Water absorption of food wheat flour – comparison of direct and indirect methods

The study aims to compare three methods used for the evaluation of water absorption of wheat flour: a) a direct method consisting of a standard procedure on a Farinograph-E device and b) two indirect methods, namely NIR spectroscopy and centrifugation. Forty-four samples of Czech food wheat were collected from the harvest year 2021. Namely, 23 samples of food wheat from the standard maturity collection ‘SM2’ and 21 samples from the early maturity collection ‘EM2’. All wheat samples were ground to obtain wheat flour of fine granulation. The flour samples were characterised by protein and ash content of 10.55-14.75% and of 0,59-0.63%, respectively. The water absorption ranged from 55.7% to 63.2% flour weight (Farinograph standard procedure), 60.1-67.1% flour weight (NIR spectroscopy), and 67.6-77.2% flour weight (centrifugation). Based on the results obtained by ANOVA statistical analysis, no significant difference was found for all qualitative parameters of SM2 and EM2 (p = 95%). According to the mentioned methods for both indirect determinations of water absorption in the sets SM2 and EM2, the prediction of the standard farinograph water absorption was more accurate using the NIR technique (minimal and maximal pair differences of 1.01 and 6.86 percentage points, in contrast to 1.78 and 14.87 percentage points for the centrifugation method). Linear regression confirmed the primary importance of protein content for the water absorption values. Also, the ash content should be considered because it reflects the dietary fibre level, and the fibre influences the water absorption values as well.