Effect of Radio Frequency Cold Plasma Treatment on Intermediate Wheatgrass (Thinopyrum intermedium) Flour and Dough Properties in Comparison to Hard and Soft Wheat (Triticum aestivum L.)

Sophie Held,George A Annor,Catrin E Tyl

doi:10.1155/2019/1085172

Abstract

Cold plasma is an emerging technology to improve microbiological safety as well as functionality of foods. This study compared the effect of radio frequency cold plasma on flour and dough properties of three members of the Triticeae tribe, soft as well as hard wheat (Triticum aestivum L.) and intermediate wheatgrass (Thinopyrum intermedium, IWG). These three flour types differ in their protein content and composition and were evaluated for their solubility, solvent retention capacity, starch damage, GlutoPeak and Farinograph profiles, and protein secondary structures. Plasma treatment resulted in dehydration of flours but did not change protein content or solubility. Farinograph water absorption increased for all flours after plasma treatment (from 56.5–61.1 before to 71.0–81.6%) and coincided with higher solvent retention capacity for water and sodium carbonate. Plasma treatment under our conditions was found to cause starch damage to the extent of 3.46–6.62% in all samples, explaining the higher solvent retention capacity for sodium carbonate. However, Farinograph properties were changed differently in each flour type: dough development time and stability time decreased for hard wheat and increased for soft wheat but remained unchanged in intermediate wheatgrass. GlutoPeak parameters were also affected differently: peak torque for intermediate wheatgrass increased from 32 to 39.5 GlutoPeak units but was not different for the other two flours. Soft wheat did not always aggregate after plasma treatment, i.e., did not aggregate within the measurement time. It was also the only flour where protein secondary structures were changed after plasma treatment, exhibiting an increase from 15.2 to 27.9% in β-turns and a decrease from 59.4 to 47.9% in β-sheets. While this could be indicative of a better hydrated gluten network, plasma-treated soft wheat was the only flour where viscoelastic properties were changed and extensibility decreased. Further research is warranted to elucidate molecular changes underlying these effects.

Highlights

Nonthermal plasma o ers a multitude of application options for food scientists
Our results are in contrast to Marti et al [11], who reported that IWG flour had higher solubility in phosphate buffer than hard red wheat, in line with its reported higher contents of albumins and globulins [12]. ese differences may be related to different flour samples used in our studies
Secondary structure, and protein aggregation measurements showed that each flour had a different response to plasma treatment

Summary

Introduction

Nonthermal plasma o ers a multitude of application options for food scientists. Aside from increasing microbiological safety, it may a ect the functionality of food constituents such as starch and proteins [1]. As for the e ect on protein, studies have reported changes in solubility [4, 5], secondary structure distribution, as well as other functional parameters such as emulsi cation properties [1]. Journal of Food Quality a systematic evaluation of the effect of nonthermal plasma on main flour constituents, in dependence of treatment conditions such as carrier gas, is warranted. Misra et al [9] reported that atmospheric pressure cold plasma treatment in the presence of air affected functional and structural parameters of soft and hard wheat flours. Our overall aim for this study was to investigate the effect of radio frequency cold plasma treatment on flour and dough properties and to evaluate how protein properties, in particular gluten network formation in dough, were affected. We evaluated changes in protein characteristics to assess the effect of nonthermal plasma on flour functionality

Materials and Methods

Results and Discussion

Conclusions