Solvent Retention Capacity and Gluten Protein Composition of Durum Wheat Flour as Influenced by Drought and Heat Stress

Drought and temperature stress can cause considerable gluten protein accumulation changes during grain-filling, resulting in variations in wheat quality. The contribution of functional polymeric components of flour to its overall functionality and quality can be measured using solvent retention capacity (SRC). The aim of this study was to determine the effect of moderate and severe drought and heat stress on SRC and swelling index of glutenin (SIG) in six durum wheat cultivars with the same glutenin subunit composition and its relation with gluten protein fractions from size exclusion high performance liquid chromatography. Distilled water, sodium carbonate and sucrose SRC reacted similarly to stress conditions, with moderate heat causing the lowest values. Lactic acid SRC and SIG reacted similarly, where severe heat stress highly significantly increased the values. SIG was significantly correlated with sodium dodecyl sulphate sedimentation (SDSS) and flour protein content (FPC) under all conditions. Lactic acid SRC was highly correlated with FPC under optimal and moderate heat stress and with SDSS under moderate drought and severe heat. SIG was negatively correlated with low molecular weight glutenins under optimal and drought conditions, and combined for all treatments. The relationship between SRC and gluten proteins was inconsistent under different stress conditions.

Zastosowanie metody SRC (Solvent Retention Capacity) do określania przydatności technologicznej mąki pszennej

Celem opracowania było przedstawienie syntetycznej wiedzy o metodzie SRC (ang. Solvent Retention Capacity), z uwzględnianiem jej historii, dostępnych wariantów aparaturowych, zasad postępowania podczas wykonania oznaczenia oraz kierunków zastosowania. Metoda SRC została opracowana w połowie XX w. do oceny jakości mąki z pszenicy miękkiej (ang. soft wheat) pochodzącej z Ameryki Północnej. W publikacjach z XXI w. przedstawiono dane wskazujące na przydatność i szeroki zakres stosowania metody SRC także do oceny jakości mąki z klasycznej europejskiej pszenicy zwyczajnej (Triticum aestivum) oraz z mąk uzyskanych z innych zbóż, jak: jęczmień, owies, pszenżyto i żyto. Metoda SRC jest testem solwatacyjnym bazującym na ocenie zdolności pęcznienia składników mąki w środowisku wybranych roztworów. Zastosowanie w omawianej metodzie nie jednego, lecz trzech roztworów (rozcieńczonego wodnego roztworu węglanu sodu, stężonego wodnego roztworu sacharozy i rozcieńczonego wodnego roztworu kwasu mlekowego) oraz wody jest kluczowe dla oceny możliwości zastosowania mąki w poszczególnych procesach technologicznych. Wykorzystanie powinowactwa tych roztworów do głównych funkcjonalnych polimerów mąki pszennej, jakim są białka glutenowe, skrobia uszkodzona oraz pentozany, pozwala na określnie ich wpływu na właściwości mąki oraz na jakość produktów końcowych w technologii piekarskiej i ciastkarskiej. Metoda SRC umożliwia ocenę właściwości mąki, dokonanie doboru odmian czy metod uprawy, co ma istotne znaczenie w młynarstwie oraz w zakładach produkcyjnych, w których mąka pszenna jest podstawowym surowcem.

Influence of Wheat Flour Milling Yield on Physicochemical, Microbial, and Antioxidant Properties of Korea Wheat (Triticum aestivum L. var. Jokyoung)

The physicochemical, microbial, and antioxidant properties of a Korean wheat variety (Jokyoung) were measured according to milling yield (60–90%) by adding fractions from millstreams. As the milling yield increased, the wheat flour showed low quality on physicochemical properties in general. Significant differences in proximate analysis, color, solvent retention capacity, pasting property, and antioxidant activity were observed as the yield increased to maximize the production of wheat flour from wheat kernels. Adding clear flour and shorts did not significantly affect the quality of the wheat flour in comparison with straight flour samples. However, as brans were added to the flour portion, the wheat flour quality parameters decreased significantly in color, solvent retention capacity, and pasting properties. On the other hand, antioxidant properties increased as brans were added. Maximizing wheat flour yield is a key to minimizing the production cost of Korean wheat flour, which is approximately three times more expensive than imported wheat flour. Adding clear flour and a certain portion of shorts did not seem to significantly influence the overall quality of wheat flour from Korean domestic wheat variety.

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.)

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.