvantages depending on the cheese type, dehydration which if high results in a very dry hard cheese, and if rapid can result in surface stress cracks from uneven shrinking, and unwanted surface molds.

Oiling surfaces of cheeses during aging can aid as barrier to excessive dehydration. To manage unwanted surface molds during aging, three methods are used, i) developing a low moisture content rind (normally done during pressing, and augmented by dry salting or brining rinds and air drying), ii) having a high salinity rind (normally from initial and in some cheese types repeated dry salting rinds, and by brining cheeses (ie Gouda & Edam)), and iii) by oiling rinds. Different oil types and their pros and cons for rinds are discussed in the Wiki: Oil Types article.

Oiling Goals

Two 4 pound Gouda's at 30 days age with oiled rinds, one cleaned of mold, second with blue surface mold due to improper aging humidity.
Two 4 pound Gouda's at 30 days age with oiled rinds, one cleaned of mold, second with blue surface mold due to improper aging humidity.

Oiling rinds is a very popular rind development method due to its simplicity and minimal equipment. The goal of oiling is over several coatings to create a firm sturdy protective layer or seal through the long cheese aging phase such that i) unwanted surface microorganisms are kept at bay and ii) it is easier to control the moisture content of the cheese from dehydration.

Note:

  • Using this method on small cheeses this will result in less pate to rind ratio. Once you build a hard rind it’s like a bowling ball, nothing bothers it, and it can be aged for years, albeit with periodic oilings.
  • In general, moist lightly pressed washed curd type cheeses such as Gouda and Edam should not be oiled but instead waxed or vacuum sealed. This is because these types of cheeses have a high pH early in the aging process and a lot of food on their surface and thus have a high potential for yeast to grow.

Application Method

Common application methods are:

  • Dip a wad of cloth or disposable paper towel in the oil, dab it on the rind, then wipe the excess off.
  • Pour a little oil on cheese and then use hands to spread thoroughly all over cheese, wipe off any excess.

Application Amount

Oil should be applied very lightly to the rind so that it quickly soaks into and conditions the outer layer of the rind. Excess oil should be polished off as over applying oil will create a slick on the cheese and with time can produce a rancid flavor.

Application Frequency

Several oils used on rinds to protect against moisture loss and against unwanted surface micro-organisms.
Several oils used on rinds to protect against moisture loss and against unwanted surface micro-organisms.

After pressing and air drying, cheeses should initially be aged for 7-10 days with a natural rind to enable the cheese to dry and mature and for the rind to toughen before oiling to seal the rind. Oiling too early with cheese still moist can result in yeast injections.

Oil should be applied repeatedly, initially about every week until it forms a skin and then monthly for long-term aging.

In between oilings, the cheese should be rubbed with dry salt to aid in obtaining an impervious barrier.

Wiki: Aging Phase

This wiki article discusses the aging phase of making cheese, thus non-aged “fresh” cheeses are not discussed. Aging is the art of aging a shaped cheese, which depending on cheese type and age wanted can vary from weeks to years. Other common names for aging the French word affinage and ripening. However ripening is the process from start to end of making and aging cheese thus ripening or to ripen is sometimes used for the curd making phase of making cheese and sometimes for the affinage or aging phase.

General

Aging at warmer than recommended temperatures such as 60F will age faster and often develop undesireable aftertaste from bitter peptides.

During this time, bacteria continue to grow in the cheese and change its chemical composition, resulting in flavor and texture changes in the cheese. The type of bacteria active at this stage in the cheesemaking process and the length of time the cheese is aged determine the type and quality of cheese being made.

Sometimes an additional microbe is added to a cheese. Blue veined cheeses are inoculated with a Penicillium spore which creates their aroma, flavor and bluish or greenish veining. Such cheeses are internally moulded and ripen from the inside out. On the other hand, cheeses such as Camembert and Brie have their surfaces treated with a different type of Penicillium spore which creates a downy white mould (known as a bloomy or flowery rind): this makes them surface ripened cheeses.

Many surface ripened cheeses have their surfaces smeared with a bacterial broth. With others the bacteria is in the atmosphere of the curing chambers. These cheeses are called washed rind varieties as they must be washed regularly during their ripening period (longer than for Camembert or Brie) to prevent their interiors drying out. The washings also help promote an even bacterial growth across the surfaces of the cheeses. As this washing can be done with liquids as diverse as salt water and brandy, it also plays a part in the final flavor of the cheese.

Wiki: Air Drying

Food grade plastic mats with capilliary forces holding water between threads resulting in poor air drying of bottom's of cheeses.

This article discusses air drying which entails drying the freshly formed cheese ia evaporation to air to remove excess moisture from the surface and thereby form a dehydrated rind that can better withstand unwanted molds and yeasts. Note, pressed cheeses include those that are pressed with an external weight or if large via their own internal weight, also some such as washed curd Gouda types are brined after pressing before being air-dried. 

For hobby and small commercial cheese makers, air drying is performed by placing the young cheese(s) on a mat at room temperature typically for 2-3 days such that moisture is evaporated into the air is enable and the cheese is periodically turned to maintain it’s shape and enable even drying of all sides. Commercially, this phase is accelerated by cold air being blown on the young cheeses. 

Note, removal of a small amount of water from the cheese naturally results in similar small amount of shrinkage. 

Air Drying Method

1 pound cheese, surface initiated fissures after 3 days improper air drying in 37 F very low humidity kitchen fridge.
1 pound cheese, surface initiated fissures after 3 days improper air drying in 37 F very low humidity kitchen fridge.

