The amount of thiol (SH) groups as a quality indicator of the wheat flour protein complex

Abstract

Since the technological quality of flour is directly influenced by protein content and quality, a great attention is paid to determination of its properties. For this purpose, a wide range of chemical, physical and rheological tests are commonly employed. The rheological properties of dough during baking processing and ultimately the quality of final product are influenced by the changes of the thiol/disulphide structure of gluten proteins. The aim of this study was to monitor the changes in the amount of thiol groups as a quality indicator of protein complex of three freshly harvested wheat samples from two localities characterized by different micro-climatic conditions in 2010/2011 production year. By modifying the method of Pérez et al. (2005), the content of thiol groups was spectrophotometrically determined in wet gluten of selected samples (λ = 412nm). Each sample was beforehand tempered at two different temperatures (30° and 37 °C) in order to imitate the flour processing conditions as well as to determine the impact of hydrolytic enzymes present. On the basis of obtained results, it was noticed that each variety manifested different trend in the amount of thiol groups over time when tempering at 30 °C, whilst tempering at 37 °C highlighted the dominant impact of selected localities on the amount of thiol groups.