18A-3

T. TEMSIRIPONG, Dept. of Product Development, Faculty of Agro-Industry, Kasetsart Univ., 50 Phaholyothin Road, Chatuchak, Bangkok, 10900, Thailand, S. Ikeda, Dept, of Food and Human Health Sciences, Faculty of Human Life Science, Osaka City Univ., 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka, 558-8585, Japan, and R. Pongsawatmanit, Dept, of Product Development, Faculty of Agro-Industry, Kasetsart Univ., 50 Phaholyothin Road, Chatuchak, Bangkok, 10900, Thailand.

Tapioca starch (TS) is used in the food industry as a thickening agent because of the high viscosity and clear appearance of its gelatinized paste. In food formulations, other ingredients (including hydrocolloids, sugars, salts) are often mixed to modify and improve the physical property of starch-based products. The objective of this study was to investigate the influence of sucrose and xyloglucan (XG) obtained from tamarind seeds on gelatinization of TS and texture profile of its gels. TS dispersions containing sucrose (0 to 20 wt%) and xyloglucan (0 and 2.5 wt%) were prepared. Gelatinization behavior was monitored using a differential scanning calorimeter. Gelatinized pastes containing 25% w/w polysaccharides and 0, 10, or 20% w/w sucrose were prepared in plastic cases to form cylindrical gels with 22 mm in diameter. The gels were kept at 5 ^oC for 24 h and cut into 20 mm in height for texture profile analysis (TPA). Gelatinization temperatures (T_o, T_p, T_c) at both TS/XG mixing ratios (10/0 and 9/1) increased with increasing sucrose concentration. The onset and peak temperatures slightly shifted to higher temperatures in the presence of XG. The gelatinization enthalpy of pastes containing 20 wt% sucrose showed a higher value for both mixing ratios of TS and XG. Sucrose increased the hardness and stiffness of the gels prepared from both TS alone and TS/XG. Incorporation of XG into TS decreased the hardness and stiffness but increased the cohesiveness of the gels compared with those of TS alone, suggesting that XG can decrease network rigidity by reducing the structure formation of the amylose in TS. These results suggest that sucrose strengthens the gels and delays the gelatinization of TS while XG substitution could be used to modify TS-based foods that require soft and cohesive characteristics.

Session 18A, Carbohydrate: General
2:00 PM - 5:30 PM, Sunday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana