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We are now shipping globally! For orders to the United States we are offering USPS Priority Mail, and for International orders we are offering DHL Express Worldwide and Globalpost Standard International shipping options.

Shipping times may vary according to the season and the volume of eCommerce orders being handled by the shipping company. Be aware that due to COVID you may see delays in the shipping speed. Please refer to your Tracking Number which you will receive once you complete your purchase.

Subject to order volume and the time of day order is placed, packages may not ship out same day. We will strive to ship orders within 24-48 business hours. Orders placed on Friday may not go out to the carrier until Monday (warehouse is closed on weekends).

Our fresh sourdough starter is prepared in a way that is capable of surviving very long transit times - even shipping across the globe. If you have trouble reviving your starter, please contact our Help Team at help@fullproofbaking.com.

Though the glass (borosilicate) jars can be run through a gentle dishwasher setting, it is best to wash the jars with warm soapy water by hand.

If you find starter has stuck to the inside or outside of the jar, soak in warm water for awhile before attempting to clean. Rinse well, so that no soap residue remains (any detergent remaining in the jar can be harmful to the microbes in your starter culture).

Use the enclosed alcohol swab to wipe the jar. Let the alcohol dry and then peel and stick. Apply firm pressure all over taking special care with the edges.

See here for a short step by step tutorial!

A sourdough starter is a doughy mixture of flour and water, and it supports a teeming, densely populated microbial community of lactic acid bacteria and acid-tolerant yeasts. These bacteria and yeasts naturally grow in the starter culture, originating from the flour and the environment. They ferment the sugars in the flour and produce acid, alcohol, and carbon dioxide which acts to leaven, or rise your bread dough! 

The overarching goal here is to maintain your sourdough starter in such a way that it is well-balanced; this means the bacteria and yeasts should achieve a harmonious symbiosis where the populations of microbes are competing for separate and distinct resources; where the acids produced by the bacteria are not allowed to build up to an undesirable level and are instead kept in check; and where the yeasts can thrive to produce optimal leavening power. 

I tend to think of my sourdough starter as a pet… I keep it nice and warm, and fed regularly (with a meal of just flour and water) - It’s actually pretty simple once you get the hang of it! A properly cared for starter can be maintained over many years and even passed down from generation to generation! 

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]

• Prep flour mix

• 350g bread flour + 150g dark rye = 500g flour total

• Stir together flour & water into a paste

• Equal weight, 1:1 (30g water + 30g flour)

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

• Equal weight 1:1:1 (20g starter + 20g water + 20g flour)

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

• Equal weight 1:1:1 (20g each)

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

• Equal weight 1:1:1 (15g each)

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

• Equal weight 1:1:1 (15g each)

Day 5 evening: [timestamp 9:47]

• Notes: minimal growth, still smelly, very runny

• Discard all but 15g (throw away discard)

• Stir in fresh flour & water

• Equal weight 1:1:1 (15g each)

Day 6 morning: [timestamp 10:35]

• Notes: 20% volume increase (1.2X), smell improving, runny

• 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]

• Notes: 30% volume increase (1.3X), smell is more mild 

• Discard all but 15g (throw away discard)

• Stir in fresh flour & water

• Equal weight 1:1:1 (15g each)

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]

• Notes: 50% volume increase (1.5X), nice mild sour smell 

• Discard all but 15g (throw away discard)

• Stir in fresh flour & water

• Equal weight 1:1:1 (15g each)

Day 8 morning: [timestamp 14:03]

• Notes: 90% volume increase (1.9X), smell is very nice 

• 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]

• Notes: 2X volume increase 

• Discard all but 15g (collect and freeze discard)

• Stir in fresh flour & water

• Equal weight 1:1:1 (15g each)

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

• Equal weight 1:1:1 (15g each)

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)

• ***Regularly do this 1:5:5 for the longer, 10 hour overnight feed (did an experiment for the video with 10g + 50g + 50g but usually feed only 5g + 25g+ 25g)

Keep in mind that each starter is unique and will develop in its own way over the first few weeks until the microbial communities reach an equilibrium. Some starters have a rapid early rise in the first few days, followed by a sudden and seemingly inexplicable loss of activity. You may worry it has died (I did when this happened to me!). During this time, new species of microbes are fighting for dominance; some strains are dying off, while some begin to flourish.  You may notice changes in aroma day by day (in the very early days the starter may smell cheesy; later on, more tangy and sweet).

