M. Carmen Polo

Wine chemistry and biochemistry

Chemical and Biochemical Aspects ofWinemaking.- Biochemistry of Alcoholic Fermentation.- Biochemical Transformations Produced by Malolactic Fermentation.- Special Wines Production.- SparklingWines and Yeast Autolysis.- Biologically Aged Wines.- Enzymes in Winemaking.- Use of Enological Additives for Colloid and Tartrate Salt Stabilization in White Wines and for Improvement of Sparkling Wine Foaming Properties.- Wine Chemical Compounds and Biochemical Processes.- Nitrogen Compounds.- Amino Acids and Biogenic Amines.- Peptides.- Proteins.- Carbohydrates.- Volatile and Aroma Compounds.- Wine Aroma Precursors.- Polyfunctional Thiol Compounds.- Volatile Compounds and Wine Aging.- Yeasts and Wine Flavour.- Identification of Impact Odorants of Wines.- Interactions Between Wine Matrix Macro-Components and Aroma Compounds.- Phenolic Compounds.- Anthocyanins and Anthocyanin-Derived Compounds.- Flavanols, Flavonols and Dihydroflavonols.- Non-flavonoid Phenolic Compounds.- Influence of Phenolics on Wine Organoleptic Properties.- Health-Promoting Effects of Wine Phenolics.- Spoilage ofWines.- Aromatic Spoilage of Wines by Raw Materials and Enological Products.- Wine Spoilage by Fungal Metabolites.- Automatic Analysers and Data Processing.- Automatic Analysers in Oenology.- Statistical Techniques for the Interpretation of Analytical Data.

Screening of biogenic amine production by lactic acid bacteria isolated from grape must and wine

The potential to produce the biogenic amines tyramine, histamine and putrescine, was investigated for lactic acid bacteria (LAB) of various origin, including commercial malolactic starter cultures, type strains and 78 strains isolated from Spanish grape must and wine. The presence of biogenic amines in a decarboxylase synthetic broth was determined by reverse-phase high performance liquid chromatography (RP-HPLC). Tyramine was the main amine formed by the LAB strains investigated. Leuconostoc strains were the most intensive tyramine formers. No potential to form biogenic amines was observed in Oenococcus oeni strains. Two strains of Latobacillus buchneri were associated with putrescine formation. None of the lactic acid bacteria produced histamine. According to these in vitro results, the commercial starter bacteria analyzed did not produce histamine, tyramine and putrescine.

Winemaking Biochemistry and Microbiology: Current Knowledge and Future Trends

The fermentation of grape must and the production of premium quality wines are a complex biochemical process that involves the interactions of enzymes from many different microbial species, but mainly yeasts and lactic acid bacteria. Yeasts are predominant in wine and carry out the alcoholic fermentation, while lactic acid bacteria are responsible for malolactic fermentation. Moreover, several optional winemaking techniques involve the use of technical enzyme preparations. Considerable progress has been made recently in understanding the biochemistry and interactions of enzymes during the winemaking process. In this study, some of these recent contributions in the biochemistry of winemaking are reviewed. This article intends to provide an updated overview (including works published until December, 2003) on the main biochemical and microbiological contributions of the different techniques that can be used in winemaking. As well as considering the transformations that take place in traditional winemaking, the production of special wines, such as sparkling wines, ‘sur lie’ wines, and biologically aged wines, are also studied.

Free and total amino acids in the non-protein fraction of an artisan blue cheese during ripening

ZusammenfassungWährend des Reifungsprozesses bei drei Partien Blauschimmelkäse wurde der Verlauf des Gehaltes an freien und gesamten Aminosäuren der in 5% iger Phosphorwolframsäure löslichen Fraktion mittels HPLC beobachtet. Die Korrelationskoeffizienten zwischen dem Gehalt an freien und Gesamt-Aminosäuren während der Reifungszeit waren positiv und größer als 0,85 für die meisten Aminosäuren. Ein geringerer Korrelationsgrad im Verlauf der Reifung war bei den Nicht-Protein-Aminosäuren zu beobachten. Die Anwendung der Faktor-Analyse wies darauf hin, daß die Reifung die wichtigste Ursache der Unterschiede zwischen den analytischen Proben war (60% der Varianz) und die zweite Ursache für die Varianz (15%) der Unterschied zwischen den Partien. Der Reifungsgrad kann in etwa aus der Konzentration bestimmter Aminosäuren geschätzt werden.SummaryChanges in the free amino acid content and total amino acid content of the fraction soluble in 5% phosphotungstic acid from three batches of blue cheeses were studied by HPLC over the ripening period. The correlation coefficients between the free and total amino acids and ripening time were positive and higher than 0.85 for most amino acids. Non-protein amino acids showed the lowest correlations with ripening. Principal component analysis performed on the data showed ripening time to be the main cause of variation between the samples analyzed, explaining 60% of the variance; differences between batches were the second most important source of variation (15%). The ripening stage can be approximately estimated from the concentration of certain amino acids.

Reversed-phase HPLC analysis of peptides in standard and dairy samples using on-line absorbance and post-column OPA-fluorescence detection.

ZusammenfassungDer Postkolonnen-Absorptions- und Fluoreszenznachweis mit orthophthaldialdehyd (OPA) wird bei der Standard- und Milchpeptidanalyse nach der Trennung durch Hochleistungs-Flüssigchromatographie (HPLC) eingesetzt. Der Einsatz beider Nachweissysteme vermittelt zusätzliche Information über das Auftreten von Peptiden in Milchprodukten. Das Ergebnis des Nachweisverfahrens ist von der chemischen Bindung der Aminosäuren im Peptid abhängig. Unter den untersuchten Peptiden weisen Glutathion, Peptide mit Lysin und Peptide mit Glykokoll im endständigen N nach der Postkolonnen-Reaktion mit OPA die größte Fluoreszenz auf. Bei Peptiden mit aromatischen Aminosäuren spricht die Absorption stärker als die Fluoreszenz an. Verschiedene Parameter wie die OPA-Strömung, der Anteil an Mercaptoethanol im Reagens OPA und die Reaktionstemperatur beeinflussen die Fluoreszenzcharakteristik des Peptids. Der Einsatz der on-line-Absorption und Fluoreszenz ist nützlich bei der Analyse von Peptiden in entrahmter Milch und eines tryptischen Hydrolysats.AbstractAbsorbance and post-columno-phthalaldehyde (OPA)-fluorescent detection were used to analyse standard and dairy peptides following reversed-phase HPLC. Using both detection systems on-line provides additional information on the presence of peptides in dairy products. The detection response depends on the amino acid composition of the peptide involved. Among the peptides used, glutathione, lysine-containing peptides and peptides with glycine as the N-terminal residue give the highest fluorescence after the OPA post-column reaction. Absorbance is more sensitive than fluorescence for peptides with aromatic amino acids. Different parameters, such as the flow rate of OPA, the amount of mercaptoethanol in the OPA reagent and the temperature of reaction, substantially influence the fluorescent response of peptides. The interest of using on-line absorbance and fluorescence detection is highlighted by analysing peptides from skim milk and from a tryptic hydrolysate.