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Wine is not something one normally thinks of as containing animal products but Rockburn Wines' winemaker Malcolm Rees-Francis said many wine-makers added a protein substance called a fining agent to their product to make the wine less tannic and more drinkable.
Agents included animal-derived products such as egg albumen, gelatin or isinglass (from fish bladder membranes).
''It is surprising how common it is,'' Mr Rees-Francis said.
He said the agents clarified the wines and removed the tannin but he did not add any agents to Rockburn's Wines.
''We like to think that our wine is good enough already and we do not need to use them.
''The quality of grapes and the technique [we use] means a more balanced wine and less tannin, although [to] have some tannin is fine.''
He said some people liked tannin as it gave the wine a fuller body.
Vegan Society of Aotearoa New Zealand media spokesperson Claire Insley said veganism was gaining interest worldwide and New Zealand was no different.
She said wines suitable for vegans were increasingly being sought after and they and the New Zealand Vegetarian Society were working towards establishing a labelling system that would identify vegan and vegetarian products.
''It will make it easier for people to hunt for vegan wines and other products,'' Ms Insley said.
She said the labelling programme was due to be released last year, but hold-ups meant the launch was delayed until later this year.
She said once it was launched, they hoped producers, such as winemakers, would register to join the scheme.
''The onus will be on them to ensure their products are what the say they are.''