Utilization of oxidized and cross-linked corn starches in wheat flour batter

Starch is often added to batters to improve the texture and appearance of fried food products. However, comparisons of commercially available starches in terms of batter characteristics are rare. In this study, various corn starches, native or modified, were mixed with wheat flour (20% dry solids basis), and the physical properties of the batters after deep-fat frying were examined. Native corn starches of different amylose contents (high-amylose, normal, and waxy) and chemically modified corn starches (oxidized and cross-linked) were tested. The batter was prepared by adding water to the starch-flour mixtures (42% solids) and deep-fat frying at 180°C for 30 sec. The texture of the fried batter was analyzed using a texture analyzer (TA) with a Kramer shear cell. The pasting viscosity profile of the starch-flour mixtures (7% solids in water) was also measured with a Rapid Visco Analyser. When the native corn starches of different amylose contents were compared, the crispness (peak number before breakage) and hardness (maximum peak force) measured using the instrument were positively correlated with the amylose content in starches but negatively correlated with the residual moisture content of the fried batters. The peak viscosity and breakdown in viscosity profiles of the starch-flour mixtures were also negatively correlated with crispness. The use of high-amylose corn starch was effective not only in increasing the crispness, but also in reducing the oil uptake. However, the fried batter containing high-amylose starch was denser and harder than the batter containing normal starch. Among the modified starches tested, oxidized (0.4% active Cl₂) and cross-linked (4% 99:1 mixture of STMP and STPP) starches showed improvements in the overall properties of the fried batters. With excessive oxidizations (>0.4% Cl₂), however, the crispness was reduced.