Maximising quality during bulk wine transport

Abstract

Wine sensory and chemical composition and temperature were tracked and assessed in a series of bulk wine shipments between Australia and the UK. No major sensory differences before and after wine transport, or between wine transportation techniques were observed in this study. The full report is available to Australian grape and wine research R&D levy payers from the AWRI helpdesk by emailing helpdesk@awri.com.au or phoning +61 8 8313 6600.

Summary

Around 60 per cent of the 1,200 million litres of Australian wine produced annually are exported and 60 per cent of these exports are now transported in bulk and packaged in-market. This is up from 20 per cent of exports 10 years ago. More Australian wine is exported to the United Kingdom (UK) than to any other country and 85 per cent of this is now transported in bulk.Given the importance of bulk wine exports to the Australian wine sector, this project studied the influence of transportation on wine composition. Wine sensory and chemical composition and temperature were tracked and assessed in a series of bulk wine shipments between Australia and the UK. A range of transportation conditions were considered including: flexitank and ISO tank bulk containers bulk container filling temperatures of 8 and 19°C shipping routes with and without transhipping Chardonnay destined for the same product was used in the majority of trials. This wine was chosen as white wines are typically more susceptible to the effects of storage and transport and Chardonnay is the largest white variety exported to the United Kingdom. A small number of containers of a Shiraz/Cabernet Sauvignon wine were also sent to determine if impacts were different for red wines. No taints were observed in any samples. From conversations with packaging facilities in the United Kingdom and Germany, pick-up of taints during bulk wine transport (e.g. TCA or naphthalene taints) has not been a major issue for the last 10 years. This is likely a testament to the management strategies introduced by the largest freight forwarders/flexitank suppliers servicing the Australian wine sector. These measures include container sorting, container lining and flexitank barrier films that provide a final stage of product protection. Whenever engaging a new freight forwarder/flexitank supplier it is recommended to ensure that well-conceived taint-avoidance strategies/materials are in place together with appropriate proof of performance. Differences in flexitank filling temperature had no sensory impact. The likely explanation is that there were approximately eight days between flexitanks being filled at the winery and being loaded onto ships, during which time wine temperatures in all flexitanks tended towards an equilibrium with the average ambient temperature. Eight days was observed in practice as a typical period between containers being filled and being loaded onto ships. Differences in shipping route had no sensory impact. While transhipping in Malaysia involved a period of more direct exposure of containers to local weather conditions near the equator, the overall transportation time was eight days faster because there were five fewer ports of call than the ‘direct’ service. In three of the four sets of trials performed in this study, transhipping occurred essentially as scheduled, with containers spending between one and five days at the transhipment port in Malaysia. In one trial, the containers were not loaded on the scheduled ship from the transhipment port and spent eight days at the port, however, this still did not have a noticeable impact on wine quality. Transhipping does present some risk as containers can sit relatively exposed to ambient temperatures for longer periods than planned, but on this route with this wine the risks were apparently relatively small. Wines shipped in flexitanks and ISO tanks were similar to each other and to the wines before transport. On average, ISO tanks resulted in marginally better retention of fruit flavour, aroma and sweetness, but in tastings with experienced winemakers, they did not consistently prefer the wines shipped in ISO tanks over those shipped in flexitanks, suggesting that the average consumer would be unlikely to be able to perceive a difference. Slight differences are likely explained by the wine in the insulated ISO tanks typically experiencing peak temperatures 4°C lower than wine transported in flexitanks. This resulted in slower hydrolysis of some particularly temperature sensitive ethyl esters. ISO tanks are inferior to flexitanks in many other respects – ISO tank availability is limited in Australia, they are more expensive (around $0.06/L more for exports to the UK), more difficult to fill, and present a greater cross-contamination risk. All flexitank shipments were made with single-layer flexitanks (with taint/oxygen barrier sleeves) which are widely used by the Australian wine sector. Residual wine remaining in flexitanks after emptying in these trials was very low, averaging only 32 L (0.1 per cent). In summary, no major sensory differences before and after wine transport, or between wine transportation techniques were observed in this study. Project number