Search

Consumption of fish has been positively associated with a lower risk of type 2 diabetes. In this study, the influence of pH on the separation of bioactive peptides with antidiabetic effects from Atlantic salmon frame protein hydrolysates by electrodialysis with filtration membranes (EDFM) was investigated. The results demonstrated that pH had no significant effect on final peptide concentration in either anionic (APC) or cationic peptide compartments (CPC) during EDFM but allowed the concentration of specific peptides that contained high concentrations of Glu, Ala, Lys, Arg and His residues. Moreover, the final feed compartment (FFC) and CPC after EDFM treatment at pH 6 were able to significantly enhance glucose uptake in L6 skeletal muscle cells grown in culture. The maximum enhancement of glucose uptake (40%) was demonstrated in cells treated with the FFC fraction at 1 ng/mL without insulin while a synergetic effect of FFC peptides at 1 ng/mL with insulin was observed (enhancement of glucose uptake by 31%). [ABSTRACT FROM AUTHOR]

A salmon protein hydrolysate (SPH) was produced from consecutive enzymatic hydrolysis of salmon muscle proteins with pepsin followed by trypsin + chymotrypsin. The SPH was separated into four (SF1-SF4) reverse-phase HPLC peptide fractions. The SF3 peptide fraction was the most active against both angiotensin I-converting enzyme (ACE) and renin activities during in vitro tests. SPH and SF3 inhibited ACE activity uncompetitively but renin inhibition was non-competitive. SPH and SF3 were orally administered (200 and 30 mg/kg body weight, respectively) to spontaneously hypertensive rats, followed by systolic blood pressure (SBP) measurements. The SF3 significantly (p < 0.05) reduced SBP by a maximum value of −42.1 ± 3.4 mmHg when compared to −21.1 ± 4.5 mmHg for SPH 2 h after oral administration. Mass spectrometry analysis showed some differences in the peptide ion composition, which may have contributed to the observed differences in SBP-reducing effects of SPH and SF3. [ABSTRACT FROM AUTHOR]

A nano-encapsulation strategy for a chitosan-coated liposomal oral delivery system using milk fat globule membrane (MFGM) phospholipids for the entrapment of antidiabetic peptides prepared from Atlantic salmon (Salmo salar) protein hydrolysates (SPH) was developed. The size, zeta potential, entrapment efficiency, stability during freeze-drying freeze thawing, and long-term storage abilities of the nano-capsules were investigated as a function of concentrations of phospholipid and chitosan coating material. Chitosan coating greatly improved the stability of liposomes. The maximum encapsulation efficiency (71.3%) and physical stability were achieved with 10% MFGM phospholipid and 0.4% chitosan. Chitosan coating significantly prolonged the release of SPH in simulated biological fluids. In conclusion, liposomes with “optimal” chitosan coating-concentration show great promise as a potential new delivery system for protein hydrolysates. [ABSTRACT FROM AUTHOR]

Abstract: Protamine, is a cationic peptide derived from fish milt (spermatic cells) and used in medical applications as a carrier for injectable insulin, a heparin antagonist and more recently as an antibacterial ingredient in some food products. To date, several procedures have been proposed for the purification and quantification of protamine. Of course purification of any natural product from a complex matrix necessitates its accurate quantification so that the commercial process may be optimized for recovery, yield and purity. A new pilot scale extraction and purification of protamine from frozen herring milt is described. The fractionation procedure is simple, inexpensive and does not involve the use of time-consuming chromatographic procedures nor organic solvents. Conditions for the optimum extraction and recovery of protamine as both its chloride and sulfate salts is given. Recoveries from frozen herring milt were 1.1% and 1.5% for protamine hydrochloride and protamine sulfate, respectively. Furthermore, the purification procedure was monitored and recoveries optimized using the new affinity chromatographic approach on heparin-agarose. The finished product was freeze-dried and either met or exceeded both the U.S. and E.U. Pharmacopeia standards. Various methods have been reported for the detection and quantification of protamine but few of the methods published to date are highly specific. The present study describes the determination of protamine using a novel fast protein liquid chromatographic separation on an agarose-heparin affinity column. Protamine was quantitatively eluted as a single peak with a buffered salt solution and peaks detected photometrically at 220nm. Sample preparation was carried out on acid extracts of spiked food samples including (ground beef and coleslaw). The run time including separation and column equilibration was about 42min and the detection limit for protamine was 30μg/mL. The affinity technique was found superior in many ways to previously published analytical procedures. [Copyright &y& Elsevier]

