Preserving foods for future use is essential as it keeps them away from disease causing pathogens. On the other hand, it prevents wastage. The most common methods of food preservation include smoking, salting, canning and freezing, among others.

However, nutritionists advise that the method of choice shouldn’t alter or negatively affect the nutrient value of the food. For that reason, some methods such as salting and smoking are encouraged more when it comes to preserving any type of food.

"Traditional or natural ways of preserving foods for instance, smoking and salting are healthy; the reason being that they have been used for centuries and most importantly the food tends to lose less or no nutrients at all,” says Isaac Bikorimana, a nutritionist at Kibagabaga Hospital in Kigali.

He adds that the artificial methods such as canning not only keeps the food for a limited shelflife, but also interfere with the nutrient contentBikorimana further cautions that some modern methods of food preservation can cause harm to consumers due to preservatives used.

Just like Bikorimana, Joseph Uwiragiye, a nutritionist at University Teaching Hospital (CHUK), is of the view that smoking is the best and safest method for long-term preservation of food.

"Certain bacteria that are present in some foods are killed or their growth slowed if food is smoked. The method also prolongs the shelf-life of certain foods. Apart from that, smoking also makes some foods like meat more tasty and appetising,” he says.

Uwiragiye explains that for foods with high water content, the best way to keep them longer without losing many nutrients is salting.

"When salted, the salt acts as a preservative which inhibits the growth of microbes. Also, it reduces the amount of water in the food, thus slowing down the growth and reproduction of bacteria,” he says.

Uwiragiye, however, warns against using too much salt as it can rupture bacterial cells due to differences in pressure between the outside and inside of the micro-organism.

For foods such as fruits and vegetables, the best way to preserve them is to add vinegar or sprinkle salt and water on them.

"Salt is vital to health thus making it a good method of preservation. Besides,one should not use excess of it as too much of it in the diet may lead to high blood pressure, which may pose the risk of heart diseases,” adds Uwiragiye.

He, however, cautions that very little salt in preserved foods may make it more prone to pathogens thus affecting its safety. So, moderate application of salt is ideal.Food should not be preserved for a long time since it may alter the colour, flavour, texture as well as its nutritional value, Uwiragiye adds.

Rene Tabaro, a dietician at King Faisal Hospital, says chilling is also one of the healthy methods of preserving perishable food, be it raw or processed. 

He adds that drying food is also a good way of preserving it. "It removes the moisture from the food, preventing the growth of bacteria, yeast or mold on it, thus preventing it from getting spoilt.

In cases where the food may ripen quickly, Tabaro advises that drying should be used as it slows down the action of enzymes which elongates its shelf-life.

He, however, cautions that some modern preservatives have a lot of chemicals which may not be healthy, emphasising that food consumed fresh from the farm or market is healthier than preserved food.

"Freshly prepared food is always superior to preserved food. Preserved food with excess oil, sugar or salt carries risk of cardiovascular diseases. Some refrigerated foods also carry germs and chemicals which can cause allergy and reduce immunity. Along with these risks, nutrients are also lost in preserving and warming,” says Tabaro.

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