Effects of heat treatment on the gel properties of the body wall of sea cucumber (Apostichopus japonicus)

Abstract

The sensory texture of sea cucumber (Apostichopus japonicus) was dramatically affected by heat treatment. In this study, sea cucumbers were heated under different thermal conditions (HSC), and divided into five groups (HSC-80, HSC-90, HSC-100, HSC-110, and HSC-120) according to the heating temperature (from 80 to 120°C). The changes in texture, moisture, gel structure, and biochemical parameters of the HSC were investigated. With increasing heating time (from 10 to 80 min), the hardness and gel structure changed slightly, and the water activity decreased as the proportion of T 21 increased by 133.33, 55.56, and 59.09% in the HSC-80, HSC-90, and HSC-100 groups, respectively. This indicated that moderate heating conditions (below 100°C) caused gelation of sea cucumbers in HSC-80, HSC-90, and HSC-100 groups. However, as the water activity increased, the hardness declined rapidly by 2.56 and 2.7% in the HSC-110 and HSC-120 groups, with heating time increased from 10 to 80 min. Meanwhile, free hydroxyproline and ammonia nitrogen contents increased by 81.24 and 63.16% in the HSC-110 group; and by 63.09 and 54.99% in the HSC-120 group, as the gel structure of the sea cucumbers decomposed in these two groups. These results demonstrated that, severe heat treatment (above 100°C) destroyed the chemical bonds, triggered the disintegration of collagen fibers and the gel structure of sea cucumbers, and transformed the migration and distribution of moisture, finally causing the deterioration of the sensory texture of the sea cucumbers.

Oxidized Oligosaccharides Stabilize Rehydrated Sea Cucumbers against High-Temperature Impact

“…Preliminary experiments showed that 0.4% to 0.6% ( w / v ) oxidized oligosaccharides solution could provide decent stabilization to rehydrated sea cucumbers, so in this study rehydrated sea cucumbers were all heated in 0.5% oxidized oligosaccharide solutions for crosslinking. The crosslinked sea cucumbers were then heated in a sterilizer at 121 °C for 10 min, which according to our previous work [ 21 ], could result in severe deterioration to normal rehydrated sea cucumbers.…”

“…Heat-promoted deterioration typically softens sea cucumber body wall and increases soluble materials, which cause serious damage to rehydrated sea cucumbers, so it is currently one of the biggest problems limiting the development of ready-to-eat products from rehydrated sea cucumbers. Our group has previously suggested that deterioration is caused by heat-promoted breakage of chemical bonds in sea cucumber collagen [ 21 ], which could be avoided by extra crosslinking. The commercial value of sea cucumber relies heavily on its unit size and integrity, so crosslinking agents have to be introduced without damaging the appearance of sea cucumbers, preferably by free diffusion.…”

Characterization of Heat‐Induced Water Adsorption of Sea Cucumber Body Wall

“…The highest W abs was observed for SCBWs cooked for 180 min and soaked beyond 40 hr, with a value of 3.4. During heating, the collagen fibers inside SCBWs are denatured to form soluble gelatin (Zhang et al., ). The degree of collagen denaturation is likely to be dependent on the heating time, which may lead to changes in the internal structures of the SCBW (for example, change of porosity) and cause the different water absorption capacities in the SCBWs.…”

“…Zhang et al. () also reported that the continuous heating of sea cucumber body wall at high temperatures breaks its internal chemical bonds, causing the decomposition of the sea cucumber collagen fibers and gel structure.…”

“…When the heating temperature is below 100 °C, the collagen fibers inside cucumber body wall will rearrange to start gelation; when it reaches 100 °C or above, the chemical bonds within the collagen fibers will be broken, and the decomposition of the sea cucumber collagen fibers and the gel structure will be triggered. At this point, the moisture content, the state of water and water distribution inside the sea cucumber body wall will change drastically, which will lead to the deterioration of the sensory and textural properties of the sea cucumber (Peng et al., ; Zhang et al., ).…”