Freezer bum

The sugar becomes like honey when the water is removed, and slight carmelization can occur in rare cases. This is to prevent "freezer bum". Any food left uncovered and placed in a freezer will. dowly freeze diy. The water in the bag is to prevent this. 

Frozen foods must be protected from dehydration and freezer bum durng storage. 

When frozen foods are left in the freezer for a long time, so much water sublimes that foods, especially meats, become dry and shrunken, a condition called freezer bum. Deposition occurs in a freezer when water vapor forms ice crystals on the surface of freezer bags and frozen food. 

Many solvents are good fuels, and will readily bum in air. Ibis can be a safety hazard in laboratories and factories. The temperature at which a solvent catches fire in the absence of a flame is called its aiitiHgnitjon tempeiatiiie. This is surprisingly high for most solvents (Table 10.2). The temperature at which the vapour pressure of a pure solvent in air is sufficient to be ignited by a naked flame is called the flash point of the solvent (Rg. 10.14). This can be very low (Table 10.2). R>r example, the flash point of petroleum ether (a fraction obtained from the distillation of cmde oil and which boils between 30 and 40°C) is —51 C. This means that petroleum ether stored in an open (or leaking) container will still represent a serious fire hazard even if stored in a freezer operating at — 51 C. Rash points are used to classify the flammability of solvents. 

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