Cyclic voltammetry : a tool to quantify 2,4,6-trichloroanisole in aqueous samples from cork planks boiling industrial process

Chloroanisoles, namely 2,4,6-trichloroanisole, are pointed out as the primary responsible of the development of musty off-flavours in bottled wine, due to their migration from cork stoppers, which results in huge economical losses for wine industry. A prevention step is the detection of these compounds in cork planks before stoppers are produced. Mass spectrometry gas chromatography is the reference method used although it is far beyond economical possibilities of the majority of cork stoppers producers. In this work, a portable cyclic voltammetry approach was used to detect 2,4,6-trichloroanisole extracted from natural cork planks to the aqueous phase during the cork boiling industrial treatment process. Analyses were carried out under ambient conditions, in less than 15 min with a low use of solvent and without any sample pre-treatment. The proposed technique had detection (0.31±0.01 ng/L) and quantification (0.95±0.05 ng/L) limits lower than the human threshold detection level. For blank solutions, without 2,4,6-trichloroanisole addition, a concentration in the order of the quantification limit was estimated (1.0±0.2 ng/L), which confirms the satisfactory performance of the proposed methodology. For aqueous samples from the industrial cork planks boiling procedure, intra-day repeatabilities were lower than 3%, respectively. Also, 2,4,6-trichloroanisole contents in the aqueous samples determined by this novel approach were in good agreement with those obtained by GC-MS (correlation coefficient equal to 0.98), confirming the satisfactory accuracy of the proposed methodology. So, since this novel approach is a fast, low-cost, portable and user-friendly method, it can be an alternative and helpful tool for in-situ industrial applications, allowing accurate detection of releasable 2,4,6-trichloroanisole in an earlier phase of cork stoppers production, which may allow implementing more effective cork treatments to reduce or avoid future 2,4,6-trichloroanisole contaminations of wine.This work was partially supported by project PEst-C/EQB/LA0020/2011, financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundacao para a Ciencia e a Tecnologia (Portugal)

Mid- to late Pliocene (3.3–2.6 Ma) global sea-level fluctuations recorded on a continental shelf transect, Whanganui Basin, New Zealand

We present a ∼900 m-thick, mid- (3.3–3.0 Ma) to late Pliocene (3.0–2.6 Ma), shallow-marine, cyclical sedimentary succession from Whanganui Basin, New Zealand that identifies paleobathymetric changes, during a warmer-than-present interval of Earth history, relevant to future climate change. Our approach applies lithofacies, sequence stratigraphy and benthic foraminiferal analyses to two continuously-cored drillholes integrated with new and existing outcrop studies. We construct a depositional model of orbitally-paced, global sea-level changes on a wave-graded continental shelf. Unlike many previous studies, these shelf sediments were not eroded during sea-level lowstands and thus provide the potential to reconstruct the full amplitude of glacial-interglacial sea-level change. Paleobathymetric interpretations are underpinned by analysis of extant benthic foraminiferal census data and a statistical correlation with the distribution of modern taxa. In general, water depths derived from foraminiferal Modern Analogue Technique (MAT), are consistent with variability recorded by lithofacies. The inferred sea-level cycles co-vary with a qualitative climate record reconstructed from a census of extant pollen and spores, and a modern temperature relationship. A high-resolution age model is established using magnetostratigraphy constrained by biostratigraphy, and the dating and correlation of tephra. This integrated chronostratigraphy allows the recognition of 23 individual sedimentary cycles, that are correlated across the paleo-shelf and a possible “one-to-one” relationship is made to deep-ocean benthic oxygen isotope (δ18O) records. In general water depth changes were paced by ∼20 kyr duration between 3.3 and 3.0 Ma, after which cycle duration is ∼40 kyr during the late Pliocene (3.0–2.6 Ma). This record provides a future opportunity to evaluate the amplitude and frequency of global, Pliocene glacio-eustatic sea-level change, independent of the global benthic δ18O record

Multiple glucosyltransferase activities in the grapevine Vitis vinifera L

© 2008 Australian Society of Viticulture and Oenology Published online at www.interscience.wiley.comThe conjugation by glycosyltransferases of sugars to primary and secondary metabolites is widespread among plants and almost certainly a prerequisite for the accumulation of secondary metabolites at high levels. In the case of the grapevine, Vitis vinifera, modulating the levels of specific secondary berry metabolites is a desirable outcome for the development of wines with particular style characteristics. This can be achieved only by a thorough understanding of the processes underlying glucoside formation and accumulation during berry development. Using protein extracts prepared from leaves and berries of Vitis vinifera cvs, we show here that glucosyltransferase activities can be detected against a wide range of substrates. Among the substrates glucosylated were several classes of phenylpropanoids, including flavonols, anthocyanidins, flavanones, flavones, isoflavones, and a stilbene. Additionally, simple phenols and monoterpenes were glucosylated. Total soluble leaf proteins subjected to ion-exchange chromatography separated into fractions with differing glucosyltransferase activities. This provided strong evidence for the existence both of multiple distinct enzyme activities, and multiple isozymes catalysing identical reactions. Polyclonal antiserum raised to a V. vinifera UDP-glucose:anthocyanidin glucosyltransferase was used to demonstrate the existence of multiple glucosyltransferases in berries and leaves of the grapevine cvs Muscat of Alexandria and Shiraz, thereby confirming data obtained previously through biochemical analyses of recombinant glucosyltransferase