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What causes food to spoil

  1. Nov 2, 2005 #1

    Pengwuino

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    I'm not sure if this is the right place for it though! What exactly cuases various foods to "go bad". What causes a tomato, for example, to ... well, be not so ripe and firm. What causes bread to go bad? What about other fruits and vegetables? Also, is there a way to keep foods from going bad (even if its impractical)?
     
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  3. Nov 2, 2005 #2

    Moonbear

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    Mold and/or bacteria growth leads to spoilage (and sometimes insects or worms contribute). The molds and bacteria are picked up from the environment and are always on the fruits, bread, etc, and as the colony grows, spoilage occurs/worsens. One thing that will help a little with fruit is to wash it as soon as you get it home. That way it isn't carrying all the molds it picked up in the grocery store from other rotting fruit near it.

    You can keep them from going bad by sterilizing them and storing them sterile; this is the basis of canning foods to preserve them for a long time. Chilling also slows the growth of the molds and bacteria, so will slow spoilage. If I notice food spoiling too rapidly in the refrigerator (such as my cheeses getting moldy too soon), I'll wash down the entire inside with a bleach solution to disinfect it.
     
  4. Nov 2, 2005 #3

    Pengwuino

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    How bout a UV lamp. I remember someone saying its a "microbial WMD" :P
     
  5. Nov 3, 2005 #4

    Moonbear

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    UV will kill bacteria, but you'd need a long exposure time to kill a lot of bacteria. Be careful of eye/skin exposure to UV though.
     
  6. Nov 3, 2005 #5

    Pengwuino

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    hmmm could you integrate a UV lamp into a refrigerator? :D That'd be neat! And it could work opposite of a refrigerators normal light. Door open? Light off, door closed, light on!
     
  7. Nov 3, 2005 #6

    Moonbear

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    I'd have to think about it...I'm not sure if it would have a negative impact on foods...nothing that immediately comes to mind, but it's just late enough at night that I might not be thinking of something obvious. It wouldn't penetrate to any depth in the food, I think it would just kill surface bacteria, but it would be better than nothing I suppose. But, that's pretty much how we operate laminar flow hoods and biosafety cabinets in labs, the UV light is on whenever it's not being used to kill off any bacteria on the surfaces, and then off while we're using it so we aren't exposed to it.
     
  8. Nov 3, 2005 #7

    Monique

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    Gamma radiation is used to sterilize food (I heard).
     
  9. Nov 3, 2005 #8

    iansmith

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    Food is expose to radiation to either reduce the amout of bacteria or to sterilize the product. So you three different type of process that will kill bacteria to different level but the most common one is irradiation which is like pasteurization.

    http://www.physics.isu.edu/radinf/food.htm

    http://www.inspection.gc.ca/english/corpaffr/foodfacts/irrade.shtml

    Potatoes and several root vegetables are usually pass through radiation to delay sprouting
     
  10. Nov 3, 2005 #9
    If there were no bacteria or fungi present, would fruits get overripe by themselves? I know fruits are programmed to ripen by breaking down some of their carbohydrates, increasing the amount of simple sugars and making them taste sweet and smell good. Maybe this process continues until they're overripe? Ethylene signals fruit to ripen, so maybe it could signal spoilage.
     
  11. Nov 4, 2005 #10
    UV light also kills good cells as well as bad ones... so i would think that food under prolonged exposure to UV light (in a fridge) would just die

    it can also cause mutations.... and i dont think i'd want to eat a mutated tomato :S
     
  12. Nov 4, 2005 #11

    Moonbear

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    chantella, all organisms have mutated cells. Plants are exposed to UV light originating from the sun all the time. Once they are plucked from the vine, they are no longer growing, so one would not expect very many cells to be continuing to undergo cell division.

    Parts of plants undergoing prolonged separation from nutrients (i.e., after harvested) are dying already.

    Nipwoni, thanks for bringing up the issue of conversion of carbohydrates to sugars. I think it's actually the sugars that feed the bacteria, and the bacteria fermenting the sugars is spoilage. Once the carbohydrates capable of producing sugars are depleted, the fruit would cease that process.
     
  13. Nov 4, 2005 #12

    Ouabache

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    Yes, the fruit would undergo senescence or physiological decay.
    Fungi have been mentioned here as part of fruit spoilage. Here is related thread, we had recently on that subject.
    Be careful about generalizing. Think of corn-on-the-cob. To taste the sweetest flavor, you should have your water boiling, before you pick it. Then run from your garden plot and toss them in your pot. Because as soon as it is picked, the sugar begins turning to starch. Have you ever eaten late-season sweet corn? :yuck:

    For dessert fruit, we anticipate ripe fruit to be sweeter, along with other flavorful biochemicals :tongue2:, than unripened. Besides tasting good, does it serve any useful purpose? It turns out to be an example of coevolution between plant and animal. Tastier fruit attract animals (like us) to eat them. Animals (following digestion) disseminate the seeds where-ever they wander along with some fertilizer. This increases the plant's chances of survival by allowing them to be seeded in diverse locations. The plants with the tastiest fruits are more fit to survive over the bland ones. At the same time, animals get to eat tastier fruit.
     
    Last edited: Nov 5, 2005
  14. Dec 9, 2005 #13
    Fruits and meat decompose. Meat decays by it's own internal chemicals and enzymes; and putrefaction, the breakdown of tissues by bacteria. However if both are kept in vacuum under low temperatures, decay occurs very slowly if it all.
     
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