- Hits: 549
Food preservation has been one of the most important needs of people since settled life. The foods in the period of hunting and gathering in human history were consumed before spoiling, but the products had to be kept between the two harvest periods after the agricultural production started. Likewise, meat, fish, and dairy products should be kept for a certain time.
In ancient times, methods such as storage, salting, smoking, burying, cooking, drying, and canning were used in cold caves by trial and error in order to preserve food. Thus, food is protected without spoiling until consumption. Today, the cold chain is used to meet this need.
Microorganisms, enzymes, temperature, and light are the leading causes of food spoilage. When microorganisms meet the appropriate comfort conditions on foods, they quickly consume nutrients and make food that should be beneficial harmful. The cold chain is a system cycle that prevents chemical, biological and microbiological effects that can occur with food spoilage. In short, it is the path from the manufacturer to the table of the consumer. It is also one of the most important parts of food safety. In order to ensure food safety, the cold chain should not be broken during the storage, packaging, shipment and display stages of the products.
If we briefly summarize the cold chain as an image, it is as follows.
Pre-cooling is the process of gradually lowering the core temperatures of the fruits and vegetables collected from the field to the storage temperature. Subjecting post-harvest pre-cooling prevents microorganisms to grow, thus extending the storage period and preventing their appearance from deteriorating. After the pre-cooling process, some products are offered for direct marketing, while some products are taken to cold storage. The products taken to the cold storage without the pre-cooling process change the structure of the products in the cold storage as they change the temperature. There are also pre-cooling with forced airflow, hydro cooling with water, pre-cooling with snow or flake ice, vacuum pre-cooling. The selection criteria of these methods vary according to the product to be cooled.
Quick Freezing (shocking) is the rapid lowering of the temperature of their products. Shocking is mandatory for products to be stored at -18 ˚C. In the pre-cooling process, some products brought to a temperature of 0-5 ˚C are taken to the freezing chambers before being taken to frozen storage storages, and this section, called the freezing tunnel, is set as the core temperature of –18 ˚C. Product freezing methods such as compressed air flow (forced air) shocking, plate freezers, brine shocking are available.
Products taken to storage rooms after pre-cooling and freezing processes. It is preserved there until the next consumption time and becomes more valuable in the market. Different methods are used today for the preservation of food. The most important of these methods is the cold application method that we use in almost every field today. Cold storages formed by the inhibition of the growth and activities of microorganisms, which also contain foods at low temperatures, can be examined under 2 main headings. The first of these is the cold storage where the products consumed in a short period are kept, usually, the fruits and vegetables are stored, and the other one is the long-term storage, usually frozen storage rooms where meat and dairy products are stored.
Cold storages are where products are stored at 0 ° C or a few degrees higher. It is not correct to give a constant temperature value since the degree of storage varies according to the product. In cold storage, the humidity has an important place besides temperature. In other words, the temperature, the humidity and the endurance period are different for each product. For this reason, the capacity and dimensions of the cooling machine and installation to be made in the cold storage vary according to the preserved product.
Frozen storage is the storage of products taken from freezing chambers at -18 ° C and below. Fruits and vegetables contain freezing water, and by converting this water into ice, the water activity of the products is reduced. The lowering of the temperature along with water activity reduces the speed of chemical and biochemical reactions and microbial activities. Temperature and humidity differ in the product, in frozen storage as well as in cold storage.
Products are put into frozen storage rooms in small packages, such as going directly to the sale, and products are also placed in large boxes for later packaging. The storage of the products can be done with special shelf systems or with the help of pallaxes to heights that exceed the length. When the products are needed to be consumed, the products are taken from the storage rooms to the processing areas at 12 ˚C.
After packaging of the products, they are loaded on the refrigerated vehicles and delivered to the consumption area. Different thicknesses and different vehicle air conditioners are attached to the refrigerated vehicles according to the storage temperature, so the products are transported at the storage temperature. While special fan cooling systems are used for +4 ˚C and -18 ˚C refrigerated vehicles, the charging method is used with the help of eutectic plates for -25 ˚C vehicles. These vehicles are mostly used in ice cream shipment. Refrigerated vehicles are not for the cooling of the product, but for the shipment of the product at the storage temperature. The products shipped with the refrigerated vehicles are taken to the display cabinets or deep freeze cabinets without breaking the cold chain, here they wait for the day when the end consumer will go to their cabinets.
