Thermal and rheological properties of tapioca starch and xyloglucan mixtures in the presence of sucrose

摘要

The influence of sucrose on thermal and rheological properties of tapioca starch (TS)-tamarind seed xyloglucan (XG) mixtures was investigated. Rapid visco-analysis profiles of 5% w/w TS/XG dispersions at different mixing ratios revealed that peak and final viscosities increased with increasing sucrose and XG contents. Loss tangent of each mixing ratio of TS/XG pastes determined from dynamic rheom-etry exhibited a lower value with increasing sucrose, suggesting solid-like properties contributed from the dissolved sucrose in the systems. Gelatinization temperatures of 25% w/w TS/XG at mixing ratios of 10/0 and 9/1 increased with increasing sucrose content whereas the gelatinization enthalpy of pastes increased in the presence of high sucrose concentration. Sucrose increased the stiffness and hardness of the 25% w/w TS/XG gels (mixing ratios of 10/0, 9.5/0.5 and 9/1) from the compression test. These results suggest that sucrose delays the gelatinization of TS and XG mixtures and strengthens the gels by increasing the elastic component.