Wiki: Surface Defects, Mold

Two 4 pound Gouda's with Canola oiled rinds, one with blue surface mold, second after brush and water cleaning.

Surface mold defects of cheese are normally cheese type dependent. Molds are common micro-organisms and some are intentionally used in cheese making for their effect on texture and flavour such as white for Camembert and blue for Blue cheeses. This wiki article is not for those but for molds on the surface of cheeses which result in unwanted textures or flavours, their common colour, causes and solutions. 

Blue-Green

Two 4 pound Gouda's with Canola oiled rinds, one with blue surface mold, second after brush and water cleaning.
Two 4 pound Gouda's with Canola oiled rinds, one with blue surface mold, second after brush and water cleaning.

Description

  • Blue to green colour on surface of cheese.

Causes

  • Contamination by airborne Penicillium rocqueforti mould commonly intentionally used in making blue type cheeses due to high humidity. Not dangerous, but visually unappealing when unwanted.

Solutions

  • Wipe or brush off of cheese and rub rind with mixture of vinegar and dry salt. Lower aging humidity and ensure that area is clean and cannot harbor mould.

Black

Description

  • Black colour on surface of cheese.

Causes

  • Contamination by airborne Mucor or pin mould due to high humidity. Not dangerous, but visually unappealing.

Solutions

  • Wipe or brush off of cheese and rub rind with mixture of vinegar and dry salt. Lower aging humidity and ensure that area is clean and cannot harbor mould.

Brown

4 pound Havarti with good white Geotrichum candidum mold and unwanted brown mold on rind.
4 pound Havarti with good white Geotrichum candidum mold and unwanted brown mold on rind.

Description

  • Brown colour on surface of cheese.

Causes

  • Contamination by airborne mould due to high humidity. Not dangerous, but visually unappealing.

Solutions

  • Wipe or brush off of cheese and rub rind with mixture of vinegar and dry salt. Lower aging humidity and ensure that area is clean and cannot harbor mould.

Pink

Description

  • Pink colour on surface of cheese.

Causes

  • More common in Penicillium candidum (white mould) cheese when aging area’s humidity is too high, reduce humidity.

White

2 kg Havarti with good white Geotrichum candidum surface mold.
2 kg Havarti with good white Geotrichum candidum surface mold.

Description

  1. White coloured powdery mold on surface of cheese. Smells earthy like sweet smelling root cellar with faint hints of fermentation.
  2. White fuzzy mold like on Camembert & Brie.

Causes

  1. Normally from Geotrichum candidum and actually a good protective mold but included in this article for completness.
  2. Normally from Penicllium candidum and normally only wanted on white bloomy type rinds such as Camemberts and Bries.

Solutions

  1. None, do not remove as good mold.
  2. Wipe or brush off of cheese and rub rind with mixture of vinegar and dry salt. Lower aging humidity and ensure that area is clean and cannot harbor mould.

Wiki: Surface Defects, Oily

This Wiki article discusses surface normally unwanted oily defects of cheese. Note that oily rinds is a common side product in Swiss type cheese making where those cheeses are held at room temperature for part of their riping to create the eyes in the cheese. Oily rinds are normally associated with rennet coagulated pressed cheeses but can appear on other cheeses types. This article discusses the description, cause (normally ripening at excessive temperature), and solutions to oily surfaced cheeses.

Description

  • Surface layer of cheese has small beads of oil on it.

Cause

  • The most common cause is cheese is being ripened at too warm a temperature or fat content of milk is high and milk fat is seeping or sweating out which if left unattended can result in contamination.

Solution

  • Wash rind with warm water to remove excess oil and age at cooler temperature.

Wiki: Surface Defects, Yeast

Surface yeast defects of cheese are normally cheese type dependent. Yeasts are common micro-organisms and some are intentionally used in cheese making for their effect on texture and flavour such as smear ripened cheeses. This article is not for those but for yeasts on the surface of cheeses which result in unwanted textures or flavours, their common causes and solutions, sorted by root problem.

Description

  • Typical excessive yeast smell is like rising uncooked bread or fermenting beer or wine and taste can be bread flavour.
  • Yeasts are common in the wild and in raw milk.

Excess Moisture

  • Most unwanted yeasts on surface cheeses are caused by air born wild yeasts fermenting on an excessively moist surface of a cheese.
  • One common location of excessively moist cheese surface is the bottom or the side against the mat or board. The cause is normally not turning the cheese frequently enough allowing excess moisture to build on the bottom or not providing a breathable mat or board, for example drying a cheese directly on an impermeable plate versus on well ventilating mats or breathable wooden boards.
  • A second common location of excessively moist cheese surfaces is all over the cheese if the cheese is in a sealed closed container without airflow and 100% humidity which also invites unwanted molds but enables yeasts to dominate as molds need oxygen to grow. The solution is correct humidity during aging.
  • Yeasts are remarkably resilient and once established, their removal is difficult, washing with vinegar will not remove them as it can only lower the pH to ~3.
  • Recommended treatment is to:
    1. Remove yeast contaminated curd with brush.
    2. Wipe the rind with vinegar then dry the surface of the cheese.
    3. Wipe rind with distillers alcohol then dry the surface of the cheese.
    4. Rub rind with salt then remove excess dry rind.
    5. Oil the rind.

