Sanitation in milk plant

SANITATION IN MILK PLANT

Sanitation implies the destruction of all pathogenic and almost all non athogenic micro organism

Definitions for Sanitizing Terms

  • Antiseptic - an agent used against sepsis or putrefaction in connection with human beings or animals.
  • Disinfectant - an agent that is applied to inanimate objects; it does not necessarily kill all organisms.
  • Sanitizer - an agent that reduces the microbiological contamination to levels conforming to local health regulations.
  • Germicide - an agent that destroys microorganisms.
  • Bactericide - an agent that causes the death of a specific group of microorganisms.
  • Bacteriostat - an agent that prevents the growth of a specific group of microorganisms but does not necessarily kill them.
  • Sanitization - the process of reducing microbiological contamination to a level that is acceptable to local health regulations.
  • Sterilization - the process of destroying all microorganisms.

The premises surrounding the dairy plant shall be kept in a clean and orderly condition, and shall be free from strong or foul odors, smoke, or excessive air pollution. Construction and maintenance of driveways and adjacent plant traffic areas shall be of cement, asphalt, or similar material to keep dust and mud to a minimum.

A suitable drainage system shall be provided which will allow rapid drainage of all water from plant buildings and driveways including surface water around the plant and on the premises, and all such water shall be disposed of in such a manner as to prevent an environmental or health hazard.

The immediate surroundings shall be free from refuse, rubbish, overgrown vegetation, and waste materials, to prevent harborage of rodents, insects, and other vermin.


Detergent should have the following desirable properties :

  • Wetting and penetrating power
  • Emulsifying power
  • Saponifing power
  • Deflocculating power
  • Sequestrating and chelating power
  • Quick and complete solubility
  • Should be non corrosive to metal surfaces.
  • Free rinsing.
  • Economical
  • Stability during storage
  • Should be mild on hands
  • Should possess germicidal action.

Dairy detergents broadly classified into 4 different groups:

  • Alkalies :Sodium hydroxide, Sodium bi carbonate, Sodium phosphates, Sodium silicate/sulphite etc.
  • Acids :Mild-Phosphoric, Tartaric, Citric, Gluconic. Mild acids can be used for milk stone removal. Strong-Nitric.
  • Polyphosphates and chelating chemicals :These are used together withacids and alkalis. Examples Tetraphosphate, Hexa meta phosphate, Tri poly phosphate, Pyrophosphate etc
  • Surface active/Wetting agents: These are used either alone or in conjunction with acids or alkalies. Examples-Teepol, Acinol N, Idet-10, common soaps etc.

Principles of cleaning and sanitization

  • Cleaning or washing of dairy equipment implies the removal of soil from the surface of each machine.

Sanitization or sterilization

  • Implies the destruction of all pathogenic and all most all non pathogenic micro organisms from the surface of the equipment.
  • Detergent s are the substances capable of assisting cleaning.
  • Sanitizers are substances capable of destroying all pathogenic and almost all non pathogenic micro organisms.

Principles of cleaning and sanitization

  • In the selection of any particular detergent consideration should be given to type of soil, quality of water supply, material of surface and the equipment to be cleaned and method of cleaning viz., soaking, brushing, spraying and or re circulation
  • Heat is most reliable sanitizer especially when both temperature and time are controlled. Thus effective sanitization can be done by steam (15psi / 5 minutes or 0 psi / 15 minutes) or scalding water (90 – 950C/10 minutes)
  • Drainage: To remove any residual loose milk and any other matter
  • Pre rinsing: With cold or hot tap water to remove as much milk residue and other matters as possible
  • Warm to hot detergent washing: With detergent solution of 0.15 to 0.60% alkalinity to remove the remaining milk solids.
  • Hot water rinsing: To remove traces of detergents
  • Sanitization: To destroy all the pathogenic and almost all the non pathogenic MO.
  • Drainage and drying: To prevent bacterial growth and corrosion. Drying readily accomplished by heat and ventilation.


Dairy detergents

Alkalies

  • NaOH
  • Na2CO3,
  • Sodiumphosphate
  • Sodium bi carbonate, Sodium silicate
  • Strongalkalies saponify the fat
  • Weak alkalies dissolve protein

Acids

  • Tartaric, phosphoric, citric, gluconic and nitric acids
  • Mild acids used to remove milk stone
  • Strong acids should not be used at more than 1%

Polyphosphates and chelating agents

  • Tetraphosphate
  • Hexametaphosphate
  • Tripolyphosphate
  • Pyrophosphate
  • All are used along with acids and alkalies

Surface active or wetting agents

  • Teepol
  • Acenol – N
  • Idet – 10
  • Common soap
  • Used alone or in conjunction with acids and alkalies

Sanitizers

  • Non toxic
  • Quick acting
  • Relatively non corrosive to hands and equipment
  • Easily and quickly applied
  • Relatively in expensive

