Microbiology of Fermented Food Production ◾ 185
produce extracellular lipases and proteinases and cause lipolysis and proteolysis during curing.
Fatty acids are both oxidized and reduced to produce methyl ketone and d-lactone, respectively.
These, along with volatile fatty acids, contribute to the sharp flavor of blue cheese.
The desired genotypes of the lactic acid bacteria starters used have been previously described.
A white variant of the mold has been isolated and used to produce this cheese without the blue
mottled color. Pen. roquefortii strains that produce mycotoxins have been identified. Strains that
do not produce mycotoxins need to be selected. Ripening for a long time can lead to formation of
biologically active amines from some amino acids (e.g., histamine from histidine).
Accelerated Cheese Ripening 8
During curing of hard and semihard cheeses, milk components are degraded through enzymatic
(from starters and secondary flora) and nonenzymatic reactions. This is necessary to develop a
desirable flavor of these cheeses. However, because of a long storage time, it is not quite economical. Thus, methods are being studied that will speed up the ripening process. Some of these methods are briefly described.
Curing at High Temperature
Because enzymatic (also nonenzymatic) reactions increase as the temperature is increased, studies were performed to cure cheese above the usual 5°C–6°C (40°F). Ripening some cheeses at
13°C–16°C (55°F–61°F) reduced the curing time by 50% or more. However, at higher temperatures, growth of spoilage bacteria has been a problem in some cheeses, and there is some concern
about the growth of foodborne pathogens.
Addition of Enzymes
As intracellular enzymes of starters have an important role in curing, enzymes obtained from
cell lysates of starter-culture bacteria have been added to increase the rate of curing. In Cheddar
cheese, the curing time has been substantially reduced but has resulted in bitter flavor.
Slurry Method
Cheddar cheese slurry has been prepared by mixing water with cheese to 40% solids (in place of
the usual 60%). The slurry is incubated at 30°C for 4–5 days with agitation. This method increases
the flavor greatly and the product can be used to make processed cheeses. The major disadvantages
are the inability to properly control the enzymatic reactions to produce uniform products and possible growth of spoilage and pathogenic bacteria.
Novel Methods
In recent years, application of a suitable bacteriocin (of lactic acid bacteria) to cheese and exposing
cheese to high hydrostatic pressure to lyse the cells of starter cultures are being studied to enhance
ripening by the released intracellular enzymes.
produce extracellular lipases and proteinases and cause lipolysis and proteolysis during curing.
Fatty acids are both oxidized and reduced to produce methyl ketone and d-lactone, respectively.
These, along with volatile fatty acids, contribute to the sharp flavor of blue cheese.
The desired genotypes of the lactic acid bacteria starters used have been previously described.
A white variant of the mold has been isolated and used to produce this cheese without the blue
mottled color. Pen. roquefortii strains that produce mycotoxins have been identified. Strains that
do not produce mycotoxins need to be selected. Ripening for a long time can lead to formation of
biologically active amines from some amino acids (e.g., histamine from histidine).
Accelerated Cheese Ripening 8
During curing of hard and semihard cheeses, milk components are degraded through enzymatic
(from starters and secondary flora) and nonenzymatic reactions. This is necessary to develop a
desirable flavor of these cheeses. However, because of a long storage time, it is not quite economical. Thus, methods are being studied that will speed up the ripening process. Some of these methods are briefly described.
Curing at High Temperature
Because enzymatic (also nonenzymatic) reactions increase as the temperature is increased, studies were performed to cure cheese above the usual 5°C–6°C (40°F). Ripening some cheeses at
13°C–16°C (55°F–61°F) reduced the curing time by 50% or more. However, at higher temperatures, growth of spoilage bacteria has been a problem in some cheeses, and there is some concern
about the growth of foodborne pathogens.
Addition of Enzymes
As intracellular enzymes of starters have an important role in curing, enzymes obtained from
cell lysates of starter-culture bacteria have been added to increase the rate of curing. In Cheddar
cheese, the curing time has been substantially reduced but has resulted in bitter flavor.
Slurry Method
Cheddar cheese slurry has been prepared by mixing water with cheese to 40% solids (in place of
the usual 60%). The slurry is incubated at 30°C for 4–5 days with agitation. This method increases
the flavor greatly and the product can be used to make processed cheeses. The major disadvantages
are the inability to properly control the enzymatic reactions to produce uniform products and possible growth of spoilage and pathogenic bacteria.
Novel Methods
In recent years, application of a suitable bacteriocin (of lactic acid bacteria) to cheese and exposing
cheese to high hydrostatic pressure to lyse the cells of starter cultures are being studied to enhance
ripening by the released intracellular enzymes.