Hiroki Saeki

Gelation of salted paste of Alaska pollack by high hydrostatic pressure and change in myofibrillar protein in it.

Frozen surimi of Alaska pollack was ground with 2.5% NaCl and treated by a high hydrostatic pressure. Strong gel was formed from the salted paste by treatment at 2.0-4.0kbar at 0°C for 10min. The gel by 3.0kbar pressure treatment had the greatest gel strength. The high pressure-induced gel was different from the heat-induced gel in its property. It had greater gel strength and is more transparent in the appearance compared with the heat-induced gel. The high pressure-induced gel had a small amount of myosin heavy chain and concomitantly a large amount of high molecular weight components. Furthermore, it also had a large amount of Cl component which was not solubilized with SDS-urea-mercaptoethanol medium, whereas the heat-induced gel had no such component. These findings suggest that gel-formation by a high pressure depend largely on the cross-linking of myosin heavy chain. These results indicated that gelation of meat paste induced by a high pressure may be advantageous to processing of a new type fabricated food from fish meat.

Loss of filament-forming ability of myosin by non-enzymatic glycosylation and its molecular mechanism.

Carp and scallop myosin and their subfragments (S‐1 and rod) were reacted with glucose to investigate the effect of non‐enzymatic glycosylation on the functionality of myosin. The filament‐forming ability of the myosin rod diminished with the progress of non‐enzymatic glycosylation and myosin became soluble in 0.1 M NaCl. The inhibition of the self‐assembly of myosin molecules occurred chemically as a result of the increase in negative charge repulsion among myosin molecules and, further, physically as a result of the introduction of the glycosyl units into the surface of the rod region.

Isolation and characteristics of trypsin inhibitor from the hepatopancreas of a squid (Todarodes pacificus).

Trypsin inhibitor was purified from the hepatopancreas of squid (Todarodes pacificus). The final inhibitor preparation was nearly homogeneous by SDS-PAGE with an estimated molecular weight of approximately 6300. The squid trypsin inhibitor was acid- and heat-stable, and active against trypsins from the pyloric ceca of starfish (Asterias amurensis) and saury (Cololabis saira) and porcine pancreatic trypsin. Amino acid composition of the squid trypsin inhibitor was compared with other invertebrate trypsin inhibitors. The squid trypsin inhibitor inhibited the autolysis of walleye pollock (Theragra chalcogramma) myofibrillar proteins.

Antioxidative Ability of Chicken Myofibrillar Protein Developed by Glycosylation and Changes in the Solubility and Thermal Stability

Myofibrillar protein prepared from chicken breast muscle was incubated with several concentrations of glucose or maltose for 6 h at 60 °C and 35% relative humidity in order to obtain glycosylated chicken protein. When the ratio of the weights of the myofibrillar protein and glucose or maltose had respectively reached 1:6 or 1:3–5, the solubility of each type of glycosylated chicken protein in a 0.1 M NaCl solution was exceeded by about 60%, although the myofibrillar protein was insoluble in a low ionic strength solution. Moreover, when the myofibril and maltose reaction (myofibril:maltose = 1:4) was extended to 36 h, the glycosylated protein did not undergo denaturation when held at 50 °C for 2 h, while it also exhibited an antioxidative function against superoxide anion radicals.

Feasibility study on water solubilization of spawned out salmon meat by conjugation with alginate oligosaccharide

A feasibility study was carried out to determine whether water-soluble salmon meat could be manufactured by conjugating a glycosyl unit using the Maillard reaction. Spawned out salmon meat was washed, mixed with alginate oligosaccharide (AO) and sorbitol, lyophilized, and then heated at 60°C and 5–95% relative humidity (RH) to introduce AO (the mean degree of polymerization was six) into the myofibrillar proteins through the Maillard reaction. The reaction progressed with an increase in the reaction humidity and the amount of AO bound to the protein reached >150 μg/mg at RH 65 and 90%. However, the protein glycosylation under high humidity impaired protein solubility and the meat protein became effectively water-soluble with the conjugation with AO at reaction conditions of 60°C and RH 35%. The improved characteristics of the meat protein were highly stable at room temperature. Further, the water-soluble protein can be prepared from the frozen salmon meat stored at −25°C for 60–90 days. These results indicate that protein glycosylation has strong potential for use with spawned out chum salmon. The suppression of protein denaturation during processing is important to obtain the high water-soluble meat protein.

Effects of manufacturing factors on the viscosity of a polysaccharide solution extracted from Gagome Kjellmaniella crassifolia.

A highly viscous polysaccharide solution was extracted from Gagome Kjellmaniella crassifolia in 20°C water. The eluted sugar concentration was 0.16%, and the extracted carbohydrates consisted of fucoidan, laminaran, and alginate at an approximately ratio of 8.2:0.8:1.0. An increase in the extraction temperature resulted in a less viscous solution, even though the amount of eluted sugar was higher than that obtained at a lower temperature. The most viscous extraction solution was obtained at a neutral pH, with a more acidic or alkaline extraction solution being a less viscous. When the highly viscous polysaccharide solution was heated, the viscosity decreased markedly with increasing temperature. The viscosity of the polysaccharide solution increased after dialysis against water and decreased with the addition of either KCl or NaCl. However, the viscosity was recovered to previous levels by following re-dialysis against water. The removal of divalent cations by EDTA and the re-addition using CaCl2 or MgCl2 also caused reversible changes to the viscosity. These characterizations will be useful for widespread applications of viscous K. crassifolia polysaccharides.

