Solid sourdough starter for panettone

General concept and criteria

General framework and criteria for fermentation, temperature, and raw materials.

1. This process is somewhat complicated: to make panettone, begin with bread sourdough starter and transform it into a panettone starter by following guidelines.
2. Products fermented with sourdough starter behave differently from those fermented with baker's yeast: the final results are better, they are more digestible, and they keep longer.
3. The flour must be high-strength Manitoba flour, W380 or W400; it will not work with flours of strength below W360.
4. Water quality, hardness, present metals, and chlorine can cause different behaviour during fermentation.
5. If there are doubts about water quality, it is better to make the feedings with mineral water.
6. Fermentation transforms sugars into gas, alcohol, and organic acids, mainly lactic and acetic acids.
7. Alcoholic fermentation is the basis of alcoholic beverages and baked goods.
8. Bacterial or lactic fermentation is responsible for flavour and aroma during baking, and provides greater preservation of the finished product.
9. A good sourdough starter will have 60% lactic acid, 20% acetic acid, and 20% other organic acids.
10. The optimal pH would be between 3,9 and 5,3, with 4,1 being ideal; a pH above 5,3 slows the process.
11. There are two ways to make a solid sourdough starter: dry and submerged in water.
12. Solid sourdough starter submerged in water is easier to control and is less acidic, because some of the acidity is diluted in the water.
13. It is a long process, but once made, the sourdough starter can last a lifetime if it is fed periodically.
14. It must be started at least 18 days in advance; preparing it for panettone requires 15 days, plus the 3 final feedings and the 2 days for the final panettone, that is, 20 days in total.
15. Experts say it is best to bake it 3 days before consuming it.
16. During the first 15 days, it must be fed every day.
17. The dough behaves like a living being, which can live and breathe in the presence of oxygen and survive and ferment under anaerobic conditions.
18. When kneading it, oxygen is incorporated, which promotes metabolism and the natural growth of yeasts; when oxygen is depleted, alcoholic fermentation begins and carbon dioxide and ethyl alcohol are produced.
19. Overnight resting times can vary between 16 and 18 hours between two feedings.
20. Keep the dough at around 26-30ºC.
21. The water for feeding must be at 30ºC to compensate for the cold temperature of the bath.
22. The ambient temperature for overnight resting must be around 18-19ºC.
23. The final temperature of the dough must be between 26ºC and 30ºC.
24. At 0ºC-4ºC, yeasts have no fermentative activity; at 4ºC-12ºC, activity slows down.
25. A cold sourdough starter, below 22ºC, has poorly developed gluten and a slower fermentation process.
26. Between 23ºC and 28ºC, exponential yeast growth occurs with high gas production.
27. Above 30ºC, enzymatic activity is too high and the dough tends to liquefy; from 32ºC onwards, signs of decomposition appear.
28. At 35ºC, maximum gas production occurs and the progressive deterioration of yeasts begins.

Equipment and initial ingredients

1. You need a good-quality organic apple, a container taller than it is wide measuring about 22 cm high x 8 cm at the base, a zip-top or freezer bag, two cotton or linen cloths, cotton twine or string, a kitchen scale, a digital thermometer, and a rolling pin.
2. The container must be just the right size to contain and support the dough; if it is excessively large, the dough will spread out and disintegrate.

First day

1. Wash the apple thoroughly and dry it with kitchen paper.
2. Cut it into quarters and grate the whole apple, including the skin.
3. Weigh the grated apple.
4. Put the grated apple and any juice it has released into an airtight glass jar.
5. Add water at 30ºC equal to the weight of the grated apple.
6. Close the jar and place it in the switched-off oven, with the light on.
7. Maintain a temperature between 28ºC and 30ºC; it is important that it does not drop below 28ºC on this first day.
8. Monitor the temperature with the thermometer.
9. If the oven cannot keep the light on, heat water and put it in a cup inside the oven; check the temperature and repeat the procedure if necessary.
10. Leave it to ferment for 24 hours.

Second day

1. Strain the contents of the glass jar, discard the pulp, and reserve the fermented water.
2. Weigh the fermented water.
3. Put the fermented water and the same weight of Manitoba flour in a bowl.
4. Mix well with a spoon until you obtain a homogeneous mixture.
5. Pour the dough into the container and mark it with a pencil or an elastic band to monitor its growth.
6. Do not cover the container: the dough must be able to breathe; cover it with a cloth.
7. Place it in the switched-off oven, with the light on.
8. Maintain a temperature between 28ºC and 30ºC; it is important that it does not drop below 28ºC on this second day.
9. Monitor the temperature with the thermometer.
10. If the oven cannot keep the light on, heat water and put it in a cup inside the oven; check the temperature and repeat the procedure if necessary.
11. Leave it to ferment for 24 hours.

