Salting fish by injection

Salting is a one of the main traditional methods used for preserving fish due to its ability to create unfavorable environment for the growth of microorganisms by lowering the water activity of the fish muscle.

There are several techniques available for the salting process of smoked salmon: traditional dry salting, injection salting, brine immersion. It has been shown that different salting techniques lead to different texture properties.

Quality of the final product depends on several factors, for example, condition of the raw material and the method used for salting and drying. The exact salting procedure varies between producers and countries, and may depend on fish species and climatic conditions.

Injection was significantly different from other methods in increasing weight yields through brining, dry salting and rehydration. Salt concentrations of the brine did not influence the weight yields of dry salted and rehydrated products.

Injection-salting technology is a process of injecting brine directly into the fish products by numerous, evenly spread needles, it features not only a shortening time of processing, but also adds a mixture of additives into the fish fillets more easily and effectively, compared with brining. Injection was found to be a suitable method to supply salt into salted fish fillets.

Injection results in a relatively homogenous salt concentration in the muscle in a short time, compared to other salting methods. Additionally, it makes it possible to add other ingredients to the products, such as proteins, which would not be possible by brining.

Disadvantages of injection are risk of microbial contamination and possible damage of the muscle structure due to the pressure applied and needle holes in the muscle.
Salting fish by injection

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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

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Preservation of food using sugar

The important of food preservation is to increase the shelf life of food as well as its supply. Although the freshness, palatability and nutritive value may be altered with time delay, perishable foods can be preserved to prevent spoilage and made to be available throughout the year. In this way, preservation helps to increase variety in our diet and makes it better balanced.

Sugar by definition is a sweet crystalline or powdered substance, white when pure, consisting of sucrose obtained mainly from sugar cane and sugar beets. Sugar is used to make delicious foods, such as cookies, chocolate and other candy.

The main use of sugar is the diet is as a sweetener and it is the only one of the mono- and disaccharides which is consumed in relatively large quantities. It is also used as a preservative.

Preservation with the use of honey or sugar was well known to the earliest cultures. In northern climates that do not have enough sunlight to successfully dry fruits, housewives learned to make preserves by heating the fruit with sugar.

Moisture content and water activity affect the progress of chemical and microbiological spoilage reactions in foods. Reduction of water activity can be obtained by drying or by adding water soluble substances, such as sugar to jams. Sugar binds moisture and thus can preserve food by preventing the growth of microorganisms if a high concentration (65% or above) is used. Products such as jams and jellies are preserved by using sugar. Bacterial growth is virtually impossible below a water activity of 0.9, which helps during food preservation.

 In ancient Greece quince was mixed with honey, dried somewhat and packed tightly into jars. The Romans improved on the method by cooking the quince and honey producing a solid texture. The three sugars most commonly occurring in food are fructose, sucrose and lactose.

Sucrose is added to many baked goods primarily for reason of taste, it is frequently also the crucial factor in their preservation. Sucrose also functions of a preservative for other products such as marzipan, nougat, chocolate and pralines.
Preservation of food using sugar

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Salt: an excellent microbial inhibitor

Salt is an excellent microbial inhibitor, mainly due to its suppression of the water activity of the material to which it is added. Its effectiveness is enhanced when the food is also dried or smoked or both. Smoking also imparts a partial preservative effect.

The early food uses of salt were for the purpose of preserving meats. This use is based on the fact that at high concentrations, salt exerts a drying effect on both food and microorganisms.

Salt can act in several ways to inhibit microbial growth and thus preserve the food. Perhaps most important, it reduces the amount of water available to micor0rganism for growth processes. Water activity (aw) is term used to express numerically degree to which water in foods is available to microorganisms.

The use of salt as a preservative serves to inhibit microbial growth by reducing the water activity and increasing the osmotic pressure of the food.

Salt (saline) in water at concentrations of 0.85-0.90% produces an isotonic condition for non-marine microorganisms. Because the amounts of NaCl and water are equal on both sides of the cell membrane, water moves across the cell membranes equally in both directions.

