Granule Morphology and Physicochemical Properties of Flours of Three Yams Species: Colocasia esculenta, Xanthosoma sagittifolium and Plectranthus rotundifolius

Abstract

Aims: Colocasia esculenta (Gahala), Xanthosoma sagittifolium (Kiriala) and Plectranthus rotundifolius (Innala) are three underutilized yam varieties in Sri Lanka, which have not been exploited sufficiently for various aspects in the food industry. Therefore, the research was conducted to evaluate the granule morphology, physicochemical and functional properties of flours obtained from three yams. Study Design:  Complete Randomized Design. Place and Duration of Study: Department of Food Science and Technology, Faculty of Livestock, Fisheries and Nutrition, Wayamba University of Sri Lanka, Makandura, Gonawila, (NWP), Sri Lanka between April 2016 and August 2016. Methodology: Granule morphology, proximate composition, swelling power (SP), solubility index (SI), least gelation concentration (LGC), water holding capacity (WHC) and oil holding capacities (OHC), viscosity, emulsifying capacity and emulsion stability, foaming capacity and foam stability (FS) of flour samples (≤0.250 mm) were determined. Gelatinization characteristics were evaluated using Brabender viscoamylograph. Results: At 80°C, higher SI were observed compared with other temperatures used and were within the range of 16.85-22.21%. LGC of all flours were within the range of 5-7% (w/v) indicating that they can be utilized as gel-forming material in food products. Gelatinization temperatures (GT) for Colocasia esculenta, Xanthosoma sagittifolium, and Plectranthus rotundifolius flour the ranged between 65-84°C, 75-94.5°C, 72-86.25°C respectively. Colocasia esculenta flour showed the lowest GT (65-84°C) and which is more preferable over other flour types. Conclusion: Hence it is perceptible that flours obtained from above yam species can be utilized in the food industry.