In this short article, we will answer the question “What is the freezing temperature?” and will answer related questions about food preservation by freezing.
One of the earliest techniques for food preservation is the use of cold. The cold applied to food causes total or partial inhibition of the main agents responsible for food alteration.
These agents are: which are microorganisms, the metabolic activities of animal and plant tissues after slaughter and harvest, enzymes, and chemical reactions depending on the temperature used in the process.
As a result, it is possible to extend the commercial viability of foods for a long time while only mildly altering their original nutritional and sensory properties when done appropriately.
What is the freezing temperature?
The precise temperature at that the water content and also the main part of the solutes in a particular food solidify is known as the freezing point.
What distinguishes food that has been frozen from that that has been refrigerated?
Reducing and maintaining food’s temperature above its freezing point is the goal of refrigeration; temperatures between 8°C and -1°C are more typical.
This procedure merely extends the commercial life by a few days or weeks since it slows down microbial growth and reduces metabolic activities, chemical processes, and enzymatic reactions.
When food is frozen, its temperature is drastically reduced, falling below its freezing point, which for most foods is a temperature lower than 0°C. Foods that are frozen are maintained at -18°C.
Additionally, some of the water in the food undergoes a physical shift that results in the formation of ice crystals. The primary distinction between refrigeration and freezing is this shift in the condition of the water.
A large portion of the water becomes immobilised as ice crystals form, making it unavailable to microorganisms and slowing down chemical and enzymatic activities.
Low temperatures and a decrease in water activity in the liquid phase enable food to be kept for months or even years. In contrast to cooling, where there is some activity in cellular metabolism, freezing fully stops it.
Food freezing: perform it quick or slow? Which is the preferable alternative?
The quicker the food is frozen, the less of its nutritional value and sensory qualities will be lost when it is thawed. Now, to prevent the growth of germs, thawing must be done gradually, under refrigerated temperature rather than at room temperature.
However, because crystals develop when food is frozen, it is nearly impossible to prevent some changes in food quality. But despite the ice crystals, the main benefit of freezing is minimising food waste among its many other benefits.
In addition, freezing makes it possible to prepare meals in advance, stock up on seasonal foods to ensure the availability of ingredients for recipes, visit the shop less frequently, and even place supplier orders.
How can food-borne ice crystals form?
A meal is frozen to create ice crystals, which are composed of a portion of the water in the food changing its state from liquid to solid. One of the main reasons why frozen meals alter in an unfavourable way is because of the creation of these crystals.
Nucleation and crystal development are the two stages of this crystallisation process. The joining of water molecules to create a tiny, organised, and stable particle is known as nucleation. The temperature needs to be below the freezing point for this to happen.
At this stage, crystalline aggregates are produced, but they do not grow to a critical size. The rate at which heat is extracted from the food determines how many nuclei are created.
It is feasible to control the crystal size by adjusting the freezing rate during the organized crystal development phase. When freezing occurs too quickly, the nucleation process proceeds more quickly, resulting in the formation of small crystals.
However, the crystal growth phase proceeds more slowly, resulting in smaller crystals that do less harm to the structure of the meal.
Cryoprotectants with an affinity for water, such as glycerol and sorbitol, which are capable of mobilising water and preventing its crystallisation, are employed to avoid issues caused by the development of ice crystals during freezing.
In this short article, we answered the question “What is the freezing temperature?” and have also answered related questions about food preservation by freezing.