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#1 2022-12-26 18:46:05

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,089

Science Friday Radio Broadcast

Science Friday was recommended by member Steve Stewart.

http://newmars.com/forums/viewtopic.php … 25#p204425

While Science Friday considers many topics, it does cover space occasionally.

The 15 minute audio recording at the link above reviews a new documentary on NASA space probes, and specifically Spirit and Opportunity.

A link to the video is included at the link above.

For Steve Stewart ... please consider posting future Science Friday episodes in this topic.

(th)

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#2 2023-01-02 07:49:11

Steve Stewart
Member
From: Kansas (USA)
Registered: 2019-09-21
Posts: 161
Website

Re: Science Friday Radio Broadcast

This is a Science Friday topic about frozen food.
I'll post a copy of this in the topic
Index >> Science, Technology, and Astronomy >> Frozen Food Preservation at 50 Kelvin


https://www.sciencefriday.com/segments/ … transcript

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The article states:

Have you ever pulled a long-anticipated pint of ice cream out of the freezer, only to find the strawberries crunchy and the normally creamy substance chalky and caked with ice? Freezer burn, a phenomenon caused by water in food crystallizing into ice inside the ice cream or fruit or meat during freezing, is a menace to taste buds, a driver of food waste, and even damages some of the nutritional benefits of food. And it’s always a risk as long as food preservation relies on very cold temperatures. Even flash-freezing, which works much faster, can still create small ice crystals.

But United States Department of Agriculture (USDA) food scientists, working with a team at the University of California-Berkeley, have a method that could help solve this problem. Normal food freezing, called isobaric, keeps food at whatever pressure the surrounding air is. But what if you change that? Isochoric freezing, the new method, adds pressure to the food while lowering temperature, so the food becomes cold enough to preserve without its moisture turning into ice. No ice means no freezer burn. And, potentially, a much lower energy footprint for the commercial food industry: up to billions fewer kilowatt-hours, according to recent research.

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#3 2023-01-07 18:54:45

Steve Stewart
Member
From: Kansas (USA)
Registered: 2019-09-21
Posts: 161
Website

Re: Science Friday Radio Broadcast

Another article from Science Friday about frozen food.
According to the USDA frozen food will last indefinitely.
I posted a copy of this in the topic:
Science, Technology, and Astronomy -> Frozen Food Preservation at 50 Kelvin


Spoiler Alert! When Does Food Actually Go Bad?

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#4 2023-01-07 19:17:51

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,089

Re: Science Friday Radio Broadcast

For Steve Steward re post #3

Thank you for this detail packed follow up to your earlier report!

I'd like to offer some "Real Universe" feedback ....

I am in the process of confirming a hypothesis, that packing frozen food in a double walled container would keep it fresh (and tasty) in the deep freeze for over a year.  The double walled container system I use was made by a subsidiary of Clorox. The products were distributed under the "Glad" brand, and as near as I can tell, they are no longer available.

The frozen foods were prepared using normal cooking procedures, allowed to cool to room temperature, and then packaged in a pair of Glad containers. The inner container is marked as 2 cups. (16 ounces).   the outer container is marked as 3.5 cups (28 ounces).

Before freezing, the plastic lids on both containers are sealed (by hand) to a reasonable degree of tightness.

I am interested in the report of reducing crystal formation using pressure, because the procedure described above ** does ** allow crystals to form inside the smaller container.

Regarding the question of taste ... I can confirm that the frozen meals saved as described above are just as flavorful as they day they were packed.  I would like to try for a two year storage period, and would like to use the pressure system, if it is available for home use.

(th)

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#5 2023-01-07 20:38:16

Steve Stewart
Member
From: Kansas (USA)
Registered: 2019-09-21
Posts: 161
Website

Re: Science Friday Radio Broadcast

Tahanson #4

I found this link about vacuum packed food:

Why Vacuum-Sealed is the Method to Preserve Food

At the end of the article (under conclusion) it states:

Traditional packaging allows oxygen to permeate the package, creating an environment for bacteria. In contrast, vacuum-sealed packaging is designed to seal out oxygen from around the product and tightly seal in flavor and juices, greatly lengthening shelf-life and over-all quality of product.

