Table S1. Formulations of sorghum sourdoughs and different bread doughs.

Control wheat bread (CWB)

Control sorghum-wheat bread (CSWB)

Control sorghum sourdough bread (CSSB)

Dextran-enriched sorghum sourdough bread

(DSSB)(g) % f.w. (g) % f.w. (g) % f.w. (g) % f.w.

Sourdough formulationWater 900 60 900 60Sorghum flour 642.9 42.9 578.6 38.6Sucrose 64.3 4.3

Bread formulationSourdough 1542.9 102.9 1542.9 106.7Water 904.5 60.3 900 60Sorghum flour 750 50 107.1 7.3 107.1 7.3Wheat flour 1500 100 750 50 750 50 750 50Yeast 75 5 75 5 75 5 75 5Sugar 30 2 30 2 30 2 30 2Salt 22.5 1.5 22.5 1.5 22.5 1.5 22.5 1.5Fat 75 5 75 5 75 5 75 5Dough weight 2607 2602.5 2602.5 2602.5Flour weight 1500 100 1500 100 1500 100 1500 100

Table S2. Formulations of model wheat breads with addition of different amounts of lactic/acetic acid or caffeine for panel training.

Bread 1 Bread 2 Bread 3  (g) % f.w. (g) % f.w. (g) % f.w.

Water 904.5 60.3 904.5 60.3 904.5 60.3Lactic acid 4.5 0.3 6.8 0.45 9 0.6Acetic acid 0.6 0.04 0.9 0.06 1.2 0.08Caffeine 3 0.2 4.5 0.3 7.5 0.5Wheat flour 1500 100 1500 100 1500 100Yeast 75 5 75 5 75 5Sugar 30 2 30 2 30 2Salt 22.5 1.5 22.5 1.5 22.5 1.5Fat 75 5 75 5 75 5

Table S3. Formulations of wheat breads with addition of fixed amount of acids or caffeine and dextran of varying concentration for magnitude

estimation test.

1 The % bread weight was calculated by the equation: ((dextran % f.w.)*flour weight) / (dough weight*(1-baking loss)). Where average baking loss = 11%.

Sour taste bread Bitter taste bread  (g) % flour

weight% bread weight 1

(g) % flour weight % bread weight

Bread formulationWater 904.5 60.3 904.5 60.3Caffeine 3 0.2Lactic acid 9 0.6Acetic acid 1.2 0.08Wheat flour 1500 100 1500 100Yeast 75 5 75 5Sugar 30 2 30 2Salt 22.5 1.5 22.5 1.5Fat 75 5 75 5

Dextran 0 0 0 0 0 03.7 0.2 0.12 3.7 0.2 0.127.3 0.4 0.26 7.3 0.4 0.26

11.0 0.6 0.38 11.0 0.6 0.3816.5 0.9 0.57 16.5 0.9 0.5727.4 1.5 0.96 27.4 1.5 0.96

Table S4. Specific volume and textural parameters of control sorghum bread with and without the addition of glucose and fructose.

Bread sample Specific Volume (ml/g)

Hardness (g, on day1) Springiness(g, on day 1)

Cohesiveness(on day 1)

CSWB 3.02 ± 0.04 499.49 ± 78.5 0.90 ± 0.03 0.50 ± 0.04

CSWB + glucose/fructose 1 2.92 ± 0.01 610.85 ± 66.0 0.89 ± 0.02 0.48 ± 0.02

1 The “CSWB + glucose/fructose” was prepared using the CSWB formulation with added glucose (0.77% dough weight) and fructose (1.16%). The sugar content was calculated based on glucose and fructose level detected after 24 h fermentation of dextran-enriched sorghum sourdough. Values are a mean ± standard deviation.

Table S5. Sensory profiling of wheat control bread, native and sourdough wholegrain sorghum breads.

CWB 1 CSWB CSSB DSSB

Texture

Resistance to pressure 0.1 ± 0.0a 6.2 ± 0.3c 7.8 ± 0.2d 2.0 ± 0.2b

Resistance to deformation 0.1 ± 0.0a 6.6 ± 0.3c 7.4 ± 0.3c 2.4 ± 0.2b

Elastic texture 9.9 ± 0.0a 3.7 ± 0.3c 4.1 ± 0.4c 7.8 ± 0.2b

Crumb coarseness 0.1 ± 0.0a 6.1 ± 0.3c 6.7 ± 0.3c 2.4 ± 0.2b

Foldability 9.9 ± 0.0a 1.9 ± 0.2c 1.6 ± 0.2c 5.5 ± 0.5b

Mouthfeel

Resilience in mouth 0.1 ± 0.0a 5.1 ± 0.4c 6.0 ± 0.4c 1.8 ± 0.2b

Crumb moisture 9.9 ± 0.0a 2.4 ± 0.2c 2.4 ± 0.3c 6.4 ± 0.3b

Dough-like/cohesive texture 9.9 ± 0.0a 1.9 ± 0.2c 1.7 ± 0.2c 5.4 ± 0.4b

Flavour

Sour smell (crumb) 1.8 ± 0.3a 3.8 ± 0.4b 2.8 ± 0.4ab

Roasted smell (crust) 2.4 ± 0.3a 2.3 ± 0.3a 3.7 ± 0.3b

Overall smell intensity (crumb) 3.1 ± 0.3a 3.8 ± 0.4a 2.9 ± 0.3a

Roasted taste (crust) 2.8 ± 0.4a 2.9 ± 0.4a 4.1 ± 0.4b

Bitter taste (crumb) 2.2 ± 0.3a 3.8 ± 0.5b 1.3 ± 0.1a

Sour taste (crumb) 1.2 ± 0.2a 4.7 ± 0.4b 2.0 ± 0.2a

Sweet taste (crumb) 1.7 ± 0.3a 1.4 ± 0.3a 3.0 ± 0.3b

Aftertaste 2.3 ± 0.2a 4.2 ± 0.4b 2.0 ± 0.2a

1 Details about the abbreviations can be found in Table S1. Values are a mean ± standard error.Different letters in the same row indicate statistical significance (p<0.05).

Fig. S1. HPAEC-PAD chromatogram showing formation of resistant glucooligosaccharides in dextran-enriched sorghum sourdough (DSSD) and control sorghum sourdough (CSSD).

CSSD

DSSD

Fig. S2. Effect of the polymer concentration (0-2.0% w/w) on the rheological properties of aqueous dextran solutions measured at 25 .℃

Fig. S3. Images of: (A) sorghum grains, whole sorghum flour, and dextran-enriched sorghum sourdough bread; (B) cut loaves from left to right: control wheat bread, control sorghum-wheat bread, control sorghum sourdough bread, and dextran-enriched sorghum sourdough bread.

A

B

Fig. S4. Images of model wheat breads: (A) with addition of fixed amount of acids (lactic/acetic acid: 0.6 / 0.08% flour weight) and varying concentrations of dextran, from left to right 0, 0.12, 0.26, 0.38, 0.57, 0.96% on bread weight; (B) with addition of fixed amount of caffeine (0.2% flour weight) and varying concentrations of dextran.

A

B