>have tried Jack Lang's aforementioned formula a couple of times this week, once with 5g of vitamin C, and once with a smaller amount (1g).
As this question has more technical content
I will answer this in the technical center
Sorudom, When I was in Melbourne several mnntha ago I was able to make naturally fermented sourdough baguettes using Australian bread flour and I even added 1-2% vital wheat gluten to improve the bread volume.
I found out that the flour 10.5-% protein content is not suffiicient for my needs so I fortified it with gluten.
The ratio of the starter to the dough flour is 30-40%. It was mixed with a spiral mixer to full dough development ( 3 minutes low speed and 8-10 minutes at fast speed until it reaches a desired dough temperature of 24 degree C as the starter was cold ( about 12-15 degreee C from refrigeration) then bulk fermented at ambient for about 8 hours at 25 degree C. then dough bin was rolled into the cold room to retard and it was divided after 6 hours in the bench, then pre shaped. Given an intermediate proof of half an hour and then molded.
Placed on baguetter trays and proofed for 3- 4 hours at 35 deg C where it was then loaded to the oven deck with lots of steam and baked at 230 deg C for 20 minutes, the temperature was reduced to 200 and further baked for 20 minutes . The bread comes out really good volume, and a 3 mm thick reddish brown crusts with slighlty open crumb structure and nice flavor..
I have noticed that the if the dough is not properly matured during bulk fermentation the bread appears heavy, and lower in volume.
That is why I used that method for my flour.
Going back to your question that if soft flour is better or to be exact it should be called medium gluten flour in the same genre as the French T55 which has an approximate flour protein content of 9.5%.
There is a likelihood that with Jack Langs method it will work milder flours but with stronger Australian flour I doubt about it..
Another thing is the Chorleywood style where the Jack langs recipe was based is suited to th medium gluten content of British flours but needs to be modified with Stronger Australian breadmaking flour.. Therefore if you give it longer mixing time the bread qualitites might improve but would your food processor will live up to the task?
I prefer to run that experiment in the institutional heavy duty food processor like the STEPHAN vertical cutter mixer.