Date: 02 Feb 1999 13:05:55 Z From: Loyd Wix <Loyd.Wix@unilever.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg299$foo@default> Subject: WARNING - Tatmjolk!!
Dear All,
I thought it was worth while putting down a few words of
caution regarding the current list interest in fermented
dairy products involving Pinguicula before some one ends up
with food poisoning!
Most milk for consumption these days is pasteurised to
ensure the removal of any pathogenic bacteria from the milk.
Prior to introduction of pasteurised milk, a whole host of
diseases such as TB and food poisoning such as Salmonellosis
were transmitted to people. Even now, each year many major
outbreaks of food borne infection are attributed to non
pasteurised milk. Thus contaminating milk with Pinguicula
leaves does run the real risk of food poisoning - just think
what may be attached to those leaves! Things will be made
worse by storing the contaminated milk at elevated
temperatures as milk is an excellent medium to grow
pathogenic bacteria. So please be careful!!!
>set (or something like that - ask a chemist if you want a
>reliably scientific description of what happens.) It
>seemed worth giving it a go in the interest of science.
OK I'm a Food Scientist (rather than a chemist) and my main
interest is in ice cream but I do know a bit about such
fermentation's. Pinguicula leaves have been used as a
substitute Rennet to make cheese over much of their European
range. The use in Scandinavia was to make these thick ropy
fermented milk products. From what I understand from the
literature most of the time a portion of an early batch of
Tatmjolk was used to start a new batch. P.vulgaris leaves
were used only when a previous batch was unobtainable or the
milk was perceived as separating too quickly. Thus I believe
we are talking about a bacterial fermentation rather
anything enzymatic from the plants.
Fresh (unpasteurised) milk contains many organisms which
although not harmful will cause changes to the milk. These
bacteria can consume the milk sugar lactose (many bacteria
cannot utilise this sugar) and produce lactic acid as a by
product. This causes the acidity of the milk to rise and
when the pH gets to below pH5.2, one of the milk proteins
(casein) starts to precipitate and comes out of solution.
This can cause the milk to separate into the precipitated
casein 'curds' and an aqueous phase of the whey proteins
which are more pH stable. With Tatmjolk type products such a
separation is undesirable though some ropy culture bacteria
have the ability to produce starch type materials and in
addition rather than forming single cells, these organisms
form long chains or ropes of cells attached to one another.
This has the effect of preventing separation of the
acidified material (starch type materials are used to
stabilise yoghurt drinks for similar reasons), as well as
introducing the peculiar stringy texture to the material.
Such bacterial starter cultures are now commercially
available and are extremely safe and reasonably reliable to
use - far less hit and miss compared to using Pinguicula
leaves.
Peters experience:
>Within 10-15 minutes it had curdled into long ropy strands
>and I figured was ready for consumption. Perhaps not
>surprisingly, it wasn't very nice - rather bitter and
>with a texture like toad spawn. Worse than sago, but then
>I've never been much of a fan of that sort of thing. I
>tried adding some sugar, but it didn't improve it much. I
>didn't finish it and wouldn't want to try it again. Even
>the cat wouldn't eat it!
From what I remember Peter you used what was left in a
carton of (pasteurised) milk getting close to its best
before date. In which case from your description I do not
believe you made true Tatmjolk. Pasteurisation also destroys
the natural milk bacteria which cause the milk to go sour
but in a non offensive manner. What tends to happen with
pasteurised milk is the milk becomes the home for low
temperature spoilage organisms whilst in the fridge such as
Pseudomonad ssp - the same organisms which can make prawns
glow in the dark. These organisms start to break down the
milk proteins and fat and thus tend to make the the milk
putrefy rather than going pleasantly sour. The bitterness
you tasted would indicate this. Tatmjolk should be sour
stringy but pleasant.
Hope this is of interest
Loyd
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