4 ms·
The paper refers to "volume" frequently (I quoted some examples), but I'm unclear on what "volume" means. Is it the thing that's being frozen? The space that it
by vosper 5y ago
The paper refers to "volume" frequently (I quoted some examples), but I'm unclear on what "volume" means. Is it the thing that's being frozen? The space that it's being frozen in? Something else?
> In recent years, taking its roots from the biomedical industry, isochoric (constant volume) freezing is gaining both research and commercial interest as an effective method of food preservation.
> During isochoric freezing, the volume of the system remains constant while variables like pressure and temperature vary in tandem.
Edit: Having read a bit further, I think "volume" is the space that the thing is being frozen in. I'm don't really understand how that's different to normal freezing though: my freezer doesn't change size when I freeze something in it.
> "In a typical isochoric process, the food material is immersed in an isotonic solution inside a rigid container that is capable of withstanding elevated pressures."
- 6nf 5y agoMost foods you'd want to freeze are high in water, which expands by 4% when it freezes, so they are talking about placing the food product in a vessel that prevents that expansion (and increasing the pressure instead)
- unwind 5y agoThe expansion is actually more than double that, 9% is the figure I've commonly seen. See for instance Wikipedia [1]: An unusual property of water is that its solid form—ice frozen at atmospheric pressure—is approximately 8.3% less dense than its liquid form; this is equivalent to a volumetric expansion of 9%. The "4" might be coming from the temperature at which water's density is the largest, which happens at 4 degrees Celsius. Water is weird. :) [1] https://en.wikipedia.org/wiki/Ice#Physical_properties https://en.wikipedia.org/wiki/Ice#Physical_properties
- istjohn 5y agoWater expands when frozen under constant pressure. Since meats and produce contain a lot of water, they normally expand when frozen, too. This expansion damages the cellular tissues, ultimately making the food less pleasant to eat. They are using rigid containers able to contain high pressures to prevent the food from expanding at freezing temperatures.
- 1MachineElf 5y agoI will say I've met a chef whose secret meatball recipe leveraged the cellular destruction caused by freezing along with salt to enhance the flavor.
- h2odragon 5y agoFreezing under high pressures makes for a different type of ice, which doesn't expand like "normal" ice we know at atmospheric pressures we're accustomed to.
- ptsneves 5y agoThe point of the article is that no phase change happens, meaning water remains liquid, and so different ice types do not matter.