The primary problem is to obtain the right speed and amount of drying, the variables being cheese size and moisture content, and air humidity, movement and temperature. 

Not enough evaporation and the cheese’s surface will stay moist and be a base for molds and yeasts. Conversely too fast will result in uneven moisture content across the cheese, the outer rind will dehydrate rapidly resulting in shrinkage while the middle stays moist and does not shrink. This results in tension stress around the surface and compression in the middle of the cheese, somewhat similar to a football but on a much smaller stress scale. 

The problem here is that cheese has very poor tensile strength and if this stress is excessive, dried too quickly, then the cheese will split in one or several places to relieve the stress. This splits will often result in deep fissure type defects as the moister middle of the cheese has even less tensile strength than the dehydrated surface. An example common environment causing this problem is air drying in household kitchen cold and low humidity fridge, even if in a higher humidity vegetable or cheese drawer. Solutions to this splitting are discussed in the Wiki: Defects articles. 

Air Drying Base

Food grade plastic mats with capilliary forces holding water between threads resulting in poor air drying of bottom's of cheeses.
Food grade plastic mats with capillary forces holding water between threads resulting in poor air drying of bottom's of cheeses.

A second common problem is how to enable the base or bottom side of cheese to dry. 

Placing cheeses on an impermeable surface such as plastic or china plates is the worst as the bottom will stay completely wet and whey as it is expelled will puddle, resulting in a severe location for molds and yeasts to start. 

At the other extreme, drying cheeses on widely spaced metal racks will result in the best circulation of air and thus drying of the bottom of the cheese, but depending on cheese hardness and wire spacing will often result in less aesthetically pleasing deep deformation “dent” lines in the young soft cheese. 

In between these two extremes are cloth and mats. Cloth and closely spaced mats also do not work well, while they let the cheese breath, capillary forces will often hold water in the mesh, a location for molds and yeast. Mats if close spaced weave will also do the same, see samples in picture at right where only the right widely spaced “thread count” mat avoids this problem and is recommended, but only when placed on a wire rack to allow good air flow beneath it. Placing a cheese on any mat on an impermeable plate will still pool whey. 

Air Drying Time & Temperature

2 kg Gouda with oil-pepper-cocoa rind, blue mold on bottom resulting from poor mat selection and poor air ventilation below mat as on impermeable surface.
2 kg Gouda with oil-pepper-cocoa rind, blue mold on bottom resulting from poor mat selection and poor air ventilation below mat as on impermeable surface.

Air drying is completed when the whey completely stops draining and the cheese’s surface is dry. At what length of time and temperature is a more difficult discussion given the range of sizes and moisture contents of cheese, and range of air temperatures and humidity levels. 

That said, normal recipe air drying time before aging to obtain a good dry rind is 1-3 days at average house temperatures of 72°F/21°C and ~70-75% humidity, assuming minimal air movement, i.e. not in front of an open window or fan. 

Temperatures above and below that will require less or more air drying time than the recipe. If room temperatures are significantly above that (ie summer or if in tropics) then best to air dry in fridge but then have to be very sensitive to rapid drying of rind from low humidity and cracking of rind, ie turn twice per day and inspect for cracks. 

Higher humidity levels significantly above 75% will require longer time, below 60% may result in cracking as described above and thus the cheese should be partially enclosed to obtain an optimum humidity level, such as by covering the cheese with a loose fitting bowl.

Wiki: Turning Cheeses

Turning gravity whey draining Camembert hoops, quick lift - turn - drop like turning a pancake.

This Wiki Article discusses the practice of turning or flipping a cheese normally upside down, which occurs at several cheese making steps depending on cheese type and recipe. Soft non-formed cheeses like yogurt and cream cheese are not turned. While a relatively simple subject there are some best procedures which if not followed can result in damage or defects to the cheese.

For all the Descriptions, Reasons, Methods, and Frequencies detailed below i) keep records for next cheese make of same cheese type, and ii) do not “sweat” attaining the exact time to turn, high accuracy is not critical. 

Turning Unpressed Cheeses During Forming

Turning gravity whey draining Camembert hoops, quick lift - turn - drop like turning a pancake.
Turning gravity whey draining Camembert hoops, quick lift - turn - drop like turning a pancake.

Description

Soft formed cheeses such as when making Camembert, Feta, or Ricotta are normally turned during draining in unpressed type mold or hoop.

Reason

To enable gravity to provide:

  • An evenly shaped versus lopsided shaped cheese for proper development and for better aesthetics.
  • Even moisture, fat, and protein distribution throughout the cheese and thus proper development of the cheese.

Method

  1. If using unpressed draining mold such as for Ricotta or Feta making, then turn mold upside down and catch cheese in hand and then drop cheese back into the mold but top down, turned.
  2. If using hoops such as for Camembert making, to hold curds together and avoid cheese going lopsided, place second mat over top of hoop, hold mat-hoop-mat sandwich with both hands, then lift quickly into air, then cheese is “weightless”, quickly turn the cheese then lower and allow cheese to slide down inside hoop. Similar to single handed flipping a pancake in a frying pan.

For both methods, initially on first turn the cheese will be soft and poorly formed but will gain firmer shape as drained further.

Frequency

If no turning schedule in recipe then turn after ½ hour, 1 hour, 2 hours, 5 hours, 12 hours, 24 hours, 3 days, etc.

