Composition, thermal and rheological properties of polysaccharides from amadumbe (Colocasia esculenta) and cactus (Opuntia spp.).

The extensive application of hydrocolloids in the food industry, coupled with their short supply and shortcomings, has led to the ongoing search for alternative sources. In this study, the compositional, rheological and thermal properties of amadumbe and cactus mucilages were investigated. The mucilages had a similar qualitative composition of monosaccharides and amino acids, except for the absence of rhamnose in amadumbe mucilage. Fractionation of amadumbe and cactus mucilages on an anion-exchange column yielded four and three fractions, respectively. The fractions eluting with protein showed no β-elimination, suggesting stronger glycosylation bonds such as those in arabinogalactan proteins (AGPs). There was no evidence of thermal depolymerisation of the mucilages up to 195 °C. Cactus mucilage showed a pseudoplastic flow behaviour whilst amadumbe mucilage showed a Newtonian flow behaviour at up to 5% (w/v) concentrations. Amadumbe mucilage may be a potential emulsifier, whilst cactus mucilage can potentially be used as a thickening or emulsifying agent.