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  1. #1
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    Freezing potatoes

    I've done it again; made too much potato-cake mixture <img src=/S/chef.gif border=0 alt=chef width=19 height=22> (boiled potatoes and sundry root vegetables, cooled, mashed, add flour, pepper etc).
    I've had a big lunch, eaten more rolled-out and fried cakes than I should have, and am once again faced with about a litre of lovely mixture that I'd like to make use of next weekend.
    It seems to me that last time I wrapped this stuff up in a plastic bag and popped it in the freezer, it looked alright, but when I took it out it went all liquidy on me, and I needed to follow my rule "When it doubt, throw it out".

    Much the same happens, although not as quickly, if i place the bag in the main part of the refrigerator.

    The remaining option (it seems to me) is to cook the lot, make a batch of 20 to 30 potato cakes, eat five of them, and then to try freezing the cooked ones, taking them out, thawing and microwaving them as needed (or more accurately, "wanted").

    Unless anyone has a better suggestion.

    (see also Post 788625)

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    Re: Freezing potatoes

    Chris, I believe that cooked potatoes will freeze okay for a month or two. Think of the frozen french fries that you can buy in the grocery store. They have been cooked and then frozen. All the buyer has to do is take them from the freezer and heat them up. HTH

    RonM

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    Re: Freezing potatoes

    >Think of the frozen french fries that you can buy in the grocery store.
    I try not to (grin!)
    Maybe I'll have another shot.

    I reason that the processed/packaged foods have been treated somewhat differently than just being shoved into my little freezer. These guys have all the advantages of thermometers, clocks, flash-freezing, possibly dropped in liquid gases etc etc.

    I had been thinking that maybe the flour had "reacted" with the potatoes to make some sort of gluey composition.
    Freezing the potatoes separately is not a solution for me; my problem is that I already have a flour-potato mixture, and need to preserve the excess.

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    [quote name='chrisgreaves' post='760308' date='21-Feb-2009 16:11']>Think of the frozen french fries that you can buy in the grocery store.
    I try not to (grin!)
    Maybe I'll have another shot.

    I reason that the processed/packaged foods have been treated somewhat differently than just being shoved into my little freezer. These guys have all the advantages of thermometers, clocks, flash-freezing, possibly dropped in liquid gases etc etc.

    I had been thinking that maybe the flour had "reacted" with the potatoes to make some sort of gluey composition.
    Freezing the potatoes separately is not a solution for me; my problem is that I already have a flour-potato mixture, and need to preserve the excess.[/quote]

    Late to the party as usual but I am not often in here

    I am not sure that you could do this with spuds but where I work there is a ready supply of dry ice and I use this to flash freeze all of my fresh fruits (berriy's mainly) in the summer.

    I have a styrofoam box into which I place a small layer of dryice and then put a sheet of grease proof paper over the ice, when you put the fruits on top of the grease proof paper it immediately flash freezes them, I then store them in old plastic ice cream tubs in the freezer. When you eat them they taste almost as fresh as picking them from a tree or bush.

    WARNING: DRY ICE BURNS, IT HURTS, TRUST ME I'VE BEEN THERE.
    Cheers

    Steve

    Asking the questions everbody wants the answers too but feels too stupid to ask themselves :-)

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    [quote name='chrisgreaves' post='760308' date='21-Feb-2009 12:11']>Think of the frozen french fries that you can buy in the grocery store.
    I try not to (grin!)
    Maybe I'll have another shot.

    I reason that the processed/packaged foods have been treated somewhat differently than just being shoved into my little freezer. These guys have all the advantages of thermometers, clocks, flash-freezing, possibly dropped in liquid gases etc etc.

    I had been thinking that maybe the flour had "reacted" with the potatoes to make some sort of gluey composition.
    Freezing the potatoes separately is not a solution for me; my problem is that I already have a flour-potato mixture, and need to preserve the excess.[/quote]

    You might want to look into a vacuum sealing system like the Foodsaver or something similar. I've used one for years and swear by it.
    <IMG SRC=http://www.wopr.com/w3tuserpics/DocWatson_sig.gif>

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    Quote Originally Posted by chrisgreaves' post='759391 View Post
    Chris, I believe that cooked potatoes will freeze okay for a month or two. Think of the frozen french fries that you can buy in the grocery store. They have been cooked and then frozen.
    Ron, I believe that the frozen french fries have only been parboiled before freezing, and so they don't suffer quite the same effect of freezing (although to my taste, they still go somewhat mealy & mushy, compared to their freshly fried cousins.)
    Samantha

    Everything in excess! To enjoy the flavor of life, take big bites. Moderation is for monks!
    Robert A. Heinlein - Time Enough for Love

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    From what I understand, freezing causes things to go mushy since during the freezing process water expands and ends up breaking the cell walls of many fruits and vegetables. Flash-freezing helps things stay crisper (can't remember the reasons, maybe water expands more uniformly or not as much). Most articles I've seen say that things that have been frozen and turn floppy or watery when thawed are probably still safe to eat, but are just unappetizing.

    It seems like some things freeze better than others. Maybe lower moisture content helps or if the texture is already soft then it doesn't change much when thawed so it doesn't matter.

    Party tip: Don't put celery sticks in the freezer because the refrigerator is full while preparing the vegetable tray. Though they do become much more flexible after being frozen.

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    [quote name='sklyer' post='768985' date='03-Apr-2009 05:45']Flash-freezing helps things stay crisper (can't remember the reasons, maybe water expands more uniformly or not as much).[/quote]
    Yes - it has to do with preventing large ice crystals forming - a brief overview here.

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    [quote name='Leif' post='769056' date='04-Apr-2009 00:10']Yes - it has to do with preventing large ice crystals forming - a brief overview here.[/quote]

    One project I always wanted to tackle, but suspect it's not viable, is a domestic scale freeze dryer. The refrigeration part would be OK, but pulling a good vacuum, especially extracting moist air, might be the major hitch. But if anyone has any bright ideas, I'd be willing to try them out.

    Alan

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    [quote name='AlanMiller' post='770096' date='11-Apr-2009 03:18']One project I always wanted to tackle, but suspect it's not viable, is a domestic scale freeze dryer. The refrigeration part would be OK, but pulling a good vacuum, especially extracting moist air, might be the major hitch. But if anyone has any bright ideas, I'd be willing to try them out.[/quote]
    I Googled this a while ago, and there was plenty of advice that didn't require a vacuum at all. Instead, they simply had you place the food in ventilated trays in your freezer. Keep it in there until all the moisture is extracted (time varies, of course). I don't have enough freezer space to try it, so I don't know whether that actually works.

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    [quote name='jscher2000' post='770137' date='12-Apr-2009 06:20']I Googled this a while ago, and there was plenty of advice that didn't require a vacuum at all. Instead, they simply had you place the food in ventilated trays in your freezer. Keep it in there until all the moisture is extracted (time varies, of course). I don't have enough freezer space to try it, so I don't know whether that actually works.[/quote]

    I think that method "sort of" works. It doesn't avoid the problem of rupturing cell walls and lessening the storage life. I had a food technologist explain it to me once - the idea is to get all the water out at a certain stage of the cooling, before ice crystals begin to nucleate. Not sure of the details, but it does require some precision and control over the processing and certainly needs the "forced" drying of the high vacuum.

    Alan

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    FAQ - DSTO Freeze-Dried Meals has jogged my memory on the essentials of the process. To quote:

    "Scientific Basis of Freeze-Drying
    Freeze-drying is based on the sublimation of ice. That is the food dries by the direct evaporation of ice to water vapour, rather than the evaporation of liquid water. This is achieved by freezing the food and then placing it in a strong chamber under a high vacuum, typically about one thousandth of air pressure. Under these conditions liquid water can not exist, only ice and water vapour. By application of heat, and removal of evaporated ice to a very cold surface, ice continues to evaporate until only a very dry, porous solid is left. This has several advantages for the quality of the dried food.

    Evaporation of water, as in conventional drying, occurs at the surface of the food. To evaporate, the water must move to the surface and as it does so it carries dissolved solids such as sugars and proteins. These solids can form a layer on the surface that effectively slows rehydration during preparation of the food before eating.

    Freeze-drying is done at low temperatures. The food need not rise above ice temperature if this is essential for product quality. The product quality is therefore higher than with other drying methods which raise the temperature of the food to speed the drying process.

    The freezing that is carried out before drying concentrates solids, particularly sugars in small areas of the product. These form a "glass" that is a very good trap for volatiles. This results in a good retention of volatiles, which are the flavour components of food. Freeze-dried foods therefore have good flavour.

    The ice crystals that form during freezing, evaporate during drying leaving a porous material. This allows rapid uptake of water when the food is rehydrated. If done carefully, a 1 cm steak can be rehydrated in minutes, compared with the hours that would be required for a similar sized hot air dried steak.

    These pores are one reason why the freeze-dried food is packed under vacuum. The pores allow oxygen in the air to get to sensitive components of the food, particularly fats in the cell membranes. These are very rapidly oxidised in the presence of air to produce unpleasant rancid flavours. Special precautions are taken with freeze-dried foods to protect them from air from the moment they are removed from the drier.

    The food typically has a moisture content of less than two percent at completion of drying. This may be compared with the more than 90% of water in many vegetables, 75% moisture in fresh meats, and the 15 to 20% moisture in dried fruits. This very low moisture means that the food has a very long shelf life even at elevated storage temperatures. This is of great importance to the military and one of the major reasons freeze-dried foods are used for military rations.

    The low moisture also means that microorganisms are not able to grow in the product during storage."

    Alan

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