Why should food be frozen quickly?
I was reading one of the articles in Uncle John's Curiously Compelling Bathroom Reader about the history of harvested ice and ice houses. The article mentioned that electrical freezers and refrigeration only entered widespread use because someone realized that food needs to be frozen quickly for it to be most effective.
Why does the speed of freezing affect the quality of the frozen food?
Best Answer
Two Reasons:
1.) The faster the food drops below the 'Danger Zone' the less spoilage it will have
If it takes that freshly-cut steak 2 hours to cool down from cow-body-temperature to a safe 40F, that's more spoilage and less shelf-life for the product. A rapid chill-down means a more valuable product.
2.) Ice-crystals damage food, and the faster water freezes, the smaller the ice-crystals
If the temperature of the water drops slowly, the water-molecules will have time to organize themselves into nice, neat rows (imagine a big snowflake). At a microscopic level, these ice-crystals will puncture cell-membranes and cell-walls, damaging the food and affecting texture.
If, on the other hand, the temperature drops rapidly, the ice-crystals will form more haphazardly, with less well-organized crystals. This means fewer ice-javelins stabbing into your food.
Try an experiment sometime: take a serving of ice-cream out of your freezer, let it melt completely, put it in an airtight container, then toss it back in the freezer. Let it freeze completely and taste it. The flavor will be roughly the same, but the texture will be much worse. There will be big, crunchy ice-crystals throughout.
The big-time ice-cream makers invest in heavy-duty freezing tech that allows them to freeze the ice-cream faster, and with smaller crystals, the less-granular, and more creamy this tastes.
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Quick Answer about "Why should food be frozen quickly?"
Rapid freezing improves the quality of the food. The faster food freezes, the smaller the crystals that form. Small crystals do less damage to cell walls. Slow freezing produces large ice crystals that punch through cell membranes.Why is it important to freeze food quickly?
Freeze food as fast as possible to maintain its quality. Rapid freezing prevents undesirable large ice crystals from forming throughout the product because the molecules don't have time to form into the characteristic six-sided snowflake. Slow freezing creates large, disruptive ice crystals.Why is freezing a food faster than thawing it?
Thawing generally occurs more slowly than freezing. Theoretically, thawing is the inverse process of freezing; they are different not only in phase change direction, cooling and heating process, but also in food freezing time and internal temperature variations (Min 2001).What happens to food frozen too long?
Food can remain frozen indefinitely and technically be safe to eat, as bacteria will not grow. However, over time all frozen food will deteriorate in quality and become unappetising to eat when defrosted.What are the advantages of freezing?
Freezing reduces the number of potentially harmful bacteria that can cause food poisoning. It does that by preventing micro-organisms from growing (which happens naturally as fresh food degrades.) Freezing suspends microbial and fungal activity in food. As long as it's frozen, it's safe.Fresh or frozen food? Using SCIENCE to prove which is best with surprising results! - BBC
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Jill Wellington, Sebastian Coman Photography, Kindel Media, Artem Beliaikin