Effect of cryogenic freezing on textural properties and microstructure of rice flour/tapioca starch blend gel

• Texture of rice flour (RF) gel was improved by blending with tapioca starch (TS).
• Blend of RF and TS at equal weight ratio showed good texture for unfrozen gel.
• Texture and morphology of frozen gel highly affected by freezing conditions.
• Blend gel ruptured if frozen via slow-rate chest freezing due to phase separation.
• Integrity of frozen blend gel remained if frozen via fast-rate cryogenic method.

Texture of rice flour (RF) gel was improved by blending with tapioca starch (TS). Fresh RF gel (40% w/w) fractured prematurely, while the RF/TS blend gel with equal weight ratio of RF and TS did not rupture under compression. Moreover, the blend gel showed the promising textural properties with the maximum hardness, and high cohesiveness and springiness. Thus, effects of cryogenic freezing and storage time on texture and microstructure of this blend gel were studied. Upon freezing and storage at −20 °C up to 3 months, the gel frozen via cryogenic freezing retained its integrity when compressed as a homogeneous distribution of small ice-rich domains was achieved. The slow-rate chest freezing, however, caused the gel fracture easily due to inhomogeneous microstructure with the presence of larger ice-rich domains. The results suggested that textural stability of the frozen RF/TS blend gel could be maintained with the use of cryogenic freezing due to the delay of phase separation.