Valorization of Acha and Iburu Grains: Optimization and Characterization of CLEA-Immobilized Amylases as Potential Alternatives to Conventional Barley and Wheat Induced- amylases
Adenike Oluwaseun Adefila *
Department of Biochemistry, Faculty of Sciences, University of Ilesa, Ilesa, Osun State, Nigeria.
Oluyemisi Omotayo Omonije
Department of Biochemistry, Faculty of Sciences, University of Ilesa, Ilesa, Osun State, Nigeria.
Kehinde Olufemi Oguntunde
Department of Biochemistry, Faculty of Sciences, University of Ilesa, Ilesa, Osun State, Nigeria.
Udoka Bessie Igue
Department of Biochemistry, Faculty of Basic and Applied Sciences, University of Africa, Toru-Orua, Bayelsa State, Nigeria.
Oluwatoyin Grace Ariyo
Department of Microbiology, Faculty of Sciences, University of Ilesa, Ilesa, Osun State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Barley and wheat are conventional sources of amylases for industrial applications; however, their cost and seasonal availability limit their utilisation. Underutilised grains, such as acha and iburu, may provide alternative sources of these enzymes. This study investigated the potential of malted acha and iburu as sources of amylases and optimised cross-linked enzyme aggregate (CLEA) technology for their immobilisation. Purified amylases obtained from the malted grains were precipitated using 80% (NH4)2SO4 for 30 min on ice, followed by cross-linking with glutaraldehyde at a final concentration of 2%. The concentrations of (NH4)2SO4 and glutaraldehyde were optimised on the basis of enzyme activity recovery. CLEAs were prepared using 80% (NH4)2SO4. The reusability of the amylase CLEAs from these grains was investigated over four cycles. The prepared CLEAs exhibited substantial residual activity after repeated use. After four successive cycles, 72% and 62% of the initial activities were retained by the acha and iburu amylase CLEAs, respectively. These findings suggest that malted acha and iburu are promising alternative sources of amylases, although further studies on scale-up, industrial applications, direct comparisons with commercial preparations and techno-economic feasibility are required.
Keywords: Acha, iburu, Digitaria exilis, Digitaria iburua, α-amylase, cross-linked enzyme aggregates, ammonium sulphate precipitation, glutaraldehyde cross-linking, enzyme immobilisation, operational reusability