Abstract

The study was conducted to investigate the effect of soy-substitution on functional properties of tapioca a partially gelatinised irregular starch grit made from cassava. Starch was extracted from cassava tubers and soy-tapioca was produced by incorporation of full-fat soy flour into moist starch at four levels of substitution; 15: 85, 25: 75, 50: 50 before granulation and gelatinization. Functional properties of soy-tapioca samples: water absorption, bulk density, swelling capacity, oil absorption capacity, dispersibility, gelation capacity, syneresis, transmittance and pasting characteristics were determined and compared with that of tapioca. Results show that functional properties of soy-tapioca differ from each other as the ratio of soy substitution increases. Gelation, oil absorption, dispersibility, swelling, viscosity and transmittance, decreased as soy-substitution increased while water absorption capacity increased. Functional properties of soy-tapioca (15:85) suggest that it can compare favourably with that of tapioca. Enrichment of tapioca with soy flour to enhance its nutritional value is feasible however; increase in the level of soy substitution beyond 15% will alter the functional properties and affect the gelatinous nature of the tapioca meal. This may affect its acceptability and utilization by the consumers. Soy–tapioca (15: 85) can provide a nutrient dense alternative to tapioca and enhance nutritional security.

Key words: Functional properties, tapioca, cassava, starch grit, soy flour, soy-enriched tapioca, viscosity, soy-substitution.

Abbreviation

LPD, Loose pack density; WAC, water absorption capacity; OAC, oil absorption capacity; LGE, lower gelation end point; PV, peak viscosity.