Isolation and Physicochemical Characterization of Tigernut (Cyperus esculentus) Starch as a Potential Industrial Biomaterial

摘要

Tigernut (Cyperus esculentus) seeds were examined for its starch composition and applicability as biomaterial in hybrid composite materials development. The physicochemical properties of the starch extracted were then compared with standard industrial maize starch. The starch was isolated using 1% w/v sodium metabisulphite solution and the obtained starch was found to be a brilliant white, crystalline, non- hygroscopic powder with yield of about 21%. The starch percentage solubility at 90°C was 2.36 with a swelling power of 13.7 and gelatinization temperature of 66°C. It had a browning temperature of 257.0 – 268.2°C, charring temperature of 281.4 – 291.6°C, water absorption capacity of 71%, pH of 5.6, foam and emulsion capacities of 2.8% and 8.17% respectively. The proximate analysis (%) was found to be: fat – 2.3, ash – 0.24, protein – 0.18, moisture – 8.67 and carbohydrates – 88.61. XRD scan (a gonio (2Θ) scan) of the starch sample at 10°C – 100°C 2Θ angle established the organic nature of the starch. Analysis of the starch sample by XRD gave amylose to be 28% and amylopectin to be 72%. The α-amylose of the starch had an orthorhombic crystal system with a high purity rate. The spectral revealed peak positions at 2Θ positions of 11.3189°, 14.9662°, 17.0105°, 17.8645°, 22.8843°, 26.4595° and 30.2574° corresponding to a Full Width at Half Maximum (FWHM) (2Θ) of 0.6593°, 0.5274°, 0.5274°, 0.3296°, 0.7252°, 0.6593° and 0.7911° respectively. The XRD analysis confirmed the starch to be of high purity and quality with a score of 83% on the ICDD database. Applicability in composite materials studies showed a high level of compatibility as binder/filler materials within the matrix and fiber materials employed. Generally, the values obtained from the characterization of tigernut starch showed that it has high potential for industrial applications especially but not limited to use as biomaterials in composites, food, textile and pharmaceutical industries.