The effect of different pretreatments followed by enzyme reaction on preparing shape-retaining softened burdock

To prepare texture-softened burdock that maintains its original shape, the effect of three different pretreatments before pectinase reaction (ENZ) up to 3 h: heating and drying (HD), freeze-thawing after heating and then drying (HFTD), or freeze-drying after heating (HFD) was compared. The hardness of raw burdock could be decreased by 15% after ENZ up to 3 h. The order of hardness by pretreatment was HFD (-93.3%) < HFTD (-80.7%) < HD (-52.8%) < R (raw), implying that the burdock could be softened by pretreatment itself. By the combination of pretreatment and ENZ, HFTD-ENZ for 3 h or HFD-ENZ over 2 h produced excellent softening. Hardness less than 2.0 × 10⁴ (N/m²) was obtained by HFD followed by ENZ over 2 h, and this could possibly be ingested by the tongue without chewing. More chlorogenic acid was also detected with those samples.