Turning During Brine Bathing Cheeses

1 kg Havarti #1, Surface Stress Crack From Improper Top Pinch Lifting By Hand Out Of Brine - CheeseForum.org
1 kg Havarti #1, Surface Stress Crack From Improper Top Pinch Lifting By Hand Out Of Brine - CheeseForum.org

Description

Some cheese making recipes such as Gouda’s use brine bathing as a method salting cheeses and building a dehydrated hard rind as protection against surface molds. Cheeses during brining are periodically turned.

Reason

As cheese is less dense than brine, during brining the cheese floats with the top above the surface of the brine similar to an iceberg where 10% is above the surface and 90% is in the sea. Here the cheese should be periodically turned to ensure even brining and thus even rind development of all surfaces.

Method

The easiest is to push cheese down into the brine and turn under the brine before resurfacing. Cheeses can also be lifted up out of the brine and turned and replaced into the brine, but if done they should be lifted from the bottom and thus placed in compression as pinching the top of a cheese to lift it can result in tears in the oft young cheese as it weak in tension.

Frequency

If no turning schedule in recipe then if brine bathing for days, turn minimum every half day, if small ~2 pound/1 kg cheeses and brining for few hours, then turn every hour.

Turning Cheeses During Pressing

Description

 

Reason

 

Method

As cheese is moist and weak in tension yet strong in compression, lift cheese from bottom and turn with hands, do not pinch and lift vertically as cheese is weak in tension and can crack.

Frequency

If no turning schedule in recipe then turn after 1/2 hour, 2 hours, 4 hours, 8 hours, 1 day, etc depending on duration of pressing.

Turning Cheeses During Air Drying And Aging

Description

Cheeses after forming are commonly air dried and then aged during which the cheeses are turned, common examples are Gouda and Edam.

Reason

The reasons for turning formed cheeses during air drying and aging are to:

  • During air drying to allow all surfaces of the cheese in early aging days to dry evenly and to minimize the cheese having a damp bottom and high risk of yeast infection developing on the bottom against the draining mat or board.
  • During aging to minimize gravity causing a lopsided pear shaped cheese resulting in:
    • Uneven moisture, fat, and protein distribution throughout the cheese and improper development of the cheese.
    • Aesthetically unpleasing cheese.

Method

When young and cheese is moist, as strong in compression, lift cheese from bottom and turn with hands, do not pinch and lift vertically as cheese is weak in tension and can crack. As cheese ages and looses moisture it generally has more tensile strength and can withstand more robust handling.

Frequency

If no turning schedule in recipe then turn after 2 hours, 6 hours, 12 hours, 24 hours, 3 days, 1 week etc.

Wiki: Dry Salting Rinds

Four 10 cm diameter Camemberts after dry salting.

This Wiki Article discusses dry salting cheese rinds, a procedure normally performed after forming the cheese and before air drying and aging. This salting method is commonly used with mold ripened cheeses such as Camembert & Brie and with washed-rind type cheeses. 

For the dry salt to be absorbed by the formed cheese, it must first dissolve and form a brine at the cheese’s surface after which it then diffuses into the cheese. As reviewed in the Wiki: Salt’s Function article, the % salt content in the type of cheese being made is critical. Thus it is important to understand the six main factors that control this method of salting cheese. 

Ambient Humidity

Soft rind dry salted type cheeses, are aged in high ~95% ambient humidity environment after dry salting. The high humidity is to prevent excessive evaporation of moisture from the surface of the cheese which would result in a dehydrated dense and tough rind being formed. Further these cheese types normally must remain with a high moisture content at their surface to enable their surface growth of molds, yeasts, and bacteria and in time their growth into the center of the cheese. 

For hard rinded cheeses, the ambient humidity is held relatively low @ 85% to encourage expelled whey to be evaporated resulting in a dehydrated surface layer of cheese, the start of the rind development process. Repeated applications of dry salt to hard rinded cheeses result in a steadily increasing dehydrated layer. 

Cheese Size

Four 10 cm diameter Camemberts after dry salting.
Four 10 cm diameter Camemberts after dry salting.

Generally, the cheese making procedure dictates the size of the formed cheese (good examples are generally uniform sized Camembert’s and Brie’s), and thus the procedures amount and method of applying the salt is matched to the size. 

However, if deviating in size of cheese, consideration should be given to the number of applications of dry salt and thus also the time to allow the cheese to reach it’s salt % content target range. 

Note, for large cheeses this becomes a problem because in time the build up of a dense hard layer from repeated dry salting the cheese’s surface will inhibit further salty brine uptake into the cheese and the dry salt will no longer be absorbed resulting in a cheese with sub-optimal % salt content. It is for this reason that large rinded wheels of cheese are often brine salted first, and then their rinds dry salted to i) reach the target % salt content and ii) to develop their hard rinds. 

Cheese Temperature

As with dry salting curds, the temperature of the cheese will be a controlling factor of the salt’s absorption rate. However their is ample time to absorb the salt while the fresh cheese is drying so this is not normally an issue and thus the temperature during dry salting more a function of the cheese’s drying and aging requirements. 

Salt Type

Standard sodium chloride, NaCl salt is used. It should be coarse granular sized rather than very fine to slow down the speed of dissolving into brine and absorption into the cheese. As with high temperatures, fine salt can result in a rapid flush of whey and fat which can wash away other salt before being absorbed resulting in incorrect salt % content of the cheese type being made. Different types of salt are discussed in the Wiki: Salt Types article. 

