As the nation's battle against food waste intensifies, the authorities are making sure they know their enemy better.

In December, the National Environment Agency (NEA) is expected to start a waste audit of shopping malls, hotels, supermarkets, hawker centres, food manufacturing and food catering establishments, as well as food warehouses.

The project, which will end in mid-2019, will categorise approximately 100kg samples of the waste, according to documents seen by The Straits Times.

The food waste will be split into categories such as meat, fruit and vegetables, bones and shells, and homogeneous food waste, which includes soya bean waste and coffee grounds, and then weighed.

"The data obtained from the waste audit will help NEA establish the potential for reducing the amount of food waste disposed of and develop programmes to reduce waste in Singapore," the agency said.

It has called a tender to conduct the waste audit, which will close at the end of the month.

More than 150 premises could be audited, with the majority being food manufacturing and catering establishments, and food warehouses. The exact number will be finalised after the tender is awarded.

Food waste accounts for about 10 per cent of the total waste generated in Singapore, and only 14 per cent is recycled. The amount generated has also climbed by about 40 per cent over the last 10 years.

Last year, more than 790,000 tonnes of food was wasted - equivalent to two bowls of rice per person a day.

NEA has waged war on several fronts, including education campaigns to cut waste at home and the installation of food waste digesters, which turn waste into non-potable water or compost, at schools and hawker centres.

Associate Professor Tong Yen Wah, from the National University of Singapore (NUS), said that the audit will help NEA in deciding on whether it is feasible to install food waste digesters, and on the kind of digesters to use, among other things.

Food waste digesters can convert food waste to non-potable water, compost, or biogas to generate electricity.

"For instance, carbohydrates, like rice, are more suitable than vegetables for anaerobic digestion, where microorganisms are used to convert the waste into biogas," said Prof Tong, who is from the NUS department of chemical and biomolecular engineering and has done research into food waste for more than five years.

Ms Jen Teo, executive director of the Singapore Environment Council, noted that food waste can be burnt to produce energy, but a lot of food waste here has high water content.

She added that "high-fibre goods like wheat and sugarcane burn well while durian shells do not".

Knowing the type and source of food waste can also help in developing initiatives to reduce food waste at its source, she said.

"For example, initiatives at foodcourts to reduce waste could be as simple as having vendors serve smaller meal portions or encouraging customers to ask for less rice so they can finish what they are served."