Physicochemical and Functional Properties of Tropical Tuber Starches: A Review

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The tropical tuber crops contain starch as the major component and thus act as important source of starch. Except cassava and to a smaller extent sweet potato, starch from other tuber crops has not been exploited for industrial applications partly because of difficulty in the extraction of the pure starches and partly because of non-availability of information about the properties of these lesser known starches. This review attempts at collating data available on the physicochemical and functional characteristics of the tropical tuber starches, highlighting their unique properties and potential field of applications. The physicochemical properties like granule shape and size X-Ray diffraction (XRD) patterns, amylose content, or content of non-starches components, show considerable variations among the tuber starches. In addition, factors like genetic origin environmental conditions and age of the plant also influence the properties. The starch granules of Colocasia esculenta and Dioscorea esculenta tubers are very small whereas dose of Canna edulis are very large, XRD patterns of yam starches are generally ‘B’, while the aroid starches posses ‘A’ patterns. DSA gelatinization temperatures are low for cassava starch and high for the aroid starches. The functional characteristics like viscosity, swelling power and solubility also depend on a number of factors such as varietal variation, method of extraction, processing conditions and instruments used for analysis. Viscosity is high for cassava and C.edulis starches, but low for most aroid starches. Clarity is good for cassava and yam starches Compared to others. Digestibility also varies among the starches. The diversity available in the tuber starches shows that some of the starches can be used in place of chemically modified starches available on the market. The realization of their important can help in value addition of these neglected crops and also provide starch with special properties for specific applications.

Keywords: Tropical tubers; Starches; Physicochemical properties; Rheological properties.

  1. Introduction
  2. Extraction Techniques
  3. Other components in Starch
  4. Colour and Appearance
  5. Granule Shape and Size
  6. Spectral Features
  7. X-Ray Diffraction Pattern
  8. Molecular Weight
  9. Amylose Content
  10. Thermal Characteristics
  11. Gelatinisation and Pasting Temperatures
  12. Viscosity
  13. Swelling Power
  14. Solubility
  15. Clarity
  16. Sol stability
  17. Digestibility
  18. Conclusions