With the warm weather we’ve been having I’ve been fermenting up a storm: boozy fizzy juice, vinegar, kimchi, pine cone syrup, and sourdough.
1. I used fruit that is naturally covered with white yeast, Saccharomyces, and maybe others (?) Where does the yeast live before it ends up on the fruit and how the heck does it get transported to the surface of fruit in trees? The only lead I found online says it is transported by insects, but why would insects hang out where there are no flowers, just unripe fruit?
2. I understand that after the yeast processes sugar into alcohol, I need to create conditions that allow it to metabolize the alcohol into acetic acid.
Same questions, what is the source of fermenting yeast/bacteria in my apartment?
Insects do travel in search of food and mates. you just need an insect to stop by to take a rest or inspect if something is edible for yeast cells, other spores and bacteria to spread from the insect on to the surface of the fruit.
Aerosolized liquids (tiny droplets floating in the air), for example, can carry bacteria, as can dust particles. Bacterial spores can also be blown around by the wind or other air currents (or even be captured from air by raindrops that bring them down).
Also, humans are covered in spores, fungi, bacteria, insects, arachnids (like the Demodex folliculorum mite)… If you get a petri dish with a nutrient base, and poke even with a washed finger on it and wait for a few days, you’ll see the area your finger touched show microbial growth. It was quite the lesson on food hygiene course to see this. Unwashed finger was much bigger source as well as a cough. Touch anything, breathe, cough, sneeze, shed dead skin, drop a hair… you’re constantly spreading and picking up microscopic life.
Currently 36 iNat observations. Now I have to find out what magnification I need to see these.
If this is a fermentation bacteria for fruits, probably it blew in on the wind. Even opening your door for the few moments it takes to step outside allows bacterial cells to blow in. Or, it could have come in on the fruit itself, the same way the yeast did.
I have read, but have not looked into the claim, that fruit flies actually farm yeast by transporting it to fruit, resulting in it growing on that fruit, then come back to the same fruit to eat the resulting yeast. There are certainly some insects that do things like this. Some wood boring beetles have special organs that hold spores of the wood-rotting fungi they eat as larvae. When they move to new trees to lay their eggs, they also deposit these spores, planting a food supply for their young.