All of this is normal! The microbes we are selecting for—lactobacilli bacteria and acid-tolerant wild yeasts—take their time winning their battles to become the dominant strains. In those early days, try to focus on characteristic changes happening to your starter. Take note of your starter’s development by monitoring changes to its consistency (becoming more liquidy/watery throughout the fermentation) and aroma (becoming more tangy/sour smelling).

Trust that it takes time and patience for the starter to mature and begin to rise in a predictable manner. It might even be over a month!

Please see the full video tutorial here: https://youtu.be/trknRolcgpY

Day 1, Morning:

1. Place the Starter Jar on the digital scale and press the [T] Tare button to zero out the weight of the Jar.

2. Open your starter pack and squeeze out a small amount of starter (about 5g) into the Jar. Make note of the amount of starter added to the Jar and set the Jar aside.

3. Use your observed temperature to choose a feed ratio:

1. [72°F/22°C] 1:1:1 ratio: with 5g starter you’d add 5g flour + 5g water.

2. [78°F/26°C] 1:2:2 ratio: with 5g starter you’d add 10g flour + 10g water.

3. [82°F/28°C] 1:3:3 ratio: with 5g starter you’d add 15g flour + 15g water.

4. Place the plastic measuring scoop on the digital scale and press [T] to zero out its weight. Measure out the recommended amount of flour into the scoop, and add the flour to the Jar.

5. Place the scoop back on the scale and measure out the recommended amount of water and add the water to the Jar.

6. Using the silicone spatula, stir well to combine the starter, flour, and water until the mixture reaches a smooth paste in consistency.

7. Position a rubber band around the Jar to mark the initial height of the dough.

8. Place the lid on top, loosely fitted (do not tighten the lid, as the fermentation can create a dangerous amount of pressure).

9. Rest the starter for 12 hours.

Day 1, Evening:

After 12 hours, it’s time for the second feed! You will follow the same basic steps as you did during your first feed, however instead of starting with 5-10g of starter from the starter pack included with this kit, you will use 5-10g of starter from the batch you mixed up during the previous feed. The remainder of the starter from the morning will no longer be needed and can be either discarded or saved. Using only a small amount of the starter for each successive feed, known as “microfeeding,” is more efficient, cost effective, and ensures you aren’t quickly dealing with buckets full of starter to feed and maintain! If you prefer to save your discard, you can collect the discard in a bowl in your freezer and use it in an endless number of delicious “sourdough discard” recipes that you can find online. Pancakes, muffins, scones, and crackers are just a few.

1. Place the second (empty) Starter Jar on the digital scale and press the [T] Tare button to zero out the weight of the Jar.

2. Using your spatula, stir down your starter from your previous feed, pick up a small amount of it (5-10g), and place it into the empty Jar. 

3. Use your observed temperature to choose a feed ratio:

1. [72°F/22°C] 1:1:1 ratio: with 5g starter you’d add 5g flour + 5g water.

2. [78°F/26°C] 1:2:2 ratio: with 5g starter you’d add 10g flour + 10g water.

3. [82°F/28°C] 1:3:3 ratio: with 5g starter you’d add 15g flour + 15g water.

4. Measure out the recommended amount of flour into the scoop and add the flour to the Jar.

5. Measure out the recommended amount of water and add the water to the Jar.

6. Using the silicone spatula, stir well to combine the starter, flour, and water until the mixture reaches a smooth paste in consistency.

7. Position a rubber band around the Jar to mark the initial height of the dough.

8. Place the lid on top, loosely fitted.

9. Rest the starter for 12 hours.

10. Discard or save the extra starter from your previous feed and wash the Jar.

Day 2, Morning:

Today you will be increasing the feed ratio because your starter will likely be more active. To ensure your starter stays contained within the Starter Jar after it rises, you will want to use a very small amount of starter (3-5g) from your previous feed for this and future feeds. 

