## 2 Materials and Methods
The Mixolab test was performed using a standard protocol: 8 min at 30 \({}^{\circ}\)C, heating for 15 min at a rate of 4 \({}^{\circ}\)C/min, holding at 90 \({}^{\circ}\)C for 7 min, cooling for 10 min to 50 \({}^{\circ}\)C at a rate of 4 \({}^{\circ}\)C/min and holding at 50 \({}^{\circ}\)C for 5 min [41]. The following rheological features were tested with Mixolab: (i) primary readings: water absorption (M-WA), protein weakening (M-C2), starch gelatinization (M-C3), amylase activity (M-C4), starch retrogradation (M-C5), slope M-\(\alpha\)--between the end of 30 \({}^{\circ}\)C period and M-C2 as the speed of the protein weakening under heating effect, slope M-\(\beta\)--between M-C2 and as an indicator of pasting (gelatinization) speed, slope M-\(\gamma\)--between M-C3 and M-C4 as enzymatic (\(\alpha\)-amylase) degradation speed [42]; (ii) secondary parameters: M-C2-C1--protein weakening range, M-C3-C2--starch gelatinization range (pasting), M-C4-C3--cooking stability range, and M-C5-C4--cooling setback (gelling) [43]. Solvent Retention Capacity (SRC) tests were performed according to an approved AACC 56-11.02 method [38]. SRC is the weight of solvent retained by the swollen flour deposit after centrifugation and is expressed as a percentage of the original flour weight (adjusted to 14% moisture). Solvents were: deionized water, 50 wt% sucrose in water, 5 wt% lactic acids in the water, 5 wt% sodium carbonate in water (WaSRC--water retention capacity; SuSRC--sucrose solvent retention capacity; LaSRC--lactic acid solvent retention capacity; ScSRC--sodium carbonate solvent retention capacity). Herein, a flour sample (5 \(\pm\) 0.050 g) was transferred to a 50 mL centrifuge tube and mixed with 25 g of solvent [44]. In the next step, the sample was left to solvate for 20 min with shaking every 5 min for 5 s. The tubes were then centrifuged at 2500 rpm for 15 min. The supernatant was poured off and the tubes were allowed to dry for 10 min. The sample was subsequently weighed and the SRC was calculated [45]. Additionally, GPI (gluten performance index) was calculated as described by [PERSON] et al. [4] based on the ICC method [37] by dividing the LaSRC value by the combined values of SuSRC and ScSRC. The content of non-starch polysaccharides (NSP) was determined by gas chromatography according to Englyst and Cummings [46] and AOAC 994.13 [47]. The total NSP (T-NSP) content is the amount of sugars: arabinose, xylose, mannose, galactose, and glucose [47]. This analysis allows us to separate the non-starch polysaccharides into two fractions: soluble (S-NSP) and insoluble (I-NSP), and to determine the composition of polysaccharides in both fractions. Total arabinoxylans content (T-AX) and soluble (S-AX) and insoluble (I-AX) fractions were assessed. All analyzes were performed in triplicate. Data were subjected to one-way analysis of variance (ANOVA) using Statistica 13.3 software (StatSoft, Inc., Tulsa, OK, USA) followed by the Fisher's least significant difference (LSD) post hoc test to compare means at the 0.05 significance level. Statistica software (version 12.0, StatSoft Inc., Tulsa, OK, USA) was applied for Principle Component Analysis (PCA) and determination of correlation coefficients at the level of significance 0.05. The analysis of the main components was employed to determine the relationship between physiochemical and rheological features and arabinoxylans in the individual flour streams. PCA input data matrix was scaled automatically. The optimal number of principal components obtained in the analysis was determined on the basis of the Cattel criterion.