A Thermophilic 4-α-Glucanotransferase from Thermoproteus Uzoniensis Retards the Long-Term Retrogradation but Maintains the Short-Term Gelation Strength of Tapioca Starch.

Gelation of starch is a process during short-term retrogradation. However, the long-term retrogradation always leads to the quality deterioration of starch-based food. In this work, a new type of modified tapioca starch (MTS) gel with maintained starch short-term gelation strength and retarded long-term retrogradation was prepared using a novel recombinantly produced and characterized 4-α-glucanotransferase (TuαGT). In the resulting MTS exterior chains of the amylopectin part were elongated and the content of amylose was reduced, due to the disproportionation activity of TuαGT. The retrogradation analysis demonstrated that the MTS possessed highly weakened long-term retrogradation characteristics as compared to the native starch. Most importantly, the strength of the gel formed by re-gelatinized MTS is very close to that of gelatinized native tapioca starch (NTS) when storing below 30°C. These findings provide a starting point for developing a novel method for the enzymatic modification of the starch-based gels.