1. Place a clean Starter Jar and the spatula on the digital scale. Press the [T] Tare button to zero out the weight of the Jar and spatula.

2. Using your spatula, stir down your starter from the previous feed, pick up a small  smear of it (3-5g), and place the spatula into the Jar on the scale. 

3. Use your observed temperature to choose a feed ratio:

1. [72°F/22°C] 1:2:2 ratio: with 5g starter you’d add 10g flour + 10g water.

2. [78°F/26°C] 1:5:5 ratio: with 4g starter you’d add 20g flour + 20g water.

3. [82°F/28°C] 1:8:8 ratio: with 3g starter you’d add 24g flour + 24g water.

4. Measure out the recommended amount of flour into the scoop and add the flour to the Jar.

5. Measure out the recommended amount of water and add the water to the Starter Jar.

6. Using the silicone spatula, stir well to combine the starter, flour, and water until the mixture reaches a smooth paste in consistency.

7. Position a rubber band around the Jar to mark the initial height of the dough.

8. Place the lid on top, loosely fitted.

9. Rest the starter for 12 hours.

10. Discard or save your unused starter from your previous feed and wash the Jar.

Day 2, Evening:

1. Place a clean Starter Jar and the spatula on the digital scale. Press the [T] Tare button to zero out the weight of the Jar and spatula.

2. Using your spatula, stir down your starter from the previous feed, pick up a small  smear of it (3-5g), and place the spatula into the Jar on the scale. 

3. Use your observed temperature to choose a feed ratio:

1. [72°F/22°C] 1:2:2 ratio: with 5g starter you’d add 10g flour + 10g water.

2. [78°F/26°C] 1:5:5 ratio: with 4g starter you’d add 20g flour + 20g water.

3. [82°F/28°C] 1:8:8 ratio: with 3g starter you’d add 24g flour + 24g water.

4. Measure out the recommended amount of flour into the scoop and add the flour to the Jar.

5. Measure out the recommended amount of water and add the water to the Jar.

6. Using the silicone spatula, stir well to combine the starter, flour, and water until the mixture reaches a smooth paste in consistency.

7. Position a rubber band around the Jar to mark the initial height of the dough.

8. Place the lid on top, loosely fitted.

9. Rest the starter for 12 hours.

10. Discard or save your unused starter from your previous feed and wash the Jar.

Day 3, Morning:

Today you will increase the feed ratio once more because your starter will likely be even more active. At this point, you might notice that the starter is now bubbling and thriving. You will want to start paying close attention to how high the starter rises between feeds - knowing whether the starter is regularly doubling or tripling will help you gauge how often and how much to feed your starter.

1. Place a clean Starter Jar and the spatula on the digital scale. Press the [T] Tare button to zero out the weight of the Jar and spatula.

2. Using your spatula, stir down your starter from the previous feed, pick up a small  smear of it (3-5g), and place the spatula into the Jar on the scale.

3. Use your observed temperature to choose a feed ratio:

1. [72°F/22°C] 1:5:5 ratio: with 3g starter you’d add 15g flour + 15g water.

2. [78°F/26°C] 1:8:8 ratio: with 3g starter you’d add 24g flour + 24g water.

3. [82°F/28°C] 1:10:10 ratio: with 3g starter you’d add 30g flour + 30g water.

4. Measure out the recommended amount of flour into the scoop and add the flour to the Jar.

5. Measure out the recommended amount of water and add the water to the Jar.

6. Using the silicone spatula, stir well to combine the starter, flour, and water until the mixture reaches a smooth paste in consistency.

7. Position a rubber band around the Jar to mark the initial height of the dough.

8. Place the lid on top, loosely fitted.

9. Rest the starter for 12 hours.

10. Discard or save your unused starter from your previous feed and wash the Jar.

Note:

With a brand new starter, the yeast activity can take extra time to balance out. This means that in the early days of starter development, dough rise is not the best gauge of when to feed next. You simply won’t see a substantial rise! This doesn’t mean, however, that you don’t have to feed your starter. So what sort of signs signal it’s time for another feed?

