Sheldon wrote:
> Ken Knecht wrote:
>> Why is blanching suggested for food to be frozen? For example, I looked
>> up celery in a book on freezing stuff I have and it tells me to blasnch
>> the celery for three minutes before freezing. Cool off, then bag and
>> freeze. What does the blanching do? What would happen if I didn't bother
>> to? Anyone know?
>
> As far as I know blanching hasn't a whit to do with enzymes/bacteria,
> freezing is what preserves the vegetable in total and at the same time
> controls any further decay/decomposition. If blanching were a
> necessary process for preservation there'd be no need to then
> subsequently freeze.

Cell metabolism not your thing, Shel? Freezing does not stop enzymatic
and bacteriologic activity. It slows it way down, but it does not stop
it. Thus the limited time that food can be stored frozen, because
decay/decomposition is not controlled or stopped but only slowed.



> And then there's parboiling, a more aggressive
> form of blanching, that will stop bacterial.enzymatic action, but then
> there'd be no subsequent freezing... parboiling is typically done prior
> to dehydrating or when food will be refrigerated for an extended period
> before fully cooking.

Parboiling is parcooking, not blanching. It may be done before
dehydrating food or before refrigeration, but the cell lysis caused by
parcooking as well as from handling to prepare and store it
automatically limits the time the food can be held under refrigeration
alone. You might as well do nothing. And just as for blanching, it will
not destroy all bacteria and enzymes. It will only slow them down.



> blanch
> 1. To plunge food (usually vegetables and fruits) into boiling water
> briefly, then into cold water to stop the cooking process. Blanching is
> used to firm the flesh, to loosen skins (as with peaches and tomatoes)
> and to heighten and set color and flavor (as with vegetables before
> freezing).

Please refer to http://ohioline.osu.edu/hyg-fact/5000/5333.html, with
particular attention to this part:
" Blanch or scald to stop enzyme action, wilt vegetables for easier
packaging, remove earthy flavors and some undesirable bacteria, further
clean product, and 'set' color. Blanch in boiling water or steam. Hard
water may toughen vegetables; if this occurs, use softened water."