Falling number of soft white wheat by near‐infrared spectroscopy: A challenge revisited

Abstract

Funding information USDA-ARS; Washington Grain CommissionBackground and objectives: Wheat Hagberg falling number (FN) is a longstanding quality test that, by means of measuring the viscosity of a heated watermeal or water-flour mixture, characterizes the activity of endogenous a-amylase, the enzyme primarily responsible for starch hydrolysis. The accuracy, time requirement, and cost of this test have come under heightened scrutiny, particularly in seasons when weather conditions have been favorable to preharvest sprouting or late maturity amylase. Near-infrared (NIR) spectroscopy, an analytical approach routinely used in the grain industry to measure contents of protein and moisture, was reexamined as a possible alternative to the FN procedure. Findings: Partial least squares (PLS) regression quantitative models developed on a genetically diverse set of Washington grown white wheat demonstrated low accuracy, with standard errors of performance ranging from 40 to 77 s. Alternatively, linear discriminant analysis and PLS discriminant analysis (PLSDA) qualitative models, developed and tested using a FN cutoff (pass/fail) value, also demonstrated low accuracy, with the best model correctly identifying 67% and 71% of the samples, respectively, above and below a threshold value established as the median value of FN in a calibration set of several hundred samples. Conclusions: Replacement of the FN test with one based on NIR spectroscopy on either whole grain or ground meal for making decisions on segregating wheat lots according to a-amylase activity is not recommended. Significance and novelty: Because NIR spectroscopy is not sufficiently accurate to quantitatively model FN or differentiate low from high FN grain, viscometry procedures for starch integrity, such as FN, will continue their use in grain commerce. K E Y W O R D Sfalling number, near-infrared spectroscopy, wheat

Impact of Cultivar and Growing Conditions on Alpha‐Amylase Properties in Wheat

“…[ 10,43 ] It has been reported that precipitation reduces the grain drying rate, [ 44 ] upon water absorption by the grain endosperm. [ 40 ] In addition, it stimulates the production of the plant hormones associated with the germination (i.e., gibberellic acid), [ 45 ] which then promotes the activity of α‐amylase. [ 4 ] However, the data presented showed that the increase in enzyme activity of grain exposed to rain was not accompanied by any visible sprouting symptoms in both cultivars.…”

“…[48] Such conditions may favor the harvest of mature grains before the induction of -amylase by precipitation at harvest time. [45] Another possible explanation is that a temperature of 15°C lead to delay in wheat germination compared to 20°C, [49] since the germination inhibitor (e.g., abscisic acid) is maintained in the embryo. [19] The chemical components of wheat grains were influenced by cultivar and site at most grain development stages (Tables 2 and 3 and Figure 3).…”

Quantitative assessment of wheat quality using near‐infrared spectroscopy: A comprehensive review

“…Based on the PLSR models, the kernel format had better performance (𝑅 2 C = .708), which was still poor in accuracy. When the two formats were combined into a larger dataset, the model performance became worse (Delwiche et al, 2018). The only acceptable result was achieved by Sujka et al (2017) using MIRS, where the 𝑅 2 P was .95 as predicted by the PLSR model based on specific spectral ranges.…”

The Ability of Near Infrared (NIR) Spectroscopy to Predict Functional Properties in Foods: Challenges and Opportunities

“…Recent reviews and reports have also highlighted the ability of NIR spectroscopy to predict different parameters associated with starch physicochemical characteristics, most of them associated with functional properties in cereals and other starchy foods [36][37][38][39].…”