Lab Cat

9 Mar 2006

Vitamins Part 2 Stability

Filed under: Food, Science — Cat @ 6:32 pm

It has been some weeks since I first posted about Vitamins and so it is time to go onto the second part of Vitamins in Food Chemistry.

The second module on vitamins in food chemistry is stability. Vitamins, especially Vitamin C (ascorbic acid), thiamin (B1) and riboflavin are exceedingly unstable. The final amount of vitamin in a food is affected by growing conditions, post harvest changes, initial treatments (washing, milling), blanching and other thermal processing, and storage. In addition to the effects above, the food itself and its chemical composition will influence vitamin stability and different vitamin structures have different stabilities. Most of the information has come from the various Food Chemistry textbooks I own and from information I have gathered over the years studying ascorbic acid reactivity (some references listed below). Most of this discussion is in reference to fruit and vegetables, which are one of the major sources of vitamins. They are also extensively studied.

Typical reactions that vitamins are susceptible to are:

Oxidation: Fat soluble vitamins, vitamin C, thiamin

Degradation and other reactions (non-enzymic browning) – ascorbic acid, thiamin

Photochemical reactions – riboflavin, beta-carotene, folic acid

Food chemists are primarily concerned with maintaining the maximal vitamin content of foods, but sometimes this is difficult. Even if we eat freshly picked produce that is then prepared at home, water soluble vitamins are lost by leaching into the cooking water. Thermally unstable vitamins are destroyed by cooking and fat soluble vitamins are susceptible to oxidation. Some vitamins, riboflavin in particular, are sensitive to photochemical changes and are destroyed by the presence of light. It has been shown that milk left of the doorstep (there are still home deliveries in the UK) had less riboflavin than milk stored in the dark. I remember also being told (personal communication with Dr T. Labuza) that pasta stored in clear plastic bags had less riboflavin than pasta stored in boxes. Also pasta at the back of the shelf, where less light got to it, had more riboflavin than the pasta at the front. Beta-carotene, provitamin A, is also sensitive to light-induced oxidation.

Growing conditions; soil, water, sunlight, as well as variety can alter the vitamin content of a food. In addition, the vitamin content of fruit changes during in maturation. Once the produce has been harvested metabolic reactions continue and vitamins can be destroyed. For example, potatoes stored through out the winter have less ascorbic acid than new potatoes. This used to be a problem in Britain as potatoes were the major winter source of this vitamin. By spring, the incidence of scurvy, Vitamin C’s deficiency disease, would increase until fresh produce was ready. Correct storage and treatment can reduce vitamin loss during post harvest.

After harvesting, food under go preliminary treatments such as trimming washing and milling. Thiamin loss is particular serious in the milling of rice. In fact, the cause of thiamin’s deficiency disease, beriberi*, was discovered due to a comparison of diets containing white rice (low in thiamin) and brown rice (high in thiamin). The loss of vitamins during milling lead to the legalization of enriched cereal grains (see part 4).

Thermal processing is an important step in food processing. At its simplest, blanching is used to inactivate enzymes and reduce micro-organism levels. Loss of vitamins occurs both by oxidation and by leaching into the cooking water. While the effect of heat on vitamins is important, during blanching the product is heated is for a very short time. Other processing steps with elevated temperatures can cause significant loss of vitamins and this loss is dependent on the chemical nature of the food. Acidity (pH), relative humidity, dissolved oxygen, presence of transition metals and other reactive compounds all influence vitamin stability during processing. Vitamins are also lost during storage.

*Wikipedia states that Christiaan Eijkman (1890) and Casimir Funk (1912) were the discoverers of the link between thiamin and beriberi, but in my notes, I have Kanehiro Takaki (1880) as the first person to identifiy it on Japanese warships.

Kanehiro Takaki

References

Fennema, O. Food Chemistry, 3 edition.; Marcel Dekker, 1997.

deMan, J.M. Principles of Food Chemistry 3rd edition, Aspen 1999

Christen G.L. and Smith, J.S. Food Chemistry: Principles and Applications, Science Technology System 2000

Davies C.G.A. Ascorbic acid degradation and its inhibition by sulphur (IV) oxospecies. PhD thesis, Leeds University 1993

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27 Comments »

  1. Very interesting. I’ve always wondered about the degredation of nutrients in stored and prepared food, and now I know.

