The present invention describes a method of producing an enzyme-treated palm kernel cake (ETPKC) and mannose oligosaccharide (MOS) simultaneously, via enzymatic treatment of palm kernel cake. The ETPKC has improved protein content compared to commercially available PKC. β-mannanase enzyme is used to hydrolysis gluctomannan available in palm kernel cake to mannose oligosaccharide. The solid-liquid suspension produced from the enzymatic hydrolysis is then, press filtered to separate the filtrate and solid residue. The solid residue of the suspension is known in the present application as ETPKC and has a protein content of about 25 – 32%. The filtrate is purified and spray dried further to produce MOS powder which can be used as feed additive for animals.
