The longest I've ever kept a culture starter alive has been about a month. I was proud of my efforts until I went on vacation and left my viili, a fermented Finnish dairy product that's very similar to yogurt, on the counter instead of putting it in the refrigerator.
It can take just one act of neglect to unintentionally ruin a starter so when I read that a woman in Canada has a 120-year-old sourdough starter, I was duly impressed. Ione Christensen has kept the starter going for 60 years, reports The Guardian. Before that, others in her family, going all the way back to at least 1897 with her grandfather, kept it fed and alive. Its origin is unknown.
Making a sourdough starter is easy, but it does require your daily attention early in the process. It's simply equal parts flour and water that have have fermented by capturing the natural yeasts in the air. Once the starter is established, it needs to be fed at regular intervals. If carefully tended to it can last forever — or at least 120 years.
Christensen's starter is part culinary history and part North American history. Prospectors kept small lumps of the yeast and bacteria in their flour sacks. They were an important part in creating the bread that fed the fortune seekers. Christensen's grandfather traveled with the starter during the Klondike Gold Rush.
A piece of her family starter is heading for the "library" of sourdough strains collected by Karl De Smedt, a Belgian baker. He already has 84 refrigerated samples from 20 different countries. Those strains are evidence of the geographically diverse varieties of natural yeast and will be available for future generations to study. The remainder of the starter will stay with Christensen, being used for breads and waffles for hopefully another 120 years.