Third and fourth day

1. If the sourdough starter develops well, it will have doubled or tripled in volume.
2. Observe how far it rose before falling back relative to the initial-volume mark; if it has not at least doubled in volume, you must start again.
3. If it has gone well, put 200 g of sourdough starter and 200 g of Manitoba flour in a glass bowl.
4. Work it with your hands until you obtain a solid dough; it is very dry and the flour is difficult to incorporate, but kneading and resting will achieve it.
5. When the dough is homogeneous, roll it onto itself.
6. Put the dough in a zip-top or freezer bag and wrap it well, ensuring all the air is expelled.
7. Wrap the bag with a tightly rolled and snug cotton cloth.
8. Finish wrapping the whole bundle with the other kitchen cloth.
9. Tie the package with string, using a tie like that used to tie meat for pot roasting, and secure both ends tightly.
10. Place the package in a pot to contain the dough if it escapes from the package.
11. Cover the pot and leave it in the oven for 48 hours; in this case, there is no need to keep the oven light on.
12. During the two days, the dough will rise greatly and, in the final hours, will begin to lose strength.

Fifth day

1. After 48 hours, you will have a more developed, toasted-cream-coloured sourdough starter.
2. Unwrap the dough and carefully remove the plastic bag; if it cannot be removed easily, cut it with scissors.
3. Take only the inner part of the dough and discard the outer walls, which are dry and contain dead cells that are of no interest.
4. Weigh the amount of sourdough starter that can be recovered and discard the rest.
5. Mix 200 g of sourdough starter with 200 g of Manitoba flour and between 30% and a maximum of 50% water at 30ºC; for 200 g, it is advisable to use between 60 and 80 g of water.
6. Do not add too much water: if the dough sticks to the work surface, too much has been added.
7. Form a ball on the work surface and knead it well until you obtain a smooth, homogeneous dough.
8. If necessary, alternate kneading with resting; during rests, cover it with a cloth to prevent it from drying out.
9. Roll out the dough with the rolling pin to refine it.
10. Roll it out, fold it into thirds, and roll it out again.
11. Repeat the rolling and folding into thirds several times, until you achieve a soft and smooth texture.
12. Let it rest from time to time so that the dough relaxes, as it will be very tense and difficult to refine.
13. When it is refined, roll it out and fold it by taking the long ends and bringing them inward, as when making a baguette.
14. Roll it out again to give it length; achieve a width slightly less than the width of the container where it will be placed.
15. It is important that the final width is slightly less than that of the container where it will be kept for the water bath, so it can climb the walls of the container without difficulty.
16. Roll the dough onto itself to form a spiral, leaving no gaps and giving it some tension; stretch it slightly before rolling it.
17. Put the dough in the container.
18. Cover it with water at 14ºC until the water covers the top of the dough.
19. Leave the container at room temperature for 20-24 hours, uncovered; you may place a cloth over it to prevent anything from getting in.

Sixth day

1. It is possible that, before 24 hours have passed, the dough has already begun to disintegrate.
2. The dough will have risen considerably and will float on the surface, with the water underneath; the top part will be dried out, the bottom part in the water will be slimy, and the first bubbles may be seen on the sides, a sign that it is gaining strength.
3. If there is a whitish layer at the bottom of the container, it means the dough has started to disintegrate and has spent too long in the water; the dough will become too liquid and much of it will be lost when the container is tipped.
4. Very carefully, remove the dried-out top part of the sourdough starter.
5. Tip the container over a large bowl and place your hand over the mouth of the container to catch the sourdough starter.
6. Remove the slimy part and drain it by gently pressing it with your hands to remove excess water, as if it were a sponge.
7. If it falls apart when pressed, this is also a sign that it has spent too long in the water.
8. Leave it on a plate.
9. Weigh the sourdough starter.
10. Mix 200 g of sourdough starter with 200 g of Manitoba flour and between 30% and a maximum of 50% water at 30ºC in a bowl; for 200 g, it is recommended to use about 60 g of water.
11. If the dough is not very firm because it has spent too long in the water, use less water when kneading it again; instead of 60 g, use 50 g less and adjust as you go.
12. Once drained, the sourdough starter should look muscular and offer some resistance when stretched to break it.
13. Form a ball on the work surface and knead it until you obtain a smooth, homogeneous dough.
14. If necessary, alternate kneading with resting and cover it with a cloth during rests.
15. Roll it out with the rolling pin to refine it.
16. Make repeated folds into thirds until you achieve a soft and smooth texture.
17. When it is refined, fold it inward as for a baguette.
18. Roll it out again to give it length.
19. Roll it into a spiral, leaving no gaps and giving it some tension.
20. Put the dough in the container.
21. Cover it with water at 14ºC until the water covers the top of the dough.
22. Leave the container at room temperature for 12-24 hours, uncovered; you may place a cloth over it to prevent anything from getting in.
23. It may need to be fed before 12 hours have passed.