- Category: Makaleler (EN)
- Hits: 547
Eutectic cooling is a form of cooling based on the use of cold energy absorbed by a eutectic solution between the plates. The system of eutectic cooling is similar to the ice-mold system put in to keep the water cold. The working principle of the system is as simple as it is efficient. Eutectic cooling systems are special systems designed to be used mostly in ice cream and frozen food distribution.
1.1 EUTECTIC PLATE Eutectic plates can absorb energy and keep the energy they absorb for a long time thanks to their special solutions. Cooling up to “+5” and “- 40” degrees can be done with eutectic plates. Eutectic plates are charged overnight. They store cold energy and slowly release it in the form of cold air, thereby they are cooling the area around them.
1.2 Structure of the Eutectic Plate Eutectic plates can consist of plastic or steel sheets. Plastic ones are lighter and cheaper. The material is determined according to the purpose of use. Steel plates are composed of two steel sheets that are cold formed and welded together by electrical resistance welding. The outer surface is covered with zinc as a thin layer. The plate contains a special eutectic solution with a fixed freezing and melting point. The eutectic evaporator (ring type) is located inside the plate and allows the solution to freeze. It forms the system together with semi-hermetic compressors.
1.2.1 Key Benefits of Eutectic Plates Zero Noise Continuous cooling even when the car engine is off Zero-emission, No fuel or energy required during delivery, Low failure rate, Environmentally friendly system, Low maintenance cost Ease of use
- EUTECTIC COOLING IN REFRIGERATED VEHICLES STORAGES The vehicle body, which is previously electrically cooled for 4-6 hours, is then cut from the energy source and set off to the destination. During transportation, the cold energy loaded on the plates will be spent and the body will be kept at the desired temperature levels. This process takes 18 to 24 hours. Therefore, the body carries the goods through its engines at reliable and pre-set temperature levels for up to 24 hours without any energy consumption.
2.1 Connection of Eutectic Plates to Refrigerated vehicle storages For the assembly of the plate; special materials should be used, consisting of stainless nuts and bolts, steel profiles and a special anti-slip rubber.
- SMALL EUTECTIC COOLED CABINETS Small eutectic cabinets are preferred for frozen or chilled foods and the pharmaceutical industry. Eutectic plates cooled outside are placed inside the insulated cabinet. The number and capacity of plates are determined according to the desired temperature and duration of use.
- CONTAINER TYPE EUTECTIC COOLING IN COLD STORAGE Eutectic cooling can also be applied in containers. The system is the same as the system in refrigerated vehicle bodies. The number and size of plates are determined according to the material to be kept inside.
BENEFITS OF EUTECTIC COOLING
It is a reliable, environmentally friendly system. It is based on reusable energy. It is extremely flexible and can be used for chilled or frozen products. It consists of virtually maintenance-free plates and it can be adjusted in order to maintain a variety of temperatures for different applications
This technology provides high energy and cost savings during cold or frozen product transportation. The goods arrive at the final destination, regardless of the factors inherent in the driver and other factors. The coolant is not connected to the vehicle engine. Therefore, it does not cause additional fuel consumption while the vehicle moves. Another advantage arising from the use of eutectic type bodies is that the same body can be divided into separate compartments to allow simultaneous transportation of both cold and frozen products.
The chilled body with the eutectic system is completely independent of the chassis, so the constant temperature is always provided. After the eutectic plates are loaded, they provide reliable and rapid cooling for a certain period of time, even with frequent door openings. In case of a vehicle failure, the goods are protected. The eutectic system also does not use diesel.
The eutectic cooled cooler bodies make it an environmentally friendly alternative that is compatible with both electric trucks and internal combustion engines. Due to the absence of zero emissions and engine noise, such refrigerated trucks are ideal, especially in urban areas. It is a thermal energy storage system that can be frozen again and again. You can charge as much as you need for your customer delivery and make your delivery without spending unnecessary energy. Since the system requires less energy, it provides continuous and even temperatures, thus facilitating maintenance and logistics and increasing profits.
- Category: Makaleler (EN)