To damage microbial enzymes, NaCl must gain access to the intracellular pool. Enzymes can be damages in a variety of ways by high ionic environment and perhaps by NaCl specifically. Many of those involved in the preservation effect of NaCl are involved with cellular recovery from stress.
Salt: an excellent microbial inhibitor

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Primary objective of food processing

The composition and moisture content of food creates an ideal environment for the growth and proliferation of pathogenic and spoilage microorganisms.

Processing operations involves not just involves just a minor change of form, from dirty to clean but it also involves processing to assure safety, to drastically alter the form of the raw materials, and to provide a product that will remain stable for many months on the shelf.

It must be acknowledge that most if not all food processing operations will influence the physical and sensory characteristics of the product.

Modern food processing preserves food quality, controls food spoilage and disease causing microorganisms, preserves desirable sensory qualities such as flavor, odor, texture, and appearance, preserves nutrients content and in many cases enhances the nutrient value as well.

Processing to retard spoilage permits foods to be consumed at a later date and frequently at a distance from the point of production.
Primary objective of food processing

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Advantages of radiation preservation

After decades of research and development, proof of wholesomeness, political debates and public scrutiny, food radiation is established as a safe and effective method of food processing and preservation.

The food industry uses four major forms of radiation, including ultraviolet light, gamma radiation, electron bean radiation and microwave radiation. The radiation preservation of foods is considered a ‘cold’ process because there is only a slight temperature rise in the food during preservations processing. Radiation brings about lethal changes in the nuclear material of microorganisms and inactive the enzyme system without raising the temperature.

These features make the process attractive for heat-sensitive aspects of food processing such as nutrient retention. With only the small temperature rise associated with radiation, adverse changes in the food, such as altered flavor, odor, color, texture, and loss of nutritional quality are minimized.

The irradiated food therefore, retains more of the appearance taste and quality characteristics of fresh raw food. Radiation preservation has the advantage of speedy operation. However high cost restricts its used as a commercial practice.
Advantages of radiation preservation

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Precautions during salting preservation

All manufacturing processes require monitoring and food preservation processes are no exception. Salting preservation method requires either a very highly concentrated brine (over 10 percent salt) or a large quantity of salt with the material.

Some precautions must be observed in the salting preservation of flesh type foods, such as fish or meats.

Be sure the water is pure, even have to boil it, for many bacteria found in normal drinking water will multiply and cause harm when they are in a sweet pickle cure.

In addition, chlorinated water can spoil the tastes of otherwise excellently cured meat. A good safety precaution is always to boil the water then let to cool before it is used.

It is important at all times that materials be kept covered with salt to prevent spoilage of the surface layer. When the products are salted several days will be required before enough salt has diffused into all parts of the product to inhibit the growth of microorganisms.

In case the precautions are not observed, the growth of spoilage of r even disease causing-bacteria may occur in some parts of the food before enough salt has diffused into the product to inhibit growth.

It is normal procedure to hold products under refrigeration during salting until adequate ‘take-up’ of throughout the food. Fish and meats should never be held at temperature above 15.6 °C during salting. Preferably holding temperatures during such procedures should be at 4.4 °C or slightly below.
Precautions during salting preservation

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What is the meaning of food processing?

Food as a material should not be studied in isolation; individual foods and the process of making food products are interlinked.

These processes may be relatively simple such as the milling of wheat to produce flour or highly complex such as creating a pizza that be cooked in a toaster.

Developing new complex today involves a lot of research experimentation, testing , testing and trialing.

A small scale recipe for a chicken korma cannot simply be multiplied up and used on a production line to create tens of thousands of meals.

Large scale machinery may affect food in a different way to a domestic cooker, causing meat to become tough or a sauce to runny.

The changes that are needed may only be subtle but they can make the difference between a profitable new product and a costly failure.

Processing foods can also involve preserving them and the latest techniques include accelerated freeze drying, irradiation and the production of dried fruits that do not require soaking.

Some preservation methods stem from the past when people had to preserved foods in order to have sufficient food all year round.

Fruits were turned into jam, onions were pickled and meals were cured.

Processed food has changes dramatically as the needs of consumers have altered and as advances in food technology have occurred.
What is the meaning of food processing?

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