The effect of malting on the crystallites and microstructure in Greek barley cultivar using x-ray diffraction and microscopic analysis

  • Adriana Skendi Alexander Technological Educational Institute of Thessaloniki (ATEITh), Greece http://orcid.org/0000-0002-7995-4741
  • Maria Papageorgiou Alexander Technological Educational Institute of Thessaloniki (ATEITh), Greece
  • Efthimios Papastergiadis Alexander Technological Educational Institute of Thessaloniki (ATEITh), Greece
Keywords: barley, starch, malting, XRD, microscopy

Abstract

Introduction: Malting was generally used to produce fermentable sugars from starch in order to permit alcoholic fermentation. Variation in the starch microstructure and crystallinity affects its water solubilisation as well as and its breakdown from the enzymes

Objectives: The starch microstructure is explored in order to understand and possibly modify the malting process of a Greek barley variety if needed. To address the issue, a combination of microscopy and X-ray diffraction inspection methods were used to evaluate the variation of the starch granule morphology and the degree of crystallinity of starch.

Methods: The effect of malting on the microstructure of barley starch was investigated for one Greek barley cultivar (Seirios). The barley seeds were provided from ELGO-DEMETER, Institute of Plant Breeding and Genetic Resources (Thessaloniki, Greece). The steeping was performed at 14°C (several soaking and aerating circles) until barley reached the desired moisture content. Then the steeped barley was allowed to germinate at 15°C. The germination was stopped by drying at 40-45°C for at least 20h (dry malt). The malt was obtained by kilning for 6 hours at 100°C. The barley, dry malt and malt were milled to pass through a 0.8mm screen before being analysed. Light microscopy photographs with Congo red staining were used to identify variation in the starch granule morphology. Moreover, the x-ray diffraction analysis of the barley meal, dry malt and malt millings were obtained. Finally, the analysis of X-ray diffractograms was performed in order to calculate relative crystallinity and the crystallite size of the starch.

Results: The results demonstrated variations in the morphology of the starch granules. The stained light microscopy photographs revealed that the starch granules in barley were round, greater, smooth, and granular, and that of the dry malt and the malt appeared smaller and more elongated with scratches on the surface. The stained confocal microscopy photographs showed the beginning of the starch damage on the surface of the granules. X-Ray diffractographs revealed that the crystallinity of the barley starch was increased during dry malt production and then decreased during kilning but still remained greater than the native barley starch.

Conclusions: Malting under the specified conditions, affected the morphology of the starch granules of Seirios variety as well as the crystallinity of the starch suggesting the partial degradation of the starch during steeping and germination as well as during kilning.

References

Ao, Z., & Jane, J.-l. (2007). Characterization and modeling of the A- and B-granule starches of wheat, triticale, and barley. Carbohydrate Polymers, 67(1), 46-55. https://doi.org/10.1016/j.carbpol.2006.04.013

Bathgate, G. N. (2016). A review of malting and malt processing for whisky distillation. 122(2), 197-211. https://doi.org/10.1002/jib.332

Benmoussa, M., Suhendra, B., Aboubacar, A., & Hamaker, B. R. (2006). Distinctive Sorghum Starch Granule Morphologies Appear to Improve Raw Starch Digestibility. Starch - Stärke, 58(2), 92-99. https://doi.org/10.1002/star.200400344

Brennan, C. S., Amor, M. A., Harris, N., Smith, D., Cantrell, I., Griggs, D., & Shewry, P. R. (1997). Cultivar Differences in Modification Patterns of Protein and Carbohydrate Reserves during Malting of Barley. Journal of Cereal Science, 26(1), 83-93. https://doi.org/10.1006/jcrs.1996.0103

Chmelík, J., Krumlová, A., Budinská, M., Kruml, T., Psota, V., ohac enko, I., . . . ydrov , H. (2001). omparison of i e Characterization of Barley Starch Granules Determined by Electron and Optical Microscopy, Low Angle Laser Light Scattering and Gravitational Field-Flow Fractionation. Journal of the Institute of Brewing, 107(1), 11-17. https://doi.org/10.1002/j.2050-0416.2001.tb00074.x

Chu, S., Hasjim, J., Hickey, L. T., Fox, G., & Gilbert, R. G. (2014). Structural Changes of Starch Molecules in Barley Grains During Germination. 91(5), 431-437. https://doi.org/10.1094/CCHEM-09-13-0174-R

olonna, P., uléon, A., & Lemarié, F. (1988). Action of acillus subtilis α-amylase on native wheat starch. Biotechnology and Bioengineering, 31(9), 895-904. https://doi.org/10.1002/bit.260310902

Dürrenberger, M. B., Handschin, S., Conde-Petit, B., & Escher, F. (2001). Visualization of Food Structure by Confocal Laser Scanning Microscopy (CLSM). LWT - Food Science and Technology, 34(1), 11-17. https://doi.org/10.1006/fstl.2000.0739

Gao, J., Vasanthan, T., & Hoover, R. (2009). Isolation and Characterization of High-Purity Starch Isolates from Regular, Waxy, and High-Amylose Hulless Barley Grains. Cereal Chemistry, 86(2), 157-163. https://doi.org/10.1094/CCHEM-86-2-0157

Gilbertson, J. A. (2018). Amyloid. In K. S. Suvarna, C. Layton, & J. D. Bancroft (Eds.), Bancroft's Theory and Practice of Histological Techniques (8th ed.) (pp. 231-253): Elsevier Limited.

