Heat Treatment in Food Preservation: Historical Development and Microbial Inactivation
The destruction of microorganisms by heat is fundamentally due to the inactivation of enzymes necessary for their metabolism. Enzymes, being proteins, are sensitive to temperature changes; high heat denatures these proteins, rendering them non-functional. This process effectively kills or deactivates the microorganisms, ensuring food safety and preservation.
The choice of heat treatment in food preservation depends on various factors, including the type of microorganism, additional preservatives used, and the impact on the food's quality. Different microorganisms have varying heat resistances; for instance, spores of certain bacteria require higher temperatures for inactivation. The presence of other preservatives, such as acids or salts, can enhance the effectiveness of heat treatment, potentially allowing for lower temperatures or shorter processing times. However, these treatments must balance microbial destruction with maintaining the food's nutritional and sensory qualities.
The modern food preservation process has its roots in early 19th-century France. Nicolas Appert, known as the "father of canning," pioneered the technique of preserving foods by sealing them in glass jars and boiling them. This innovation earned him a prize of 12,000 French francs from the French government in recognition of his method's potential to preserve food safely for extended periods.
In 1819, William Underwood established the first canning factory in Baltimore, USA, marking the beginning of the commercial canning industry. However, the initial method of boiling water required approximately six hours to preserve foods, which was inefficient. The addition of salt to the water bath raised the boiling temperature, reducing the processing time but causing corrosion to the cans. This challenge led to the development of heating in steam under pressure, a method that significantly shortened processing times and enhanced efficiency. These early pressure chambers have since evolved into modern retort systems, which are standard in the industry today.
In 1945, researchers investigated the effects of heating the germ at various moisture levels and durations in a hot air oven on enzyme activities and storage stability at 37°C in laminated metal foil. Their studies revealed that all heat treatments completely destroyed lipoxidase activity, while proteolytic activities were significantly reduced, contingent on moisture levels. Surprisingly, raw germ samples exhibited a smaller increase in peroxides compared to heat-treated samples, highlighting the nuanced effects of heat treatment on food preservation. This research contributed to the optimization of heat treatment processes, ensuring both food safety and quality.
Heat Treatment in Food Preservation: Historical Development and Microbial Inactivation
