Formation of Shelf-Stable Pickering High Internal Phase Emulsion Stabilized by Sipunculus nudus Water-Soluble Proteins (WSPs)

To form a stable emulsion system, the water-soluble proteins (WSPs) of Sipunculus nudus were prepared as the sole effective stabilizer for the high internal phase emulsion (HIPEs), of which the influence of the WSPs concentration and environmental stability was investigated. The HIPEs were fabricated using a simple one-pot homogenization process (10,000 rpm/min, 3 min) that involved blending the WSPs (0.1, 1, 2, 3, 4, and 5 wt%) with soybean oil (60, 65, 70, 75, 80, 85, and 90%). The microstructure and properties of stable HIPEs were characterized by particle size, ζ-potential, visual observations, optical microscopy, and dynamic rheology property measurements. As the concentration of WSPs increases, the mean particle diameter of HIPEs decreases, on the contrary, the apparent viscosity and storage modulus gradually increase. At a given emulsifier concentration (3 wt%), the stable and gel-like HIPEs were formed at the oil internal phase (ϕ) values of 70–75%, all the pH range in values from 3 to 9, and the ionic strength from 100 to 500 mM. Furthermore, the HIPEs that were stabilized formed a gel-like state that was relatively stable to heat and storage (30 days). And there was a new phenomenon that the destabilized HIPE of the freeze-thaw treatments could still return to a gel-like state again after homogenizing. The study results suggest that the WSPs of S. nudus as a natural emulsifier could be widely used in the food industry.

Dietary Carbohydrate and Protein Levels Affect the Growth Performance of Juvenile Peanut Worm (Sipunculus nudus): An LC–MS-Based Metabolomics Study

The peanut worm (Sipunculus nudus) is an economically important fishery resource in China. To determine how dietary carbohydrate and protein levels affect the growth performance of juvenile S. nudus and identify the mechanisms underlying observed patterns, five isoenergetic and isolipidic diets with different levels of carbohydrate and protein were formulated and fed to juvenile S. nudus; the experimental groups were referred to as EG1, EG2, EG3, EG4, and EG5, respectively. After 90 days of feeding, S. nudus had significantly lower survival rates when fed D5 compared with other diets (P < 0.05), and the highest survival rate was observed in EG2 individuals. The weight gain rate and specific growth rate were significantly higher in EG2 compared with the other groups (P < 0.05). Metabolomic profiling using liquid chromatography–mass spectrometry revealed 83 significantly differential metabolites (POS: 59; NEG: 24), which were identified via an in-house MS2 database. Pathway analysis indicated that the significantly different metabolites were involved in 22 metabolic pathways (POS: 9; NEG: 13), including tyrosine, phenylalanine, and tryptophan biosynthesis; phenylalanine metabolism; D-glutamate and D-glutamine metabolism; proline and arginine metabolism; aspartate, alanine, and glutamate metabolism; and aminoacyl-tRNA biosynthesis. These analyses implied that the biosynthetic capabilities of juvenile S. nudus were greater in the EG2. The results of this research enhance our understanding of the effects of dietary carbohydrate and protein levels on the growth performance of juvenile S. nudus.

Collagen Peptides Derived from Sipunculus nudus Accelerate Wound Healing

Marine collagen peptides have high potential in promoting skin wound healing. This study aimed to investigate wound healing activity of collagen peptides derived from Sipunculus nudus (SNCP). The effects of SNCP on promoting healing were studied through a whole cortex wound model in mice. Results showed that SNCP consisted of peptides with a molecular weight less than 5 kDa accounted for 81.95%, rich in Gly and Arg. SNCP possessed outstanding capacity to induce human umbilical vein endothelial cells (HUVEC), human immortalized keratinocytes (HaCaT) and human skin fibroblasts (HSF) cells proliferation and migration in vitro. In vivo, SNCP could markedly improve the healing rate and shorten the scab removal time, possessing a scar-free healing effect. Compared with the negative control group, the expression level of tumor necrosis factor-α, interleukin-1β and transforming growth factor-β1 (TGF-β1) in the SNCP group was significantly down-regulated at 7 days post-wounding (p < 0.01). Moreover, the mRNA level of mothers against decapentaplegic homolog 7 (Smad7) in SNCP group was up-regulated (p < 0.01); in contrast, type II TGF-β receptors, collagen I and α-smooth muscle actin were significantly down-regulated at 28 days (p < 0.01). These results indicate that SNCP possessed excellent activity of accelerating wound healing and inhibiting scar formation, and its mechanism was closely related to reducing inflammation, improving collagen deposition and recombination and blockade of the TGF-β/Smads signal pathway. Therefore, SNCP may have promising clinical applications in skin wound repair and scar inhibition.