Fermentation efficiency of cells immobilized on delignified brewers' spent grains after low- and high-temperature thin layer thermal drying.
Low-cost dried yeasts immobilized on delignified brewers' spent grains for use in wine making and brewing were produced by simple thermal drying techniques. To optimize the thermal drying process, vacuum and air stream conditions were examined. Drying of thin layers of the biocatalysts was performed at low (30-38 degrees C) and high temperatures (40-70 degrees C). The fermentation efficiency of the thermally dried biocatalysts was acceptable, with immobilized cells showing a significantly higher thermotolerance compared with free cells. Immobilized cells dried at high temperatures presented slightly improved glucose fermentation efficiency compared with the low-temperature dried biocatalysts. Gas chromatography-mass spectrometry analysis of aroma volatiles of the fermented products revealed an increase of esters, lower higher alcohol formation, and significantly lower concentration of carbonylic compounds.
Tsaousi
Konstantina
K
Food Biotechnology Group, Department of Chemistry, University of Patras, Patras 26500, Greece.
Koutinas
Athanasios A
AA
Bekatorou
Argyro
A
Loukatos
Paul
P
D055162:Biocatalysis; D018914:Cells, Immobilized; D002855:Chromatography, Thin Layer / Q000379:methods*; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D008855:Microscopy, Electron, Scanning; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D013696:Temperature; D015002:Yeast, Dried / Q000378:metabolism*