this is Coliform Bacteria
this problem is found in the cheese manufacturers which use raw milk and it is a hygiene problem
and if your milk is infected you can not do anything (personally I throw because is not freindly bacteria)
the time of their Appearance depends on the initial quantity in milk
a high rate of coliform = rapid swelling
low levels of coliform = late swelling
-there are three type of perforate early 1-Coliform
The group of the bacteria coliformes understands several species of which Escherichia coli, Klebsiella pneumoniae…
For example, among the principal stocks of Camembert cheeses to believed milk, one finds Hafnia alvei, Escherichia coli, Enterobacter cloacae and Serratia liquefacians.
They have the property to ferment lactose what involves the production of acids, alcohols and gas
The early swelling (holes observed in moulded curd and cheeses) which can result from this is due to the carbonic gas formation but especially to that of hydrogen which has a very low solubility in cheese.
The acetic acid causes a sour, unpleasant odor. Certain stocks of coliformes produce only very little gas, such as for example, E.coli.
The more massive the contamination will be, the more swelling will be early.
They are normal hosts of the digestive tract of the man and warm-blooded animals from 100,000 to 1 million germes/g of deposit).
One also finds them in the ground, the water surface and used, dust, the plants, mud….
One generally distinguishes the “fecal coliformes”, coming from the instestins of the man and the animals, and the “nonfecal coliformes” of the environment.Remedies:
search the nests of the contamination on all the circuit of milk. This will pass by:
to check general hygiene
to dismount the milking machine and the circuit of milk
check the state of “cleanliness” of the udders and the litters
check the cleaning of the equipment of cheese factory (attention to often failing descaling).
limit the air intake during the installation and deposits claws during the draft
They are characterized within the lactic bacteria by their metabolism hétérofermentaire: they produce lactic acid, CO2 and ethanol starting from lactose of milk.
They are bacteria mésophiles. Their optimal temperature of growth is of 18°à 30°C. Their minimal temperature of growth is of 5°C, that maximum is of 40°C. They do not develop with 45°C. They produce CO2, ethanol, lactic acid (D).
Their optimal pH of growth is from 6.3 to 6.5.
They are not able to acidify in pure culture and to produce gas below pH = 5.
They produce gas beyond 10 6 to 10 7 UFC/g.
They have a great aptitude to form biofilms with production of gelatinous substances.
They are able to produce active bactériocines against unquestionable pathogenic.
Species: Ln. mesenteroides, Ln. dextranicum, Ln. lactis, Ln. cremoris.
Degradation of lactose by the leuconostocs: 1 lactose molecule = 2 molecules of lactic acid + CO2 + ethanol + acid acetic.Remedies:
change the whey
decrease the temperature by two degrees (until 18°C) on fast profile of acidification,
take rather the whey with 50°Dornic nine hours after emprésurage in order to use it for the following manufacturing you can store the whey with 4°C during 2 days before using it
stop cold pre-maturations (10-14°C during 12-14 hours) you can use leavens commercial 100% homofermentaires in lactic technology,
turn over cheeses moulds some as soon as possible (3 hours after moulding): this will limit the gas formation3-yeast
( The most important species met in the dairy products are: Kluyveromyces lactis , Kluyveromyces marxianus , Candida famata , Candida versatilis. As for Geotrichum candidum, it is classified like mushroom levuriforme, i.e. which it is intermediate between yeasts and the moulds. )
In the dairy products, 4 species (K. lactis, K. marxianus, Candida famata and C. versatilis) are able to ferment lactose. This fermentation involves the formation of made up of flavours (odor of yeast, of apple) and of CO2 (formation of holes).
Moreover, the production of alcohol can give an alcoholic odor which is found sometimes when the cheeses are confined.
They can colonize the ground, the air, water and more particularly water polluted, the ensilages, and develop on the skin of the man and the animals, in their digestive system or respiratory and be isolated from their excrements.
They belong to the normal flora of raw milk.Remedies:
cleaning and disinfection of all equipment
find an atmosphere of healthy milking
limit grain dust during milking
storing milking equipment in a well ventilated area and clean
think descaling equipment including cheese molds (acid cleaning)