The extensive and some times over use of cleaners and sanitizers can sometimes cause them to be found in the milk.   Previously, only chlorine sanitizers were used and seldom did they do any harm to production, as they were inactivated in the milk during storage.    The milk has to contain high concentrations of chlorine sanitizers before noticeable changes in the milk, and before acid production ability is affected.  The appearance of different types of disinfection agents has on the other hand been much more annoying for cheese production, by being more harmful to acid development.    The Danish Government Dairy Research Plant reports that when investigating 4 different types of quaternary ammonium compounds, addition of only 0.0002 - 0.005% of these to milk has shown a reduction in acid production (aroma-bacteria are even more sensitive - E. Skovmose/Voss Trials).    Rapid detection of these compounds in the milk must be in place.  Chlorine sanitizers are easily detected with the help of the Wodes test and the same is the case with hydrogen peroxide, but today fairly simple methods to determine quats in milk are also available.    Antibiotic   Antibiotics can easily be determined in milk.  Testing equipment under brand names of Charm, Penzym and others are today used for testing milk to ensure that milk is free of any antibiotics before cheese making.   Bacteriophage                                          Plants must gear themselves to a higher standard of hygienic conditions, if they wish to avoid bacteriophage infection.    The whey should, under all circumstances, be pasteurized to kill lactic acid, bacteria (the bacteriophage' hosts).    Whey and cheese milk should not be treated in the same HTST heat treatment system.  (But, if necessary, always finish all milk before running whey.)   If the whey tank is in the basement, and the whey is drained directly into it, air must not be allowed to escape into the cheese room.  Whey spills on the floor, etc., should be avoided and the floor should be rinsed with chlorine sanitizer several times a day and disinfected carefully after work has been completed.  Grouting should be carefully maintained.  Waste water spraying and other treatment of waste water should be done as far from the cheese plant as possible.    Personal hygiene should be accommodated by having easy access to disinfectant and sanitizers, e.g. iodophore and chlorine sanitizers.   Hands and arms should always be sanitized before handling any food and room temperature should be at a comfortable level to avoid sweating, which could contaminate products. This all promotes better work.

Cheese starter should be propagated in a special room where utmost consideration is taken to avoid infection.  The cheese make room is the wrong room in which to place the culture tank.