In early April, the entire Italian wine industry decamps to Verona for the mother of all trade fairs:

VinItaly. I was one of the 140,000 people there, battling my way round the 25-acre site and its collection of vast sheds representing wine regions from Piedmont to Sicily.

With more than 4000 stands ranging from simple booths to two-storey castles, it was fairly mind-blowing.

If I close my eyes now, I can still see a shimmering wall of glass bottles, but in that sense VinItaly may be swimming against the tide of bulk wine whose shipments have more than doubled since 2005. Today, more than half of Australian and two-thirds of South African and Chilean wine arrives in the UK in a flexitank - a giant, 24,000-litre bag-in-box.

This is the industry's unglamorous backside, revealed by Gregg Wallace on BBC's Supermarket Secrets last December.

"What we're doing is moving large volumes of wine as efficiently and carefully as possible," explained Tesco's wine chief, Dan Jago, before prodding an enormous plastic bladder that had spent seven weeks at sea from Australia.

Bulk is certainly efficient given the extra weight and space taken up by bottles, and it's more environmentally friendly.

You can use lighter bottles if you are bottling here, it helps keep costs down and is good for the planet - so what's not to like?

Well, in South Africa, with unemployment running at 25%, they have lost around 1000 jobs on bottling lines so far, and the country's government has threatened to retaliate by importing Scotch whisky in bulk.

Among producers I have met, there is cynicism about the motives behind the shift to bulk. Instead of being a green initiative, they see it as all about money and something that threatens the image of wine by making it nothing more than an anonymous commodity traded solely on price.

In theory it shouldn't matter where a wine is bottled and yet there is something unsettling about those wine bladders squished into containers wobbling their way across the seas. Nor should it have any effect on the credibility and sense of provenance of the wines concerned, although curiously the world's third biggest importer of bulk wine is France. It does make you wonder.