See below for my day-to-day notes on how to develop a sourdough starter from scratch! I have provided a full tutorial for you to follow along (see the video tutorial here and note the timestamps below correspond to the time point in this tutorial). You'll need a couple starter jars with lids, cheesecloth, a spatula (or spoon), a rubber band (optional), unbleached flour, and purified water.
Day 1: [timestamp 1:48]
Day 2: [timestamp 3:47]
Stir paste mixture
Transfer to fresh jar
Day 3: [timestamp 4:50]
Notes: volume increased, caught wild yeast
Discard all but 20g starter (throw away discard)
Stir in fresh flour & water
Day 4 morning: [timestamp 6:34]
Notes: lots of activity, unpleasant smell
Begin 2 feeds per day
Discard all but 20g starter (throw away discard)
Stir in fresh flour & water
Day 4 evening: [timestamp 7:45]
Notes: lots of activity, very unpleasant smell
Discard all but 15g (throw away discard)
Stir in fresh flour & water
Day 5 morning: [timestamp 8:41]
Notes: loss of all activity! Very unpleasant smell, very runny
Discard all but 15g (throw away discard)
Stir in fresh flour & water
Day 5 evening: [timestamp 9:47]
Day 6 morning: [timestamp 10:35]
Discard all but 15g (throw away discard)
Stir in fresh flour & water
Equal weight 1:1:1 (15g each)
Day 6 evening: [timestamp 11:21]
Day 7 morning: [timestamp 11:49]
Notes: 100% volume increase (2X), smells nice, bit of sour, consistency is less runny, stronger
Discard all but 15g (throw away discard)
Stir in fresh flour & water
Equal weight 1:1:1 (15g each)
Day 7 evening: [timestamp 13:35]
Day 8 morning: [timestamp 14:03]
Discard all but 15g (*begin to collect and freeze discard)
Stir in fresh flour & water
Equal weight 1:1:1 (15g each)
Discard cheesecloth, now use a loose-fitting lid
Day 8 evening: [timestamp 14:54]
Day 9 morning: [timestamp 15:21]
Notes: 2.5X, definite sour notes!
Discard all but 15g (collect and freeze discard)
Stir in fresh flour & water
Day 9 evening: [timestamp 15:50]
Notes: 2.5X, lots of activity!
Discard all but **8g (collect and freeze discard)
Stir in fresh flour & water
Begin 1:2:2 feed (8g starter + 16g water + 16g flour)
Day 10 morning: [timestamp 16:40]
Notes: starter peaked at 2.5X and then fell/collapsed
Discard all but 8g (collect and freeze discard)
Stir in fresh flour & water
Feed at 1:2:2 (8g starter + 16g water + 16g flour)
Day 10 evening: [timestamp 17:20]
Notes: starter peaked at 2.5X and then fell
Discard all but **5g (collect and freeze discard)
Stir in fresh flour & water
Begin 1:3:3 feed (5g starter + 15g water + 15g flour)
Day 11 morning: [timestamp 18:00]
Notes: starter peaked at 2.5X
Discard all but 5g (collect and freeze discard)
Stir in fresh flour & water
Begin 1:4:4 feed (5g starter + 20g water + 20g flour)
Day 11 evening: [timestamp 18:26]
Notes: starter peaked at 2.5X & fell
Discard all but 5g (collect and freeze discard)
Stir in fresh flour & water
Begin 1:5:5 feed (5g starter + 25g water + 25g flour)
Day 12 morning: [timestamp 18:53]
Notes: starter peaked at 2.5X, smell is wonderful (sweet & sour)
Discard all but 5g (collect and freeze discard)
Stir in fresh flour & water
Begin 1:5:5 feed (5g starter + 25g water + 25g flour)
**Flour mix change: [timestamp 19:20]
From 30% rye to 10% rye
Math: Total remaining flour weight = 155.5g
This means there is still 155.5*0.3=46.5g rye in the mix
For 10% rye, we need 46.5g rye in 465g total flour
So bring up total flour weight from 155.5g to 465g
Added in 309.5g bread flour, whisk well
Day 12 evening: [timestamp 20:23]
Notes: starter peaked at 2.5X, peaked & fell
Discard all but 5g (collect and freeze discard)
Stir in fresh flour & water
Feed with 10% rye 1:4:4 (5g starter + 20g water + 20g flour)
Day 13 morning: [timestamp 21:01]
Notes: starter peaked at 2.5X, peaked & fell, stronger discard
Discard all but 5g (collect and freeze discard)
Stir in fresh flour & water
Begin 1:5:5 feed with 10% rye (5g starter + 25g water + 25g flour)
Day 13 evening: [timestamp 21:38]
Notes: starter peaked at 2.5X, wonderful activity
Discard all but 5g (collect and freeze discard)
Stir in fresh flour & water
Feed at 1:5:5 (5g starter + 25g water + 25g flour)
Day 14 morning: [timestamp 22:15]
Notes: starter peaked at 2.5X, will now begin 3x per day feeds
Discard all but 8g (collect and freeze discard)
Stir in fresh flour & water
Feed 1:2:2 (8g starter + 16g water + 16g flour)
Day 14 afternoon: [timestamp 23:08]
Notes: starter peaked at 2.5X, will now begin 3x per day feeds
Discard all but 8g (collect and freeze discard)
Stir in fresh flour & water
Feed 1:2:2 (8g starter + 16g water + 16g flour)
Day 14 evening: [timestamp 23:34]
Notes: starter peaked at 2.5-3X, will now begin 3x per day feeds
Discard all but 5g (collect and freeze discard)
Stir in fresh flour & water
Feed 1:5:5 (5g starter + 25g water + 25g flour)