Hello,

About the natural leaven (I prefer that appellation to sourdough which can be just a fermented dough with yeast), you can start it as you want.
The advantage of using fruits is to boost the process. The fruits' skin (better with organic fruits) is full of wild yeasts and bacteria. Moreover, the fruits contain sugars which help too.
But, when you refresh your leaven, you use only flour and water. So, after a while, the population (bacterias and yeasts) of your leaven will be much more influenced by your flour, your hands (eventually) and your bakehouse rather than the fruits you used at the origin, even if it as a certain influence.
An other thing is very important is the method you use for your refreshing. The temperature, the proofing time of your "chef" ("mother"), the oxygenation, the hydration, ... are very important. They give different type of leaven, of populations and, of course, of taste and flavours.
For exemple, when I was in Australia, I developped a leaven to make croissants (without baker's yeast) which had a taste of yoghurt. And there wasn't any trace of milk in it... I think Graham tasted the croissants.

Eric I have to agree with you, the most influential parameters on sourdough flora, hence bread character - which includes, flavour, aroma, and to a lesser extent, loaf appearance are;

* hydration
* temperature range
* fermentation time

Of course this not only applies to the sourdough but also to the bread dough.

 

This shows that, apparently, even if the origin of the leaven influences it, the flour tend to influence mainly the leaven on a long time.

So, there is a way which is interesting to explore : it is to refresh a leaven regularly
with a fruit extract to bring some special bacterial strains which are not from the flour or the bakehouse environnement in order to get special flavours in the leaven and, obviously, in the bread.
In fact, in this case, this is working with a flavoured leaven.

Cool! Will definitely keep the article in mind. Maybe I'll try and see if I can find wheat flours from different regions when travelling around in July to see if I can come up with a short experiment later on.

Could you describe the way you start your fruit starter though? Do you soak it in water (I'm looking at the pictures)? I tend to just crush the fruit and let it ferment in its own juices.  

p.s. Hmmm...wouldn't the fruit a make a nice fruit wine as well especially with the nice purple hue? I'm sure people who be intrigued at the very least.

Thank you Danubian for these links.
gul_dekar, if you want to start a leaven with fruits, take some organic fruits like grapes, apples, pears, or whatever could ferment easily producing nice flavours, acidity and gaz.
Do not wash them and make a purée with the whole fruit (including the skin). Keep this in a warm place for several days in order to get the searched for fermentation with this typical slightly bubbleling. Then, you filter this purée to get the fermented juice. So, you use this like water to start your leaven, liquid or stiff, as you wish.

Jacklang (that's funny, Jack Lang is the name of a former minister of culture), I am sorry but the fruit juice is not there mainly to bring some acidity or gaz but some sugar as a booster and, especially, microorganisms to start the leaven (wich is a culture of bacterias and yeasts).

The wine - fermented liquid - aroma was much like a late harvest wine, something like a Tokaji. It was beautiful. This surprised me a little since lilly pilly fruit isn't overly sweet.

The reason I used water was to make a large enough amount with a single cycle because I wanted to bake a few loaves for family members who expressed interest and agreed to be the taste testers. The reason for a bake test with only one cycle was to keep the process as gererationally close to the fruit ferment as possible to gauge the flora influence before species dilution dissipated the specific flavours and aromas. Of course I was going to continue to cycle this and bake every time to see what changes if any occur with each subsequent generation.

With lilly pilly - a rainforest tree - it was a matter of seeding the fruit, it contains a single pip. Although not strictly necessary I do it anyway since it allows me to break the fruit open to expose the flesh then cover with water and put a plastic film over it to protect it from outside influences such as spore forming moulds. Needless to say my containers were clean although not sterile.

After 7 days I strain the liquid into a bowl and discarded the solids. The liquid was then added to organic stoneground wheatmeal flour with a dough yield (DY) of 200. allowed to ferment for 24hrs; I guess this is technically a generation cycle but I counted it as and introduction phase since the flora was going from a fruit substrate to a flour substrate. I was amazed how active it was, although showed only modest acid formation it was a very efficient gas producer. The next cycle which I counted as the first, was also active doubling in size within 3hours confirming yeast dominance. It was allowed to ferment for 24hrs and introduced into a bread dough. The bread had good volume and an interesting mix of flavours and aromas with a nocticable peppery backnote that lingered. It was not unpleasant but a little surprising.

The next cycle yielded bread of slightly lesser volume with almost no pepper backnote but a lingering honey flavour. The only variable was the additional cycle, every other variable was maintained as much as is humanly possible.

Several family tasters found a noticable difference. Although they liked the second bread they were also taken by the first. They described it as being different to any bread they had tasted before.

There's no question the fruit was the source of the microflora but also provided the necessary nutrients to support maximum flora population growth. There's plenty of evidence that many of the species of yeasts and lactics found in sourdough are also found living with other plants and specifically on plant fruit. Of course species and strains vary from place to place, substrate to substrate but there seems to be some overlap with sourdough flora.