Seventh to fifteenth day

Daily maintenance feedings and temperature adjustment.

1. Repeat the same procedure every day for the next 9 days.
2. It may need to be fed every 12 hours, because it may be very strong and rise quickly.
3. If it rises too quickly, make the bath water colder: instead of 14ºC, use water at 4ºC.
4. The bath water is not the feeding water: the feeding water for kneading the dough must always be at 30ºC.
5. Try to have the dough reach the ideal feeding point 12 hours after the previous one, so that feedings can be done every 12 hours.
6. As the days pass, adjust the fermentations; if the dough is very compact, you can vary the amount of water in the feeding up to 80 ml instead of 60 ml.
7. At the end of this process, you will have a solid sourdough starter ideal for beginning the bagnetto and the three final feedings before starting to knead the panettone dough.

Storage of activated sourdough starter

1. Once you have the solid sourdough starter, you can keep it indefinitely with periodic feedings.
2. The first 15 days of daily feedings are unavoidable, but afterward the activated starter can be kept in the refrigerator for between 7 and 21 days without feeding, bearing in mind that the longer it remains cold, the more acidity it will develop.
3. To keep it for 7 days, make a standard 1:1:1 feeding, let it float on the surface, and refrigerate it at 4ºC.
4. To keep it for 14 days, make a 1:4:2 feeding, let it float on the surface, and refrigerate it at 4ºC.

Bagnetto

Corrective bath before the three final feedings.

1. Before doing a bagnetto and the three preparatory feedings, begin with a solid sourdough starter that is strong, stable, and predictably behaved.
2. The sourdough starter prepared for the bagnetto must have been fed between 12 and 14 hours beforehand, in an environment with an ambient temperature between 24ºC and 26ºC, so that it is at an optimal stage of maturity.
3. The bagnetto consists of submerging the solid sourdough starter, previously drained, in a fresh bath of sugared water.
4. The specific ratio is 3 parts water to 1 part sourdough starter and 0,0025 sugar, for a maximum of 15-18 minutes.
5. Example: 600 water, 200 flour, and 0,5 g sugar.
6. Example: 1000 water, 333 flour, and 0,8 g sugar.
7. It is advisable to do a bagnetto before starting the three final feedings; if the dough has become acidic again because a few days have passed without feeding it, another bath can be done, but a sugared bath, while reducing acidity, also weakens the dough.
8. If overnight resting is well controlled and the dough does not become excessively acidic, doing it only once will be enough.
9. The bagnetto is essential when working with dry solid sourdough starter; when working with submerged solid sourdough starter, it can be omitted, but it is recommended if overnight rests have been carried out in the refrigerator.
10. For dry solid sourdough starter, the water must be at room temperature and the duration is 15-18 minutes.
11. For submerged solid sourdough starter, the water must be between 33ºC and 35ºC and the duration is 15-18 minutes.

Sourdough starter quality and correction

Quality diagnosis, corrections, and purging bagnettos.

