When eating out at a new or favoured restaurant, most of us tend to focus only on the tantalising choices to be made from the menu.

But do we ever think about what happens to the food that's discarded behind closed doors by kitchen staff as they prepare our prime sirloin steak, dainty halibut ceviche or new-season grouse with all the trimmings?

If the thought of fatty offcuts or fish innards makes you gag, you're clearly not as fashion-forward a foodie as you thought you were; for such issues are well to the fore within the industry as Scotland gears up for a not-so-distant future where landfill contains zero biodegradable waste. Sustainability is a burning issue which can no longer be swept under the carpet - or poured down the drain - with impunity, and it has become as important as the ethical sourcing of ingredients.

On January 1 next year, Waste (Scotland) regulations come into force which stipulate that urban food businesses (restaurants among them) which produce more than 50kg of food waste per week must present that food waste for separate collection by arrangement with their local authority or with a private contractor - and failure to comply will incur a fine of up to £10,000.

Sewer blockages, flooding and pollution are often caused by the discharges from restaurants and pubs hoping to dodge waste collection fees, and now Scottish Water has regulatory targets to reduce this. It will identify areas where there are repeated or widespread problems from the disposal of food waste to sewer.

Some restaurants are already well on the way to meeting targets - propelled by a customer base that demands it. The Sustainable Restaurant Association's most recent 2013 consumer survey found that more than half of those surveyed said they would pay more for their meal if they knew the restaurant was investing in reducing its environmental impact and taking its social responsibility seriously. The SRA also runs annual awards and several Scottish restaurants are already performing well.

There are other benefits for those who comply. The Aberdeen pub and restaurant The Mains of Scotstown Inn claims to be making £8000 of yearly savings by implementing unique ways of handling its general waste. Besides encouraging guests to take away uneaten food in a box made of recycled cardboard, food waste is added to a wormery in which there are more than 1000 worms capable of eating their own body weight in two days. The wormery creates excellent compost, which is then used on the pub's herb, fruit and salad garden. Any waste beer or cider from line cleaning is used to water the herb and salad garden.

And the head chef at the Scottish Cafe in Edinburgh - which, like The Mains of Scotstown Inn, got the maximum three stars from the SRA - gets all her vegetables, herbs and soft fruit from the owner's kitchen garden, uses them all up either in recipes or for compost, and says as a result she's learning more about seasonality and passing this on to staff and diners.

So next time you're eating out, ask for details - and, where appropriate, remember to tip.