Evaluation of new cassava varieties for adhesive properties
Department of Chemical Engineering, University of the West Indies, St Augustine, Trinidad and Tobago; Department of Food Science and Technology, Bowen University, Iwo, Osun State, Nigeria
Cassava varieties: Red stick, Butter stick, Maracas Black stick, and M Col 22 were evaluated for pulp yield, starch yield, amylose, and protein contents in a screening exercise of new cassava varieties. Starch content of the tubers was determined. Starch was extracted from freshly harvested nine-month-old tubers using standard method. The starch paste was air dried before final drying at 50°C for 8-h in an oven. Amylose and protein contents of the starch were determined by approved methods. Adhesive was made by heating 10% starch slurry in 0.1-M KOH solution to 70 and 80°C, respectively. Color, pH, viscosities, adhesive force, adhesiveness, stickiness, and storage properties of the adhesives were determined. Pulp yields (74.1-83.1%), starch yields (11.8-20.3%); starch amylose (23.5-26.5%) and protein contents (0.34-0.82%) of cassava tubers differed. Also peak viscosity (297-393 RVU), breakdown viscosity (195-263 RVU), and set back viscosity (43-52 RVU) of the starches were significantly different. Similarly the adhesive force (-77 to -146 and adhesiveness (-1952-gs to -3075-gs) varied significantly. Adhesive from variety M Col 22 resolved into two fractions at two weeks of storage and completely broke down by week three. Pastes produced at 80°C were less viscous, had lower adhesiveness and adhesive force and were darker than pastes produced at 70°C. Storage reduced the adhesive force and adhesiveness of the adhesives. The adhesive pastes were alkaline (pH10.69-11.58). The Maracas Black Stick and Butter Stick varieties produced the best adhesives in terms of stickiness and resistance to degradation than the other two varieties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Adhesives; Alkalinity; Cyclodextrins; Plants (botany); Proteins; Screening; Starch; Viscosity; Adhesive properties; Breakdown viscosity; Cassava; Cassava varieties; Peak viscosities; Properties; Protein contents; Storage properties; Adhesive pastes; Manihot esculenta