Salt Amount

As reviewed in the Wiki: Salt’s Function article, final salt content of the cheese type you are making is critical. Thus follow the cheese making procedure accurately on amount/weight of salt being applied versus weight of final cheese(s). If making several cheeses such as Camemberts in one make, ensure salt is allocated evenly. 

Salt Application

There are two salt application methods for dry salting rind cheeses: 

  1. For soft rind type cheeses, sprinkle measured amount of dry salt onto the whole rind including sides. Care should be taken to ensure the salt does not land off the cheese otherwise sub-optimal % slat content will be obtained.
  2. For hard rind type cheeses, rub dry salt onto the rind.

Wiki: Pressing Cheeses

Two 1.5-2 kg final cheese weight Kadova brand Gouda shaped pressing molds with formed mesh nets and mesh lined followers.

This article discusses pressing cheeses which is primarily performed on rennet coagulated lower moisture content aged cheeses after curds are prepared, (steps dependent on cheese type being made). Many cheeses have whey drained by gravity either by hanging the prepared curds in cheese cloth or by placing in a mold, these are not discussed in this article. Pressed cheese are in general pressed by placing the prepared curds in a cheese cloth lined hoop, on top of a draining mat, then placing a follower on top of the curds and then placing weights on top of the follower.

Pressing Goals

0.5 kg Gouda cheese pressing in homemade hoop and cloth bag shaped liner, expelled whey needs to be drained.
0.5 kg Gouda cheese pressing in homemade hoop and cloth bag shaped liner, expelled whey needs to be drained.

The goals of pressing the prepared curds are to:

  • Reform a large cheese shaped drier curd, normally without any voids.
  • To dehydrate the curd at the surface and form a tough rind that is less susceptible to unwanted micro-organisms.
  • To knit the curds into a homogeneous cheese.

Some cheeses when manufactured in large wheels such as Stilton are not externally pressed, but are effectively pressed under their own weight. Making smaller artisan or hobby sized wheels of these cheeses often requires light pressing. Some cheeses such as washed curd Gouda’s need only light pressure versus some like cheddar require high pressure to form a knit. However, Dutch cheese makers of old pressed their large wheels with high pressures not to form a knit but to form a very dry and hard environmentally resistant rind as they had poor control of the weather and thus poor control of their aging environment.

Hoops & Molds

In gravity draining whey from cheese, commonly a thin mold or hoop and mats are used. In pressed cheeses the form is often called a hoop as it was historically in the shape of a round hoop as that shape was better to withstand the sometimes high hoop stresses from the applied weights.

Inside a cloth liner was placed inside the hoop in hold the initially moist and soft curds, but modern manufacturing has enabled more heavy-duty mold type devices with integrated bottoms and form fitted mesh liners and lids.

Pressing Method

Two 1.5-2 kg final cheese weight Kadova brand Gouda shaped pressing molds with formed mesh nets and mesh lined followers.
Two 1.5-2 kg final cheese weight Kadova brand Gouda shaped pressing molds with formed mesh nets and mesh lined followers.

The following is the standard method for pressing cheeses, it will vary depending on hoop or mold type and on cheese type.

  1. A hoop, commonly with small holes to enable whey expulsion is placed on some sort of mat that additionally allows whey to flow out of the bottom of the cheese.
  2. Inside the hoop a cloth is placed to initially hold the curds so that they aren’t extruded out the holes.
  3. The prepared curds are placed in the cloth and a round disk-shaped “follower” placed on top of the curds.
  4. While pushing down on the follower, the cloth is pulled up straight all the way around the sides to minimize wrinkle-fold lines in the sides of the cheese.
  5. Initially a light weight is applied on top of follower to apply a light pressure. Going light at first gives the excess whey in the interior time to move out of the cheese before the curds at the edge are dehydrated effectively sealing the whey inside the cheese, a location for unwanted micro-organisms to grow. If heavy weight/high pressure was applied initially then i) the fresh very soft curd can be extruded up around the follower or out of weep holes if no liner is used, and ii) the curds at the surface would rapidly dehydrate forming a barrier to further whey expulsion.
  6. After a short period, the very sort formed single curd is removed from the cloth and turned and replaced. Again while pushing down on the follower pull the cloth up verticlly aroound the circumference of the formed curd and then apply a heavier pressure. This is to i) enable the previously top of cheese to also form a slightly dehydrated layer and ii) enable a more uniform shaped and moisture content cheese to be created, iii) to minimize the curds impregnating and sticking to the cloth, and iv) to minimize cloth wrinkle-fold lines on side of the forming cheese.
  7. The above step is repeated with steadily longer times between turnings and with steadily higher pressures, depending on the cheese type and recipe-procedure.

Notes:

  • Some cheese makers only use the cloth lining for the initial light pressings to minimize the cloth imprint around the sides of the cylinder during higher pressure pressings.
  • Some cloths are sewn to snuggly fit the inside of the hoop and thereby reduce ridge lines around the periphery of the cheese.

Presses

Final pressing two 4 lb Gouda's in Kadova Brand molds using stepladder and large bucket of paint as weights.
Final pressing two 4 lb Gouda's in Kadova Brand molds using stepladder and large bucket of paint as weights.

Presses range from the simple improvised (exercise hand weight, jugs of water, step-ladder balanced one end on the hoop) to highly leveraged or geared machines to modern pneumatic (air powered) machines and are the subject of a future separate article.