Gauge feed times based on change in starter aroma and consistency. Look for the starter to transform from a thick paste to a more liquidy/watery consistency. (Hint: try jiggling the jar to get a sense of how firm the dough is.) It will also become more pungent in aroma. In other words, when it becomes syrupy and smelly, feed it.

As your starter matures after a couple of weeks and becomes more of an established, mature starter, you will notice it takes a certain amount of time to “peak” (rise to max volume) after a given ratio feed. At this stage, you can aim to feed your starter every time it reaches peak (and ideally before it over-ferments and begins to break down and collapse in the jar). Feeding regularly at peak will benefit your starter’s strength and power.

The overarching goal is to give your starter enough food (flour/water) so that it doesn’t over-ferment, over-acidify, and collapse before you can feed it again! Build up of acids (lactic and acetic acid produced by the lactobacili) can weaken your starter over time. It’s best to refresh at peak at every opportunity.

Ratios are usually written such as “1:1:1”, and they tell you how many parts each of starter, flour, and water to mix together. Equal parts 1:1:1 could mean you’re mixing 5 grams (g) each; or it could mean you’re mixing 15g each starter, flour, and water; or 100g each! The ratio can stay the same though the total volume/weight can change. For a 1:2:2 ratio on the other hand, you could feed 1 part starter (5g) with 2 parts flour (10g) and 2 parts water (10g). It is still a 1:2:2 ratio if you’re mixing 100g starter, 200g flour, and 200g water.

Lower ratio feeds (1:1:1 or 1:2:2) will need to be performed more often, while higher ratio feeds (1:5:5 or 1:10:10) will need to be performed less often. This is due to how much you are diluting your starter. In essence, it will take longer for a heavily diluted starter to ferment.

Use this information to your advantage to schedule out your feeding routine. If your starter is peaking too soon, you can increase your feed ratio to help slow down your fermentation. If your starter is taking too long to peak, try lowering the ratio to allow it to ferment more quickly.

Every starter is different - it has a terroir based on your own kitchen, air, flour, water, kitchen utensils, hands that feed it. Feed not according to anyone's specific instructions... You must watch your starter closely and feed accordingly. Bakers use their starters in different ways, but for me, I always strive to ensure mine is as active as possible before using as a levain... it can take awhile for a newborn starter to become quite active and powerful - it takes time and patience. Stick with it and it will mature with age.

Generally, before using in a bake, I like to see my starter at maximum activity. This means it has the capability of rising to peak (ideally at least tripling) within a 4-6 hour window after a feed. To get my starter to that capability, I find that a day or two of warm, rapid refreshments out of the refrigerator works wonders.

For general maintenance, it’s usually recommended to feed at least twice a day. How many times you should feed depends on your starter’s current activity level, the type of flour you’re using, the starter’s hydration, and the temperature.

See my tutorial covering how to feed twice daily, as well as my tutorial covering how to feed three times a day. Feeding on a 12-hour schedule (morning and evening) tends to be more manageable for most people, however I normally feed three times daily (morning, early afternoon, evening). Feeding three times per day does the best job of really ensuring the acid burden stays as low as possible, and gives me maximal leavening activity.

If you are not baking any time soon, there is no need to keep up the feedings at warm room temperature. The refrigerator is the perfect spot to store your starter during times you are not actively baking. Just give your starter a feed of 1:1:1 and pop in the fridge for up to a couple weeks!

Lower temperature can most definitely slow starter fermentation, since sourdough starters, and particularly the resident yeasts, are temperature-sensitive. A room temperature consistently below ~75°F/24°C can slow down the process of developing a new starter from scratch and even slow down an established starter from quickly reaching peak. Consider finding a warmer spot (~78-80°F/26-27°C) to rest your starter and give it a boost in activity!

Here are a few warm spots you can try:

• Inside your oven, with the light on. Make sure to leave the door cracked open so it doesn’t get too warm (try to keep it between about 72°F/22°C - 82°F/28°C).