Wiki: Surface Defects, Cracks

1 lb Gouda, Surface Stress Cracks After Rapid Surface Dehydration From Aging In Dry Household Fridge One Night - CheeseForum.org

Surface crack type defects of cheese can be many and are cheese type dependent. This article explores the common surface crack defects, their common causes and solutions, sorted by root problem. But first the description.

Defect Description

1 lb Gouda, Surface Stress Cracks After Rapid Surface Dehydration From Aging In Dry Household Fridge One Night - CheeseForum.org
1 lb Gouda, Surface Stress Cracks After Rapid Surface Dehydration From Aging In Dry Household Fridge One Night - CheeseForum.org
  • Single or multiple cracks in surface of pressed cheese ranging from small to large fissure depending on severity.
  • Unknown in unpressed cheeses.

Rapid Drying

Cause

  • Most common is drying a natural rind of a pressed cheese in an aging environment’s where the humidity is far too low. Common examples are in post pressing air drying phase or if trying to age in a very low humidity environment such as uncovered in a cold household forced air style fridge. The rapid dehydration of the cheese results in rapid shrinkage of exterior, but not interior of cheese resulting in high tensile stress in surface of cheese and compression of interior of cheese somewhat like a football but to  lower extent. As cheese has lower tensile than compressive strength, the cheese surface eventually tears or cracks to partially relieve the stress. The cracks become progressively larger if humidity is not corrected. High moisture content fresh pressed cheeses such as washed curd Gouda’s are more susceptable to this than low moisture content fresh pressed cheeses such as Parmesan due to the higher possible moisture content differential between surface and interior.

Solution

  • The short term solution is not to seal i.e. by waxing but to reasonably heal the cracks. This is done by minimizing further dehydration and enabling the moisture content of the cheese to re-equalize between surface and middle to relieve the stress within the cheese enabling the crack(s) to mostly heal. This can be done by placing the cheese in a high humidity environment, an example are placing on a mat on a board or plate and placing a lid such a bowl over top to mostly seal the humidity in. Normally the cheese will still be giving off enough moisture that providing extra humidity from a bowl of water etc is not required. Note, during this healing period ensure that humidity is not 100%, i.e. condensation, puddling of water, otherwise normally unwanted surface molds will be activated. Another additional option is to semi-seal the exterior of the cheese but not the internal cracks by rubbing exterior with oil which will develop a firm not soft or sticky rind.
  • The longer term solution is, for future cheese making, to develop a better humidity control system.

Curds Too Cold

2 kg Gouda, Surface Stress Cracks From Rapid Dehydration From Low Humidity Environment, Partially Closed After 1 Day Under Bowl - CheeseForum.org
2 kg Gouda, Surface Stress Cracks From Rapid Dehydration From Low Humidity Environment, Partially Closed After 1 Day Under Bowl - CheeseForum.org

Cause

  • If making cheddared (stacked and milled) type cheese, curds may have become too cold causing uneven texture.

Solution

  • Short term solution is if cheese is straight out of press, to repair cracks, seal the cheese in 65C / 150F water for 1 minute.
  • Longer term solution is, for future cheese making, to ensure stacked curds are kept warm.

Brine Too Acidic

Cause

  • If making cheeses that require a brine bath such as Washed Curd type cheeses (i.e. Gouda, Edam), if brine is too acidic, the bathing cheese will have a pH shock which can result it small series of cracks all over rind.

Solution

  • Short term solution is to remove cheese from brine, let air dry in high humidity environment as described above, then when cracks reasonably healed, continue brining with pH adjusted to ideal 5.5-5.6.
  • Longer term solution is, for future cheese making, ensure brine pH is in optimal range.

Cheese Cloth

0.5 kg Cheese After Pressing, Surface Ridges From Cheescloth Lined Hoop, Cloth Too Thick & Improperly Pulled - CheeseForum.org
0.5 kg Cheese After Pressing, Surface Ridges From Cheescloth Lined Hoop, Cloth Too Thick & Improperly Pulled - CheeseForum.org

Cause

  • Pressing cheeses is often performed using a cheese cloth sheet lined hoop to hold the soft curds during pressing. Folds in cloth due to using sheet in shape of cylinder result in indented grooves or “wrinkles” in pressed cheese. This problem is more prnouced in small versus larger cheeses due to geometry.

Solution

  • First, ensure cloth is thin, not thick to minimize indent grooves.
  • Second, during initial light pressing’s, cloth should be pulled vertically straight up around perimeter while holding follower down to ensure cloth is vertical and minimal around cheese or alternatively, sew cloth into a cylinder shape to match size of hoop to reduce excess cloth around periphery, use with seams facing outward.
  • Third, after initial pressings, curds should have started to knit, for subsequent heavier pressings, remove the cloth liner.

Poor Knitting

Cause

  • In pressed cheeses, if the curd wasn’t fully knit during pressing, subsequent drying can cause shallow cracks all over the surface of the cheese. One cause of poor knitting is under-pressing.

Poor Handling

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

Cause

  • Pressed type cheeses during and after pressing are commonly still moist and heavy with little tensile strength. Improper handling such as pinching /squeezing around periphery to lift the cheese can result in closed cracks in surface of cheese.

Solution

  • Lift cheeses from bottom as they are much stronger in compression from their own weight than in tension.