Probing thermal transitions and structural properties of gluten proteins using ultrasound

Abstract

Purpose To probe the thermal and structural properties of gluten proteins using ultrasound. Methods A new ultrasonic approach for characterizing the quality of wheat gluten proteins is described. Low frequency (50 kHz) longitudinal ultrasonic velocity, v L , measurements were performed on gluten samples extracted from three wheat flours differing in protein content and in wheat endosperm hardness. Results At room temperature, v L for gluten extracted from soft flowers (Fielder) was found to be (870 ± 92) m/s, while for gluten extracted from extra strong flours (Glenlea) it was found to be (1,940 ± 90) m/s. In the second set of experiments, which aimed at probing thermal properties of gluten proteins, the variation in the numerical value of v L propagating in the wet gluten was found to be substantial (about 1,000 m/s) when the temperature of the gluten was raised from 20 to 90°C, and also when gluten from different flour types was investigated. A continuous structural phase transition was observed, which was different for glutens extracted from different flours. Upon cooling, the velocity also varied depending on wheat type. Conclusions These experiments demonstrate that ultrasonic velocity measurements can be used as a selection tool and study changes in properties of wheat proteins, particularly the thermal transitions that are critical to the quality of end products such as noodles, pasta, and bread. It was also shown that v L is sensitive to gluten class (strength or protein content), showing the potential of such measurements as an early-generation selection tool in wheat breeding programs.Keywords Ultrasound Á Gluten proteins Á Thermal transitions Á Quality Á Structure Riassunto Obiettivo Sondare le proprietà termiche e strutturali di proteine di glutine che usano l'ultrasuono. Materiali e Metodi Un nuovo approccio ultrasonico per caratterizzare la qualità di proteine di glutine di frumento è descritta. La frequenza bassa (50 kHz) la velocità longitudinale ultrasonica, il v L , le misure sono state eseguite sui campioni di glutine estratti da tre farine di frumento che differisce nel contenuto di proteina e nella durezza di endosperm di frumento. Risultati Alla temperatura ambiente, il v L per il glutine estratto dai fiori morbidi (l'Esterno) è stato trovato per essere (870 ± 92) il m/s, mentre per il glutine estratto dalle farine extra forti (Glenlea) è stato trovato per essere (1940 ± 90) il m/s. Nella seconda serie di esperimenti, che ha mirato a sondare le proprietà termiche di proteine di glutine, la variazione nel valore numerico di v L che propaga nel glutine bagnato è stata trovata per essere sostanzioso (circa 1000 m/s) quando la temperatura del glutine è stata alzata da 20 a 90°C ed anche quando il (2013( ) 16:101-110 DOI 10.1007 glutine dai tipi di farina diversi sono stati investigati. Una transizione di fase continua strutturale è stata osservata, che era diverso per i glutini estratti dalle farine diverse. Sul raffreddamento, la velocità il tipo di frumento di dipendere da anche var...

Probing the Properties of Dough with Low‐Intensity Ultrasound

“…Given the potential of ultrasound to serve as a means of determining dough strength and its ability to acquire information from dough or gluten samples as small as 4–7 g (Elmehdi 2001; Elmehdi et al 2003b, 2013) or even 2 g (Alava et al 2007), ultrasonic technologies have obvious applications as wheat quality screening tools in the early stages of wheat‐breeding programs. One group that has significantly advanced the technology's commercial exploitation in this regard is the Sensor Systems Group at the Universitat Politècnica de Catalunya in Barcelona.…”

Advancing the science of wheat quality evaluation using nuclear magnetic resonance (NMR) and ultrasound‐based techniques

“…NDT ultrasound can be employed to evaluate microstructure and mechanical properties of materials, as well as to acquire information on microscopic inhomogeneities and discontinuities with no destruction of the test specimen (Shah & Ribakov, 2009;Wu, Jen, Kobayashi, & Blouin, 2011). An extensive use of lowintensity ultrasound to evaluate the mechanical properties of wheat flour doughs has been reported in the literature (Alava et al, 2007;Bellido & Hatcher, 2010;Daugelaite, Strybulevych, Scanlon, & Page, 2016;Elmehdi, Scanlon, Page, & Kovacs, 2013;Garc ıa-Alvarez, Salazar, & Rosell, 2011;Hatcher et al, 2014;Mehta, Scanlon, Sapirstein, & Page, 2009;Owolabi, Bassim, Page, & Scanlon, 2008;Peressini et al, 2017;Skaf, Nassar, Lefebvre, & Nongaillard, 2009). That is, the propagation of ultrasonic waves through food materials is affected by their structural and mechanical properties, that is, the speed and the energy of the ultrasound are changed due to its propagation through foods.…”

“…However, the authors mentioned inability of the shear ultrasound at this frequency to discriminate between biscuit wheat varieties used for wheat flour dough preparation (Kidmose et al, 2001). Overall, ultrasonic study of wheat flour dough is mostly carried out with the use of transmission techniques (Bellido & Hatcher, 2010, 2011Daugelaite et al, 2017;Diep, 2014;Elmehdi et al, 2013;Hatcher et al, 2014;Mehta et al, 2009;Salimi Khorshidi, 2016). Despite successful use of both transmission and reflection techniques for wheat flour dough systems, each of these techniques has its own advantages and disadvantages.…”

“…Moreover, the possibility of propagating ultrasonic waves at various frequencies through samples allows for structural and mechanical characterization of food constituents with various size scales (Scanlon & Page, 2015). An extensive use of lowintensity ultrasound to evaluate the mechanical properties of wheat flour doughs has been reported in the literature (Alava et al, 2007;Bellido & Hatcher, 2010;Daugelaite, Strybulevych, Scanlon, & Page, 2016;Elmehdi, Scanlon, Page, & Kovacs, 2013;Garc ıa-Alvarez, Salazar, & Rosell, 2011;Hatcher et al, 2014;Mehta, Scanlon, Sapirstein, & Page, 2009;Owolabi, Bassim, Page, & Scanlon, 2008;Peressini et al, 2017;Skaf, Nassar, Lefebvre, & Nongaillard, 2009). Ultrasonic waves could propagate through wheat flour dough systems in shear or transversal (Leroy, Pitura, Scanlon, & Page, 2010) and compressional or longitudinal (Daugelaite et al, 2017) modes.…”

“…On the other hand, the ultrasonic signal is less attenuated with the use of the reflection technique rather than transmission technique, but the acquired signal only provides information about surface properties of the wheat flour dough (Coupland, 2004). Overall, ultrasonic study of wheat flour dough is mostly carried out with the use of transmission techniques (Bellido & Hatcher, 2010, 2011Daugelaite et al, 2017;Diep, 2014;Elmehdi et al, 2013;Hatcher et al, 2014;Mehta et al, 2009;Salimi Khorshidi, 2016).…”