• In the microwave, next to a glass of boiling water.

• In a dough proofer box, such as the Brod & Taylor.

Remember, warmer temperatures can cause your starter to ferment fast... You don’t want to regularly under-feed your starter if the temperature is too warm, because then it will eat through the food too fast and cause your starter to become over acidic and sour and weaken the doughy mixture. 

Cooler temperatures on the other hand can slow down the fermentation. You don’t want to over-dilute your starter with flour and water if the temperature is cool because then it won’t fully ferment the mixture by the time you have scheduled the next feeding.

Starters can be made using any mix of flour you prefer. Bakers around the world use all sorts of different flour mixes: Rye, whole wheat, and all-purpose flour are common. I prefer a mix of 90% bread flour (for strength) and 10% rye (for nutrient content and enzymatic activity). Different flour mixes will cause changes in aroma, dough consistency, speed of fermentation, and height of peak. Higher percentages of whole grain in a starter can supply more nutrients and enzymatic activity which can make the starter more active while also giving the starter a more sour flavor. Higher percentages of white flour in a starter can make the starter more sweet in aroma and flavor. While changing the flour will change the physiology and behavior of the starter, it’s part of what will make your starter unique!

I like to prepare a bowl of my flour mix ahead of time. This way, I’m not measuring out the individual flours at every feed. In my Flour Feed Bowl, I whisk together 450g bread flour and 50g rye flour. This 500g flour mix usually lasts me a week or two if I’m feeding daily.

The peak height your starter grows to in your jar is highly dependent on many variables: the flour your starter is fed with; the amount and type of water you use; the temperature you rest your starter at during the day and overnight; and the ratio you’re feeding at (how much starter to flour to water you’re adding), and how often you are feeding. 

A starter straight from the refrigerator may not rise as high as one that’s been refreshed a few times at warm room temperature (it can take a few feeds sometimes for a starter to become “refreshed” and “revived” after a long spell in the refrigerator). A starter fed with low protein flour may not rise as high as one fed with high protein flour (strong flour can help “capture” those gasses produced during the ferment). A starter refreshed more often using lower ratio feeds may rise higher than one fed at higher ratio feeds less often (a starter fed less often can degrade due to the action of enzymes and acid build-up, and this acidification can weaken the gluten network so that less gasses can be retained). A starter kept warm may rise higher than one kept at cooler temperatures.

So it is important to know that every starter is going to be different! Even starting off with the same Full Proof Baking fresh sourdough starter, over several feeds the starter will become your own starter. It will adapt to your environment and take on different characteristics and growth rates over time, as your flour and water and temperature will select for different microbes than were selected for in my kitchen.

I’ve noticed that when I switch up the flour I’m using to feed my starter, it can take several feeds for the starter to adapt and balance out/adjust to the new grain. If you’re using a much different flour feed mix than I use (I use 90% King Arthur organic bread flour and 10% Arrowhead Mills whole rye flour), it can surely take more time and care to get the starter back to full activity. Have patience and keep testing one variable change at a time to see what your starter likes best. Try feeding for several days using one flour mix. If you’re not feeling great about the flour and how the starter is behaving, try swapping out a little of the flour for another and see how the starter behaves after a few feeds. Same with the water: try water from the tap, and compare to filtered or purified water, bottled water, etc. Sourdough starter is a living community of microbes, and until they are adjusted to your environment, it can take a little playing with and experimentation to optimize its activity.

Most importantly: keep in mind that every starter is different, and this is what makes your starter unique and your own! Knowing how long it takes to peak, and trying to optimize your starter so that it reaches that peak in a predictable and speedy manner, will help you get the most powerful and efficient fermentation on your main bread dough!

See here for additional resources:

Pre-recorded workshop on Sourdough Starter and Levain

How To Activate Your Starter and Build an Active Levain

Using a Stiff Starter (can be good if you're living in an especially warm/humid climate)

That liquid layer, called a “hooch,” is a build-up of alcohol—and it’s a sign your starter is hungry and it needs more flour and water! Try feeding more often and/or switching to higher ratio feeds. Chronic under-feeding will cause a starter to become acid-laden, and it will not perform as actively as it could if fed in an optimized manner.

