Common Preliminary Operations: Cleaning, Sorting, Grading

The raw materials for the food industry are usually collected or harvested in farms and open land, and the means of transporting them to the processing plants take many forms. Raw materials arriving at processing factories are, therefore, exposed to various contamination sources, so the logical order of preliminary operations is cleaning, sorting, and grading. Transporting of raw materials includes such varied operations as hand and mechanical harvesting on the farm, refrigerated trucking of perishable produce, box car transportation of live cattle, and pneumatic conveying of flour from a rail car to bakery storage bins. Throughout such operations, emphasis must be given to maintaining sanitary conditions, avoiding product losses, maintaining raw material quality, minimizing bacterial growth, and timing all transfers and deliveries so as to shorten the holdup time, which can be costly as well as detrimental to product quality.