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Chemistry (including Biochemistry)/preserving odor/other packing storage ideas

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QUESTION: Hi Trista
You provided a long term packing and storage procedure for occasional access to the collection of the ladies used footwear by using Tyvek mailing envelopes, aerate with only nitrogen, seal and freeze them.
I will now need to look at a packing and storage procedure for regular access to the collection.
A textile chemist answered the shoes could be stored in sealed polyethylene bags.  Polyethylene has some permeability.  If sealed completely in an air tight package volatile components from degradation products could damage the shoes.  It is a balance between trying to retain the smell for as long as possible and the best practices for the long term preservation of the objects.
A non conservator answered the residual odor of any pair of shoes will vary according to the amounts of these components absorbed onto the material of the footwear, the length of time from the last contact with the skin of the wearer, and the conditions in which the shoes were stored thereafter.
The point to note is that these are volatile components- that is they gradually disappear during contact with air.  Now the last time we corresponded, I answered under the assumption that you wanted a balance approach between preserving the odor on the fabric of the footwear itself.  If the ultimate goal is to preserve the odor, then vacuum packaging is the best way to go.  No air in the package means no evaporation, and hence containment of the volatiles you want.  These were the words of the non conservator.
Would you please give an example of a balanced approach for a long term packing and storage procedure? and an example of  vacuum packaging?
People have different views with vacuum packaging.  A female scientist answered in general, keeping things stored in an airtight container, preferably even vacuum sealed, keeps the aromatic chemicals trapped.
A male scientist said I don't think vacuum sealing is what you are looking for.  Creating a vacuum will always tend to draw volatiles out of any material, and it will do so by usually pulling out lighter molecules more than large ones, thereby changing what you are trying to preserve.  Vacuum is a very unnatural state for any material to experience at the Earth's surface.
An expert in climate control answered you will need a good oxygen barrier bag, fabricated with a wide heat seal.  Alu foil composite film is ok, so is Escal, other materials are available.
The non conservator also mentioned LDPE is, of course breathable, permitting a certain amount of air exchange into the package, and thereby posing a slight risk of losing odor.  Polypropylene is essentially gas tight, and will hold odor 100%, but may, over a very long period of time cause a LOW risk of fungal growth, unless the interior of the package is kept dry by the use of silica gel.
You have to choose one risk over the other.  For the conservator, he would prefer to risk the loss of odor over the risk of destruction of the item by mold or fungal growth.
I would also rather risk the loss of odor over time than destruction of the objects, but he is wrong about using silica gel as silica gel will absorb odors.
There are zipper lock bags found at talasonline.com.  These bags are made from virgin, uncoated polyethylene and are suitable for long term archival storage and are acid free.  They also come in a heavyweight 4mil, thickness for added protection. The textile chemist said the shoes could be stored in sealed polyethylene bags so maybe these bags would be a good choice long term and for regular access to the collection while trying to preserve the original odor (foot scent) from the footwear for as long as possible.  You may recommended using the zipper lock LDPE bags 4 mil for regular access to the collection  as a balanced approach, trying to retain the smell for as long as possible and the best practices for the long term preservation of the objects.
Thank you!

ANSWER: Hello!

Given the data you have presented, I would argue your last option seems the best - utilize the 4mil polyethylene.

However, I had an idea about the polypropylene. Have you considered Drierite? (anhydrous calcium sulfate) Chemically, it prefers to resorb water and other very small molecules.  Most odor-causing molecules are of sufficient size the Drierite will not adsorb them. It may be regenerated in an oven for multiple uses. We use this in organic chemistry labs to remove water from reaction products, and I believe should not absorb your volatiles. (Though experimenting would be best, as always.)

I think small amounts of Drierite in muslin tea bags (for example) should be sufficient to resorb water for articles that are regularly accessed in the collection. Just drop in a fresh Drierite bag when resealing the articles after use.

Thank you for your patience, and interesting questions!

---------- FOLLOW-UP ----------

QUESTION: Thank you Krista.  I have a few last questions for you  please before closing this subject.
The textile chemist answered the shoes could be stored in sealed polyethylene bags.
It is a balance between trying to retain the smell for as long as possible and the best practices for the long term preservation of the objects.

Once each ladies shoe or pair of shoes are placed inside each 4 mil polyethylene bag, how much air will I need to remove from inside of bag using a drinking straw or how will I know when to stop sipping air from the straw?
The textile chemist does not recommend sealing completely in an air tight package. She did not mention about removing air from the inside of the low density polyethylene bag once the shoe or shoes are stored inside before sealing up quickly.  I find using a drinking straw is a quick and efficient way to remove at least some of the air from inside of bag.

The other thing is a lady who owns an arts & craft store answered  air tight storage will not work for you, as you'd  have to use desiccant and that would absorb smells.
You mentioned Drierite will not absorb odor molecules.  Where inside the bag should the Drierite bag be placed and how often to change with a fresh one?
I'm thinking placing the Drierite bag either at the corner of the bag or placing underneath the shoe or shoes or maybe you do not recommend the Drierite come in contact with the shoes inside of bag.
It seems you recommend using Drierite  bags only with polypropylene plastic bags  whether 2 mil or 4 mil and not with low density polyethylene bags.
Thank you Krista.  I just need to be sure about all of this.

Answer
Hello!

I cannot recommend you a specific amount of air to retain in the bags. Since shoes are irregularly shaped by nature, I'd suggest sipping enough air out that the plastic sides meet. That is likely to be sufficient.

I do not know if polyethylene or polypropylene will serve you better - that is outside my expertise. I'd suggest trying both and using whichever seems best after some storage.

