Cleaning Methods
1. Soaking
Soaking is used as a preliminary stage in the cleaning of root vegetables and other foods,
which are heavily contaminated. Adhering soil is softened and some is removed, together
with stones, sand and abrasive materials, which would damage the machinery, used in the
later stages of cleaning. The efficiency of soaking is improved: i) by moving the water
relative to the product by means of caged propeller-stirrers built into the tank, ii) by
moving the product relative to the water either by means of slow-moving paddles or by
feeding the raw material into a horizontal perforated drum which rotates whilst partially
submerged in the soak tank. Warm water improves the efficiency of soaking but the rate of
spoilage of foods may be increased.
2. Spray washing
The efficiency of spray washing depends on: water pressure employed, the volume of
water used, the water temperature, the distance of the food from the spray origin, the time
of exposure of the food to the sprays and the number of spray jets used. A small volume of
water, at high pressure, is the most effective general combination. However damage may
be caused to ripe soft fruits such as strawberries and to delicate vegetables like asparagus.
Spray drum washers and spray belt washers are used.