The factors contributing to the loss of phenolic content and DPPH radical scavenging activity of Taiwanese yam, Dioscorea alata Tainung No. 1 (TNG1), in the 20% TNG1-containing pollock surimi gel were investigated. Heating at 90?C for 30 min decreased both the total phenolic content and DPPH radical scavenging activity in 50% ethanolic extract from TNG1, but no significant effect was found for adding 2% NaCl. Blending 20% TNG1 with pollock surimi without heating or adding 2% NaCl could reduce the DPPH radical scavenging activity. For 20% TNG1-containing surimi samples, heating at 90?C for 30 min decreased the total phenolic content, while the combination of the heat treatment and
2% NaCl resulted in further decrease. It was suggested that heat treatment might also cause an interaction between the denatured fish proteins and phenolic compounds in TNG1, thus decreasing the extractability of the phenolic compounds.
