Principles of Food Sanitation

Floor drains and ventilation systems con-
tribute to contamination from airborne
microorganisms instead of acting as a sani-
tation barrier. A properly designed ventila-
tion system with air filtration can improve
air quality. Inexpensive filters remove dust
and other contaminants that would nor-
mally be drawn into these spaces or rooms.
Equipment should be designed and ori-
ented for easy cleaning and reduction of
contamination. Traditionally, equipment
layout has been important to operational
efficiency, with the effects on the sanitation
operation of only secondary importance.
The most critical considerations related to
equipment sanitation include a location to
permit sanitary operations between equip-
ment and walls or partitions, an exterior
with an easy-to-clean surface, and a design
to permit effective sanitation between the
equipment and floor. All equipment should
be accessible, easy to clean, and designed for
draining and sanitizing.

Soil characteristics in dairy plants

In the dairy industry, soil consists
primarily of constituents of minerals, lipids,
carbohydrates, proteins, and water. Other
soil constituents may be dust, lubricants,
microorganisms, cleaning compounds, and
sanitizers.
White or grayish films that form on dairy
equipment are usually milkstone and water
stone. These films usually accumulate slowly
on unheated surfaces because of poor clean-
ing or use of hard water, or both. Calcium
and magnesium salts precipitate when
sodium carbonates are added to hard water.
During cleaning, some of this precipitate
may adhere to equipment, leaving a film of
water stone. When proteins denatured by
heat adhere to surfaces and other compo-

nents absorb them, milkstone may form

quickly on heated surfaces. Because they

become less soluble at high temperatures,

calcium phosphates from milk are present

in large quantities. The nature of soil on

heated and unheated surfaces usually differs

in composition. Thus, each type of soil

requires a different cleaning procedure.

Milkstone is usually a porous deposit that

will harbor microbial contaminants and

eventually defy sanitizing methods. It can

be removed through an acid cleaner to dis-

solve the alkaline minerals and remove the

film. Heavy soil deposits require a stronger

cleaning compound than lighter soils. Also,

freshly deposited soil on an unheated surface

is more readily dissolved than the same

soil that has dried or has baked on a heated

surface.

Soil deposition can be reduced and subse-

quent removal eased by application of the

following principles:

●Generally, product surfaces should be

cooled before and immediately after

emptying of heated processing vats.

●Foams and other products should be

rinsed after the production shift and

before they dry.

●Where possible and practical, the soil

deposits should be kept moist until the

cleaning operation starts.

●Rinsing should be accomplished with

warm (not hot) water.

Soil deposition is increased in ultra-high-

temperature heaters if milk contains high

acidity and is complicated by low-velocity

movement and poor agitation during the

operation. Preheating and holding at a high

temperature reduce film deposition.

The nature of the surface determines the

ease or difficulty of soil removal. Pits in cor-

roded surfaces, cracks of rubber parts, and

crevices in insufficiently polished surfaces

protect soil and microorganisms from the

Dairy Processing Plant Sanitation 287