Thermal Processing

Abstract

The development of the modern heating process started in France during the first decade of the 1800s by Nicholas Appert, who preserved foods in sealed glass jars in boiling water. In 1810, Peter Durand of England developed the metal can, which was fabricated and sealed by hand soldering. In 1819, William Underwood of the United States started the first canning factory in Baltimore. But preserving 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, the salt corroded the cans, so the next innovation was to heat in steam under pressure. The higher the pressure, the higher the temperature at which water boils (see Table 10.1) and the shorter the processing time. These early pressure chambers evolved into the modern retort.