Talk:Freeze drying

Wiki Education Foundation-supported course assignment
This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): CL116, Bcmich, Chronley.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 21:51, 16 January 2022 (UTC)

Student Project, Dec 4-15, 2006
Hey, I'm expanding this article for a bioseparations class I'm taking in college. Here's a link to my Professor's projects page. I may also work on the organization of this article. Wwc26 04:41, 4 December 2006 (UTC)

Thanks Will. This article on lyophilization is being edited by the above user as part of a WP:SUP student project on Downstream_processing at Cornell University. The article is slated for scientific peer review by the user's classmates and instructor over the next two weeks and will be finalized (for the purposes of the class) by 15 Dec 2006. If you would like to help, please hold off from the normal "bold editing" process until after December 15, and instead leave comments and suggestions for Wwc26 here on the article discussion page. Your thoughtful review will be very much appreciated! Jean Hunter, instructor, BEE 464 susato 17:33, 4 December 2006 (UTC)

Photo, Please!
I am requesting a photo of freeze dried food. I'm sure somebody could provide one. Ice cream is a popular freeze dried novelty because it doesn't melt, so maybe one of that? Prome theus  -X303-  21:30, 9 November 2006 (UTC)


 * You can find this at the www.nasa.gov site, where all images are noncopyright. Try "astronaut food" as a search term. susato 18:18, 13 December 2006 (UTC)

I'm going to scale up freeze drying fresh fruit,some fruit like mango、apple、peal、peach.How much will be charged per kirogram?
 * Well if you're going to "scale up" which usually means doing something on a large scale, you may want to look into purchasing your own equipment. But try googling for "freeze drying service", and that brings a few links. It looks like they don't care about the weight, but charge by the space the objects take up, and the characteristics of the material being freeze dried. Here's one site that shows their pricing online. They charge by the space and time, and I don't know how long a piece of fruit would take to freeze dry, maybe a couple days depending on the piece size. I'm thinking a whole piece of fruit would not be very satisfactory because the skin would inhibit drying, but who knows. - Taxman Talk 14:17, July 16, 2005 (UTC)


 * If a freeze-dried substance is sealed to prevent the reabsorption of moisture, the substance may be stored at room temperature without refrigeration, and be protected against spoilage for many years. Freeze drying tends to damage the tissue being dehydrated less than other dehydration methods, which involve higher temperatures. Freeze drying doesn't usually cause shrinkage or toughening of the material being dried, and flavours/smells also remain virtually unchanged.

In this section I find something what does not make sense.--Hannu 11:26, 26 June 2006 (UTC)

Taxodermy
What about taxodermy. I just saw a thing on TV about freeze drying pets. --Gbleem 03:03, 23 August 2006 (UTC)
 * Freeze drying specimens has been a common practice in the taxidermy industry for many decades. I will add that application to this article. Down time (talk) 17:33, 22 February 2020 (UTC)
 * I just added the section. Thank you for the suggestion. – Down time (talk) 20:37, 24 February 2020 (UTC)

Phase diagram
Is this recycled clip-art? Although it seems to have been named/uploaded specifically for this article, it's not clear why. In particular I am speaking of the irrelevant red-arrow. It is not mentioned in the text, nor is it especially important. What does supercriticality have to do with freeze-drying? --Belg4mit 18:22, 9 October 2006 (UTC)
 * I second the note about the red arrow. It's pointless. 213.243.137.56 (talk) 16:35, 27 March 2009 (UTC)
 * This is not water's phase diagram, the solid-liquid boundry should curve to left not right. —Preceding unsigned comment added by 130.188.8.11 (talk) 10:01, 4 March 2010 (UTC)

The coffee is never freeze dryed.
Hello. There is a mistake in this article : the coffee is never freeze dryed, because this process is too expensive. Instead, the coffee industry use a vaporisation of concentrated coffee on hot plates. I will correct this detail in the article. I hope I will not made too much english faults. rds. O.Gechter (freeze drying engineer)
 * Perhaps coffee is never freeze dried for the French market, but freeze dried instant coffee is common in the US. The coffee extract is concentrated in a wiped-film or falling-film evaporator (on "hot plates" as O. Gechter explained) followed by freeze drying. Ref:

FAQ page at manufacturer's website: http://www.verybestcoffee.com/Faqs/TastersChoicefaqs.aspx   see #7.
 * In the UK all premium instant coffee claims to be freeze dried. Looking at a typical supermarket shelf, that appears to account for about half the products available. 82.69.227.118 (talk) 17:04, 11 September 2019 (UTC)

Messages from Gokhan
Hi Will, I read your article. Here is my concerns: You are right! Introduction part should be reorganized and shortened. It would be better if you expand remaining parts under "Freeze-drying Process" and "Freeze-drying Equipments" sections a little bit. Also, a "References" section should be created and references should be added. GBoran 22:35, 4 December 2006 (UTC)

Review
Hello Will, I agree, the intro needs to be rewritten. It would be nice if you could see the categories of the articles when you first open the page. Keep the intro simple, and then divide up the rest of what you wrote in the intro into other categories like, "why this is used", "in what products this is used", etc, to make it easier to read. Overall, good job!

