INVESTIGADORES
BRECCIA Javier Dario
congresos y reuniones científicas
Título:
Plant-based foods: how can enzymes improve their aroma and flavor?
Autor/es:
BRECCIA JD
Reunión:
Conferencia; VII Congreso Internacional de Ciencia y Tecnología de los Alimentos; 2018
Resumen:
Monoterpene alcohols (MTAs) are characteristic flavour-imparting compoundsin plant based products that are liberated following hydrolysis by specificenzymes during manufacturing. Fermented products likely rice, sweet potato,barley or other starchy materials have unique tastes and distinct flavours, whichare in part attributed to MTAs such as geraniol, nerol, linalool, terpineol andcitronellol. These compounds are believed to exist as monoglycosidicprecursors that are liberated from the glucose moiety by β-glucosidaseenzymes (EC 3.2.1.21). However, increasing β-glucosidase activity had nodirect effect on enhancing the concentration of MTAs. By contrast, recentstudies on plant aroma formation suggest various aroma compounds arepresent as diglycosides such as primeverosides (6-O-β-D-xylopyranosyl-β-Dglucopyranoside), acuminosides (6-O-β-D-apiofuranosyl-β-D-glucopyranoside)and vicianosides (6-O-α-L-arabinopyranosyl-β-D-glucopyranoside) andrutinosides (6-O-α-L-rhamnopyranosyl-β-D-glucopyranoside). It is thereforeplausible that a large amount of MTAs are stored predominantly in the form ofdiglycosides and characteristic volatile compounds could effectively be releasedby diglycoside-specific enzymes. For such metabolites, deglycosylation is thefirst catabolic step followed by the oxidation of the terpenic structure and thedeglycosylation in a single reaction is catalyzed by diglycosidases, enzymesthat release the aglycone and the disaccharide. We explored the orderHypocreales (genera Acremonium and Sarocladium) for fungal diglycosidasesusing rutinosylated flavonoids as carbon sources (rutin, diosmin andhesperidin). Just seven strains were identified as diglycosidases producers, thestrains S. strictum DMic 093557 and Acremonium sp. DSM 24697 wereselected for their higher rate of rutin degradation (quercetin-3-O- (6-O-α-Lrhamnopyranosyl-β-D-glucopyranoside). Since Acremonium sp. DSM 24697was previously isolated in our laboratory as a producer of a specificdiglycosidase (α-rhamnosyl-β-glucosidase I) for 7-O-rutinosides, unable tohydrolyze the 3-O-rutinosylated flavonoids. When growing on rutin as solecarbon source, this organism produced α-rhamnosyl-β-glucosidase II (αRβG II)that deglycosylated rutin. The biocatalyst, αRβG II, showed higher promiscuityin comparison to the diglycosidases reported. It was able to hydrolyze 3-Orutinosides,7-O-rutinosides and with lower specificity also hydrolyzed 7-Oneohesperidosides,xylan and laminarin. The αRβG II gene was identified in thegenome of Acremonium sp. DSM 24697 (functionally expressed in Pichiapastoris) and classified as glycoside hydrolases family 3 (GH3), unlike theknown diglycosidases belonging to GH1 and GH5. It is the first GH3 endoVIICongreso Internacional de Ciencia y Tecnología de Alimentos, Córdoba, Argentinaacting enzyme and in agreement with the retaining mechanism of family GH3,αRβG II was able to transglycosylated primary, secondary and phenolicalcohols. the high promiscuity of this enzyme suggest that it might be useful forcontrolling aroma formation during plant-based foods manufacturing, and mayultimately contribute to diversifying their quality.