The Use of UV-mutagenesis in wine yeasts to improve the quality of wine

Kakovost vina je poleg ampelografskih posegov in klimatskih razmer v vinogradu odvisna tudi od uporabljenih starterskih kultur kvasovk, ki ob vzpostavitvi optimalnih fermentacijskih pogojev zagotavljajo voden potek alkoholne fermentacije. V okviru izboljšave fermentacijskih, tehnoloških, aromatičnih in metabolnih lastnosti izbranih sevov kvasovk smo uporabili UV-mutagenezo, s katero smo ugotovili, da podaljšana izpostavitev kvasovk UV-sevanju negativno vpliva na živost celic kvasovk, vpliv UV-sevanja pa se odrazi na spremenjenih makromorfoloških lastnostih kolonij kvasovk mutant. Te so nepravilnih oblik z nazobčanim robom ter svetlejše in bolj prozorne barve v primerjavi z neobsevanimi kvasovkami. Fermentacijska kinetika kvasovk mutant se v splošnem ne razlikuje od kontrolnih sevov, so pa posebej razvidne razlike pri analizah fizikalno-kemijskih lastnosti pridelanih vin, predvsem pri tvorbi hlapnih kislin in vsebnosti reducirajočih sladkorjev. Rezultati parametrov kakovosti vina kažejo statistično značilen vpliv časa izpostavitve kvasovk UV-sevanju in uporabljenih sevov kvasovk. Skalarno povečevanje količine uporabljenega mošta in bolj osmofilni pogoji fermentacije pa so prispevali k razvoju negativnih arom vina, zlasti v tretjem fermentacijskem poskusu, kjer smo v mošt sorte malvazija inokulirali 30 sekund obsevano mutanto seva LALVIN EC1118.In addition to ampelographic interventions and climatic conditions in the vineyard, the quality of the wine depends on the yeast starter cultures used, which provide guided alcoholic fermentation. In the framework of the improvement of fermentative, technological, aromatic and metabolic properties of selected yeast strains, UV-mutagenesis was used. We determined that prolonged yeast exposure to UV-radiation has a negative effect on the cell viability, and that the effect of UV-radiation is reflected in changed macromorphological properties of yeast colonies such as in irregular shapes with a jagged edge and in brighter and more transparent color. Compared to the non treated yeasts the fermentation kinetics of the yeast mutant generally do not differ from the control strains, but the differences in the analysis of the physicochemical properties of the produced wines are evident, especially in the production of volatile acids, glycerol concentration and in the content of reducing sugars. The results of wine quality parameters show a statistically significant influence of exposure of yeasts to UV-radiation and the yeast strains used. The scalar increase of grape must volume and the more osmotic fermentation conditions contributed to the development of negative wine aromas, especially in the third fermentation experiment where we used 30 seconds irradiated mutant of the strain LALVIN EC1118 in the grape must of the Malvasia variety

Grape lipidomics: an extensive profiling thorough UHPLC–MS/MS method

8openInternationalItalian coauthor/editorLipids play many essential roles in living organisms, which accounts for the great diversity of these amphiphilic molecules within the individual lipid classes, while their composition depends on intrinsic and extrinsic factors. Recent developments in mass spectrometric methods have significantly contributed to the widespread application of the liquid chromatography-mass spectrometry (LC–MS) approach to the analysis of plant lipids. However, only a few investigators have studied the extensive composition of grape lipids. The present work describes the development of an ultrahigh performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) method that includes 8098 MRM; the method has been validated using a reference sample of grapes at maturity with a successful analysis and semi-quantification of 412 compounds. The aforementioned method was subsequently applied also to the analysis of the lipid profile variation during the Ribolla Gialla cv. grape maturation process. The partial least squares (PLS) regression model fitted to our experimental data showed that a higher proportion of certain glycerophospholipids (i.e., glycerophosphoethanolamines, PE and glycerophosphoglycerols, PG) and of some hydrolysates from those groups (i.e., lyso-glycerophosphocholines, LPC and lyso-glycerophosphoethanolamines, LPE) can be positively associated with the increasing °Brix rate, while a negative association was found for ceramides (CER) and galactolipids digalactosyldiacylglycerols (DGDG). The validated method has proven to be robust and informative for profiling grape lipids, with the possibility of application to other studies and matrices.openMasuero, Domenico; Škrab, Domen; Chitarrini, Giulia; Garcia-Aloy, Mar; Franceschi, Pietro; Sivilotti, Paolo; Guella, Graziano; Vrhovsek, UrskaMasuero, D.; Škrab, D.; Chitarrini, G.; Garcia-Aloy, M.; Franceschi, P.; Sivilotti, P.; Guella, G.; Vrhovsek, U

Mono-locus and pyramided resistant grapevine cultivars reveal early putative biomarkers upon artificial inoculation with Plasmopara viticola

10openInternationalBothOne of the most economically important grapevine diseases is Downy mildew (DM) caused by the oomycete Plasmopara viticola. A strategy to reduce the use of fungicides to compensate for the high susceptibility of V. vinifera is the selection of grapevine varieties showing pathogen-specific resistance. We applied a metabolomics approach to evaluate the metabolic modulation in mono-locus resistant genotypes carrying one locus associated with P. viticola resistance (Rpv) (BC4- Rpv1, Bianca- Rpv3-1, F12P160- Rpv12, Solaris- Rpv10), as well as in pyramided resistant genotypes carrying more than one Rpv (F12P60- Rpv3-1; Rpv12 and F12P127- Rpv3-1, Rpv3-3; Rpv10) taking as a reference the susceptible genotype Pinot Noir. In order to understand if different sources of resistance are associated with different degrees of resistance and, implicitly, with different responses to the pathogen, we considered the most important classes of plant metabolite primary compounds, lipids, phenols and volatile organic compounds at 0, 12, 48, and 96 h post-artificial inoculation (hpi). We identified 264 modulated compounds; among these, 22 metabolites were found accumulated in significant quantities in the resistant cultivars compared to Pinot Noir. In mono-locus genotypes, the highest modulation of the metabolites was noticed at 48 and 96 hpi, except for Solaris, that showed a behavior similar to the pyramided genotypes in which the changes started to occur as early as 12 hpi. Bianca, Solaris and F12P60 showed the highest number of interesting compounds accumulated after the artificial infection and with a putative effect against the pathogen. In contrast, Pinot Noir showed a less effective defense response in containing DM growth.openCiubotaru, R.M.; Franceschi, P.; Zulini, L.; Stefanini, M.; Skrab, D.; Rossarolla, M.D.; Robatscher, P.; Oberhuber, M.; Vrhovsek, U.; Chitarrini, G.Ciubotaru, R.M.; Franceschi, P.; Zulini, L.; Stefanini, M.; Skrab, D.; Rossarolla, M.D.; Robatscher, P.; Oberhuber, M.; Vrhovsek, U.; Chitarrini, G