As the number falls, alternatives to the Hagberg–Perten falling number method: A review

Abstract

This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end‐product quality mainly due to starch degradation by the enzyme α‐amylase. By viscometry, the FN test indirectly detects the presence of α‐amylase, the primary enzyme that digests starch. Elevated α‐amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α‐amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α‐amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract‐specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α‐amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high‐ and low‐FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near‐infrared spectroscopy, and hyperspectral imaging.

Incorporation of Buckwheat Flour at Different Particle Sizes and Distinctive Doses in Wheat Flour to Manufacture an Improved Wheat Bread

“…The α-amylase activity was assessed with a Falling Number equipment (FN 1305, Perten Instruments AB, Stockholm, Sweden), and the test also provided valuable information about starch grain quality [ 40 ].…”

Finding the LMA needle in the wheat proteome haystack

“…Wheat marketing for milling grades dictates that below a certain FN value, grains are no longer suitable for human diet and must then be discounted causing significant financial losses to the suppliers (17). FN assesses starch degradation resulting from LMA activity which can be assayed in flour samples using the Ceralpha method (37) for instance.…”

“…It is made available under a preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in The copyright holder for this this version posted January 23, 2023. ; https://doi.org/10.1101/2023.01. 22.525108 doi: bioRxiv preprint OFFICIAL OFFICIAL of profit (17). The low FN values manifests as a loss of viscosity upon mixing starch-degraded flour with water can alter appearance and texture of end-products (18), however, it might not deteriorate baking functionality (19) and could be used instead in alternate preparations (20).…”

“…Intact starch polymers provide the gelatinization and retrogradation needed for an acceptable product. Failure to meet receival standards for milling grades due to starch degradation measured in the wheat industry using the Hagberg–Perten falling number (FN) method (16) leads to grain discount and downgrading to animal feed, which incurs a loss of profit (17). The low FN values manifests as a loss of viscosity upon mixing starch-degraded flour with water can alter appearance and texture of end-products (18), however, it might not deteriorate baking functionality (19) and could be used instead in alternate preparations (20).…”

Streamlined alpha‐amylase assays for wheat preharvest sprouting and late maturity alpha‐amylase detection

“…Higher‐throughput α‐amylase enzyme assays are an important selection tool for lowering mature‐grain enzyme activity in wheat ( Triticum aestivum L.)‐breeding programs (Brown et al., 2018; Derkx & Mares, 2020; Henry, 1989; Liu et al., 2021b). The wheat industry detects elevated α‐amylase in wheat meal or flour using the Hagberg–Perten falling number (FN) method in which a lower FN, measured in seconds, is associated with higher α‐amylase activity (Hu et al., 2022; Perten, 1964; Ross & Bettge, 2009). The FN method detects α‐amylase in wheat meal or flour based on reduced viscosity resulting from loss of pasting capacity with enzyme digestion of starch.…”