Tricks & Traps

Common tricks and traps in pressing cheeses are:

  • Sticking of the curds to the cheesecloth of hoops or to the mesh liner in some molds, this normally occurs when the curds pH is too low or when the weave is too coarse and the pressed curds are imbedded into the cloth. Solutions are to turn the cheese a few times in the first couple of hours to build up a good rind, use a tighter weave, and additionally if required to soak the cloth or nets with warm whey with addition of Calcium Chloride (warmth helps curds to knit) or to spray with a salt/vinegar/CaCl2 solution. If required the cloth liner can be additionally sprayed between cheese turnings while in the press.

Wiki: Breaking Or Cutting The Curd

Rennet coagulated cow's milk, starting to cut curd with bread knife Curd Cutter.

This article discusses how to break or cut the coagulated milk, a critical process in making cheese. When to break or cut the curd is discussed in the article Wiki: Curds, When to Cut.

When the milk first coagulates, it has a natural tendency to contract and expel whey. This property is called syneresis and it depends on several factors, the largest being surface area of the coagulum or curd. Small surface area versus volume of the coagulum results in slower and less whey expulsion, larger surface area results in faster/more whey expulsion. The purpose of cutting or breaking the curd is to increase it’s surface area and thereby increase it’s expulsion of whey and reduce the water content of the curds and in the final cheese.

Lactic Acid Coagulated Cheeses

Light Cream Cheese primarily lactic acid coagulated cow's milk, ladling in to muslin sock for gravity draining.
Light Cream Cheese primarily lactic acid coagulated cow's milk, ladling in to muslin sock for gravity draining.

Lactic acid coagulated cheeses commonly employ three different methods to break or cut the coagulum depending on cheese type:

  • Some cheeses such as Quark are broken by simply stirring the coagulum.
  • Some cheese such as Cream Cheese are ladled directly from the coagulum in the vat into the cheese cloth or molds without being cut or stirred.
  • Some cheeses such as Cottage Cheese are cut with wire knives similar to rennet coagulated cheeses.

Rennet Coagulated Cheeses

Rennet coagulum’s are normally cut into similar size particles, the size and shape varies depending on the type of cheese being made. Smaller cut curds generally result in drier cheese, larger in moister cheese. The cutting patterns listed below have been refined over centuries of cheese making to allow the right amount of whey to be expelled for that type of cheese. Ideally every curd particle is of the same size to:

  • Create a uniform cheese, large range in cut curd sizes will result in areas of high and low moisture content in the cheese. High moisture can result in sour or fermented areas.
  • Create uniform temperature among the cut curds, especially if cooking the curds. Different sized cut curds will heat at different rates resulting in different internal temperatures which will cause differing whey expulsion and acid production rates.

Method: Cubed Cutting

Rennet coagulated cow's milk, starting to cut curd with bread knife Curd Cutter.
Rennet coagulated cow's milk, starting to cut curd with bread knife Curd Cutter.

Cutting of the coagulum into cubes is the most common system and used for making many cheeses. Cut sizes range from 6-25 mm / 0.25-1 inch cubes, for example Cheddar normally requires 1 cm / 3/8″ cubes. To cut the cubes, commercial cheese makers normally use rectangular shaped Curd Cutters or Harps or Curd Knife with evenly spaced wires. Two of these tools are normally used, the first with horizontal wires to cut the coagulum into horizontal sheets, the second with vertical wires to cut vertically into horizontal square rods and then again vertically but at 90 degrees to create the cubes. Generally a cross-hatched grid curd cutter is only used for large sized cut curds, as for smaller it generally tears the curd into irregular sized pieces as the forces on the curd are too great.

These professional Curd Cutters are normally built to match the size and shape of the large volume vat. Home/hobby small scale cheese makers commonly use a large stockpot for their vat. For them, a common workaround is to use a long thin food grade object as a Curd Knife and:

  • First, slice the curd vertically into parallel even thickness sheets.
  • Second, slice the curd again vertically but perpendicular, at 90 degrees to the first row, resulting in vertical square rods of curd.
  • Third, slice a third row of cuts but at 45 degrees to the first two rows of vertical cuts and with the curd knife tilted at 45 degrees from vertical to form “diamond” shaped cut curds.
  • Fourth, a row of cuts at 90 degrees to the previous 45 degree row and with knife still tilted at 45 degrees, to fully and reasonably evenly form the cut curds.
  • Fifth, circle the knife around the edge of vat to detach cut curd from vat.

Common kitchen examples for a stockpot Curd Knife are: Bread Knife, Cake Knife, or Icing Spatula. Note, if the tool is too thick (like a metal cookie cooling rack) then the curd will be torn rather than cut.

Method: Rice Cutting

Rennet coagulated cow's milk rested 10 minutes after cutting into diamonds.
Rennet coagulated cow's milk rested 10 minutes after cutting into diamonds.

Drier type cheeses like Swiss normally have the coagulum cut into rice sized pieces using a “Spino” harp shaped tool. Often this is improvised in home/hobby cheese making by using a large metal whisk.

Method: Italian Cutting

An egg shaped device for Italian cheeses. Again, this is often improvised in home/hobby cheese making by using a large metal whisk.

Method: Partial Cutting

Camembert cheese making uses only parallel vertical cuts and sometimes 90 degree parallel vertical cuts resulting in long square rods of cut curd. This is normally done with a long single cutting knife or sword. The partially cut curd is then horizontally cut by a tool called a Pelle or with a flat ladle when removing the cut curds from the vat and placing them into the gravity draining hoops.

