Christopher Colby

Cold stabilisation is a widely used industrial process to prevent tartrate instability in bottled wines. In this article, current knowledge regarding performance and cost of cold stabilisation and alternative technologies for tartrate stabilisation is reviewed. Whilst there have been occasional cost comparisons between cold stabilisation and alternative technologies published in the literature, existing data is not satisfactory to permit an accurate economic evaluation of the different process options. Therefore, alternative technologies to cold stabilisation, including the Westfalia process, nanofiltration and electrodialysis were compared for both technical and economic performance. The engineering calculations and conceptual cost estimates were based on real world data from an Australian winery. Product loss was a key cost driver in differentiating tartrate stabilisation processes. Cold stabilisation was found to be the most economic treatment process irrespective of scale or winery size. Westfalia process and nanofiltration were the next most cost effective options.

A new laboratory‐based method for obtaining gram quantities of a principal heat‐unstable thaumatin‐like protein (VVTL1), in wine is presented. Separation and purification from grape juice was achieved by cation exchange and ultra‐filtration. Purity was confirmed by HPLC, sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE), gel permeation chromatography (GPC) and high‐sensitivity amino acid analysis. This alternative method is more rapid and compact and can efficiently produce much larger quantities (>100×) than the current laboratory technique. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.

Field tests to evaluate in-line dosing with bentonite followed by centrifugation as an alternative to batch fining for protein haze control in white wine or juice were undertaken. The tests were performed at a commercial winery with a Sultana wine and Gordo (Muscat of Alexandria) juice and using two types of bentonite: Vitiben and SIHA-Active-Bentonite G. Fining performance was monitored by heat testing and quantification of heat unstable protein by HPLC. Heat test turbidity and heat unstable protein concentration decreased to stable values between 30 s and 2 min after bentonite injection. Sensory evaluation of Sultana wine fined with Vitiben by balanced reference duo-trio difference tests detected no difference between untreated, in-line dosed, and batch fined wine. Furthermore the volume of wine or juice occluded in lees can be substantially reduced by centrifugal compaction. However, incomplete separation of bentonite from wine or juice during centrifugation produced a carryover of 30% of the added bentonite into the clarified wine. This carryover problem may be mitigated, inter alia, by reducing operating flowrate through the centrifuge or using multiple centrifugation steps (in parallel or series). Therefore, inline dosing followed by centrifugation provides a rapid processing method for protein haze reduction in wine or juice with a decreased volume of lees. It can reduce significant value losses presently arising in the wine industry from batch fining and the resulting quality downgrades that occur in wine recovered from bentonite lees by rotary drum vacuum filtration.

Commercial interest is growing in biomimetic methods that employ self assembled mono‐layers (SAMs) to produce biocompatible HA coatings on Ti‐based orthopedic implants. Recently, separate studies have considered HA formation for various SAM surface functional groups. However, these have often neglected to verify crystallinity of the HA coating, which is essential for optimal bioactivity. Furthermore, differing experimental and analytical methods make performance comparisons difficult. This article investigates and evaluates HA formation for four of the most promising surface functional groups: OH, SO₃H, PO₄H₂ and COOH. All of them successfully formed a HA coating at Ca/P ratios between 1.49 and 1.62. However, only the SO₃H and COOH end groups produced a predominantly crystalline HA. Furthermore, the COOH end group yielded the thickest layer and possessed crystalline characteristics very similar to that of the human bone. The COOH end group appears to provide the optimal SAM surface interface for nucleation and growth of biomimetic crystalline HA. Intriguingly, this finding may lend support to explanations elsewhere of why human bone sialoprotein is such a potent nucleator of HA and is attributed to the protein's glutamic acid‐rich sequences. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006