Vegetable Processing after Harvesting

Vegetable Processing after Harvesting

After harvesting, the heat system can be applied as the harvesting criterion for crops for which the required heat units for optimum maturity are known (e.g., beans, corn, peas). Heat units may be expressed as F-days or F-hr. heat units are those days or hr above the minimum growing temperature multiplied by the degrees that the ambient temperature exceeds the minimum growing temperature. For example, the minimum growing temperature for given vegetables is 40 F (4.4 C), and during a 2 day period the ambient temperature average 60 F (15.6 C), then the number of heat units accumulated during the 2 days period can be calculated as

(60 F – 40 F) x (2 days) = 40 F-days

All vegetables sealed in cans or glass must be heat processed and sometimes at higher temperature to make them commercially sterile. Commercially sterile means that all disease bacteria have been killed, and all bacteria and bacteria spores, which might grow out and cause spoilage under the conditions in which the product will be handled after processing, have been destroyed. The time during which heat preserved vegetable must be processed top attain commercial sterility depends on the size of the container, the temperature at which the product is processed, the type of container (glass, metal or plastic), whether or not the product is agitated during heating, whether the vegetables product heats by convection or conduction, and other factors.
Vegetable Processing after Harvesting