Milk goes sour in about a week, even if you keep it in the fridge. That's because Lactobacillus, the "good bacteria" that's found in yogurt, is constantly going about the job of oxidizing the lactose sugars in the milk into sour-tasting lactic acid - the same chemical that makes your muscles sore after exercise. But since this souring process requires the presence of oxygen, theoretically it could be slowed down even further if you kept the milk out of contact with oxygen. Rather than going with a high-tech nitrous contraption like the N2Wine globes we wrote about recently, one (seemingly) anonymous entrant to this year's James Dyson awards has come up with something devilishly simple: a shrinking milk jug that squeezes all the air out as you empty it. The inventor claims it lets milk last as much as a week longer. Simple and brilliant!

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I remember when I was a kid, my brothers and I would have had no idea that milk went off if you left it in the fridge - because we'd go through a couple of liters a day, often chugging it straight out of the carton, leaving just enough for Mum to have a few drips in her cup of tea so that she'd be the one that finished it, and thus the one who'd have to go get more. Heh heh.

These days, my partner and I have to put in a concerted effort to finish a 2-liter bottle before it goes off - and we're not alone in that. It'd be interesting to know what percentage of milk ends up going down the sink because it's soured in the fridge. The Fresh shrinking milk jug seems like a great idea.

The Fresh is a spring-loaded jug with flexible sides. You pop it out to its full height to fill it (perhaps with a low-waste bag of fresh milk, like the way you buy your washing detergent), then put the airtight lid on. Then you press the release valve and push down on the lid until the milk starts pouring out the nozzle. You don't have to lift the jug or tilt it to pour in this way.

When you're done pouring, you release the valve button and the milk is sealed inside the jug, free from contact with any oxygen. Starved of the oxygen it takes to process the milk, and kept at a chilled temperature to slow them further, the Lactobacillus bacteria take a lot longer to turn the milk sour - up to a week longer, the inventor claims.

Being a design study, there's no immediate plans for production - but we know plenty of Gizmag readers are venture capital speculators, so here's one that might be worth checking out, guys! In the meanwhile, I've gone to my fridge and squeezed all the air out of the plastic bottle, but it might not be necessary - all this talk about milk's making me thirsty!

Via TreeHugger.