Grade 8 Science : Food Preservation - Part 3

As we have discussed about the food preservation methods in the previous article, let us explore the reasons for using the respective methods and how they facilitate food preservation. We have learnt about a series of food preservation methods such as drying, control of temperature by freezing and deep freezing, concentration or immersing the food in honey, smoking and addition of preservatives that are made of chemicals. 

 

Food preservation is possible through drying as it helps to remove water in food. Water is a factor that influences microbial growth. Hence, removal of water can suppress it where food can be prevented from spoilage. We know that a favorable temperature is crucial for the growth of microbes. Thus, methods like freezing and deep freezing help to control the growth of micro-organisms on food as they operate under very low temperatures. In the past, concentration of food was achieved by immersing them in bee honey that acts as a good vacuum seal. However, at present this vacuum seal is achieved by following techniques like bottling and canning. Concentration or immersing food in bee honey will help to control microbial growth by the removal of water from food. Smoking also helps to control the microbial growth and activity due to the removal of water from food and the presence of chemicals in smoke. Today, several preservatives that are made of chemicals are widely used in the process of food preservation. These preservatives help the removal of water present in food and it will eventually help in suppressing the microbial growth on them. 

 

 

In the present world, liquid milk comes in different forms that could be kept for a long period of time in refrigerators and methods such as pasteurization, ultra pasteurization and sterilization are being widely used in the process of production. Heating milk at high temperatures (differs from each method) is a technique followed in common by these methods. Here, all microorganisms (example: pathogenic bacteria) are destroyed. 

 

 

 

 

 

 

 

By Mekhala Egodawele

Photo source : Internet