Heat Processing

Heat Processing
The destruction of microorganisms by heart is due to the inactivation of the enzymes required for metabolism.

The heat treatment selected will depend upon the kind of microorganism, other preservative to be employed and the effect on the food.

The development of the modern eating process started in France during the first decade of the 1800s by Nicholas Appert who preserved foods in sealed glass jars in boiling water.

He eventually received a prize of 12,000 French francs from the French government for inventing a method for safety preserving foods for long term storage.

In 1819, William Underwood of the United States started the first canning factory in Baltimore.

But to preserve foods in boiling water took too long, requiring about 6 hours, so salt was added to the water bath which increased the boiling temperature, thereby shortening the processing time.

However salt corroded the cans so the next innovation was to heat in steam under pressure. The higher the pressure, the higher the temperature and the shorter the processing time.

These early pressure chambers evolved into the modern retort.

In 1945, researchers studied the effect of heating the germ, at various moisture levels for different periods in a hot air oven, on the enzyme activities and its stability during storage at 37 degree C in laminated metal foil.

They found that all the heat treatments completely destroyed lipoxidase activity; the proteolytic activities were reduced considerably, depending on the moisture level.

The enzyme-active raw germ samples showed an unexpectedly smaller increase in peroxides compared with the heat treated samples.
Heat Processing