MILK !
HOW HAS IT CHANGED ?
For years we have been told of the benefits of milk.
Milk builds strong bones!
Milk its Good for you!
A milk mustache is Cool!
Milk is Sexy!
Got Milk!
Then
we started making cheese with milk, oh what a joy. Making and
aging our own cheeses. One day things were not quite the same.
What happened?
Well, the cows are still out there
doing their thing, maybe not quite like in the days of Elsie but
you can still find cows on grassy pasture. The changes we see
are what we do to the milk after leaving the cow. It began as a
simple heating of the milk thanks to Mr. Pasteur's science (perhaps
a good thing at the time) and this didn't seem to cause a big
problem. In recent years however, the large companies have
stepped in and their premise has been that if a little heating
of milk is a good thing then perhaps if we really heated the
milk we could hold if for a long time on the shelf and ship it
long distances. As it turns out, not such a great idea.
What we know about milk for
cheese making?
Milk is essentially a complex of almost 90% water, a lot of
protein, some calcium, other minerals, and varying amounts of
butterfat. It is these proteins in the milk that make our
cheeses and it is the calcium that holds it all together. In a
nutshell, this is all there in making cheese.
How has the new milk processing
affected our cheese milk?
Originally pasteurization was defined as heating the milk to
145F for 30 minutes (called vat pasteurizing today). Then
science decided that heating to 161F for 16 seconds, HTST
(High temperature short time) was better.
Either of these are currently the legal requirement of
pasteurizing today. Both of these methods alter the milk
structure somewhat but with the addition of calcium chloride can
still make fine cheese.
Then the
bright idea of Ultra Pasteurization (UP) came to be. This
process is damaging enough to place the milk out of the cheese
making picture. Fortunately this milk must be labeled by law so
it is easy to avoid.
To give you an idea of where this
is going:
Ultra-Pasteurization (UP) - Involves the heating of milk and
cream to at least 280° F (138° C) for at least 2 seconds, but
because of less stringent packaging, they must be refrigerated.
The shelf life of milk is extended 60 to 90 days.
Single serve milks are packaged in aseptic tetrapaks and
unopened will keep at room temperature up to seven months or
until the date code. The milk is pasteurized using UHT or
ultra-high temperature process which is similar to UP or
ultra-pasteurization, in which the milk is heated to 280 F or
greater for 2-3 seconds
Our current problem is milk in the
pasteurized temperature range between traditional pasteurization
and UP. Specifically for
our 30 minute Mozzarella any milk heated over 172F will be
problematic for cheese making and this has no labeling
requirement. This now becomes the "grey zone
milk".
The other factor in milk
resources, often overlooked, is storage of milk. The longer milk
is cold stored, the more its quality deteriorates. Calcium
useable in cheesemaking begins to deteriorate in a short time.
This is why most cheese makers using cold stored milk use
Calcium Chloride. The other significant factor is cold
temperature bacteria (psychrotropic) which begins to attack the
proteins and break them down while still in the milk phase.
What makes these milks
Problematic?
Going back to the proteins involved in making our cheese. There
are 2 types of proteins to be concerned with, The main cheese
proteins (Curd Proteins) that make our cheese and then another
group of proteins (Whey Proteins) that normally run off with the
whey and are not normally involved in the cheese making process.
When milk is heated above 172F these whey proteins become
desabilized and enter into the cheese making process. If we are
making Ricotta or Yogurt this is good because these proteins
provide the structure for these products. However if we try to
make a soft or hard cheese from this milk, these destabilized
whey proteins remain and interfere with the bonding of the curd
proteins by calcium resulting in a weak curd. This weak curd
problem increases as the milk is heated to higher temps above
normal pasteurization temps.
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 |
|
These 2 images
reprsent the curds from overly processed milk on the
left and properly pasteurized milk on the right. Note
how the curd firmness holds the shape on the right but
disintegrates on the left |
How do we work with
this milk?
For our 30
minute mozzarella recipe I
have included a few specific pointers for working with
those milks that are pasteurized slightly above the
traditional 161F temps (161-172F). This should help the
curds dry out and form together better
- Begin with milk heated between 95-100F
- If the initial curd
is
soft and jelly like it will easily break apart if
handled or stirred too much.
- Is your curd firm enough to hold a knife cut
following coagulation?
- If so cut into 1/2 - 3/4 inch squares with
horizontal and vertical cuts (if not raise the
temp another 5 degrees for your next batch).
- You will end up with long pieces of curd
here then let it sit for 3-5 minutes.
- Then begin to slowly heat to 105F while moving
these long pieces of curd slowly around the pot. You
can cut them into shorter pieces as you go with the
spoon.
- The curd should begin to firm up now and
there will be a lot more whey as you go.
- Keep this up for 5-10 minutes (or longer
depending on milk quality) until the curds seem
firm.
- Let it all set for 2-3 minutes before pouring
off the whey and transfer the remaining curds and
whey. Try to gently fold these curds in the bowl to
release more whey. Keep pouring off the whey as it
develops until little whey develops.
- Now you are ready to heat in the microwave and
continue as per the recipe.
If the curd is not holding
together at this point you will have to try another
milk. This one will not work (it has probably been
highly processed).
How do we find a better milk?
The best plan for finding good milk
is to find a local dairy providing a
milk that does not have to travel so
far. This milk will need less
processing. We currently are
developing a listing of milks that
are working for our customers.
You
will find it here. To really
find out more about your milk, do
not be shy about calling the people
processing your milk and ask them
the details. Also, note their
location to get an idea of how long
that milk was stored and how far it
had to travel.
Why is this processing
needed?
In the 1930's when
pasteurization was
introduced, the milk supply
in America was in a foul
state with TB being one of
the worst health problems
transferred from dairies.
Pasteurization was the
immediate solution but
proper herd management and
inoculation was the long
range solution. As dairies
became larger milk
"processing plants" and
larger quantities of milk
were cold stored for longer
periods of time, shipped
longer distances, and held
for longer periods on store
shelves the need for higher
processor temperatures has
evolved. All of this is good
for the producers but not so
good for consumers seeking
quality milk.
According to several
conversations with milk
processors across the
country during the past 2
years we have become aware
of a tendency for regulating
agencies to strongly suggest
increasingingly higher
pasteurization temperatures.
This issue of higher
pasteurizing temps and times
seems to be an attempt to
eliminate Johne's
(pronounced yo-neez) disease
(Mycobacterium
.Paratuberculosis) from our
milk supply. This disease
has increased in recent
years and seems to be most
serious in the larger
industrial herds.
The tendency has been to
increase pasteurization
temps to 174-180F plus and
increase the hold times for
this .
This is in spite of research
done in Ireland and at
Guelph Ontario showing that
traditional vat
pasteurization of 145F/30min
totally eliminates the
bacteria and that HTST
pasteurization 163F/16secs
shows small numbers in the
milk. Further research is
being done on holding at
163F but increasing the
times. The research has also
shown that exposing the milk
to a higher temperature
would not be a good option
because a higher temperature
could be detrimental to its
nutritional value.
Rather than trying to force
industrial dairies to clean
up their act in order to
improve the health of their
herds, the FDA has put its
support behind
higher-temperature
pasteurization.
Pasteurization should not be an
excuse to produce dirty milk.
In other
words much of what is being done
for milk processing today is
based on bad science
