Browsing by Author "Bordeu, Edmundo"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Comparative study of wine tannin classification using Fourier transform mid-infrared spectrometry and sensory analysis
    (SOC APPLIED SPECTROSCOPY, 2007) Fernandez, Katherina; Labarca, Ximena; Bordeu, Edmundo; Guesalaga, Andres; Agosin, Eduardo
    Wine tannins are fundamental to the determination of wine quality. However, the chemical and sensorial analysis of these compounds is not straightforward and a simple and rapid technique is necessary. We analyzed the mid-infrared spectra of white, red, and model wines spiked with known amounts of skin or seed tannins, collected using Fourier transform mid-infrared (FT-MIR) transmission spectroscopy (400-4000 cm(-1)). The spectral data were classified according to their tannin source, skin or seed, and tannin concentration by means of discriminant analysis (DA) and soft independent modeling of class analogy (SIMCA) to obtain a probabilistic classification. Wines were also classified sensorially by a trained panel and compared with FT-MIR. SIMCA models gave the most accurate classification (over 97%) and prediction (over 60%) among the wine samples. The prediction was increased (over 73%) using the leave-one-out cross-validation technique. Sensory classification of the wines was less accurate than that obtained with FT-MIR and SINICA. Overall, these results show the potential of FT-MIR spectroscopy, in combination with adequate statistical tools, to discriminate wines with different tannin levels.
  • No Thumbnail Available
    Item
    Influence of grape quality tier, harvest timing, and yeast strain on mannoprotein content, phenolic composition, and color modulation in young red wines
    (Elsevier Ltd, 2025) Galaz Torres, Cristian; Vidal Zuñiga, Josefina Victoria; Vargas, Sebastián; Zincker, Jorge; Brossard, Natalia; Bordeu, Edmundo; Ricci, Arianna; Parpinello, Giuseppina P.; Versari, Andrea
    Besides the impact of harvest timing and grape quality, this study investigated the performance of selected yeast strains overproducing mannoproteins versus the conventional strain AGL 804 in terms of mannoprotein release and its consequences on the composition and color modulation of short-aged commercial red wines. The study fills a gap of volume and actual red wine production by comparing 36 winemaking conditions, each of 850 kg of grapes. The results showed that AGL 804 produced the same or more concentration of mannoproteins than the alternatives. Then, an apparent threshold was found for all yeasts when the dissolved solids content of grape musts at harvest exceeded 22 °Bx, beyond which no increase in mannoprotein production was observed. Only below this limit, an independent effect of yeast strains on tannin concentration and tannin-to-anthocyanin ratio (T/A) in wines was observed. These two parameters exhibited a moderate correlation with mannoprotein concentration (R2 = 0.534 and R2 = 0.696, respectively), and a low-moderate correlation for mannoprotein concentration with CIELAB color parameters. Wines produced from grapes > 22 °Bx showed only harvest-related variations in tannin concentration and T/A and no correlation between parameters analyzed and mannoprotein production. The study revealed that, although yeast strains influence the color of red wine after six months of bottling, their effect is secondary to the harvest timing. Moreover, the influence of the yeast strain itself was not consistent across the different harvest dates. Additionally, the study provides winemakers with an improved and practical assay for measuring mannoprotein levels in red wines, especially for small winery laboratories. It also introduces a novel 3D graphical representation of the CIELAB color parameters, which simultaneously integrates the real visible color of the wines and its visual discriminability to the human eye.