    Comment by Britton Cole — 20 Mar 2006 @ 2:20 pm

  2. Glad to help. If you have any questions or want further information on other food chemistry topics let me know.

    Comment by Cat — 21 Mar 2006 @ 1:04 pm

  3. I would like to know the temperature at which vitamin C breaks down rapidly. Specifically, I take a Vitamin C pill with orange juice in the morning, but then drink my coffee and was wondering if the hot coffee would destroy the chemical bonds making up Vitamin C.

    Thanks for any info you could provide . . .

    Bill Jensen

    Comment by Bill Jensen — 2 May 2006 @ 8:44 am

  4. Bill,

    I think you should be all right taking your vitamin C tablet with orange juice followed by hot coffee. I’m not sure about absorption rates, but vitamin C is a small water soluble molecule and so I would propose that it is absorbed very rapidly. If you are concerned you could eat something between drinking orange juice and coffee.

    Most studies on food have been done at 40 oC and above. The higher the temperature the more rapid the destruction of vitamin C. The biggest problem is when you boil vegetables for a long time, as vitamin is both degraded by the heat and leached into the cooking water.

    Thanks for you commment, I hope I answered your question.

    Comment by Cat — 2 May 2006 @ 10:04 am

  5. hi! I am a student in Technion, Israel. I am working on a project about infant milk formula’s shelf life. I need information about the vitamin C degredation during the storage as a result of the heat processing , temperature during storage and other factors.
    I olso read that the vitamin C degredation products can result maillard reaction and radicals reaction and couse loss of amino acids and fatty acids in the product.
    I would be really glad to get any usefull information on this topic.
    thanks,
    Olga

    Comment by Olga — 13 Jun 2006 @ 7:58 am

  6. Hi Olga

    I was going to write a separate blog on this very subject. I can direct you to articles if you email me cdavies at udel dot edu

    Who are you working with at Technion? Dr Shimoni and I did a review article on vitamin C stability when we were in Minnesota – you could see if he has a copy.

    Comment by Cat — 13 Jun 2006 @ 8:22 am

  7. Hi again!
    Dr Shimoni is my lecturer. I would be very glad if you could direct me to articles on this topic.
    my email is solga100@t2.technion.ac.il
    thanks

    Comment by Olga — 14 Jun 2006 @ 4:19 am

  8. I would like to know the thermal stability of beta carotene, at what temperature it will be degraded.
    Thank You

    Comment by lukman — 16 Aug 2006 @ 8:20 am

  9. I don’t know that kind of detail off the top of my head. I’m sure this information is available in Merck Index or somewhere similar.

    Comment by Cat — 16 Aug 2006 @ 2:37 pm

  10. hi! I am a student in master physics, yemen. I am working on a project about the effect of light and temperatur on stability of vitmin a . I need information about the mechanism of degredation during the storage as a result of the heat processing , temperature during storage and other factors. also theectivition energy

    Comment by mohammed — 2 Oct 2006 @ 3:47 pm

  11. Mohammed

    Hi,

    As I told Lukman – I don’t know that kind of detail about vitamin A. Do you have access to a food chemistry text book? The information should be in there.

    Good luck with your research.

    Comment by Cat — 3 Oct 2006 @ 11:37 am

  12. Companies such as DSM and BASF have vitamin stability data under various manufacturing and storage conditions. They would be good contacts.

    Rob Stuart, Stuart Products, Inc.

    Comment by Rob Stuart — 7 Dec 2006 @ 5:54 pm

  13. Hi,

    I’m a student of food technology on University of Belgrade, Serbia. I’ve stumbled upon your post, while searching for information I need on vitamin stability in foods, focusing on ready meals. I think you need to know that the literature containing data linked to this matter is hard to find, and I need as much as I can get. This actually, is a very difficult task, cause many books I’ve came across are not accessible to me. Many sites require subscription, and I’m just not in the position to fulfill those demands. Is there anything you can do to help me.

