a detergent composition comprising an alkaline metal hydroxide , an alkaline metal salt of l - aspartic - n , n - diacetic acid , optionally a scale inhibitor and / or an alkaline metal salt of gluconic acid . this detergent composition is used for removing soils , stains and other contaminants adhering to or deposited on the surfaces of glass , plastics , metals , etc ., specifically the hard surfaces of , for example , containers for foodstuffs such as drinks and process foods , container boxes , piping of food production equipment , tanks , sterilizing plates , plate heat exchangers , filling machines and the like , by such means as soaking the parts to be cleaned in a cleaning solution , circulating a cleaning solution in the facilities to be cleaned , or spraying a cleaning solution over the surfaces to be cleaned . this detergent composition has excellent cleaning performance and excellent biodegradability .