Scotland wastes an astonishing £1 billion a year throwing away perfectly good food.

Research which uncovered the massive cost of throwaway food has now prompted a new campaign by Scottish ministers to persuade people to cut back on extravagant waste.

As much as one-fifth of the food and drink people buy ends up being dumped in the bin, costing the average Scottish household £430 a year – yet most of it could be consumed.

Top of the most-wasted league are the 70,000 tonnes of drinks dumped down the sink, worth about £140 million. Then there's the 62,000 tonnes of fresh vegetables, the 46,000 tonnes of baked goods and the 34,000 tonnes of fresh fruit that are annually discarded.

According to the Scottish Government, nearly 400,000 tonnes of the food thrown out every year can be avoided and householders could save themselves £35 a month by reducing their waste.

Wasting food also has a high environmental cost. Most of it is dumped as landfill and rots to produce methane and other greenhouse gases.

This week, ministers are launching a renewed drive to get people to buy less, cook less and waste less. The key, they say, is better household planning, improved storage and smarter shopping.

The campaign will use TV advertising, social media and a Government website to help people reduce food waste. A national information roadshow will start touring Scotland later this month.

Some of the helpful tips available include not to go shopping when you're hungry and to buy lemons and herbs to perk up leftover food.

The Environment Secretary, Richard Lochhead, accepted that everyone wasted food, but added: "By making a few simple changes to the way we plan our meals, to our weekly food shopping, to using up leftovers and to better storage, we can help our pockets and the environment, too.

"The new food waste reduction campaign aims to benefit everyone by providing help and advice. It seeks to empower everyone to shop smarter, waste less, save more and help create a greener, cleaner Scotland now and for the future."

Reducing food waste is seven times better for the environment than recycling it, the Government says. But if food does have to be thrown away, it can be composted for fertiliser or used to generate renewable energy.

The campaign has been welcomed by the Convention of Scottish Local Authorities (Cosla) as a key step towards achieving the objective of "zero waste". Councils say they are helping people reduce and recycle food waste.

"Good progress has been made," said Cosla's spokesman for development, economy and sustainability, councillor Stephen Hagan. "Small steps by individuals to tackle food waste will make continuing this progress an easier task in hard times."

Ministers were criticised, however, by the Scottish Greens for missing the point.

"Instead of continually lecturing the public, the Scottish Government needs to give people their choices back when it comes to food shopping," said the Green MSP, Patrick Harvie.

"Ministers, as well as local authorities, have allowed corporate interests to take priority, with our towns and cities surrounded by massive supermarkets that encourage you to fill up the boot of your car, often with hard-to-resist special offers like BOGOFs – Buy One Get One Free.

"It's time we told the retail giants to BOGOF and gave local shops a helping hand to compete."

The top five

foods wasted

Drinks: 70,000 tonnes worth £140 million

Fresh vegetables: 62,000 tonnes worth £100 million

Bakery items: 46,000 tonnes worth £90 million

Fresh fruit: 34,000 tonnes worth £70 million

Meat and fish: 20,000 tonnes worth £130 million