I suggested putting the Drierite in a muslin bag because Drierite is chalky and porous by nature, and I didn't think you wanted to get too much of the dust on your shoes. It should not react with the shoes or anything, but who wants gravel dust in their shoe? At the same time, it needs to be near the shoes to be effective. Perhaps put it on the outside of the sole of one shoe, held in place by the plastic?

Some Drierite can be purchased dyed; it changes colors to let you know when it has to be cooked again to be useful. Alternately, if the shoes are only opened once every few months, pop a fresh bag in when you repackage the shoes for storage.

Good Luck!
--Trista

Chemistry (including Biochemistry)

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Trista Robichaud, PhD

Expertise

No homework questions, especially ones copied and pasted from textbooks. I will answer questions about principles or give hints, but I do not do other's homework. I'm comfortable answering basic biochemistry, chemistry, and biology questions up to and including an undergraduate level of understanding. This includes molecular biology, protein purification, and genetics. My training/inclination is primarily in structural biology, or how the shapes of things affect their function. Other interests include protein design, protein engineering, enzyme kinetics, and metabolic diseases such as cancer, atherosclerosis, and diabetes. My chemistry weaknesses are that I do not know organic or inorganic synthesis well, nor am I familiar with advanced inorganic reactions. I will attempt quantum mechanics and thermodynamics questions, but primarily as they relate to biological systems. Furthermore, I cannot tell you if a skin photograph is cancerous, or otherwise diagnose any disease. I can tell you how we currently understand the basic science behind a disease state, but I cannot recommend treatment in any way. Please direct such questions to your medical professional.

Experience

I hold a PhD in Biomedical Science from the University of Massachusetts Medical School in Worcester. I specialize in Biochemistry, with a focus on protein chemistry. My thesis work involved the structure and functions of the human glucose transporter 1. (hGLUT1) Currently I am a postdoc working in peptide (mini-protein) design and enzymology at the University of Texas Health Science Center in San Antonio, Texas. I am in Bjorn Steffensen's lab (PhD, DDS), studying gelatinase A and oral carcinoma.

Organizations
2001 American Association for the Advancement of Science
2007 American Chemical Society
2007 Protein Society
2011 UTHSCSA Women’s Faculty Association


Publications
Levine KB, Robichaud TK, Hamill S, Sultzman LA, Carruthers A. Properties of the human erythrocyte glucose transport protein are determined by cellular context. Biochemistry 44(15):5606-16, 2005. (PMID 15823019)
Robichaud TK, Appleyard AN, Herbert RB, Henderson PJ, Carruthers A “Determinants of ligand binding affinity and cooperativity at the GLUT1 endofacial site” Biochemistry 50(15):3137-48, 2011. (PMID 21384913)
Xu X, Mikhailova M, Chen Z, Pal S, Robichaud TK, Lafer EM, Baber S, Steffensen B. “Peptide from the C-terminal domain of tissue inhibitor of matrix metalloproteinases-2 (TIMP-2) inhibits membrane activation of matrix metalloproteinase-2 (MMP-2)” Matrix Biol. 2011 Sep;30(7-8):404-12. (PMID: 21839835)
Robichaud TK, Steffensen B, Fields GB. Exosite interactions impact matrix metalloproteinase collagen specificities. J Biol Chem. 2011 Oct 28;286(43):37535-42 (PMID: 21896477)

Poster Abstracts:
Robichaud TK, Carruthers. A "Mutagenesis of the Human type 1 glucose transporter exit site: A functional study." ACS 234th Meeting, Boston MA. Division of Biological Chemistry, 2007
Robichaud TK, Bhowmick M, Tokmina-Roszyk D, Fields GB “Synthesis and Analysis of MT1-MMP Peptide Inhibitors” Biological Chemistry Division of the Protein Society Meeting, San Diego CA 2010
Robichaud TK; Tokmina-Roszyk D; Steffensen B and Fields GB “Catalytic Domain Exosites Contribute to Determining Matrix Metalloproteinase Triple Helical Collagen Specificities” Dental Science Symposium. UTHSCSA 2011
Robichaud TK; Tokmina-Roszyk D; Steffensen B and Fields GB “Exosite Interactions Determine Matrix Metalloproteinase Specificities” Gordon Research Conference on Matrix Metalloproteinase Biology, Bristol RI 2011


Education/Credentials
Oakland University, Auburn Hills MI BS, Biochemistry 1998
University of Massachusetts Medical School, Worcester MA PhD, Biochemistry & Molecular Pharmacology 2001-2008
University of Texas Health Science Center, San Antonio TX Postdoc, Biochemistry 2009-Present


Awards and Honors
1998 Honors College Graduate, Oakland University
2009 Institutional National Research Service Award, Pathobiology of Occlusive Vascular Disease T32 HL07446
2011 1st Place, Best Postdoctoral Poster, Dental Science Symposium, UTHSCSA, April 2011


Past/Present Clients
Invited Seminars:
Robichaud TK, Fields GB. “Synthesis and Analysis of MTI-MMP Triple Helical Peptide Inhibitors” Pathology Research Conference, University of Texas Health Science Center San Antonio Pathology Department (June 18th, 2010)
Robichaud TK & Hill, B “How To Give A Great Scientific Talk” Invited Lecture, Pathobiology of Occlusive Vascular Disease Seminars, UTHSCSA (Nov 11th 2010), Cardiology Seminar Series, Texas Research Park (Feb 21st, 2011)
Robichaud TK; Tokmina-Roszyk D; Steffensen B and Fields GB “Exosite Interactions Determine Matrix Metalloproteinase Specificities” Gordon-Keenan Research Seminar “Everything You Wanted to Know About Matrix Metalloproteinases But Were Afraid to Ask” Bristol, RI (Aug 6th, 2011)

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