Volume 17 Part 1 Article 32: Quality Evaluation of Gamma-Irradiated Cereal Grains for Spawn Production

Volume 17 Part 1 Article 32
Year 2008
Title: Quality Evaluation of Gamma-Irradiated Cereal Grains for Spawn Production
Authors: H.S. Shekhar Sharma, B. Cunha, M. Kilpatrick, G. Lyons, H. Wichers and J. Hoozee


The cereal grains used in the production of spawn for Agaricus bisporus and other mushroom species are millet, rye and wheat. The aim of this study was to develop an alternative substrate sterilisation protocol to minimise energy cost by irradiating grains instead of autoclaving. The treated grains were also analysed for compositional differences, such as carbon, lipid, starch, ash and minerals. All samples were scanned for visible and near infrared spectra (Vis-NIR) and regressed against treatment dose and autoclaving time. Score plots of Vis-NIR spectra of the samples showing clustering of treated samples were presented along with significant relationships between spectra and measured parameters. Thermal analysis of the grains was also carried out to evaluate compositional changes caused by the treatments. Both of these techniques could be useful for assessing spawn substrate quality. The chemical and physical analyses of grains indicated that irradiating rye, wheat and millet grains had no significant effects on their chemical composition or physical appearance compared to unirradiated samples. In contrast, conventional treatments, including boiling and autoclaving, did cause significant changes in the chemical composition and physical appearance of all three substrates when compared with untreated samples. A cropping trial of test spawns using two Agaricus strains, Sylvan (A15) and Fungisem (F9-18), prepared using irradiated and autoclaved rye grains was carried out. The comparative trial showed that yield differences between the two strains were not significant.

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