Enzymatic removal of off-flavors from apple juice.
Contaminating microorganisms such as Actinomycetes, Alicyclobacillus, and Chlostridium can generate off-flavors in apple juices. Such bacterial metabolites represent, besides phenol types such as guaiacol and 2,6-dibromophenol, a broad range of other chemicals, for example, geosmin, 2-methylisoborneol, or alpha-terpineol. A laccase from Trametes hirsuta was purified, immobilized, and applied for the selective elimination of off-flavor substances in apple juice caused by microbial contamination. The evaluation using GC-MS showed that enzymatic treatment could reduce the amount of guaiacol and 2,6-dibromophenol in apple juice significantly by 99 and 52%, respectively. Upon addition of mediators, the degradation could be increased and the spectrum of substrates extented. Furthermore, commercial apple juices spiked with off-flavors were treated in a continuous-flow reactor and tested by sensory evaluation.
Schroeder
M
M
Department of Environmental Biotechnology, Graz University of Technology, Graz, Austria.
Pöllinger-Zierler
B
B
Aichernig
N
N
Siegmund
B
B
Guebitz
G M
GM
D001628:Beverages / Q000032:analysis*; D004800:Enzymes, Immobilized; D005511:Food Handling / Q000379:methods*; D005638:Fruit / Q000737:chemistry* / Q000382:microbiology; D008401:Gas Chromatography-Mass Spectrometry; D006139:Guaiacol / Q000032:analysis; D006801:Humans; D042845:Laccase; D027845:Malus / Q000737:chemistry*; D010636:Phenols / Q000032:analysis; D012677:Sensation; D013649:Taste
D004800:Enzymes, Immobilized; D010636:Phenols; C038964:2,6-dibromophenol; D006139:Guaiacol; D042845:Laccase