Food preservation: The smoking process

Smoking is an ancient method of food preservation, which is also known as smoke curing, produces products with very high salt content (more than 10%) and low water activity (~0.85). While smoking process, some reactions occur between food and smoke Smoking operation which adds some volatile compounds to the product inhibits bacterial growth and gives a specific taste to the product.

Smoking is the process of flavoring, cooking, or preserving food by exposing it to smoke from burning or smoldering material, most often wood. It is an ancient method of preserving food using wood smoke. It is believed to be almost as old as the use of fire itself.

This process is usually characterized by an integrated combination of salting, drying, heating and smoking steps in a smoking chamber. The drying effects during smoking, together with the antioxidant and bacteriostatic effects of the smoke, allow smoked products to have extended shelf-life.

Smoking is still widely used in fish and meat and some other foods. The smoking process allows cured meats, poultry, game and seafood to be subjected to smoke in a controlled environment. The smoke is produced by smoldering hardwood chips, vines, herbs, fruit skins, or spices.

Different species of fish require different preparation techniques. Salmon are usually prepared by removing the backbone and splitting. Bottom fish are filleted. Small fish such as herring and smelt should be headed and gutted before brining.

Smoke is generated from the incomplete combustion of wood at certain temperatures followed by thermal disintegration or pyrolysis of high molecular organic compounds into volatile lower molecular mass (. Smoke is composed of two phases: a particulate or dispersed phase and a gaseous or dispersing phase. The major parts of dispersed phase are particles in the droplet form having an average diameter of 0.196 to 0.346 µm.

While smoking process, some reactions occur between food and smoke. After smoking process, a second covering shell occurs in food or meat products. Smoking operation which adds some volatile compounds to the product inhibits bacterial growth and gives a specific taste to the product. This smoke influences the flavor, aroma, texture, appearance and shelf life of foods. The process can be performed at temperatures that range generally from 65°F to 250°F.

Food smoking is part of a revival of old crafts and traditional foods, and an increase in food awareness – people want to know what's in the food they are eating. The trend is towards high-quality ‘slow’ food, with local, natural ingredients free from chemical additives. Smoking is a way for farmers, smallholders, hunters and fishermen to make use of large amounts of meat or fish at certain times of the year.
Food preservation: The smoking process