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Characterization of Waxy Rice Cakes (Mochi) with Rapid Hardening Quality by Instrumental and Sensory Methods

¹National Agriculture and Food Research Organization, National Food Research Institute, Kannondai, Tsukuba, Ibaraki 305-8642, Japan. ²Corresponding author. Phone: +81-29-838-8031. Fax: +81-29-838-7996. E-mail: tomokos@affrc.go.jp ³National Agriculture and Food Research Organization, Institute of Crop Science, Kannondai, Tsukuba, Ibaraki 305-8518, Japan. ⁴Ibaraki Agricultural Center, Plant Biotechnology Institute, Mito, Ibaraki 311-4203, Japan.

The textural properties of cooked waxy rice cakes made from four waxy rice varieties including the unique varieties Kantomochi 172 (K172) and BC3 with the property of rapid hardening were analyzed by instrumental and sensory methods. For the instrumental analysis, a compression test, adhesiveness test, and tensile test were conducted. The waxy rice cakes made from K172 and BC3 showed significantly higher compressive force and resistance to break under tensile load. Significant difference in amylopectin chain-length distribution was observed between each variety, and this difference strongly reflected the hardness of waxy rice cakes. The peak area ratio of amylopectin branch chains with 6–12 degrees of polymerization negatively correlated with the compressive force required for 50 and 80% strain. Sensory evaluation showed that the waxy rice cakes made from these varieties had a significantly harder, less stretchable, less smooth surface, whereas the scores for adhesiveness and ease to cut off (hagire) were preferable to those for other rice varieties.