Microbiological activity in stored olive oil.
The disappearance of the bitter taste of newly produced olive oil during storage is due to the enzymatic hydrolysis of the bitter-tasting secoiridoid compound known as oleuropein. Current knowledge attributes the enzymatic hydrolysis of the oleuropein to the beta-glucosidase present in the olives. The present study, however, has demonstrated for the first time that oleuropein present in olive oil can be hydrolysed by beta-glucosidase from the yeasts Saccharomyces cerevisiae and Candida wickerhamii. The enzymatic analyses carried out directly on the untreated olive oil and on sterilized olive oil inoculated with the above-mentioned yeasts proved the beta-glucosidase activity through the hydrolysis of both the synthetic substrate p-nitrophenyl-beta-D-glucopyranoside (PNPG) and the oleuropein. The absence of lipases in the isolated S. cerevisiae and C. wickerhamii examined lead us to believe that the yeasts contribute in a positive way towards the improvement of the organological quality of the oil without altering the composition of the triglycerides.
Ciafardini
G
G
Department of Animal, Plant, and Environmental Sciences, Agriculture Faculty, University of Molise, Campobasso, Italy. ciafardi@unimol.it
Zullo
B A
BA
D002175:Candida / Q000201:enzymology*; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D006868:Hydrolysis; D057888:Iridoid Glucosides; D039823:Iridoids; D000069463:Olive Oil; D010938:Plant Oils / Q000378:metabolism; D011714:Pyrans / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013649:Taste; D013997:Time Factors; D001617:beta-Glucosidase / Q000378:metabolism*
D057888:Iridoid Glucosides; D039823:Iridoids; D000069463:Olive Oil; D010938:Plant Oils; D011714:Pyrans; C002769:oleuropein; D001617:beta-Glucosidase