Late-maturity α-amylase (LMA) testing and its methodological challenges

Wheats affected by late-maturity α-amylase (LMA) contain abnormal amounts of α-amylase with a high isoelectric point (pI), causing their flours to have low falling number (FN), a standard industry test. LMA-affected wheats are often rejected at grain receival points, as low FN is perceived as sign of poor quality. To improve LMA detection and increase screening throughput, an LMA-ELISA has been developed. The present study evaluated the analytical performance of LMA-ELISA and confirmed the correlation between LMA content and enzymatic activity. The LMA-ELISA test demonstrated good discrimination and high precision for intra- and inter-assay measurements. However, results were not reproducible when using three different LMA-ELISA batches acquired in two consecutive years, indicating that LMA-ELISA suffered from batch-to-batch variation. Consistent with previous studies, LMA-ELISA was highly correlated to total α-amylase activity (R = 0.95). LMA-affected flours also had enzymatic activity similar to enzyme-supplemented flours that have been shown to produce some end-products such as bread and noodles that are of satisfactory quality. These results highlight the need to address LMA-ELISA batch-to-batch variation. • Late-maturity amylase can arise in wheat from excess moisture. • If detected, market value of wheat is downgraded. • However LMA-ELISA test for this is not reproducible. • Shows need to reconsider ELISA test methodology. • The present test may be downgrading some wheat unnecessarily.