Wiki: Dry Salting Curds

Four 10 cm diameter Camemberts after dry salting.

This article discusses the five main factors that control the dry salting of curds method of salting cheese, curd size and temperature, and salt type, amount, and application method. Many cheese making recipes or procedures call for dry salting cut curds after cooking or washing and draining whey and before forming the cheese by placing the cut curds in molds to drain or in hoops for pressing.

US Made Morton Brand Non-Iodized Canning & Pickling Salt
US Made Morton Brand Non-Iodized Canning & Pickling Salt

As reviewed in the Wiki: Salt’s Function article the salt % content in the type of cheese being made is critical, thus it is important to understand the factors that control dry salting curds.

For salt to be absorbed by the curd it must first dissolve and form a brine at the cut curd surface after which it then diffuses into the curd.

Curd Size

Ideally you want all the curd pieces, whether cut or milled, to have the same size so that the same amount of salt is absorbed and the same amount of whey expelled, resulting in a uniform cheese.

Large curd pieces are of special concern as they will result in high moisture and low salt content which can result in sour and fermented defects.

Curd Temperature

Curd temperature during direct dry salting should be between 87-92°F/31-33°C.

Higher temperatures result in a higher flush of whey which will:

  1. Carry away salt before it can be absorbed resulting in the cheese having sub-optimal salt % content.
  2. Carry away excess fat resulting in a greasy/seamy texture.

Temperatures below this range can result in a limited flush of whey and thus a limited brine forming around the curd pieces resulting in lower, sub-optimal uptake of salt.

Salt Type

US made Morton brand 25 pound bag of non-iodized Table Salt with anticaking sodium silicoaluminate
US made Morton brand 25 pound bag of non-iodized Table Salt with anticaking sodium silicoaluminate

Salt types are discussed in the article Salt Type’s, A To Z. For dry salting curds, standard dry crystalline non-iodized no anticaking additive sodium chloride salt is used.

It should be coarse granular sized (not rock or kosher grain size salt) rather than very fine to slow down the speed of dissolving into brine and absorption into the curds. As with high temperatures, fine gained salt can result in a rapid flush of whey and fat which can wash away other salt before being absorbed resulting in incorrect salt % content of the cheese type being made.

Salt Amount

As reviewed in the Salt’s Function, A to Z article, final salt content of the cheese type being made is critical. Thus follow the cheese making procedure accurately on amount/weight of salt being applied versus weight of final cheese(s).

Salt Application Method

Generally, rather than in one large application, dry salt should be sprinkled onto cut or milled curds in several equal increments with gentle stirring or mixing in between. This is for the same reason as correct temperatures and coarse grained salt are optimal, to slow down the rate of salt absorption into the curds.

The gentle stirring or mixing helps to distribute the salty whey fully around the curd pieces rather than just where the salt is applied. Note, excessive or rough stirring is not recommended as it will result in smaller pieces of curds and a larger unwanted size distribution of the curds.

Two to three such increments spaced ~10 minutes apart are common. After the last salting, the curds should be allowed to rest for ~10 minutes to stabilize before proceeding to the next step in the cheese making procedure, normally forming the cheese.

Wiki: Ingredients, When To Add

Malaka Brand Vegetarian Liquid Rennet Retail Box - CheeseForum.org

This Wiki Article discusses the several common cheese making ingredients which can be added to milk at the start of the cheese making process before the curd is formed. It provides a short description, Order to add, Measuring, When Add, and Adding Method. Which ingredients to add and their amounts are cheese type – recipe specific and not discussed here. If your recipe and the recommendations below differ, follow the recipe. This article is to understand Typical cheese curd ingredients are:

  1. Cheese Base such as milk, cream, or whey.
  2. Milk Enrichers such as creams or milk powder.
  3. Starter Culture to ripen the milk by creating lactic acid and aid in coagulation.
  4. Colourants to change the cheeses colour from common default white.
  5. Lipase as a flavour augmentor.
  6. Calcium Chloride to aid in rennet coagulation if using store bought pasteurized milk.
  7. Rennet as a coagulant.

Cheese Base

  • Description: Milk, Cream, Whey
    • Can be from single or multiple animals
    • Can be from combination of raw and pasteurized.
  • Order: First as base for cheese and needs to be heated or cooled to recipe temperature before other ingredients added.
  • Measuring: Standard volume or weight measuring devices.
  • When Add: Start of cheese making.
  • Adding Method: Pour into cheese vat with minimal foaming to minimize oxidation of milk.

2 – Milk Enrichers

Common Household Kitchen Food Colourants - CheeseForum.org
Common Household Kitchen Food Colourants - CheeseForum.org
  • Description: Creams, Milk Powder.
  • Order: Second as normally diluted into cheese base.
  • Measuring: Standard volume or weight measuring devices.
  • When Add: Directly after placing cheese base in vat as need to adjust temperature before adding other ingredients.
  • Adding Method: Pour liquids and dry powder directly in cheese base in vat with minimal splashing or foaming to minimize oxidation of milk. Stir until additional fluid is fully diluted or powder is fully dissolved.

3 – Colourants

  • Description: Annatto or other food grade dyes, normally liquid.
  • Order: After cheese base and any enrichers to ensure good dilution, before Starter Culture is added to minimize stirring after adding. Can be added before or after Lipase or Calcium Chloride (if used).
  • Measuring: Small volumes by drops from an “eye dropper” bottle, larger with liquid measuring device.
  • When Add: While adjusting vat ingredients temperature to recipe requirement as Colourants are normally inert and not temperature sensitive.
  • Adding Method: Normally highly concentrated thus to ensure optimal dilution, pre-dilute in non-fluoridated water then trickle into vat from low height to minimize splashing then stir in with vertical strokes of perforated ladle to thoroughly dilute (unless want streaky coloured cheese in which case stir less). Some colorants will degrade rennets’ effect, thus ensure your dilution container is cleaned before using it to dilute rennet.

