Hi, I'm a newbie to bread baking and have learned a lot from the accumulated information on this site. Hoping someone more knowledgeable or experienced can advise me on this.
About 1 1/2 months ago, I created a starter using whole wheat flour and pineapple juice that I eventually converted to a white flour starter. I usually keep about 60g of starter, retaining 10g and feeding it with 20g water / 30g bread flour about once or twice a week. When not feeding, I keep it in the fridge. I've made a few experimental loaves which have turned out ok (at least by my novice standards).
Yesterday, I took my starter out of the fridge to feed and there was a pale orange streak across the top. Almost as though someone had dabbed an orange highlighter on their finger and run their finger across the doughy mass. I had read that orange or pink in starters = bad, so this got me quite anxious.
The orange only seemed to be on the surface, so I dug out 10g from the middle and fed it my usual way. It seems to be rising as usual, and I don't see any more traces of orange now.
My question is - is the starter safe to use now? Or is the risk too great and should I throw it all out and start over? I don't want to make anyone sick.
I'm sorry about your starter. I'm only a newbie myself, but I would throw that out. It is not worth the risk of getting someone sick. Really. There are so many people willing to share starters, commercially available starters, and then there is Carl's Friends where I got mine for cost of postage and a donation if you can. I believe the only tests would be commercial tests which equate to more money and difficulty (and probably not available to a home baker like us) than throwing out the new starter you created. I'm sorry.
A sourdough culture is easily invaded when the starter is chilled too soon, before the starter culture lowers pH low enough to defend itself.
I have to ask, how soon after feeding is the starter stored in the fridge? Is it allowed to rise before chilling? Upon removal from the fridge to feed, is it mature? Has it peeked and shows some evidence of fermentation?
I have to agree that orange is scary and I would dump my starter if it was orange or pink. I would also seriously examine the feeding schedule as it is not working. Something has to be changed in order to maintain a healthy starter.
I was hoping someone more knowledgeable would answer you, but I'll jump in - even though you must remember I'm a newbie and I certainly have a lot to learn yet.
You ask how the contamination can happen - that's sadly very easy. With a brand new starter especially, the good-guy-bacteria that you want in your culture can not always fight off every "bad guy" bacteria that comes along. This is why it is often a better idea for us newbies to use a well established culture so we can learn about baking without getting too deep into the science of keeping our culture (starter) clean. The contamination possibilities are everywhere. Regardless of being a neat and tidy housekeeper, a home is not sterile. It is unlikely that we keep all of our jars, stir sticks, spoons, counter-tops, hands, etc. sterile while we work with our starter cultures. Every day, we walk across surfaces that are less than ideal - and we then carry back various bacteria (fungi, viruses, etc.) without knowing it. If we have pets - they can carry it in. When we touch a shopping cart handle, we gather more new germs. Etc. This is just life. It sounds like a horror film, but it is just the way life is. Therefore, there are millions of opportunities for bacteria (or other things) to invade a starter. The older and more established starters are stronger and more able to kill off invaders before they take over. But even they are not immune.
As for the orange streak - remember, please that although you see the orange and can scoop it out, that doesn't mean you've captured all of the "bad guys". Before they become visible to the human eye, they can still be in there - waiting to bloom.
Just advice from a newbie. I wish a more experienced person would offer advice to you as well.