An area of interest for lots of us has been discovering what a starter likes to eat. Like all creative types, home bakers are, if anything, keen experimenters. I get some great stories about what works, and why, so I'd like to share some of them now.
Use filtered or natural spring water (the latter is usually best, unless it's very 'hard') to feed your starter, especially at first. Unfiltered water straight from the tap is full of chlorine and other chemicals (These chemicals were mostly added to stop things growing in the water).
If you would like to get a graphic example of how heavily treated town water actually is, put some straight out of the tap into a drink bottle, and close the lid. Leave it for a few minutes, remove the lid and smell the water inside the bottle. You will most likely experience a rather unpleasant smell of chlorine. Compare the smell to that of a bottle of pure water. A dramatic difference!
However, once you have established your starter, regular tap water won't hurt it. While I would still recommend using some sort of filter, I use tap water myself and my starters are very healthy. This is because they are very well established.
Following is a brief list of excellent sourdough starter food, and a brief explanation of what each thing will do to your ferment, as well as how to prepare it, if it requires preparation at all.
LIQUID SOURDOUGH FOODS:
Raisin Water: take a handful of raisins or sultanas, about 200 ml of warm water, and combine. After a few days, the water will have absorbed the yeasts from the raisins. You can use this water in your starter. The fruit can be used in a dough.
Pineapple juice: this is probably the simplest and most effective means of promoting activity in your starter. Make sure it's unsweetened, though, because sugar will produce different types of enzyme activity - not the kinds we need for sourdough fermentation. Just use instead of water for a few feeds. You will observe a decided increase in activity, as the slightly acid pineapple juice is ideal for sourdough starter fermentation.
Beer or wine lees: the powdery substance at the bottom of some wine and beer bottles - the lees - is great fermentation food. Just be sure to hold back on the liquid - the alcohol is too strong for fermentation. It's okay to use a bit of the liquid though - just mix it with water.
CARBOHYDRATES TO ENHANCE ACTIVITY
Whole grains: sourdough starter loves whole grains, because they have lots of natural yeasts under their skin. The best way to incorporate them is to cook them first very well - till they are over cooked - and then, if you have a potato masher or a food processor, turn the porridge into a gruel. If you don't have these implements, the cooked grain just needs to cool, water and all, and be combined with the starter. Be aware that if you don't turn it into a gruel, the grain will turn up in your bread. This is fine if you are making grainy bread, but not so attractive in a pristine white Continental style bread. I allow my porridge to cool overnight. This also allows a bit of secondary fermentation to occur before use..
Blanched wholemeal flour: blanching wholemeal flour is excellent to get fermentation going. Follow the directions in the 'Porridge Method' article. Be aware that the longer you leave the 'porridge' to ferment, the better it is as food for your starter.
Mashed potato: there are numerous ways to prepare potato for starter, including simply grating it. But if you prepare it first by boiling one in unsalted water, then mashing it without adding anything, it'll work exceedingly well in promoting fermentation. Potato has virtually no protein, and as such is available as food for fermenting greeblies straight away.
Grapes: these can simply be mashed up roughly and incorporated into your starter. Grapes are excellent fermentation food - just be aware that the skins will turn up in the bread. If this isn't your thing, just blanch the grapes and remove the skins first.
Wholemeal flours: often, we like to make nice white bread, and so we feed our starter exclusively white flours. This is fine; indeed, many bakeries only feed white flour to their starter. But wholemeal flours contain lots of wild yeasts, and as such can really get a sourdough starter active. I recommend a feed of wholemeal flour once or twice a season to enrich and fortify the ferment. It may not be necessary at all, but in my experience this is a kind of insurance policy - regular yeast, Saccharomyces cerevisiae, thrives on white flour. It tends to overrun other types of yeast, so I just do this as a way of reintroducing alternate strains.
FRESHLY MILLED GRAINS TO USE TO ENHANCE FERMENTATION ACTIVITY
If you have a home flour mill (or an unused coffee grinder even) or have access to really fresh flour (let's just say that buying flour from the supermarket most likely won't be fresh enough), use this flour or meal to feed your starter - it'll reap instant rewards, I promise!
It's not necessary to do this all the time, just now and again.
Rye meal or wholemeal rye: even used at about 10% of the total flour in your starter, wholemeal rye will boost the activity substantially. Simply feed as you would using any other flour. The greater the amount of rye in the starter, the more it will flavour your bread. Keep this in mind. I tend touse it every few months in my starter for a feed, though there are plenty of sourdough bakers who disagree with me on this point. My experience has been that immediately after feeding the starter with rye, it grows stronger for the next half a dozen bakes or so.
Barley meal: another great yeast food. I use this in conjunction with my sourdough starter powder to help get enzyme activity occurring faster. Same as rye - feed occasionally.
Wheat meal: really coarse, freshly milled wheat meal is just brilliant to get your starter flying along.
Want to get going but haven't yet got some decent fermentation action? You can buy my 30 year old starter from our School of Sourdough website. We can freight anywhere in Australia for free.
Unfortunately, we cannot freight starter overseas. Various quarantine regulations make it all too hard. Sorry!