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33397Re: Modern Way - Fermenting Star Fruit

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  • jamesonbeam1
    Feb 4, 2009

      Hi Baker,

      Yes, your correct.  Boiling the potatos will kill off any microbes on there skin.  Using just the waters containing nutrients and some sugars and starches open to the air will cause airborne wild yeasts to infect it. 
      More comments below in Bold:

      > Okay, Jim, I think I see where you are coming from; by
      > pasteurization/ stirilisation you are ensuring you get only AIR-BORNE
      > wild/natural yeasts, not the yeasts that might be carried on/in the
      > FRUITS, or in this case the potatoes?
      > But it seems to me (and this is not based on knowledge, it just seems
      > to make sense) that the case of a natural yeast for fermenting a
      > fruit wine is very different to yeast for bread.

      Not really Baker, both bread yeast and wine yeasts are mainly from the genus Saccharomyces  and species  cerevisiae  within the species Saccharomyces cerevisiae (check it out in Wikipedia), there are over 1500 strains of this yeast that have been cultured for making bread yeast, wine yeast, whiskey yeast, ale yeasts etc., etc..  These strains were originally cultivated from wild yeasts that have been found on the skins of fruit (or grains) which have formed a symbiotic relationship with the fruit or grain.  The other main species of yeast for making wines (mainly champagnes) is  Saccharomyces bayanus  a more alcohol tolerant species of yeast.   One can make bread from a strain of wine yeast and make wine from a bread yeast.

      > The process of boiling the potatoes could have little importance in
      > its sterilization effect; a yeast from the potato skin might be as
      > effective as an airborne yeast. 

      Again this depends on how good or bad that wild yeast strain could be..

      > The boiling of the potatoes could be important mainly because it
      > gelatinises the starch in the potatoes (and thus any residual starch
      > in the potato water?)

      Correct again Baker:     "Common media used for the cultivation of yeasts include; potato dextrose agar (PDA) or potato dextrose broth,"

      > This would make it somewhat similar to bread flour; and if I am right
      > about a little bread flour being mixed in the potato water that would
      > increase that effect.
      > It is of course possible to include potato flour, or mashed potato,
      > (in other words, gelatinised potato) in breads and that might add
      > credence to my thoughts here.

      Corrct again.

      > There are a lot of wineries not too far from where I live and I know
      > it has been the practice years ago, and perhaps even yet to a very
      > much lesser extent, to ferment the grapes in open concrete tanks; and
      > often by the use of the natural yeasts from the bloom on the skins of
      > the grapes.

      Yes, due to the symbiotic relationship, the wild yeasts on the skin of each varietal grape was used to start the fermentation.  Eventually, these were cultivated into various red and white wine,  grape specific strains.

      > It would seem that a yeast that has evolved on or in a fruit, and
      > thus is adapted specifically to ferment that fruit in the conditions
      > in which it is found (climate, etc.,) would be more likely to ferment
      > it well than an air-borne yeast; in the same way as has been found in
      > the case of the grape wines (ignoring commercial yeasts, which anyway
      > have been cultured from natural yeasts originally).

      Correct again - see above.

      > Just kicking the ideas around, it's interesting.
      > Bacteria I haven't thought much about, I guess if you sterilize the
      > fruits that cuts out a lot of possible bacterial infections, leaving
      > only the air-borne ones...

      Yes - the worst ones being vinegar producing bacteria - acetic acid bacteria.

      Vino es Veritas,

      Jim aka Waldo.

      > Regards,
      > The Baker

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