Effect of Dehydrofreezing on the Quality of Frozen Walleye Pollock Ovaries Used as a Raw Material for Preparing Tarako Products

Abstract

Summary Eating pickled roes of various fishes is a popular custom in Japan. Tarako is a salted or salt-seasoned product prepared from walleye pollock and/or cod ovary, and accounts for the majority of pickled roe products in the Japanese market. These products are prepared using 90% or more frozen ovaries as the raw material. Freezing damage, however, is a serious issue in tarako production. To prevent freezing damage of roes, cryoprotectants such as sugars are added before freezing. Further, it has recently been demonstrated that dehydrofreezing effectively prevents freezing damage in many foods. In this study, the use of high concentrations of NaCl solution in the dehydrofreezing process during tarako production was assessed. Walleye pollock ovaries were dehydrated using 3%, 10%, 17% and saturated NaCl solution before freezing and storage. The ovaries were evaluated after thawing by drip loss, alteration in color and microscopic observation. The results revealed that the freezing damage decreased with increase in the concentration of NaCl solution.