ReginaSophia 20:51, 7 December 2006 (UTC)

Babu's Review
Wassup Will, good job combining a lot of information into one article. I feel that your introduction isn't really an introduction, but the body of your article. I would consider converting the very first sentence into your introduction and use an "introduction" heading. Then divide the rest of that first paragraph into separate body paragraphs with headings like, "heat transfer," "applications," etc. Definitely put a picture of frozen ice-cream that you used in your presentation. Technical aspects are sound, but do correct O. Gechter's comment. Also, put some equations relating to the thermo aspect...maybe. Don't forget to link terms in your article to other Wiki. articles. Babusingh252 03:17, 8 December 2006 (UTC)

Elaine's Review
Hey Will! Great article! I think you that you have great content but that you should reorganize the introduction. It might be better you talk about the overall applications and how it is done at the end of the article or beginning to separate the content easier. For the most part, I agree with Babu. You don't really need to add more information, but just reorganize the content.

Emk39 19:55, 8 December 2006 (UTC)

Review from a regular Wikipedian
I left this on Will's talk page, but not sure how often he'll see that.
 * Hi, your expansion to Freeze drying looks pretty good, but isn't as valuable without citing your sources. If you don't want to deal with the reference templates, just site the sources however you want, and somebody else can clean them up. Harvard references (Lessig 2006, pg 23) are fine for example. Thank you - Taxman Talk 03:17, 10 December 2006 (UTC)

Picture sizing issue
I think the pictures I added aren't sized as well as they can be, since they both extend beyond their sections. It would be great if someone more experienced with adding pictures to articles could fit this. —The preceding unsigned comment was added by Wwc26 (talk • contribs).


 * The ice cream should be ok. The pic of the machine might need resizing, but it's probably going to be deleted soon.  BTW, thanks for the pics.  Prome  theus  -X303-  07:52, 17 December 2006 (UTC)

Freeze drying must first include medical and pharmaceutical applications
Vaccines and use in Pharmaceutical Industry was omitted! Freeze drying was "invented" by Incas to preserve potatoes. It was also probably used by Vikings to preserve fish. Even washed clothes drying outdoors below 0°C in a sunny morning or afternoon can be freeze drying!. The concept evolved and was industrially applied with the progress of the XX century, particularly to assist war casualties. Therefore, if freeze drying is all about, the article in wikipedia should start with freeze dried vaccines and blood plasma, to follow with pharmaceutical products, which with their high cost, can incorporate the excess of production cost in the price. Food comes next. It is becoming important today, but next —The preceding unsigned comment was added by 201.255.81.36 (talk) 22:18, 11 February 2007 (UTC).

Used on the Iditarod
I, well my mother, found this example of freeze drying being used during the current Iditarod Trail Sled Dog Race to dry clothing on a clothesline. Perhaps other Alaskan's do this regularly? It seems pretty interesting and usable for this article if (perhaps) another source can be found.--Cory Kohn 17:24, 18 March 2007 (UTC)

Nitrogen inert?
The article states that the vacuum is broken at the end of freeze-drying usually by an inert gas such as nitrogen. I didn't think nitrogen was inert (nitride, nitrate, etc...?)

Perhaps changing to "unreactive" would be more appropriate? Thanks, Jonabofftalk 18:18, 18 May 2007 (UTC)

The s/z Problem
This is only a minor thing, but could "lyophilise" link to this page as well as "lyophilize"?--Agaricus 18:31, 31 July 2007 (UTC)

IQF freezing
Need discussion/article on IQF freezing (I think it's a patented process of "individual quick freezing"). Badagnani (talk) 02:30, 18 December 2007 (UTC)

History
There seems to be a big gap in this article around the history of both this processes' development and a timeline of its practical application. -- 208.81.184.4 (talk) —Preceding undated comment added 23:49, 16 July 2009 (UTC).

