ねり製品の保水性に関する研究 ＩＶ 塩ずりおよび加熱によるすり身の保水性の変化

Abstract

Changes in the Water Holding Capacity of Surimi Caused by the Addition of Water and Sodium Chloride and by the Subsequent Heat Treatment Yoshiaki Akahane*2 and Yutaka Shimizu*3Changes in the states of water in frozen surimi of Alaska pollack during grinding with water (25%) and Nacl (2.5%), and the subsequent heating (90°C, 120°C), were investigated. The water in surimi was categorized into three types: Ip, IIp and IIIp, by using our press method. Type Ip water, to be regarded as bulk phase water, increased with adding water into thawed surimi, whereas types IIp plus IIIp water, tightly immobilized in protein network, changed little. However, the type Ip water in ground surimi markedly decreased with the addition of NaCl while types IIp plus IIIp water increased, according to the hydration of the proteins. After the salt-ground surimi was heated, type Ip water increased again and types IIp plus IIIp water decreased proportionally. On the other hand, the type Ip water could be classified into two further sub-states, Ip-A and Ip-B, by compressing gel slices under a series of low pressures between 3 and 10kg/cm2. The type Ip-A water was regarded as “free” and Ip-B as “entrapped” in gels. With the passing of heating time, Ip-A water went on increasing and Ip-B did the reverse, although Ip (Ip-A plus Ip-B) water changed little. The increase of Ip-A water was accompanied by the apparent increment of the released water on the cut surface of specimen. The amount of Ip-A from gels highly correlated with “Hardness” as measured by a texturometer.