Mechanically and Thermally Induced Degradation and Modification of Cereal Biopolymers during Grinding

Abstract

It is presumed that structural and functional alterations of biopolymers, which occur during grinding, are caused by a mechanical modification of polymers. As a result, thermally induced changes of flours are neglected. In this study, the impact of thermo-mechanical stress (TMS), as occurring during general grinding procedures, was further differentiated into thermal stress (TS) and mechanical stress (MS). For TS, native wheat flour, as well as the purified polymers of wheat—starch and gluten—were heated without water addition up to 110 ∘ C. Isolated MS was applied in a temperature-controlled ultra-centrifugal grinder (UCG), whereby thermal and mechanical treatment (TMS) was simultaneously performed in a non-cooled UCG. TS starch (110 ∘ C) and reference starch did not show differences in starch modification degree (2.53 ± 0.24 g/100 g and 2.73 ± 0.15 g/100 g, AACC 76-31), gelatinization onset (52.44 ± 0.14 ∘ C and 52.73 ± 0.27 ∘ C, differential scanning calorimetry (DSC)) and hydration properties (68.9 ± 0.8% dm and 75.8 ± 3.0%, AACC 56-11), respectively. However, TS led to an elevated gelatinization onset and a rise of water absorption of flours (Z-kneader) affecting the processing of cereal-based dough. No differences were visible between MS and TMS up to 18,000 rpm regarding hydration properties (65.0 ± 2.0% dm and 66.5 ± 0.3% dm, respectively). Consequently, mechanical forces are the main factor controlling the structural modification and functional properties of flours during grinding.

Effects of Transglutaminase on the Protein Network and In Vitro Starch Digestibility of Asian Wheat Noodles

“…A small increase (non-significant) in onset temperature as well as gelatinisation enthalpy with transglutaminase concentration was observed. A higher onset temperature may have been due to impeded water absorption into the denser protein network, thus requiring a higher temperature for gelatinisation [33]. An increase in gelatinisation enthalpy indicates that more energy was required to 'melt' the starch, as a result of the denser protein network acting as an effective barrier to gelatinisation.…”

Chemical Modification and Characterization of Cotton Pulp as Cationic Material for Protiens Separation

“…The alterations of biopolymers occurred during the processing of food, thus affecting the quality of food (Pilli & Alessandrino, 2020). Hence, various kinds of physical forces appeared during processing and affected biopolymer modi cations on microscopic, nanoscopic and molecular scales (Paulik, Jekle, & Becker, 2019). Natural and arti cial biopolymers are making their way in many elds like science, bio-interface engineering, tissue engineering, drug delivery and material science.…”

Texture design of gluten-free bread by mixing under controlled headspace atmosphere

“…The finale volume of baked goods depends on the gas production or gas entrapment of dough, as well as the gas stabilization during dough preparation and baking process [1,2]. Long time, scientific focus was on the optimization of gas stabilization in gluten-free (gf) dough, for instance by the addition of hydrocolloids or other functional polymers to the bulk phase, as well as the improvement of the hydration properties of dough [3][4][5][6][7]. In recent approaches, the finale gas volume ratio of gf breads is optimized by focusing on the gas introduction in gf dough by the adaption of the mixing process [8] or extrusion processes [9].…”