Aloha from Hawaii Island,
I have been working with a rye sourdough starter for about 2 years now, and had it suddenly turn explosive on me. It pushed its way past a screwed tight lid IN MY REFRIGERATOR when it had only been a half full jar, leaving a domed lid on a pressurized peanut butter jar. Then, when a few weeks later I had my husband open the jar for me, it went from a half full jar to foaming out like it was super pressurized and filling a mixing bowl. All of this is while chilled.
My husband is afraid I am going to poison our family if I use my beloved starter. Can anyone give me a techinical explanation of what is going on here? Do I have the mother of all starters, or is my starter contaminated with something really nasty like botulism and I have to start all over? There is no wierd smell or colors, in fact it has less oxidation than I usually get when I haven't baked in a while and the starter has been living unfed in the back of my frig.
Mahalo for any help from the land of $7 a loaf garbage bread.
Replies
Big Island,
Sourdough starter cultures contain both aerobic and anaerobic microbes. By sealing your jar you are killing off the aerobic culture and allowing the (anaerobic) or microbes that don't require oxygen, to increase resulting in more CO2 - thus the explosion. See below:
Aerobic respiration uses oxygen to release energy from sugar and has the word equation:Glucose + oxygen energy + carbon dioxide + water
Anaerobic respiration releases energy without needing oxygen (although you get less energy this way) and has the word equation
In plants and fungi such as yeast
Glucose~~> energy + ethanol + carbon dioxide In animal cells and bacteria.
Read more: http://wiki.answers.com/Q/What_is_the_difference_between_anarobic_and_aerobic_respiration#ixzz1ZjRyfsGQ
It is highly recommended that you do not seal your storage jars when storing your culture, both for safety and for the health of your starter. So do not seal the jar that you store your starter in. For more info on storing and care of your starter check out the beginners blog here.
PS... by the way, I am sure others here have made the same mistake before
Terri
...just to add to Millciti's excellent technical explanation... There's certainly nothing wrong with your starter - it's just doing what it's supposed to do.
Any healthy starter should at least double, and possibly triple or quadruple - so half-filling a tightly sealed jar is asking for trouble. You just need to give it a bit more headroom, and not screw the lid down tighly to allow for expansion and the creation of CO2 gas.
Starters are pretty much self regulating, despatching almost all nasties. I've never had a starter go off or get contaminated. A healthy starter smells healthy - often fruity, but there is a range of aromas. If it's been let go a bit, the smell will be vinegary or like ethanol (paint thinner) - no harm there, just needs feeding to return to full vigor.
I keep my starter in the fridge with a lid on when I am not using it and have never had any problems. However, I only store it in the fridge AFTER it has been fed and doubled in size. So does this mean that Big Island has put her starter in the fridge fed but before it has doubled or am I in for a similar experience to her at some time in the future??
Could someone please clarify this for me?
Hello Annel,
As Panfresca says, provided that you have a good amount of head room (fairly large jar) and do not have an absolutely airtight lid then there will be no problems.
My jar has a simple screw top lid that I only screw on about half way - it probably wouldnt be airtight even if I did screw it on all the way. The main idea of a cover is to protect your culture from contamination by things falling into it - it could just as easily be a piece of GladWrap.
Hope this puts your concerns to rest.
Farinam
Actually I never ever screw tight the lid, in this case it first overflowed the jar unnoticed while in the frig, when I saw that I removed the starter and had started to open the lid when it exploded all over. It had sealed itself when it overflowed the first time, but I had always kept the lid on loosely before that. I also had not fed the starter since doubling it and the jar was only half full when I put it in the frig. Here in Hawaii we have to keep sourdough refrigerated because our 200+ species of fruit flies all seem attracted to the starter.
I've been baking with sourdough for over twenty five years on and off, and with this starter for 2 years, but this was a new one on me. It is working fine though, we had some dandy hunter's 100% rye and wheat/rye sandwich loaves from it this week.
Wow!! Sounds like your yeasts are as active as your fruit flies!