Protocol for Submitting Sourdough Samples

The Dunn and Wolfe labs are interested in the diversity of microbes that exists in sourdough starters around the world. If you have a starter and a method for making sourdough that has proven to make a risen loaf, send us a sample of your starter!

Please plan to package and send your sample on the same day. If you can, send your sample on a Monday so that samples arrive before the weekend. We don’t want your sample to sit in a shipping warehouse over the weekend!

You will need:

  1. ¼ cup of active sourdough starter
  2. 3 unused Ziploc bags (or a comparable brand)
  3. 1 bubble mailer envelope

To prepare your starter in advance of shipping: “Activate” your starter using your normal method. We are most interested in the microbes that live in the starter right before you use it to make a new batch of bread. Usually this means right after feeding/growing, but before the salt or additional flour has been added. Your starter will likely be bubbly and have a consistency similar to pancake batter.

The day you ship your sample:

Make sure you have filled out the sourdough starter questionnaire (and received your confirmation email with your unique Participant ID number).

Participant ID number example

Label all three of the new, unused quart-sized Ziploc bags with:

  1. The date you prepared and shipped your sample,
  2. Your email (the same one you listed on the online questionnaire), AND
  3. Your unique PARTICIPANT ID number listed in your email confirmation.

Pack your sample:

  1. Measure and add 1/4 cup (60mL) of your sourdough starter into a bag. Expel any air from the bag and seal the bag tightly.
  2. Place this bag into a secondary Ziploc bag, expel the air from the bag, and seal again.
  3. Place this bag into a third bag and, again, expel any air and be sure that the bag is sealed.
  4. Put the nested Ziploc bags inside the padded-envelope.

A note on choosing a padded-envelope: You can use any standard bubble-wrap padded envelope. If you do not already have a padded envelope, USPS carries a variety of shipping envelopes, including bubble-mailer envelopes which can be purchased at the post office, priority mail padded flat-rate envelopes, and priority mail express padded flat-rate envelopes.

Label the outside of your bubble-wrap padded envelope with your PARTICIPANT ID number on the FRONT and the BACK (see images below).

Your Participant ID number is the unique number you received in your confirmation email

Address envelopes to:
Elizabeth Landis / Wolfe Lab
200 Boston Ave, Suite 4700
Medford, MA 02155

For mail carriers requiring a phone number:
(617) 627-0691

Mail your sample:

  • It is best to ship samples on a Monday so that they arrive before the weekend. Regardless of shipping method, make sure that the sample will arrive at the lab within five days of shipping.
  • You can send your bubble-wrap padded envelope using either priority mail or standard shipping. For most locations in the US, standard shipping is adequate. Sourdough starters are considered liquids and are perishable, but conform to the guidelines set forth by USPS. Other mail carriers, such as FedEx and UPS are fine to use, as long as expected shipment times are no longer than 5 days.
Thank you again for your participation! After we receive your sample, it may take over a year to get the whole story from your sourdough starter. We are just as anxious as you to learn as much as we can, as quickly as we can, about what makes sourdough so magical.