Starter and levain are essentially the same thing. I tend to refer to starter as the small amount of dough I am regularly feeding and maintaining over time. When I’m ready to mix up a dough, I will first build up a larger amount of my starter, which I call my levain—the starter I am adding directly to my dough. 

Most often I use the same flour to feed my starter as I do to build my levain. But if I wanted to mix up a 100% whole wheat recipe, I would want to take a small bit of my starter and begin feeding it 100% whole wheat flour for a day or two to get my starter microbes adjusted to the new flour feed mix.

The bacteria present in sourdough cultures produce lactic and also acetic acid. If you notice your sourdough is smelling/tasting more like yogurt, your starter is likely balanced more towards lactic acid. If your sourdough is smelling/tasting more like sharp vinegar (I always pick it up as a strong cider vinegar aroma), this means you’re balancing more towards acetic acid. 

A starter re-fed at peak each time will tend to have a lower acidity overall, and less of a sharp tanginess. A starter chronically under-fed (repeatedly feeding after the starter has peaked and fallen/collapsed) will yield a starter with more concentrated acid burden and a more sharp sour tanginess. Starters that are fed at peak and are not burdened by a high acid concentration will tend to have better yeast (rise) activity, as high acidity can stress the yeast population.

So, if you’re looking for a sweeter/more mild flavor profile and more robust rise activity, consider feeding at lower ratios (1:1:1) and keeping the starter nice and warm (try to feed again right when the starter hits peak); If you’re looking for more sour tanginess to your starter, consider feeding at higher ratios (1:10:10) and allowing a longer duration between feeds.

For more advanced-level detail into the balance of sweet and sour starters and how to optimize your starter behavior, see my pre-recorded workshop here: https://www.airsubs.com/pros/full-proof-baking/on-demand/sourdough-starter-levain-201

Regarding regular maintenance, I highly recommend “micro feeding” your starter at each feed. This entails entails feeding small amounts of starter, flour, and water together at each feed time. This results in only a small amount of discard over time, which can be stored in the freezer throughout the week. Hypothetically, if you never discarded, you will build up your volume quickly. In just a few feeds you could be looking at gallons of starter! For the small scale home baker, this is just too much. Discarding all but about 3-10g at each feed will help you save on flour and money in the long run.

I like to use the same flour mix as I normally use during the starter feeds/refreshments to build my levain. If you want to make a big change to your levain, I’d recommend taking a small amount of your starter and begin feeding a few times on the new flour feed mix to get the starter used to the new flour. Usually it will adapt and balance out quickly, but sometimes, especially if you’re swapping a higher whole grain flour mix for one with more white flour, you may notice it takes a few feeds to get the starter balanced out and completely active again.

You can build your levain 1:1:1, 1:2:2, 1:5:5, or 1:10:10! If you feed lower ratios, plan to have your levain peak and ready to use sooner than if you were to use a higher ratio. What’s nice about a low ratio build is you can have your levain ready to use in just 4-6 hours! What’s nice about a higher ratio build is you can build your levain overnight and have it ready first thing in the morning!

I regularly mix up a little extra levain than I need. The reason is two-fold. I often lose a little weight in evaporation. And I find it’s good to have 5-10g extra, so after scooping out the levain there’s always a little left over to propagate and continue refreshments of the active starter.

If you want to perform a 1:1:1 feed and need 180g levain, you’ll want to add up the ratio values 1+1+1=3. Then divide the total volume amount by this value (180/3)=60. This gives you your 1X value of 60g. So you would want to mix up (1x) 60g starter + (2x) 60g flour + (2x) 60g water to give you your total 180g levain you need for your bread dough.

If you want to perform a 1:2:2 feed and need 180g levain, you’d do the same math: 1+2+2=5. (180/5)=36. So your 1X value in this case is 36g. Mixing up (1x) 36g starter + (2x) 72g flour + (2x) 72g water will give you your total 180g levain you need for your bread dough!