A review of vibrational frequencies reported for tannin molecules is provided to create a database with typical fingerprints for different types of tannins. This will provide researchers working on vibrational spectroscopy applications and technicians a fast, easy, and reliable method to assess the quality and authenticity of these compounds, both extracted in laboratories and provided from commercial sources. The widespread use of these compounds has highlighted the need for a systematic characterization of the vibrational frequencies and molecular fingerprints for their identification and discrimination. According to our knowledge, this is the first systematic collection of typical peak frequencies for tannins, which can be applied in several research fields and technological applications.

This review article summarizes the state of the art on Leuconostoc oenos, the bacteria responsible for malolactic fermentation in wine. Both basic and practical aspects related to the metabolism of this microorganism and malolactic fermentation in general are critically reviewed. The former examines the role of genetics for the identification and classification of L. oenos and energetic mechanisms on solute transport (malic and lactic acid). The latter includes practical information on biomass production, optimal growth conditions and stress factors, which are important in growth optimization of malolactic starter cultures. Extensive data and references on the effect of malolactic fermentation on wine composition and sensory analysis are also included.

An improved high performance liquid chromatography (HPLC) method for the analysis of the main organic compounds in musts and wines is presented. A column packed with hydrogen sulfonated divinyl benzene-styrene copolymer and two detectors connected in series were used (UV at 210 nm and RI, respectively). The addition of acetonitrile (6%) to the mobile phase (0.045N H2SO4) allowed the simultaneous separation and quantification of several organic acids, glucose, fructose, glycerol, and ethanol. Direct injection and sample clean-up with a SAX cartridge was tested and compared. The SAX fractionation gave satisfactory results, however the direct injection of diluted wine (1:20) provided the best precision (CV ≤ 2.1%) and accuracy of analysis. Statistical analysis (paired t-test) disclosed significant differences only for glucose, fructose, α-ketoglutaric, and pyruvic acid. The role of column temperature for the analysis of vitamin C (ascorbic acid) was also investigated. Vitamin C underwent thermal degradation ...