    Thanks.

    p.s. My English is a bit rusty, so I hope that you understood what I was talking about

    Comment by Nemanya — 16 Feb 2007 @ 5:31 pm

  14. Thanks for the article,
    I’m a student at Sydney Girls High School (Australia) and I’m doing a Science Research Project (SRP) on whether vitamin C decreases in orange juice in the fridge over time. I was wondering if you could tell me what can decompose vitamin C and if any similar experiments have been attempted before, as I havent found any others on the net.
    Thanks

    Comment by alex — 7 Mar 2007 @ 12:52 am

  15. hello sir, i am mehul from RMIT, melbourne. i am doing master of food science and now, i am working on the project ” stability of vitamins in processed veg & fruits”. i read your article, its quite interesting. but sir, i need more details on stability of vitamins, specially, water solubles, before and after thermal processing.
    if you have any references on above mention topic, please, advice me.

    i am sure, you will help me out. i am waiting for your kind reply.

    with warm regards

    Comment by mehul — 24 Jul 2007 @ 8:17 pm

  16. hi. im having problems giving multi-vitamins to my kids and was wondering if incorporating them into the lollipops/candies i make was possible. I was planning to incorporate vit A, B-complex, C, D, E, etc. but I’ve read that heating vitamins/minerals would render them almost useless, but how useless? The heat from cooking candies/lollipops could reach 300F or 150C. Any solutions, pls?

    Comment by Alvin Florentino — 16 Aug 2007 @ 9:11 pm

  17. Alvin

    Heating those vitamins, especially vitamins A, some B vitamins and C, will totally destroy their activity. You buy commercially prepared vitamins in candy for children where the vitamins are added after processing. Or you could do what my Mum used to do when I needed to take aspirin (in the days when kids were allowed to take aspirin). She crushed the tablets and mixed it with jam or jelly. I loved to get a spoonful of jam when I was ill.

    Comment by Cat — 16 Aug 2007 @ 9:18 pm

  18. Do you have any information or could your recommend any recourse to find direct information on Vitamin (fat/water soulble) derogation in low pH(2.5-1.5) solutions.

    Comment by Jacob — 18 Jul 2008 @ 8:26 am

  19. To what extent is B12 affected by heating?

    eg. smoked oysters.

    Comment by Roni-Sydney:Aust — 9 Nov 2008 @ 4:15 am

  20. [...] Internal changes to the chemical make up of food. A good example would be loss of vitamins [...]

    Pingback by Tasty Tuesday: Food Preservation Introduction – Reducing Moisture availability « Lab Cat — 2 Dec 2008 @ 7:38 am

  21. I submit a question !!!
    I read here :
    <>

    How about amino acids ?

    Comment by Siegfried — 30 Jan 2009 @ 9:49 am

  22. Thank you for creating this blog. I am also interested in vitamin stability. I would like to ask whether you have created a blog for all references that you sent to individual?

    Kind regards,
    Lina

    Comment by BuiL — 15 Oct 2009 @ 8:03 pm

  23. i m the student of Eastern medicin.at Islamia university of bahawalpur.Pakinstan. i had to assign to make some fomulate a herbal nutritional supplement. on getting vitamins from natural souce , i hav incountered by thermal degradation of vitamins. i have collected information as many as i can do. it is a difficult task but not impossible. if you coan help me to giving me knowledge about prevention of vitamins from thermal degradation.

    Comment by hafiz abdul sattar — 30 Oct 2009 @ 3:42 pm

  24. [...] Stability of Vitamins (Many references for different vitamins, so quoting a few, a google scholar search will give u many academic publications) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1253064/ http://cdavies.wordpress.com/2006/03/09/vitamins-part-2-stability/ [...]

    Pingback by Always eat fruits before a meal?? The science behind false claims | Contemplation — 16 Aug 2010 @ 6:32 pm

  25. Most home-made recipes for rose hip syrup involve prolonged boiling both for extraction from the fruit and then to create a syrup. They are also promoted for high Vit C content! Is this true or is it likely that most will have been destroyed? Tastes good though!

    Comment by Mike welch — 6 Sep 2010 @ 10:40 am

  26. […] Stability of Vitamins (Many references for different vitamins, so quoting a few, a google scholar search will give u many academic publications) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1253064/ http://cdavies.wordpress.com/2006/03/09/vitamins-part-2-stability/ […]

    Pingback by Always eat fruits before a meal?? The science behind false claims | Akshat Rathi — 30 Dec 2013 @ 12:53 pm

  27. […] contribution deserves its own category to draw reader attention to it. This essay discusses the stability of vitamins during processing. The author, Lab Cat, is a new contributor to Tangled Bank, so be sure to make her feel welcome by […]

    Pingback by Tangled Bank 49, The Science, Nature and Medicine Blog Carnival | This Scientific Life — 24 Jul 2014 @ 4:20 pm


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