The physical stability of food clearly depends on the stability of each system component, and in addition, the instability of one system component may also cause instability of other components.

low temperaturePre freezingIt can enhance stability, but often has the opposite effect. We will discuss low temperaturePre freezingInfluence on true solution, colloid system, emulsion, foam and cell system, and the effect of water onFZG Food Freeze Drying MachinePre freezingThe role of stability in the food system.

one、truesolution

A true solution consists of two parts: the solute part, which is the dissolved substance; The solvent part refers to the substance that dissolves or diffuses solutes. For food, the focus is on studying the solutions formed by solids, liquids, and gases in water.

existordinaryThe real solutions in food are often diluted water systems, and their freezing performance mainly depends on the temperature range, that is, above or below the freezing point.

(1)existFZG Food Freeze Drying MachineThe impact of cooling above the freezing point

Solid substances absorb heat during dissolution, such as when dissolving sugars and most salts, but their solubility is poor at lower temperatures. Conversely, when dissolving gases in liquids, solubility increases with decreasing temperature. The diffusion coefficient and osmotic pressure decrease with decreasing temperature, but the viscosity increases with decreasing temperature.

（2） InFZG Food Freeze Drying MachineEffects of cooling below freezing point

1. General mode of freezing process

The freezing point of an aqueous solution can be defined as the highest temperature at which ice crystals form.

The freezing point of a real solution decreases with increasing solute concentration. The freezing point is determined by the molar concentration of solute. Compared to the freezing point of pure water, the decrease in the freezing point of a dilute solution isFor a solute containing one mole in 1000 grams of water, it is a constant, which means that regardless of the properties of the substance, it is equal to 1.86 ℃.

The decrease in freezing point in dilute solutions containing electrolytes that do not dissociate or bind△trCan be used for FrenmaThe formula (2.1) for Fennema and Powrie 4 is determined.

WhereΔ tr freezing point decrease value, ℃;

Kr mole freezing point constant=1.86 ℃ (when dissolved in water)a pharmaceutical or other chemical preparationtime);

G - number of grams of solute;

G-grams of solvent;

M - the molar weight of a solute;

M - molar concentration.

When solute electrolysis dissociates, at the same molar concentration,The Δ tr value is relatively large.

Next article to be continued preview:FZG Food Freeze Drying MachinePrinciples and Freeze Drying Technology-Pre freezingThe impact of food（three）