choosing the Approrpriate Detergent

The determination of the correct type of detergents for any cleaning process in a food processing factory is subject to a number of selection criteria. These include:

•  the type of soil present
•  the manner in which the soil is formed
•  the chemical composition of water supplies
•  the nature of the food processing steps
•  plant design, construction and material used for the same
•  the extent of cleanliness and sanitation required and
•  the cleaning and sanitizing techniques available.

 i. Milk Soil

Any equipment that stores, carries, contains, or contacts milk will accumulate particles of milk on its surface. This is the ‘milk soil’. These particles, if are not detected in time and removed, will act as nuclei onto which further clustering of milk particles occur. Eventually, these result in larger and dried particles of milk soil,commonly called ‘milk stones’. The accumulated dried soil consists largely of fat,protein (precipitated, coagulated and baked-on by heat), insoluble calcium salts from water and washing detergent and bacteria. These are stubborn and difficult to remove. They then cause problems of inefficient heat and material transfers during processing and also bacterial contamination that may eventually lead to food safety hazards.The composition and concentration of cleaning compounds and the cleaning methods used are dependent upon the type of soil on the surface to be cleaned. The nature of soils from foods varies, based on the composition of the food and processing conditions. The chemical composition of typical milk soils is given Table

Chemical composition of a typical milk soil*

The concentrations of water-soluble, alkali-soluble and acid-soluble soils will vary with the type of food and the processing it has received both before, and in, the equipment to be cleaned. The variation in some milk constituents with respect to their solubility and reaction to cleaning is shown in below Tables.

Solubility and ease of cleaning of milk soil

ii. Quality of Water

Water is the major ingredient in all cleaning and sanitizing operations used in a dairy plant. Pure water presents no problem, but no water supply in a dairy plant is ideal.The cleaning compound, therefore, must be selected after carefully assessing the individual plant water supply. Water impurities that are significant with regard to cleaning operations are:

•  Suspended matter - These must be kept to a minimum to avoid deposits on clean equipment surfaces.
•  Water hardness - Salts of magnesium and calcium pose the major problem in the use of cleaners by reducing effectiveness and by forming surface deposits. 

Water hardness may be classified as shown in below Table

Suspended matter and soluble iron and manganese can be removed only by treatments such as filtration and deionization. Small amounts of water hardness can be taken care of by addition of seques-tering agents in the cleaning compounds.However, in case of hard or very hard water supplies, it is generally more economical to pretreat the water to remove or at least minimize water hardness.

Classification of hardness of water

The ingredients of modern commercial cleaning compounds modify the nature of water so that it may efficiently penetrate, dislodge and carry away surface contamination (soil). Although water alone will act as a good cleaning agent if enough external energy is put into the system (generally in the form of heat and applied force). Cleaning compounds decrease the external energy requirements by increasing the internal potential energy of the water.