4 – Lipase

Danisco Brand Mild Calf Lipase, 16 Ounces - CheeseForum.org
Danisco Brand Mild Calf Lipase, 16 Ounces - CheeseForum.org
  • Description: Normally manufactured freeze-dried product.
  • Order: After cheese base and any enrichers to ensure good dilution, before Starter Culture is added to minimize stirring after adding. Can be added before of after Colourants or Calcium Chloride (if used).
  • Measuring: By volume as can be partially rehydrated depending on storage practices.
  • When Add: Preferably after adjusting vat ingredients temperature to recipe requirement as Lipase is minimally temperature sensitive.
  • Adding Method: Sprinkle freeze-dried into bowl of non-fluoridated water to rehydrate for 20 minutes. Then trickle directly into the milk then stir in vertically with perforated ladle just barely breaking surface to minimize splashing and foaming to full depth of vat for 1 minute to ensure optimal dilution.

5 – Calcium Chloride

  • Description: Normally diluted aqueous liquid.
  • Order: After cheese base and any enrichers to ensure good dilution, before Starter Culture is added to minimize stirring after adding. Can be added before or after Colourants or Lipase (if used).
  • Measuring: Liquid measuring device.
  • When Add: While adjusting vat ingredients temperature to recipe requirement as Calcium Chloride is inert and not temperature sensitive.
  • Adding Method: Normally highly concentrated thus to ensure optimal dilution, pre-dilute in non-fluoridated water then trickle into vat from low height to minimize splashing then stir in with vertical strokes of perforated ladle to thoroughly dilute (unless want streaky coloured cheese in which case stir less). Some colorants will degrade rennets’ effect, thus ensure your dilution container is cleaned before using it to dilute rennet.

6 – Lactic Acid Starter Culture

Danisco's Choozit Product Line, MM100, 250 Dose Mesophilic Lactice Acid Producing Starter Culture - CheeseForum.org
Danisco's Choozit Product Line, MM100, 250 Dose Mesophilic Lactice Acid Producing Starter Culture - CheeseForum.org
  • Description: Natural in milk, whey from previous cheese making, concentrated buttermilk, manufactured liquid or frozen or freeze dried. Mesophilic or Thermophilic or combination.
  • Order: After other ingredients and before rennet (if used) after which do not want to stir as break curd.
  • Measuring: Set of small volume measuring devices for liquids and a mini scale for solids.
  • When Add: After other curd ingredients added and before rennet added (if used) and vat materials are at recipe’s recommended temperature.
  • Adding Method: Pour liquid or frozen into vat minimizing any splashing or sprinkle freeze-dried directly onto the milk and allow to rehydrate for 5 minutes. Then stir in vertically with perforated ladle just barely breaking surface to minimize splashing and foaming to full depth of vat for 1 minute to ensure optimal dilution. Note, after diluted, do not stir (unless adding rennet) during ripening period as excessive aeration can reduce the rate of acid production resulting in longer ripening times required to get to the correct pH before renneting.

7 -Rennet

  • Description: Normally diluted aqueous liquid, tablet, or freeze-dried.
  • Order: After other ingredients as do not want to stir as break curd while curd is forming until correct point to break or cut curd.
  • Measuring: Set of small volume measuring devices for liquids and a mini scale for solids, pill cutter if need part of tablet for tiny batches.
  • When Add: After all other curd ingredients added and ripening time or pH drop after adding starter culture as determined by recipe.
  • Adding Method: Dilute or dissolve rennet in small amount of non-fluoridated water, then pour liquid into vat minimizing any splashing. Note, tablets can take up to 45 minutes to fully dissolve. Then stir in vertically with perforated ladle just barely breaking surface to minimize splashing and foaming to full depth of vat for 1 minute to ensure optimal dilution. Note, after diluted, do not stir during coagulation period until point to break or cut the single large curd. Note, some colorants will degrade rennets’ effect, thus use separated clean dilution container or colourant dilution container is cleaned before re-using to dilute rennet in.

Wiki: Coagulation

Rennet coagulated good quality curd, checking with finger Clean break method.

All cheeses use coagulation of the milk as an essential cheese making step. This articles discusses how coagulation works and the different types generally used in cheese making.

General

After acidification, the next step in making cheese is coagulation. Coagulation of milk is the first step towards concentration of milk’s casein and fat and expulsion of whey made up of water and milk’s soluble components. During coagulation the casein micelles form long chains that branch in all directions and bond with themselves forming a three dimensional matrix that encompasses and all the milk including fat and water. Cheese makers call this matrix the curd.

The process of coagulation occurs through two different mechanisms, primarily acid coagulation and primarily enzyme coagulation. Each method results in two very different families of cheese. To be literally correct, rennet is the historical name of the product from animals, but in cheese making rennet is the generic term for all types of enzymes, whether of animal, plant, microbial or fermentation origin, that are used to coagulate milk.

The most common method is enzyme or rennet coagulation as it produces a lower moisture content and longer shelf life curd without excessive hardening. Virtually all hard cheese are made using rennet coagulation.

