Rapid analysis of wheat gluten composition using a triple ELISA.

BACKGROUND: Gluten composition is an important quality parameter of wheat flour. Reversed-phase high-performance liquid chromatography (RP-HPLC) is a state-of-the-art method for its analysis. As this is a very labour-intensive and time-consuming procedure, alternative faster methods are desirable. Enzyme-linked immunosorbent assay (ELISA) is a high-throughput method often used for the analysis of gluten traces in gluten-free products. In this proof-of-principle study, we introduce an experimental triple ELISA for the relative quantitation of gliadins, high-molecular-weight glutenin subunits (HMW-GS) and low-molecular-weight glutenin subunits (LMW-GS) of one wheat flour extract. RESULTS: The results of 80 common wheat flour samples obtained from the triple ELISA and RP-HPLC were correlated. The results for gliadins (r = 0.69) and HMW-GS (r = 0.81) showed a medium and high correlation, respectively. Only a very weak correlation of ELISA and RP-HPLC results was observed for LMW-GS (r = 0.49). Results for glutenins (r = 0.69) and gluten (r = 0.72) had a medium correlation. The gliadin/glutenin ratio (r = 0.47) and LMW-GS/HMW-GS ratio (r = 0.40) showed a weak or no correlation. The gliadin, LMW-GS and gluten contents were lower and the HMW-GS content was higher in the ELISA measurement compared to RP-HPLC. CONCLUSION: The quantitation of gliadins and HMW-GS by the experimental triple ELISA showed comparable results to RP-HPLC, whereas no strong correlation between the results from the two methods was found for LMW-GS. Overall, the experimental triple ELISA is suitable for relative gluten quantitation, especially for the analysis of large sample sets. Further work will focus on improving the experimental procedure of the ELISA. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Prediction of wheat gluten composition via near-infrared spectroscopy.

Gluten composition is an important quality parameter for wheat flour, because it is strongly correlated to baking quality. Wheat proteins are commonly extracted stepwise and analysed using RP-HPLC-UV to determine the gluten composition. This procedure is very time-consuming and labour-intensive. Therefore, a new, fast and easy method to quantitate gluten proteins was established using NIR spectroscopy (NIRS). PLS-regression models were calculated containing 207 samples for calibration and 169 for test set validation. Albumin/globulin (ALGL), gluten, gliadin and glutenin content was predicted with a root mean square error of prediction (RMSEP) of 2.01 mg/g, 6.09 mg/g, 4.25 mg/g and 3.50 mg/g, respectively. High-molecular-weight glutenin subunits (HMW-GS) and low-molecular-weight glutenin subunits (LMW-GS) were predicted with a RMSEP of 1.12 mg/g and 2.38 mg/g. The relative error was too high for ALGL, LMW-GS and HMW-GS, but that of gluten, gliadins and glutenins was in a range comparable to the reference method. Therefore, the new NIRS method can be used to estimate the gluten composition of wheat flour, including the gliadin/glutenin and the LMW-GS/HMW-GS ratio.