A graphical solution of multimodal optimization to improve food properties

Abstract When the search spaces were set excessively broad, the random‐centroid optimization (RCO) was difficult to home‐in on the global optimum in the case of multimodal functions. A preliminary narrowing strategy was introduced based on the general trend of steeper slopes toward the global optimum than those toward local optima. The search spaces were narrowed to half for factors at either end by comparing response values at both extreme terminals (0.1 and 0.9 in the full space of 0‐1.0) of the search space (half‐space design). The differences (or ratios) of these two values represented the slopes. This new method was more reliable than repeating probabilistic random search to narrow search spaces prior to RCO as reported in the previous paper (Nakai et al., 1998a). However, for most of the ordinary optimization projects with reasonable sizes of the search spaces, there was no need of using this half‐space design search. Application of the RCO, by changing the amount of FeCl2 to add to fish actomyosin ...

In vitro and in vivo anti-inflammatory activity of digested peptides derived from salmon myofibrillar protein conjugated with a small quantity of alginate oligosaccharide

Salmon myofibrillar protein (Mf) was investigated as a source of edible anti-inflammatory products. Peptides produced by stepwise digestion of Mf (without carbohydrate) with pepsin and trypsin had little effect on the secretion of inflammation-related compounds from lipopolysaccharide-stimulated RAW 264.7 macrophage cells. However, peptides prepared from Mf conjugated with alginate oligosaccharide (AO; 19 μg/mg protein) (dMSA) through the Maillard reaction in the presence of sorbitol significantly reduced the secretion of the pro-inflammatory mediators nitric oxide, tumor necrosis factor (TNF)-α and interleukin (IL)-6, as well as mRNA expression of TNF-α, IL-6, inducible nitric oxide synthase and cyclooxygenase-2. Additionally, dMSA inhibited acute inflammation in a carrageenan-induced model of paw edema in mice, but had no effect on natural killer cell cytotoxic activity or macrophage phagocytosis. These results suggest that fish Mf conjugated with AO may be a potential food material with anti-inflammatory function. Graphical abstract The digested peptide suppressed localized acute inflammation by oral administration in mice carrageenan-induced edema test.

Transcriptome analysis of the duodenum in Wistar rats fed a trypsin inhibitor derived from squid viscera.

To investigate the effects of oral administration of a trypsin inhibitor (TI), normal Wistar rats were fed a TI derived from squid (Todarodes pacificus) for 10 weeks and gene expression profiles in the duodenum, pancreas, liver, and muscle were then analyzed using DNA microarrays. Although no significant changes could be observed in growth, food intake, tissue weight, or blood tests among the tissues tested, the duodenum showed the most remarkable changes in the global gene expression profile. Significant up-regulation of mRNAs encoding gastrin, gastrokine, cholecystokinin and somatostatin in the duodenum was validated by qPCR analysis. In gene ontology (GO) analysis of the up-regulated differentially expressed genes (DEGs), GO terms related to keratinization and innate mucosal defense were enriched (p < 0.001) in the category of biological processes in addition to assumable terms such as regulation of secretion and response to nutrients, vesicle-mediated transport, and so forth. In the same analysis, calcium ion binding was listed at the deepest hierarchy in the category of molecular function. These results indicate that the duodenum responds to TI treatment by a wider range of physiological processes than previously assumed such as keratinocyte differentiation and innate mucosal defense, in which calcium plays a crucial role.

Anti-inflammatory effects of dulse (Palmaria palmata) resulting from the simultaneous water-extraction of phycobiliproteins and chlorophyll a

The use of dulse (Palmaria palmata) as a source of edible anti-inflammatory products was evaluated in this study. Phycobiliproteins and chlorophyll a were simultaneously extracted from lyophilized dulse leaves via water-extraction, and subjected to thermolysin digestion to produce thermolysin-digested water-extract (d-DWE). d-DWE significantly reduced tumor necrosis factor-α, interleukin-6, and nitric oxide in LPS-stimulated murine macrophages (RAW 264.7 cells), and orally administered d-DWE mitigated acute inflammation in carrageenan-induced paw edema of mice. Mass spectrometry revealed d-DWE contained peptide LRDGEIILRY (derived from phycoerythrin β-chain) and chlorophyll a decomposition products, and they individually reduced the secretion of the proinflammatory mediators in LPS-stimulated RAW 264.7 cells. These results indicate the anti-inflammatory activity could be from a combined effect of phycobiliprotein and chlorophyll a decomposition products prepared from the water-extract of dulse. Thus, inexpensive and safe water-extraction method is effective for the extraction of anti-inflammatory components from dulse.