It's my understanding that most/all forms of life need oxygen.

respiration and breathing

It sounds like the trick is to keep oxygen out of the container so that bacteria cannot survive.
Maybe a double-walled container works because it's better at keeping oxygen out. (?)
As Caliban mentioned Mars is plenty cold to keep food frozen, and we don't need a fancy building to store food.
On Mars, perhaps a frozen storage area with a high concentration of CO2 in the surrounding air would help keep the oxygen out.

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#6 2023-01-08 12:00:08

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 17,089

Re: Science Friday Radio Broadcast

For Steve Stewart ... Thank you again for showing this program from Science Friday!

I've captured a crucial part of the transcript ... it should be interesting to read in full if forum visitors have about five minutes or so ...

11/26/2021
New Cold Storage Method Solves Freezer Burn—And Saves Energy
12:10 minutes

READ TRANSCRIPT MORE FROM THIS EPISODE
<snip>
Cristina Bilbao-Sainz is a food technologist at the USDA’s Agricultural Research Service.
<snip>
Matthew Powell-Palm is a mechanical engineer and postdoctoral scholar at UC Berkeley.

<snip>
CRISTINA BILBAO: We were pleasantly surprised at how similar these food products are to the fresh products. In terms of the appearance, they don’t lose volume. They don’t lose mass– the texture, the color, even the nutrient content. So it’s very, very similar to the fresh products.

IRA FLATOW: Huh. So it even tastes the same way?

CRISTINA BILBAO: We have only tested tomatoes and raw potatoes, and they tasted the same. Yes.

IRA FLATOW: Not every fruit and vegetable is a good fit, right? What kinds of food would this method be best for?
<snip>
MATTHEW POWELL-PALM: Yeah, so isochoric– the word means constant volume. So what we’re doing is we’re taking foods and we’re trapping them in a constant-volume box, a constant-volume container. And what this does, thermodynamically speaking, is it cuts them off from the atmosphere.

And so what we find is that if we take food products that are mostly water and we cut them off from the atmosphere and we start to freeze them, cool them down in a confined volume, then ice– because it wants to expand relative to liquid water, ice will try and expand. But the container will push back against it, and this sort of tug of war will create an internal pressure in the system.

And essentially the confinement of the system prevents the ice from freezing the food. So just a little bit of ice grows at the sort of periphery of the container. And it drives this hydrostatic pressure that stabilizes the whole system at sub-zero temperatures without allowing the foods to freeze solid. That was maybe a little more info than you were looking for, Ira.

IRA FLATOW: So we need a little bit of water inside the little freezing chamber in order for this to work, then?

MATTHEW POWELL-PALM: Indeed, indeed. So we’re swapping– if you think of conventional food freezing as happening in air, this mode of food freezing happens in water and takes advantage of the, quote, unquote, “incompressibility” of liquids.

IRA FLATOW: You know, this seems like such a simple principle in some ways. It’s sort of the opposite of the pressure cooker. Instead of heating it up, you’re keeping it cold, right?
<snip>
IRA FLATOW: Dr. Matthew Powell-Palm, postdoctoral scholar and mechanical engineer with the University of California at Berkeley.

Copyright © 2021 Science Friday Initiative. All rights reserved. Science Friday transcripts are produced on a tight deadline by 3Play Media. Fidelity to the original aired/published audio or video file might vary, and text might be updated or amended in the future. For the authoritative record of Science Friday’s programming, please visit the original aired/published recording. For terms of use and more information, visit our policies pages at http://www.sciencefriday.com/about/policies/

MEET THE PRODUCER

The freezing method appears to involve placing the food into a container that cannot expand, as plastic does in my two-container freezing system.  If I understand the process correctly, it might be possible for home cooks to take advantage of this freezing method, by placing the food to be preserved into a container with a quantity of water at the outside, and then sealing the container with screw latches.

The entire container can then be placed in the freezer.

Edit: If I understand the process correctly, there can be NO air left in the container at the time of sealing. There must be more water in the container than can fit when the lid is squeezed shut, so a specially designed lid is needed, to force liquid to the edges and out at the rim as the lid is secured.

This should be a business opportunity for sure, since the kind of containers needed do not exist on the open market.

If any NewMars members have knowledge of suitable containers for home cooks to use for a test, please add links to this topic.

If there is someone in the forum readership who would like to add to the topic, please see Recruiting for procedure.

(th)

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