The art of food preservation


by Hiya Islam

scienceFOOD, one of life’s simplest yet most treasurable pleasures is absolutely crucial to survival. While most of us eat to live, some live to eat. Food revolves around them like the earth revolves the sun. It is there, 24/7 on their plates or their Instagram roll. Rather than a necessity, it has grown into a habit of insatiable lust for hungry tongues. But, how often do we spare a moment to ponder on how this very necessary element is processed to enhance longevity?

The art of food preservation goes a long way back. Often times, the process itself leads to the creation of a new food that is loved just as much as when fresh such as, cheese, pickles, fruit jam and dried fruits. Refrigeration and freezing are two of the popular forms. While refrigeration slows down bacterial growth, freezing completely inactivates them. This method works as the drop in temperature inhibits enzymatic activity and hence the bacterial metabolism for growth. One disadvantage of freezing is that it changes the texture of the food, for example, frozen fruits turn out mushy when defrosted. On the other hand, fermentation, canning, pasteurisation require more than just one step. Pasteurisation is applicable to milk, cream, juices and even eggs. Although it can be categorised under many types (flash pasteurisation, UHT-Ultra heat treated), all expose food to high temperatures for a very short period to kill off pathogenic or disease-causing bacteria. The heating standards once again vary as different foods contain different bacterial flora. Canning too uses heat to treat the food. The heat drives out air and as the food cools, a vacuum seal is formed thus preventing re-entry of air and contamination. This is why canned food must be refrigerated once opened. The broken seal undoubtedly brings in a fresh supply of microbes. Carbonation, the process of dissolving carbon dioxide under high pressure is why some of our soft drinks are ‘fizzy’. The idea is to drive out oxygen which is mandatory for aerobic microbes. If these ways fall short, chemical preservatives are added. Examples include benzoates, nitrites, sulfites and sorbic acid which work similarly by tampering with bacterial enzymes.

No matter which form of preservation takes place, the principle is the same- either kill all bacteria or hamper its growth. For each type of food, there exists a given approach to preserve it. Other than preventing food spoilage, these steps ensure that the food is safe from the toxins of pathogens. Incidents of tuberculosis, botulism, diphtheria, typhoid, food poisoning have significantly decreased with improved methods of preservation. Another added advantage is better shelf-life which not only aids in transport but makes sure that the products are available all around the year.

Hiya Islam is a student of BRAC University.



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