Aquaculture cold storage is one of the fields of activity for which Highend produces professional solutions, as well as all kinds of agricultural and animal food.

In terms of nutrition, seafood is among the foods with high nutritional value due to the nitrogenous compounds it contains. However, since fishery products are sensitive to spoilage, they should be consumed fresh immediately after fishing or precautions should be taken to ensure that they preserve their original freshness as much as possible. The leading methods used for this purpose are cooling and freezing technology. By cooling, aquaculture products can be kept cold at -1ºC/+4ºC; However, as the development of microorganisms and biochemical events are slowed down during cold storage, the shelf life of seafood products is limited. The development of microorganisms is completely prevented by freezing, biochemical events and enzyme activity continue at a slow pace. Accordingly, it is possible to obtain seafood products that can maintain their freshness for a long time and are of higher quality.

The idea of refrigerating freshly caught fish to prolong their storage period first emerged in the 18th century when salmon was transported by sea from Scotland to London. However, it is stated that before this method, Chinese fishermen used ice collected from naturally icy lakes, streams and pools. Ice was first used on British fishing boats in the 1850s, and towards the end of the 19th century, mechanically produced ice was tested on fishing boats. A number of systems have since been developed, none of them as useful as ice for cooling fish. Opportunities to benefit from seafood at the required extent are realized by preserving the quality until they are consumed. It is possible to deliver the fish to the consumer without deteriorating the quality of the fish during periods of high fishing, with cold storage under appropriate conditions.

Chilling is the process of reducing the temperature of the fish to 0ºC, the temperature just above freezing. The purpose of cooling is to preserve the food as close to its natural state without using preservatives. The main purpose of cooling is to reduce or stop the activities of microorganisms in the environment by lowering the temperature, and to prevent physical, chemical and biochemical events that occur under normal conditions as much as possible. Cooling does not completely stop the deterioration, but it does allow it to be delayed for a certain period of time.

Freezing process to extend the storage period of seafood plays a very important role in minimizing spoilage and economic loss, as well as in controlling public health problems and foodborne pathogens. Enzyme activity stops at very low temperatures (-30°C). Generally, the temperature during freezing and freezing storage is -18°C and below. Microorganisms can maintain their biological activities down to -5/-8°C, yeasts down to -10/-12°C, and molds down to -12/-18°C. Products can be stored at temperatures of -18°C and below without microbial deterioration. In foods, water is a solution containing a large number of dissolved substances. The freezing point of the food is a temperature below 0°C, depending on the type and amount of dissolved substance in the water contained in the food. The number of the smallest frozen particles of water in the meat should be as high as possible. This is called maximal crystallization in the freezing technique. In order to maximize the number of frozen water crystals in the whole fish from the outside to the middle in the freezing place, the temperature should be reduced from 0°C to -4°C in 30 minutes.

Factors Affecting Freeze Storage

At the beginning of the factors affecting the preservation by freezing; material (raw material), pre-treatments, freezing temperature, glazing, storage temperature, storage conditions and time. Critical control points at these points should be considered and necessary precautions should be taken in order to freeze seafood products in a quality and reliable manner.

Thawing Frozen Product

Thawing is the final stage of the freezing process. At this stage, the temperature of the frozen product rises to 0°C. Significant changes in the product during thawing are associated with the melting of ice crystals formed during freezing and the reabsorption of tissue fluids by muscle fibers. The dissolution conditions must ensure that the initial properties of the product are preserved.

Just as fast freezing is important in maintaining the quality of frozen seafood products, rapid thawing is equally important. This prevents the product from being exposed to high temperatures for a long time. As it is known, enzymatic and bacterial activities accelerate at high temperatures.

The method used to thaw the frozen product should be chosen to prevent overheating of the product, loss of drops, dehydration and bacterial growth. During thawing, the ambient temperature should never exceed 20°C.