Nutrition Meets Food Science

What are Processed Foods? The pros and cons.

Food processing has a long history. When people were consuming fruits, vegetables, milk, meat and fish, they found that most of these foods can be stored for short times before they start spoiling. The foods start changing colour, smell, taste and appearance and becoming undesirable. They start having fungal or microbial growth making them distasteful.

Some of the foods could be stored for a longer time if they were dried in the sun e.g. fruits, meat and fish. During winters, many vegetables and meats would last for a longer time. People also found that if milk was fermented to curd or buttermilk, it could be stored for a longer period. Even some vegetables were fermented for longer storage. Salt would increase storage of vegetables, meat and fish while sugar would store fruits for longer periods. This was used by people on a larger scale, hence starting the manufacturing of processed foods.


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Although processed foods were prepared originally to lengthen the storage time, there are many other benefits of processing the foods.

  • In the early 1800’s French confectioner Nicholas Appert found that if foods were sealed in a container and then heated, they would last for a long time without spoilage. This was the beginning of the canning process.

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  • More than 50 years later, it was discovered by Louis Pasteur that spoilage of foods including wines and milk is caused by microorganism or microscopic bugs and if these are destroyed or stopped from growing, food would not spoil for a long time. Many of the food poisoning incidents are caused by bacteria which turn food toxic. Heating was one of the most effective means to destroy these bugs.
  • Cooking has been traditionally practiced to make sure food is safe. Water and milk is boiled at home, making them safe. This is another advantage of processing Milk is pasteurised and vegetables are blanched to destroy microbes in which most pathogens are killed.
  • Heat is not the only means of stopping microbes from growing and spoiling. As microbes need water for survival and growth, drying the foods would make it inaccessible and stop spoilage. Sun drying was earlier practiced, and is still used for fish and certain fruits, but newer more rapid methods like mechanical drying (dehydration) using heat, dry air and vacuum are being used to dry many foods including fruits, vegetables, meat, fish and spices.

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  • Some more advanced methods include spray drying to prepare powders from liquid foods like milk, and freeze drying to prepare instant coffee.
  • At a very low temperature, most common spoilage microbes will stop growing. Freezing was thus another means to process vegetables, meat and fish for long time without spoilage.
  • It was also observed that fermentation produced acids like citric and acetic that would slow down the growth of many spoilage microbes. Sometimes processors would add these acids to foods rather than fermentation. They also found that many chemicals or preservatives could be used to stop the growth of microbes.
  • Another advantage of processing is to make the food more appealing by adding various additives such as colours, flavours, flavour enhancers, emulsifiers, stabilisers, acidulants, antioxidants, sweeteners etc. Some of them may be natural but many are Food can be made very tasty by the use of and some ingredients such as salt, sugar and fats.

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  • Another major advantage is that convenience can be provided by foods and ingredients that are processed. Preparing coffee would be a labouring process where roasted coffee beans would have to be ground, and then a decoction is prepared with boiling water. Instead instant coffee just needs to be added to boiling water to make coffee, reducing effort and time.
  • Similarly frozen vegetables would reduce the drudgery of buying vegetables, cleaning, washing and cutting them in order to use them in a preparation. The ultimate convenience is in frozen TV dinner which has various parts of a meal prepared and frozen and packed. All one has to do is heat it in an oven and consume. Although the taste of most leave a lot to be desired, the convenience is remarkable.


Although processed foods were a novelty and luxury some decades ago, today we have urbanised so much that fresh fruits, vegetables, meats, milk etc. come from long distances. Thus, without the help of some means to controlling microbes, the quality and safety of these would be far from desirable. Some of the vegetables are now processed soon after harvest -they’re frozen very near the farms so they have not only the sensory, but also nutritional quality required. These are better than vegetables that people buy in fresh markets in cities as these have to travel long distances and at times without cooling and protection from spoilage.

Health professionals criticise processed foods for some reasons. The processing does cause some losses of nutrients, especially heat sensitive vitamins. They are also worried about the additives that are used to make many food products more attractive. They caution that some manufacturers would add excessive amounts of salt, sugar and fats to make the products more palatable which may be unhealthy.

These concerns may be true in case of some food products. However, in modern times it is impossible and unnecessary to avoid all processed foods.  . Due to urbanization and our lifestyles, it is increasingly more important to have our foods or ingredients processed to some degree. Even the rice we cook at home is milled, dals, wheat and flours are milled, and the cooking medium we use is processed. Milk is pasteurised. Spices are processed. Except for fresh fruits and vegetables and eggs most of the other things we use in our food preparation are processed to some extent.

Fortunately, the government has compelled manufacturers to mention nutritional information along with ingredients listed on labels of packages of food products which give a lot of information. We must read this and try to buy products that are safe and more nutritious. We may also try to control our intake of salt, sugar and fat to avoid excess either through processed foods or through home cooked foods. In the next blog we may see how some processed foods are made.

Dr Jagadish Pai

Editor, PFNDAI


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