1. If the sourdough starter does not float, it is a sign of too much microorganism activity and that it has become too acidic.
2. Mature sourdough starter will have a pH between 4,1 and 4,3, will be aromatic, sweet and slightly acidic in flavour, off-white in colour, and have elongated alveoli.
3. Very strong sourdough starter can be strong but not acidic, or strong and acidic.
4. If it is strong but not acidic, there are too many yeasts and the balance with lactic bacteria has been disrupted; if it is ready before 3 hours, it is a bad sign.
5. If it is strong and acidic, too much acetic acid is being produced; it will have a sour and bitter flavour, pH below 4, grey colour, and sticky consistency.
6. In this case, the sourdough starter must undergo a purging bagnetto: submerge 200 g of sourdough starter in 600 g of cold water at 18ºC with 0,4 g of sugar, keep it in the bath for 15 minutes, then drain it and feed it according to the 1:2:1 ratio, that is, with 200 g sourdough starter, 400 g W400 or W380 flour, and about 200-210 g water.
7. If the sourdough starter is very weak, it will have a pH between 5 and 5,5, show no acidity, have a sweet taste, an aroma reminiscent of flour, white colour, and few alveoli.
8. To strengthen it, make a first feeding according to the 1:0,8:0,4 ratio, that is, with 250 g sourdough starter, 200 g flour, and 90 g water; then continue feeding with the usual quantities until the sourdough starter rises 1+1/2 of its initial volume in about 3 hours or 3 and a half hours.
9. If the sourdough starter is sour, it will have a very low pH, a pungent and strong aroma, bitter flavour, and dark grey colour.
10. When lactic acid predominates, it can cause a weaker and stickier first dough, difficulty incorporating fats, a baked panettone that breaks when turned upside down, and a sourdough starter with small, round alveoli.
11. To balance an excess of lactic acid, act in every feeding and storage stage, introducing actions that generate acetic acid.
12. Possible solutions: feed with cooler water, between 24ºC and 22ºC; carry out overnight rests at low temperatures; submerge the sourdough starter in water at 4ºC or, if it is a dry sourdough starter, keep it at 10ºC; if the first dough is very sticky, discard it, start again, and make the three feedings again, correcting the starter in the first feeding with 20 g egg yolk for every 500 g solid sourdough starter.
13. If there is difficulty incorporating fats, stop panettone production and make the three feedings again, correcting the starter in the first feeding; increase the flour at a ratio of 1 to 2, add 20 g egg yolk for every 500 g solid sourdough starter, and add 0,2% salt relative to the amount of flour in the 2nd and 3rd feedings.
14. If the product collapses once baked, reduce the % of water even to 40% relative to the flour weight.
15. If there are small, round alveoli, do a bath, or bagnetto, with cold water at 19ºC before making the three feedings, with 3 parts water for every part sourdough starter and 2 g fructose for every litre of water.
16. When acetic acid predominates, it is easier to identify because it is volatile and detected by smell; it has a harsh, pungent odour and a less bitter flavour than excess lactic acid, but one that is perceptible on the tip of the tongue.
17. An excess of acetic acid causes a more resistant and less extensible first dough, a product with little flavour, elongated alveoli, and greater mould proliferation.
18. To balance an excess of acetic acid, promote the production of lactic acid: dissolve the sourdough starter in warm water before incorporating the flour, increase the % of water up to 55% if necessary, and knead it well.
19. To obtain good results, a perfect balance between bacteria and yeasts must be maintained.

Three feedings before beginning to knead the panettone

Sequence of final feedings immediately before the first dough.

1. Kneading temperature: aim to keep it as regular as possible, around 27ºC, and do not let it vary outside 26ºC to 28ºC.
2. Overnight maintenance temperature of the sourdough starter: the ideal temperature is between 16ºC and 18ºC; when working with solid sourdough starter submerged in water, it should be rather firm and dry, because during resting it will absorb water and tend to disintegrate.
3. Overnight resting time: the ideal time is between 16 and 18 hours.
4. Hydration percentage and dough consistency: a very firm dough promotes excessive development of acetic acid; 4% water can be added, that is, 44%-46% depending on the flour, and it must be kneaded very well, sheeted, and the sourdough starter folded to oxygenate it and allow better yeast reproduction.
5. First feeding: at 8:00 am, with an ambient temperature between 26ºC and 28ºC; mix 30 g solid sourdough starter, 30 g Manitoba W360 or W380 flour, and between 12,6 and 10,5 ml water at 26ºC-28ºC, according to the water absorbed during the bagnetto.
6. Second feeding: at 11:45 pm, with an ambient temperature between 26ºC and 28ºC; mix 60 g solid sourdough starter from the first feeding, 60 g Manitoba W360 or W380 flour, and 25,2 ml water at 26ºC-28ºC.
7. Third feeding: at 15:45 pm, with an ambient temperature between 26ºC and 28ºC; mix 140 g solid sourdough starter from the second feeding, 140 g Manitoba W36 flour, and 59 ml water at 26ºC-28ºC.
8. Calculate the ideal temperature of the bath water before each feeding.

Storage and maintenance notes

1. The sourdough starter can be kept in the refrigerator for between 7 and 21 days without feeding; the longer it remains cold, the more acidity it will develop.
2. To keep it for 7 days, make a standard 1:1:1 feeding, let it float on the surface, and refrigerate it at 4ºC.
3. To keep it for 14 days, make a 1:4:2 feeding, let it float on the surface, and refrigerate it at 4ºC.