Nonenzymatic Softening Mechanism of Collagen Gel of Sea Cucumber (A postichopus japonicus )

Abstract

HSC (sea cucumbers treated by high pressure steam) were easy to degrade during storage, even if microorganism and endogenous enzyme were inactivated. To explore the softening mechanism of HSC, packaged samples were stored at 37C for 33 days. The hardness value decreased sharply from 374.60 to 35.00 gf in 33 days, as well as springiness, cohesiveness, chewiness and restorability. The proportion of transverse relaxation time (T23) increased from 0.841 to 0.917 in 24 days, indicating that the proportion of free water ascended significantly. Nuclear magnetic resonance images showed that part of bound water in body wall transformed into free water in 18 days. Collagen fibers were broken in 27 days as Van Gieson stained images showed. Ammonia nitrogen and e-amino group increased significantly, and free hydroxyproline level also increased from 8.33 to 24.12 μg/g, indicating the degradation of HSC. Therefore, softening of HSC may be caused by moisture migration, break of collagen fiber and degradation of collagen. Practical Applications High pressure steam treatment can inactivate microorganisms and enzymes without affecting the flavor and nutrition of sea cucumbers. However, sea cucumbers treated with high pressure steam (HSC) can also degrade after being stored for several days. This restricts the development of sea cucumber products. Therefore, it is important to study the nonenzymatic softening mechanism of HSC during storage. This will be a basis for the study in resolving the autolysis of sea cucumbers.