The kitchen waste fraction in municipal solid waste contains high organic matter particularly carbohydrate
that can contribute to fermentable sugar production for subsequent conversion to bioethanol. This
study was carried out to evaluate the influence of single and combination pretreatments of kitchen waste
by liquid hot water, mild acid pretreatment of hydrochloric acid (HCl) and sulphuric acid (H2SO4) and
enzymatic hydrolysis (glucoamylase). The maximum total fermentable sugar produced after combination
pretreatment by 1.5% HCl and glucoamylase consisted of 93.25 g/L glucose, 0.542 g/L sucrose, 0.348 g/L
maltose, and 0.321 g/L fructose. The glucose released by the combination pretreatment method was
0.79 g glucose/g KW equivalent to 79% of glucose conversion. The effects of the pre-treatment on kitchen
waste indicated that the highest solubilization was 40% by the combination method of 1.5% HCl and
glucoamylase. The best combination pre-treatment gave concentrations of lactic acid, acetic acid, and
propionic acid of 11.74 g/L, 6.77 g/L, and 1.02 g/L, respectively. The decrease of aliphatic absorbance bands
of polysaccharides at 2851 and 2923 cm-1 and the increase on structures of carbonyl absorbance bands at
1600 cm-1 reflects the progress of the kitchen waste hydrolysis to fermentable sugars. Overall, 1.5% HCl
and glucoamylase treatment was the most profitable process as the minimum selling price of glucose
was USD 0.101/g kitchen waste. Therefore, the combination pretreatment method was proposed to
enhance the production of fermentable sugar, particularly glucose from kitchen waste as the feedstock
for bioethanol production.