Lactic Acid Coagulation

General

Primarily lactic acid coagulated curd from store bought cow's milk after sitting overnight.
Primarily lactic acid coagulated curd from store bought cow's milk after sitting overnight.

Several soft cheeses such as cottage cheese, quark, and traditional cream cheese use lactic acid coagulation which occurs as response to a reduction in pH from production of lactic acid by the starter culture. Pasteurization including Ultra Pasteurization and UHT milks are fine for making Lactic Acid cheeses, they will give a thicker lactic acid set curd than when using raw milk.

The procedure for setting is to add a precise amount of mesophilic starter culture to milk at a temperature of ~21°C / 70°F, much lower than for rennet coagulated cheese, although some recipes – procedures use warmer temperatures.

The starter culture causes lactose to be converted to lactic acid, lowering the pH with full coagulation into a solid curd occurring around a pH of 4.6 – 4.7. This can take 4 to over 24 hours, depending on the temperature and the amount and activity level of the starter culture.

The curd that is formed from lactic acid coagulation is much weaker than from rennet coagulation and the curd more strongly resists the expulsion of whey. Thus the resulting cheese is softer and higher moisture than rennet coagulated cheeses.

As the resultant cheeses are softer and moister, they have a shorter shelf life and are consumed young and thus in some countries such as USA, milk is required to be pasteurized for health reasons.

Milk Type

Primarily lactic acid coagulated curd using store bought chocolate flavoured cow's milk.
Primarily lactic acid coagulated curd using store bought chocolate flavoured cow's milk.

For lactic acid coagulated cheeses, when cow’s milk is used, it is normally pasteurized or skimmed otherwise cream will separate during the long incubation time resulting in an non-homogeneous curd. Whole non-homogenized cow’s milk is used but the whole curd must be re-worked to form a homogeneous mixture. Some cheese making recipes-procedures use both acid and rennet coagulation, here rennet is normally added in significantly smaller amounts than when rennet coagulating milk as it is added not to cause coagulation but rather to enable better whey separation and better curd formation, and thus less cream separation when using non-homogenized milk.

Conversely non-homogenized sheep and goat’s milk do not easily cream and thus there is less need for rennet addition or homogenization in lactic acid coagulated cheeses, however some recipes still call for the addition of small amounts of rennet when using sheep or goat’s milk for lactic acid coagulated cheeses.

If using rennet in lactic acid coagulated cheeses, the lower setting temperature than for rennet coagulated cheeses still allows the non-enzymatic phase of rennet coagulation but not the second enzymatic phase.

Rennet Coagulation

General

Rennet coagulated good quality curd, checking with finger Clean break method.
Rennet coagulated good quality curd, checking with finger Clean break method.

Rennet coagulation originally used enzymes from the lining of the fourth stomach of calves and from the stomachs of kid or lamb as they have these enzymes naturally in their stomach to better digest milk and as that was what was commonly available. There are two prime enzymes in these stomachs that coagulate milk, initially chymosin and later after weaning, pepsin. It is the chymosin enzyme that is the stronger milk coagulant. Since the 1990’s other forms of “rennet” (fermentation, microbial) have been made.

Rennet coagulation is a two stage process involving an initial enzymatic phase during the first ~10 minutes where a chemical change is occurs as preparation for second non-enzymatic phase where the casein micelles start forming linked chains and eventually a full solid curd is formed, if enough calcium is present.

Rennet is discussed in detail in Wiki: Rennet, different types of rennet are discussed in Wiki: Rennet Types.

Milk Preparation

Milk is warmed to optimum rennet coagulation temperature of 30-36°C / 86-96°F. Higher temperatures up to ~40°C / 104°F result in faster coagulation times. Above 40°C / 104°F and the rennet becomes inactivated. Lower temperatures result in slower coagulation, below ~18°C / 65°F coagulation will not occur.

Starter culture, CaCl2, lipase, colourants such as Annatto and flavor additives must be added to the milk before renneting so that they are incorporated evenly in the curd. See Wiki: Ingredients, When To Add.

Other additives such as dill weed, caraway or cumin seeds, or smi dried fruit like apricots can be mixed in later, normally after the curd is cut and whey is drained.

Note, many rennet coagulated cheese making procedures have a pre-ripening time of up to 1 hour after adding the starter culture and before adding rennet.

Adding Rennet To Milk

Rennet coagulated store bought cow's milk curd, after diamond cutting, imprint of bowl from spinning bowl flocculation test.
Rennet coagulated store bought cow's milk curd, after diamond cutting, imprint of bowl from spinning bowl flocculation test.

Rennet is very concentrated, so adding it directly to the milk would cause it to set the milk in just that area and not in the overall milk. Even if one stirred it after adding directly, it would still coagulate in areas resulting in a poor curd formation. Therefore the common method of adding rennet is to first dilute / dissolve in cool non-chlorinated water before adding to the milk. Dilution amounts are discussed in the Animal Based Rennet webpage.

Best practices for rennet preparation and addition are:

  1. When ready to add rennet, dilute or dissolve rennet in cool un-chlorinated water. Chlorine is a strong oxidizing agent and rapidly destroys the rennet enzymes.
  2. Trickle the diluted rennet into the milk while stirring the milk with a skimmer for a maximum of 60 seconds in an up and down method without breaking to surface (no splashing). Do not dilute rennet in advance of adding to milk as its strength deteriorates when diluted.
  3. Stop the swirling of milk after stirring with skimmer to enable better coagulation.