|
The
Crunch Factor
Salt can help your pickles in yet another way.
When you put vegetables in salty brine, the water inside
the vegetables flows out into the brine, making the pickles
crunchier. This passage of water, known as
osmosis,
occurs because of the tendency of substances to move through
a membrane—like a cucumber skin—from an area
of high concentration to an area of low concentration.
In this case, the salty brine solution has a lower water
concentration than the water inside fresh vegetables,
so water will flow out of the vegetables.
|
All foods are continually assaulted by many kinds of microorganisms,
racing to eat as much as possible. When you pickle vegetables
by fermentation, you help one type of microbe win this "race."
More specifically, you create special conditions in your pickle
crock that keep away "bad" spoilage-causing microorganisms,
and that allow a unique class of "good" bacteria,
called lactic acid bacteria, to colonize your cucumbers.
Why are lactic acid bacteria good?
As lactic acid bacteria grow in your pickle crock, they digest
sugars in the cucumbers and produce lactic acid. Not only does
this acid give the pickles their characteristic sour tang, it
controls the spread of spoilage microbes. Also, by gobbling
up the sugars,
lactic acid bacteria
remove a potential
food source for bad bacteria.
Salt gives the good guys an edge
.
Adding salt to your pickling brine is one important way to help
lactic acid bacteria win the microbial race. At a certain salt
concentration, lactic acid bacteria grow more quickly than other
microbes, and have a competitive advantage. Below this "right"
concentration, bad bacteria may survive and spread more easily,
possibly out-competing lactic acid bacteria and spoiling your
pickles.
Too much salt is also a problem: Lactic acid bacteria cannot
thrive, leaving your vegetables unpickled. What’s more,
salt-tolerant yeasts can spread more quickly. By consuming lactic
acid, yeasts make the pickles less acidic—and more hospitable
to spoilage microbes.
Oxygen gives the bad guys one leg up
.
During fermentation, it’s important to keep your crock
covered to seal out the air. That’s because oxygen encourages
the spread of spoilage microbes. Any exposed pickle or brine
becomes a breeding ground for the bad microbes, which can spread
to spoil the entire batch.
Too hot . . . too cold . . . just right
.
A pickle-maker can also control the microbial garden in a pickle
crock by adjusting the temperature. The ideal temperature range
for lactic acid bacteria—and successful fermentation—is
70° F–75° F. If it’s too chilly or too toasty
in the room, other microbes may gain a competitive advantage
over lactic acid bacteria.
Additionally, temperature influences the speed of fermentation:
The lower the temperature, the slower the pickles will ferment.
By slowing fermentation, you can gain more control over the
process.
|
|
|
|
