Proso millet (Panicum miliaceum L.): An Evaluation of the Microstructural Changes in the Endosperm during the Malting Process by Using Scanning-Electron and Confocal Laser Microscopy
Martin Zarnkow1,2,4, Alexander Mauch2, Werner Back1, Elke K. Arendt2 and Stefan Kreisz1,3
1 Lehrstuhl für Technologie der Brauerei I, Technische Universität München Weihenstephan, Weihenstephaner Steig 20, 85354 Freising, Germany.
2 Department of Food and Nutritional Sciences, National University of Ireland, University College Cork, College Road, Cork, Ireland.
3 Novozymes A/S, Krogshøjvej 36, Bagsværd, 2880, Denmark.
4 Corresponding author. E-mail: Martin.Zarnkow@wzw.tum.de
J. Inst. Brew. 113(4), 355–364, 2007 | VIEW ARTICLE
ABSTRACT
Scanning electron microscopy (SEM) and confocal scanning laser microscopy (CLSM) were used to investigate the microstructural changes in the endosperm during the malting process. SEM was a suitable tool to characterise the microstructural constitution of starch granules in proso millet and the changes occurring during malting. An early visible degradation (after 24 h) of starch granules located in the floury endosperm, which is close to the embryo, could be observed. Due to this degradation, using confocal scanning laser microscopy, a less dense packaging of this part of the endosperm was observed. Degradation of starch granules in the vitreous endosperm was obvious at a distinct later stage of malting (78 h) and a preferred attack of small granules (<2.5 μm) was detected. Changes in protein structure could not be detected by either SEM or CLSM.
Key words:
Confocal Scanning Laser Microscopy (CSLM), malting, Proso millet (Panicum miliaceum L.), Scanning-Electron Microscopy (SEM).
Publication no. G-2007-0128-524 ©2007 The Institute & Guild of Brewing