Greenwood, C. T., & Thomson, J. (1959). A comparison of the starches from barley and malted barley. Journal of the Institute of Brewing, 65(4), 346-353. https://doi.org/10.1002/j.2050-0416.1959.tb01470.x

Jaiswal, S., Båga, M., Ahuja, G., Rossnagel, B. G., & Chibbar, R. N. (2014). Development of Barley (Hordeum vulgare L.) Lines with Altered Starch Granule Size Distribution. Journal of Agricultural and Food Chemistry, 62(10), 2289-2296. https://doi.org/10.1021/jf405424x

Källman, A., Vamadevan, V., Bertoft, E., Koch, K., Seetharaman, K., Åman, P., & Andersson, R. (2015). Thermal properties of barley starch and its relation to starch characteristics. International Journal of Biological Macromolecules, 81, 692-700. https://doi.org/10.1016/j.ijbiomac.2015.08.068

Kong, X., Kasapis, S., Zhu, P., Sui, Z., Bao, J., & Corke, H. (2016). Physicochemical and structural characteristics of starches from Chinese hull-less barley cultivars. International Journal of Food Science & Technology, 51(2), 509-518. https://doi.org/10.1111/ijfs.12984

Lamb, J., & Loy, T. (2005). Seeing red: the use of Congo Red dye to identify cooked and damaged starch grains in archaeological residues. Journal of Archaeological Science, 32(10), 1433-1440. https://doi.org/10.1016/j.jas.2005.03.020

Li, W., Xiao, X., Zhang, W., Zheng, J., Luo, Q., Ouyang, S., & Zhang, G. (2014). Compositional, morphological, structural and physicochemical properties of starches from seven naked barley cultivars grown in China. Food Research International, 58, 7-14. https://doi.org/10.1016/j.foodres.2014.01.053

MacGregor, A. W., & Ballance, D. L. (1980). Hydrolysis of large and small starch granules from normal and waxy barley cultivars by alpha-amylases from barley malt. Cereal Chemistry., 57(6), 397-402. Retrieved from: https://www.aaccnet.org/publications/cc/backissues/1980/Pages/Number6.aspx

Naguleswaran, S., Vasanthan, T., Hoover, R., & Bressler, D. (2013). The susceptibility of large and small granules of waxy, normal and high-amylose genotypes of barley and corn starches toward amylolysis at sub-gelatinization temperatures. Food Research International, 51(2), 771-782. https://doi.org/10.1016/j.foodres.2013.01.057

Oates, C. G. (1997). Towards an understanding of starch granule structure and hydrolysis. Trends in Food Science & Technology, 8(11), 375-382. https://doi.org/10.1016/S0924-2244(97)01090-X

Pérez, S., & Bertoft, E. (2010). The molecular structures of starch components and their contribution to the architecture of starch granules: A comprehensive review. Starch - Stärke, 62(8), 389-420. https://doi.org/10.1002/star.201000013

Samim, M., Sandkuijl, D., Tretyakov, I., Cisek, R., & Barzda, V. (2013). Differential Polarization Nonlinear Optical Microscopy with Adaptive Optics Controlled Multiplexed Beams. International Journal of Molecular Sciences, 14(9), 18520. https://doi.org/10.3390/ijms140918520

Singh, V., Ali, S. Z., Somashekar, R., & Mukherjee, P. S. (2006). Nature of Crystallinity in Native and Acid Modified Starches. International Journal of Food Properties, 9(4), 845-854. https://doi.org/10.1002/star.20100001310.1080/10942910600698922

Sujka, M., & Jamroz, J. (2007). Starch granule porosity and its changes by means of amylolysis. International Agrophysics, 21(1), 107-113.

Waduge, R. N., Hoover, R., Vasanthan, T., Gao, J., & Li, J. (2006). Effect of annealing on the structure and physicochemical properties of barley starches of varying amylose content. Food Research International, 39(1), 59-77. https://doi.org/10.1016/j.foodres.2005.05.008

Yangcheng, H., Gong, L., Zhang, Y., & Jane, J.-l. (2016). Pysicochemical properties of Tibetan hull-less barley starch. Carbohydrate Polymers, 137, 525-531. https://doi.org/10.1016/j.carbpol.2015.10.061

Zhu, F. (2017). Barley Starch: Composition, Structure, Properties, and Modifications. Comprehensive Reviews in Food Science and Food Safety, 16(4), 558-579. https://doi.org/10.1111/1541-4337.12265

Published
2018-09-27
Section
Agriculture, Food and Veterinary Sciences