Attempts at improving sourdough using glutinous rice flour

I've recently had a few great bakes that had glutinous rice flour in them and it seemed that it assisted with a strong oven spring, especially if cooked first as a roux (tangzhong/yudane).

To understand it further, let's look at an experimental bake of four small breads (each with 500g of dough and each where 5% of the flour was a rice flour, and 20% whole spelt):

1. Control bread using regular white rice flour as flour addition.
2. Sticky rice as flour addition, not as roux
3. Sticky rice roux (200% hydration)
4. As per 3 but higher hydration, that's the thing with a roux it makes the hydration behave differently

The roux for bread 3 on the left at 200% hydration; on the right the roux for bread 4 at 600% hydration.

Overall hydration was 67.5% for samples 1-3; for sample 4 the hydration was 85% simply because I made an error with the maths and the tangzhong had a 600% hydration instead of the intended 300% and so it was over hydrated!

The base recipe for each loaf was 208g Caputo Manitoba Oro, 52g spelt wholemeal, 4.7g salt, 150g water, 52g levain, and a roux of 13g glutinous rice flour with 26g of water. This was adjusted as follows: for sample 1 glutinous rice flour was swapped with regular white rice flour; for samples 1 and 2 no roux made and the 26g of additional water added to the base water (176g of water); for sample 4 the roux was 13g glutinous rice flour with 78g water and it had a higher hydration than the other 3 breads.

From left to right breads 1 to 4.

As you can see from the photos, the expected strong oven spring didn't happen. However breads 3 and 4 with the roux did open properly at the straight score whereas the other two breads did not.

Crumb of breads 1 to 4 from left to right. Bread 4 was over-hydrated. No strong difference in oven spring, altough you can see that the two roux containing breads on the right opened up at the score nicely.

Taste testing notes, subtle differences in flavour: bread 1 was distinctly more sour and the taste of breads 2-4 (containing glutinous rice flour) were preferred. Also, it was noticeable that the texture of breads 3 and 4 was better.

In conclusion - some benefits were there, but were subtle and there was no noticeable improvement in oven spring (unlike what was expected!)

-Jon