  • Thumbnail Image
    Item
    Influence of mealybug (Pseudococcus spp.)-infested bunches on wine quality in Carmenere and Chardonnay grapes
    (WILEY, 2012) Bordeu, Edmundo; Troncoso, Diego O.; Zaviezo, Tania
    This study evaluated the effects of processing grape with different proportions of mealybug-infested bunches in wine quality in cultivars Chardonnay and Carmenere. No differences in chemical composition of musts were found. Basic chemical composition for white and red wines was similar. In both cultivars total polyphenols decreased as the proportion of infested bunches increased, from 266 to 239 (mg L-1 gallic acid) in Chardonnay and 2124 to 1820 in Carmenere. The same trend was observed in Carmenere for anthocyanins and tannins, by spectrophotometry and high performance liquid chromatography. Dimethyl amino cinnamaldehyde index in Carmenere went from 28.6 in wines 100% healthy bunches to 22.0 for the 100% infested, and tannin galoilation went from 3.85 to 0.74%. Sensory analysis showed that wines with larger proportion of infested grapes were associated with negative descriptors and lower quality. These results show that mealybugs have the potential of negatively impacting wine quality and this deserves further attention.
  • Thumbnail Image
    Item
    Post-veraison sunlight exposure induces MYB-mediated transcriptional regulation of anthocyanin and flavonol synthesis in berry skins of Vitis vinifera
    (OXFORD UNIV PRESS, 2009) Thomas Matus, Jose; Loyola, Rodrigo; Vega, Andrea; Pena Neira, Alvaro; Bordeu, Edmundo; Arce Johnson, Patricio; Antonio Alcalde, Jose
    Anthocyanins, flavan-3-ols, and flavonols are the three major classes of flavonoid compounds found in grape berry tissues. Several viticultural practices increase flavonoid content in the fruit, but the underlying genetic mechanisms responsible for these changes have not been completely deciphered. The impact of post-veraison sunlight exposure on anthocyanin and flavonol accumulation in grape berry skin and its relation to the expression of different transcriptional regulators known to be involved in flavonoid synthesis was studied. Treatments consisting of removing or moving aside the basal leaves which shade berry clusters were applied. Shading did not affect sugar accumulation or gene expression of HEXOSE TRANSPORTER 1, although in the leaf removal treatment, these events were retarded during the first weeks of ripening. Flavonols were the most drastically reduced flavonoids following shading and leaf removal treatments, related to the reduced expression of FLAVONOL SYNTHASE 4 and its putative transcriptional regulator MYB12. Anthocyanin accumulation and the expression of CHS2, LDOX, OMT, UFGT, MYBA1, and MYB5a genes were also affected. Other regulatory genes were less affected or not affected at all by these treatments. Non-transcriptional control mechanisms for flavonoid synthesis are also suggested, especially during the initial stages of ripening. Although berries from the leaf removal treatment received more light than shaded fruits, malvidin-3-glucoside and total flavonol content was reduced compared with the treatment without leaf removal. This work reveals that flavonol-related gene expression responds rapidly to field changes in light levels, as shown by the treatment in which shaded fruits were exposed to light in the late stages of ripening. Taken together, this study establishes MYB-specific responsiveness for the effect of sun exposure and sugar transport on flavonoid synthesis.
  • Thumbnail Image
    Item
    Prevalence and pathogenicity of fungi associated with grapevine trunk diseases in Chilean vineyards
    (2013) Díaz, Gonzalo A.; Auger, Jaime; Besoain, Ximena; Bordeu, Edmundo; Latorre, Bernardo A.
  • No Thumbnail Available
    Item
    Scientific productivity and collaboration in viticulture and enology in Latin American countries
    (2013) Luis Aleixandre, Jose; Bordeu, Edmundo; Luis Aleixandre-Tudo, Jose; Bolanos, Maxima; Aleixandre-Benavent, Rafael
    The aim of this study was to analyze the scientific activity of Latin American researchers in viticulture and oenology through bibliometric analyses of articles included in the Science Citation Index Expanded database for the period of 2006 to 2010. A total of 917 research articles were published in 364 domestic and international journals. We highlight the important growth in the number of research papers published during the period, especially in Brazil, Argentina and Chile, as well as an increasing number of international collaborations, mainly with non-American grape- and-wine producing countries. A social network analysis of collaborations between institutions and countries was also performed. The combined analysis of productivity, collaboration and scientific impact provides a global and integrated vision of the research conducted in this area in Latin America.