1. Department of Microbial, Biochemical and Food Biotechnology; University of the Free State; Bloemfontein; 9300; South Africa
2. Centre for Microscopy; University of the Free State; Bloemfontein; 9300; South Africa
3. Department of Physics; University of the Free State; Bloemfontein; 9300; South Africa
4. SAB Ltd Brewing Centre of Excellence; PO Box 123902; Alrode; 1451; South Africa