Pets BS
Under 'Other Uses' there is a statement about recently taxidermists freeze-drying pets. This is garbage. The citation is based on a 1986 television episode. Patsobest (talk) 00:26, 26 August 2010 (UTC)

Awkward Wording
"Pretreatment includes any method of treating the product prior to freezing. This may include concentrating the product, formulation revision (i.e., addition of components to increase stability and/or improve processing), decreasing a high vapor pressure solvent or increasing the surface area. In many instances the decision to pretreat a product is based on theoretical knowledge of freeze-drying and its requirements, or is demanded by cycle time or product quality considerations. Methods of pretreatment include: Freeze concentration, Solution phase concentration, Formulation to Preserve Product Appearance, Formulation to Stabilize Reactive Products, Formulation to Increase the Surface Area, and Decreasing High Vapor Pressure Solvents.[2]"

The last sentence is basically a rewording of the entire second sentence. Harmonex (talk) 18:22, 9 November 2013 (UTC)

Negative Pressure doesn't exist
in the part where:

5.2 Food and agriculturally-based industries Although freeze-drying is used to preserve food, its earliest use in agriculturally based industries was in processing of crops such as peanuts/groundnuts and tobacco in the early 1970s. In freeze drying moisture is removed from frozen material through negative pressure in the chamber where that material is located.

As long as I remember in my physics classes, there is no such a thing as negative pressure, when you reach full vacuum you can't keep on 'sucking' (extracting) any more matter out of the ambient so, pressure get all the way down to 0 ATM.

Please, do correct me if I'm wrong! Juanm55 (talk) 19:54, 16 September 2014 (UTC)
 * Actually negative pressure can exist, when ever a string is pullet taut, its tension pressure is the force of tension over area which is more than 3 atm because the string is so thin and it still doesn't break. The stress in any solid is a vector sum of pressure stress and pure shear stress and the pressure component of the string's total stress is surrounding pressure - $1⁄3$ of the tension pressure and so the pressure component of its stress is less than 0. It's a lot rarer for a liquid to experience negative pressure than a solid but that can happen too. According to http://ilm-perso.univ-lyon1.fr/~fcaupin/fichiersPDF/AdvChemPhys_Caupin-Stroock.pdf, a liquid can exist under negative pressure. The reason we almost never observe it in water is because it usually has either microscopic bubbles in it or air filled cracks in the walls of the tube its in to act like nucleation sites but if you put a super smooth glass tube that's longer than 10.3 m in bubble free water that has way less air dissolved in it than it can hold and let the air out of the tube then bull the closed end to higher than 10.3 m, the water at the top of the tube will be under absolute negative pressure and still not fall back down to the height of its vapor pressure which is a bit less than 10.3 m. Suppose you have a pump at the top of a super smooth tube sucking up water that's unsaturated with air, then if the pump starts off higher than the height of the vapor pressure of water, it can't suck water higher than that height but if the pump starts off lower than that height and keeps going higher, it can suck water to higher than 10.3 m making it be under absolute negative pressure, but if a bubble gets into the tube, it will rapidly expand once it gets to 10.3 m preventing the water from being sucked up anymore. Blackbombchu (talk) 00:40, 20 November 2014 (UTC)

Sublimation of Healthy Nutritients?!
Wiki says: "Freeze-drying also causes less damage to the substance than OTHER dehydration methods using higher temperatures. ... However, water is not the only chemical capable of sublimation, and the loss of other volatile compounds such as acetic acid (vinegar) and alcohols can yield undesirable results".

Do we lose all volatile compounds with other drying methods also?

Do you recommend buying "freeze-dried berry powder" or "dried berry powder"?

ee1518 (talk) 19:57, 27 September 2014 (UTC)

How freeze drying works
Is the reason why food doesn't shrink if it dries when it's frozen because the ice in it is rigid and so won't change shape with the force of capillary action pulling the pores smaller? Are there any reliable sources that explain why it works? Also, how does heat keep getting added to the frozen food to enable sublimation to continue? Blackbombchu (talk) 00:52, 20 November 2014 (UTC)

Redirected from lyophilic
Getting here from a search on the term "lyophilic" is about as random a link as I can think of.40.142.187.175 (talk) 19:45, 18 August 2017 (UTC)

External links modified (January 2018)
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The history section should link to earlier applications of freeze-drying
For example https://en.wikipedia.org/wiki/Chuño which predates the current first example by several hundred years — Preceding unsigned comment added by 2A01:4B00:85EA:2F00:956B:30B5:AC2B:6039 (talk) 07:59, 25 October 2020 (UTC)

Inca Claim
In order for water to sublimate at 25 C, the vacuum must be below 6 mbar. It not possible these conditions can be met by climbing a mountain. If you look at the phase diagram, decreasing the temperature requires even stronger vacuum for sublimation. 161.162.26.20 (talk) 21:22, 26 October 2022 (UTC)