Developing an NIRS method for assessing black point in single kernels of malting barley

Malt and Grains Session
Glen Fox, The University of Queensland, Toowoomba, Queensland, Australia
Co-author(s): Loraine Watson, University of Queensland, Toowoomba, Australia; Alison Kelly, DEEDI, Toowoomba, Australia; Cheng Dao Li, DAFWA, Perth, Australia; Wendy Lawson, DEEDI, Warwick, Australia

ABSTRACT: Malting barley grain buyers purchase grain that meets a number of physical and chemical specifications, such as grain size and protein content, respectively. These traits are measured using objective testing. However, there are grain traits that are measured using subjective (visual) assessment. Black point (BP), also called black tip or germ-end staining, is one of these subjective traits. BP is a brown/black discoloration over the germ (embryo) of the grain. In Australia, less then 5% of any malting barley load can have BP to reach domestic malting specifications. For some export markets, 0% is the standard. Historically, BP has been associated with fungal infection and in some cases with unusual environmental conditions. Even a slight level of BP is viewed as a defect in malting barley. In our study, we have used near infrared spectroscopy (NIRS) to ascertain key wavelengths to assess BP with a view to develop an objective single kernel assessment system. Single kernels plus and minus BP, as well as individual husks removed from BP plus and minus kernels, were scanned using a Foss NIRSystems 6500 (400–2,498 nm) at 2 nm increment (WinISI V1.5). The spectral data showed significant changes in wavelengths around 1,868–1,888 nm that are associated with C=O and NH bonds. These chemicals bonds are associated with fiber (cellulose and lignin) and protein in the single kernels and single husk scans. There was an increase in other chemical regions in the BP plus single kernels, for example proteins, which would be associated with biological activity of the germ producing a chemical response to the induced stress (fungal attack or physiological stress). The results showed the potential to use NIRS technology to assess for BP in single kernels. However, at this stage there is one major issue to overcome and that is the orientation of the kernel as it is seen by the NIR instrument. The instrument must see the germ to be able to collect spectra associated with BP. While this issue presents a challenge in engineering, the opportunity to assess single kernels that could be segregated from a bulk sample would improve the subjective assessment and provide samples to understand the effect of BP on quality post-harvest, in storage, and on malting and brewing quality.

Glen Fox joined the University of Queensland, Queensland Alliance for Agriculture and Food Innovation, in 2010 after 25 years of conducting research projects with the Queensland government. His areas of research are in cereal quality, specifically barley, wheat, sorghum, and maize. He has a vast amount of knowledge in value-added cereals, in particular barley, malt, and beer quality. He has been a project leader in numerous national grains projects for barley. His main research area has been near-infrared spectroscopy (NIRS), with calibration development in cereals (wheat, barley, triticale, sorghum, and maize), peanuts, soybeans, and animal feed. Currently, Glen is researching use of NIRS on single kernels of grain, as well as hyperspectral imaging of single kernels. He has more than 150 publications, including book chapters, journal articles, and conference papers. He has also supervised many post-graduate students in Australia and overseas. Glen is on a number of technical committees, including the Institute of Brewing & Distilling Asia-Pacific Analytical Methods sub-committee and has been on a number of specific sub-committees for the American Society of Brewing Chemists. In 2011, he was made an adjunct associate professor at Stellenbosch University in South Africa for his contribution to the science of NIRS in cereal and grains.