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Winning Wines

Preliminary investigations by researchers at Lincoln University have shown there is potential to produce organic-style wines that do not use sulphur dioxide (SO2) as a preservative.

Dr David Heatherbell and Masters student Nicole Tucker who did this work are from the Wine Science Group in the university's Animal and Food Sciences Division. The two researchers set up a small-scale trial to see if it were possible to produce wines that were of acceptable quality and stability and which did not contain the routinely added preservative.

"Reported health implications and an increasing demand by the consumer for the production of foods and beverages that are free of additives, including preservatives, highlight the need to develop technologies for the production of wines free from SO2 added during processing," says Heatherbell.

Previously wines with reduced SO2 have been produced but were of poor or reduced quality, stability and shelf-life. This trial investigated whether there were other ways of increasing the shelf-life and quality of wines produced without added SO2.

Riesling grapes from Canterbury were used for the three different treatments. The first treatment was processed conventionally and had SO2 added; the second treatment had no SO2; and the third treatment was subjected to hyperoxidation (the addition of extra air/oxygen) of the crushed grapes or must. Treatments two and three were then divided in half, with one half having an oxygen-scavenging enzyme known as glucose oxidase added at bottling stage and the other half having no addition. Standard production processes were used in all treatments, and the wine was regularly subjected to the standard wine quality tests during its 18-month storage at 12oC.

"We were quite pleased with how some of the wines turned out," says Heatherbell. "There was some loss of flavour and quality characteristics with all treatments which did not contain SO2. Treatments however, without SO2, but with hyperoxidation and glucose oxidase added, produced wines which had acceptable characteristics. Tests showed that the addition of the enzyme increased the shelf-life of SO2 free wines from three months to 17 months."

"Further investigating is needed in this area of course, but this is a promising start to what may in the future be a good-sized market.".