The commonly used dairy sanitizers are steam, hot water and chemicals like chlorine compounds, iodophor and quaternary ammonium compounds. The methods of chemical sanitization broadly consists of flushing, spraying, brushing, fogging and submersion

Name of the sanitizer

Mode of action

Chlorine compounds like chlorine gas, chloramines-T, hypochlorites, hexachlorophenol, dichloroisocyanic acid and trichloroisocyanic acid

Cl2 + H2O ------ à HOCl + H+ + CH­­­­-

HOCl is highly bactericidal

Nascent H+ destroys microbes by inhibiting enzymic reactions and glucose oxidation

Iodophors like iodine

Acts through halogenation and oxidation of sulphhydral groups. Dissociation of iodine from the surfactant is responsible for bactericidal action

Quaternary ammonium compounds like acetyl trimethyl ammonium bromide

Acts on cell membrane causes disintegration and denaturation of proteins essential for growth and metabolism. Inactivates special enzyme system essential for respiration of cells.

Methods of cleaning dairy equipment: These include hand washing, mechanical washing and Clean – in – place or CIP method.

Hand washing

  • Prepare 0.8 to 1.0% of detergent mixture in tap water so as to give a minimum alkalinity of 0.5% in a wash up tank and maintain the temperature at about 500C
  • Thoroughly rinse the utensils with clean cold water
  • Introduce the detergent solution in to the equipment thoroughly brush the equipment surface, inside and out side with a clean can brush
  • Wash the utensils with enough fresh cold water using a clean brush again if needed to remove all traces of detergents
  • Allow the equipment to drain thoroughly and let it dry for at least one or two hours
  • Sanitize the equipment surface by steam or hot water after cleaning and or by rinsing with chlorine solution (200 ppm available chlorine) just before using

Mechanical washing: This consists mainly of can and bottle washing

  • Can washing
    • Drainage stage for liquid milk residue
    • Pump-fed pre rinsing with cold or Luke warm water
    • Drainage stage
    • Pump fed jetting with detergent at not less than 700C
    • Drainage stage
    • Rinsing stage – Pump fed or by steam and water ejector at not less than 880C
    • Final fresh water rinsing with steam and water ejector at 88 – 930C
    • Live steam injection
    • Hot air drying at 95 – 1150C
  • Bottle washing
    • Pre rinse using water at 32 – 380C
    • Detergent wash usually with 1 – 3 % caustic soda together with chelating and wetting agents, given preferably in two stages at different temperatures with in 60 – 750C. Sanitize the bottles as well
    • Warm water rinse: To remove all traces of detergents. Reduce the bottle temperature for next stage. Water temperature varies from 25 – 450C and is usually re circulated.
    • Cold water rinse: Normally re circulated chlorinated water (containing 35 to 50 ppm available chlorine) is used to prevent re contamination of bottles
    • Draining after the bottles come out of the machine

Cleaning – in – place: This refers to that system of cleaning and sanitization which does not require the daily dismantling of dairy equipment.

  • Pre rinse with cold water till discharge water runs clear
  • Acid rinse with phosphoric acid solution of 0.15 to 0.60% acidity, re circulated at 65 to 710C for 20 to 30 minutes (wetting agent may be added to increase cleaning ability)
  • Drain out acid solution
  • Hot water rinse with water at 65 to 71ºC for 5 to 7 minutes. Rinse water should drain out
  • Alkali rinse with alkali detergent solution of 0.15 to 0.60% alkalinity, re circulated at 65 to 710C for 20 to 30 minutes (wetting agent may be added to increase cleaning ability)
  • Drain out alkali solution
  • Final hot water rinse with water at 71 to 820C till the whole system has been heated. Rinse water should be drained out.

Merits of CIP system

  • Ensure that all equipment receives uniform heat treatment day after day by eliminating the human factor
  • Less damage to equipment
  • Saving of total clean up costs and in man hours
  • Reduces possibility of contamination through human error
  • Improved plant utilization and appearance

Success factors

  • Proper selection of pipes and fittings, installation and development of circuits
  • Proper temperature of cleaning solution
  • Adequate velocity of cleaning solution
  • Use of detergents designed specifically for re circulation cleaning
  • Proper concentration of detergent solution
  • Sufficient cleaning time

Merits

  • Eliminates the human factor
  • Less damage to equipment
  • Time saving
  • Reduces the possibility of contamination through human error
  • Improved plant utilization and appearance

Types of CIP systems

  • Manual control
  • Automation
    • Low level
    • Medium level
    • High level

Cleaning is the process of removing food and other types of soil from a surface, such as a dish, glass, or cutting board. Cleaning is accomplished using a cleaning agent that removes food, soil, rust stains, minerals, or other deposits.

Last modified: Tuesday, 19 June 2012, 7:03 AM