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In order to improve the utilization of scallop byproducts, scallop female gonad hydrolysates (SFGHs) were prepared using alcalase and ribose at a mass ratio of 1:2 and pH 7.0 (95°C, up to 12 h) to develop heterogeneous Maillard-type antioxidant and flavor compounds. The formation of Schiff's base as well as modification of the amide bands in Maillard reaction products (MRPs) were investigated using ultraviolet–visible, fluorescence, and Fourier transform infrared spectroscopy. The significant decrease of amino acid residues explained the strong Maillard reactivity of SFGHs. MRPs with enhanced ABTS+ radical scavenging capacity over SFGHs promoted the survival of HepG2 cells treated with hydrogen peroxide. Moreover, 19 new volatile compounds were produced by the reaction of SFGHs with ribose. These results suggest that SFGHs–ribose MRPs can be potentially used as antioxidants with flavor properties. Abbreviations: SFGs: scallop female gonads; SFGHs: scallop female gonad hydrolysates; ABTS: 2ʹ2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid); BHT: butylated hydroxytoluene; Trolox: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; MRPs: Maillard reaction product; H2O2: hydrogen peroxide; HS-SPME/GC/MS: Headspace solid phase micro-extraction/gas chromatography/mass spectrometry. [ABSTRACT FROM AUTHOR]

In order to provide the fundamental basis for control and application of sea cucumber autolysis, the contribution of cathepsin L to intestinal proteolysis in sea cucumber (Stichopus japonicus) was investigated. Cathepsin L mRNA expression was significantly up-regulated by 1.80 ± 0.44-fold with ultraviolet irradiation (p< 0.05). According to the protein pattern identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and determination of the release of trichloroacetic acid (TCA)-soluble oligopeptide, high intestinal protein degradation was observed at pH 4.4 and 48°C. Intestinal protein proteolysis was strongly inhibited by cathepsin L inhibitors, including trans-epoxysuccinyl-L-leucyl-amido (4-guani-dino)butane (E-64), iodoacetic acid (IA), and antipain (AP). These results imply that cathepsin L is involved in intestinal autolysis in the sea cucumber S. japonicus. Abbreviations: TCA: trichloroacetic acid; Z-Phe-Arg-AMC: Z-Phe-Arg-7-amido-4-methylcou-marin; IA: iodoacetic acid; E-64: trans-epoxysuccinyl-L-leucyl-amido (4-guanidino) butane; AP: antipain; SBTI: soybean trypsin inhibitor; SDS-PAGE: sodium dodecyl sulfate polyacrylamide gel electrophoresis; RT-PCR: reverse transcription-polymerase chain reaction [ABSTRACT FROM AUTHOR]

In the present study, the rheological behavior of hydrolysates from scallop male gonad hydrolysates (SMGHs) was studied. The hydrolysates were obtained from scallop male gonads (SMGs) using papain. The changes in molecular mass of proteins in SMGHs were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results showed that the proteins of SMGs were significantly degraded after hydrolysis with papain. The degree of hydrolysis reached to 17.8% and 20.8% for SMGHs treated by papain at 300 and 3,000 U/g protein, respectively. The SMGHs exhibited a weak strain overshoot behavior as well as non-Newtonian shear thinning flow behavior. Moreover, the rheological properties of SMGHs possessed a papain dose-dependent manner. These results suggest that SMGHs could be applied as a potential gelling and thickening agent in food formulations. [ABSTRACT FROM AUTHOR]

Maillard reaction products (MRPs) were produced in sea cucumber gut hydrolysates (SCGHs)-ribose system at 75°C, 85°C, and 95°C with a pH value of 7.0 or 8.0 for 12 hour. The parameters of amount of intermediate products, fluorescence intensity, browning development, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability showed a positive correlation with each other in SCGHs-ribose system. The amount of intermediate products, fluorescence intensity, and browning development followed the zero-order kinetic with activation energy from 62 to 91 kJ/mol in the Maillard reaction of SCGHs-ribose system. Moreover, 2-methyl-butanal has positive and significant correlation with DPPH radical scavenging ability of SCGHs-ribose MRPs. These results suggest that Maillard reaction improves the antioxidant activity of SCGHs, which contributes to the generation of intermediate, fluorescent, browning, and volatile products of SCGHs-ribose system. [ABSTRACT FROM PUBLISHER]