title: Evolution of volatile byproducts during wine fermentations using immobilized cells on grape skins.
abstract: A biocatalyst was prepared by immobilization of Saccharomyces cerevisiae cells on grape skins. Repeated batch fermentations were conducted using this biocatalyst as well as free cells, at 25, 20, 15, and 10 degrees C. Solid phase microextraction (SPME) was used in monitoring the evolution of volatile byproducts. The effect of immobilization and temperature on evolution patterns of volatiles was obvious. The major part of esters was formed after consumption of 40-50% of the sugars. Similar processes were observed for amyl alcohols and 2-phenylethanol, whereas 1-propanol and 2-methyl-1-propanol were formed during the whole alcoholic fermentation period at an almost constant formation rate. Acetaldehyde and acetoin were synthesized in the early stages of fermentation. Afterward, their amount decreased. In most cases, immobilized cells exhibited higher formation rates of volatiles than free cells. The final concentration of esters was higher in wines produced by immobilized biocatalyst. Their amount increased with temperature decrease. The opposite was observed for higher alcohols.
authors.affiliation: Food Science and Technology Department, Agricultural University of Athens, Iera Odos 75, Athens, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Mallouchos
authors.forename: Michael
authors.initials: M
authors.lastname: Komaitis
authors.forename: Athanasios
authors.initials: A
authors.lastname: Koutinas
authors.forename: Maria
authors.initials: M
authors.lastname: Kanellaki
mesh_terms: D000079:Acetaldehyde / Q000378:metabolism; D019342:Acetic Acid / Q000378:metabolism; D000093:Acetoin / Q000378:metabolism; D000438:Alcohols / Q000378:metabolism; D005285:Fermentation; D005638:Fruit; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D027843:Vitis; D014835:Volatilization; D014920:Wine / Q000032:analysis*
chemical_list: D000438:Alcohols; D000093:Acetoin; D000079:Acetaldehyde; D019342:Acetic Acid