Cleaning Methods and Considerations

i. Methods

The following methods may be employed for cleaning of dairy equipment and containers:

Manual Cleaning: It is the removal of soil by scrubbing manually with detergent solution followed by water rinsing.

In-place cleaning: In-place cleaning is most popularly known as C.I.P.( Cleaning-in-place).It is the cleaning of equipment including that of pipe lines, with water and detergent solution without dismantling. A minimum fluid velocity of 1.5 meter per second with turbulent flow is required for effective cleaning of pipelines. Wherever possible, parts of equipments which can’t be satisfactorily cleaned by this method should be identified and should be dismantled and cleaned manually to prevent the possible build up of contaminants.

Low pressure high volume spray: In this method of cleaning, water and/or detergent solution is applied in large volume at pressures up to approximately 6.8 bar or Kg/sq.cm. (100 psi).

High pressure low volume spray: It is the application of water and/or detergent solution in low volume at high pressure, i.e. up to 68 bar or Kg/sq.cm (1,000 psi).

Foam cleaning: Detergent solution in the form of foam is applied and remained in contact for 15-20 minutes over the surface and then it is rinsed off with a water spray.

Washing machines: There are containers like milk cans, crates and bottles etc.,which are commonly used, in the dairy industry. The large in number and smaller in sizes make manual cleaning of these items quite expensive, labour oriented,tiresome and involving huge manpower. These containers could be easily and effectively cleaned by special designed washing machines. The machine performs cleaning procedures as above with the addition of disinfection by hot water rinse at the completion of the cleaning cycle.

In dairy plants following type of washing machines are used:a) can washer, b) bottle washer, and c) crate washer

In all type of washing machines, the cleaning method incorporates rinsing, application of detergent, washing and rinsing with water followed by sterilization with steam/hot water or chemical sanitizers. The solutions are applied by soaking or jet arrangements.

  

ii. Considerations for effective cleaning and sanitization 

 

Milk handling and processing equipments are normally fabricated from highly corrosion resistant materials like stainless steel to provide very good hygienic conditions.Cleaning and sanitization process, by the use of proper system, chemicals and cleaning parameters, should support this feature. In this context, some of the aspects are discussed below:

a) Soap or detergent solutions of effective concentration remove soilings like grease and dirt due to their good wetting and penetrating capabilities and hold them in suspension. Thorough washing with a water rinse is followed by complete drying
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b) Neutral or general purpose detergents of pH between 7 to 9 are useful for light to moderate heavy foaming type cleanings. These detergents foam well in water and are safe to use on most surfaces.

c) Removal of tightly deposited milk solids/milk stone, atmospheric stains, oils/grease and other light discoloration is carried out with alkaline detergent solutions without using much manual scrubbing. Strong alkaline solutions may be useful in cleaning of heavy greased surfaces. Weak alkaline cleaning agents can be used on most surfaces, however care should be taken to ensure they do not damage the surface.

d) Removal of water scale and milk stone is usually done by acid type detergent solutions, having pH less than 7. Acid detergents are used specially for the removal of mineral scale from metal surfaces of dishwashers and hot water runs.

e) Abrasive cleaning processes use grains/granules, available in the form of a paste, cream or powder, to remove soiling from the hard surfaces. However,use of ordinary steel wool or brushes should be avoided to save surface from damage. As far as possible, spongy or soft fibrous materials like cloth pads should be used.

f) For cleaning of newly installed equipment, soldering flux should be first neutralized with a 5-10% sodium carbonate solution or ammonia water and then, rinsed or washed and dried.

g) Prolonged contact of sanitizers containing chlorine, iodine etc. should be avoided to prevent rusting of surfaces.

h) Stain spots caused due to excessive heating should be removed by scouring with powder.