The Canadian Food Inspection Agency (CFIA) is developing a risk assessment model aimed at quantifying the food safety risk associated with food establishments under its jurisdiction. To support the development of this model, the current study was undertaken to quantify the relative importance of selected criteria considered for inclusion in the model. This process also aimed at estimating the risk associated with specific clusters of criteria. Overall, 173 criteria were presented to experts during a two-round face-to-face expert elicitation to estimate their relative risk to human health. Twenty-nine Canadian experts participated in the expert elicitation including members from academia (31%), industry (31%), and government (38%). A good consensus on the relative risks given to most criteria and clusters of criteria was achieved, and experts assessed them as significantly affecting the risk related to a food establishment. None of the experts expressed opposition to the inclusion of any criterion or to the way they were clustered. Experts assigned a relative risk of ≤4, of 4–8, and of ≥8–67% (116), 29.5% (51), and 3.5% (6) of the 173 criteria identified, respectively. Those having the highest impact on establishment food safety risk were: historical food safety recalls and lack of compliance for the sanitation program, the control of critical control points, followed by the equipment maintenance and calibration program, and the general food hygiene program. Having a sampling plan with trend analysis and follow-up actions was considered as an important mitigation factor. As a result, the median values calculated for each criterion and cluster will be used in the new Canadian Food Inspection Agency Establishment-based risk assessment model to support the allocation of inspection resources based on risk. [ABSTRACT FROM AUTHOR]

Mechanically-deboned cod muscle proteins were sequentially hydrolysed using pepsin and a trypsin + chymotrypsin combination, which was followed by passing the digest through a 1 kDa equipped tangential flow filtration system; the permeate (<1 kDa peptides) was collected as the cod protein hydrolysate (CPH). Reversed-phase high performance liquid chromatography (RP-HPLC) was used to separate the CPH into four peptide fractions (CF1–CF4) and their in vitro antioxidant properties investigated. Results showed that most of the peptide fractions (CF2–CF4) displayed significantly higher ( p < 0.05) oxygen radical absorbance capacity values (698–942 μM Trolox equivalents, TE/g) and 2,2-diphenyl-1-picrylhydrazyl scavenging activities (17–32%) than those of CPH (613 μM TE/g and 19%, respectively). However, the unfractionated CPH displayed improved capability to scavenge superoxide and hydroxyl radicals as well as significantly higher ( p < 0.05) ferric iron reduction and chelation of iron than the RP-HPLC peptides. The CPH and peptide fractions displayed a dose-dependent inhibition of linoleic acid oxidation. [ABSTRACT FROM AUTHOR]

Abstract: Deboned salmon flesh proteins were digested with three proteases (pepsin, trypsin and chymotrypsin) and the digest passed through a <1kDa equipped tangential flow filtration system; the permeate was collected as the salmon protein hydrolysate (SPH). SPH was separated by reverse-phase HPLC into four peptide fractions (SF1–SF4) and their in vitro antioxidant properties investigated using different assays. The results showed that most of the peptide fractions (SF2–SF4) displayed significantly higher (p<0.05) oxygen radical absorbing capacity values (1315–1541μM TE/g) than the SPH (819.3μM TE/g). Most of the peptide fractions also significantly (p<0.05) scavenged 2,2-diphenyl-1-picrylhydrazyl and superoxide free radicals when compared to the non-fractionated SPH. However, metal chelating activity of the SPH was significantly higher (p<0.05) than that of the peptide fractions. Overall, the free radical scavenging capacity of the peptides increased with hydrophobicity, except for hydroxyl radicals. Glutathione exhibited superior antioxidant abilities in most assays except for chelating and reducing of metal ions, where SPH and its purified fractions showed better activities. SPH and the peptide fractions strongly inhibited linoleic acid oxidation in the following order SPH=SF2=SF3>SF1>SF4, especially at 0.1 and 0.5mg/mL peptide concentrations. Therefore, salmon peptides may serve as useful ingredients to improve shelf life of lipid-containing foods and also for the formulation of nutritional products aimed at oxidative stress reduction. [Copyright &y& Elsevier]

Abstract: Bacteria isolated from the digestive tracts of blue mussels (Mytilus edulis) contaminated with paralytic shellfish toxins (PSTs) were screened for the ability to reduce the toxicity of a PST mixture in vitro. Bacteria were isolated on marine agar and grown in marine broth supplemented with a mussel extract and an algal extract containing PSTs (saxitoxin, neosaxitoxin, gonyautoxins 2 and 3, decarbamoyl-gonyautoxins 2 and 3 and C1/C2 toxins). Toxin levels were measured before and after 5d of incubation, using high performance liquid chromatography (HPLC) and reduction of overall toxicity verified by mouse bioassays. Of the 73 bacterial cultures screened, seven isolates were designated “competent” PST degraders, individually reducing the overall toxicity of the PSTs by at least 90% within 3d. Most isolates degraded 100% of the saxitoxin and neosaxitoxin within 1–3d. In all cases, the overall kinetics of degradation of the toxicities was first order, as were the individual degradation kinetics of most of the individual toxins. This is the first report of nearly complete elimination of PSTs through bacterial action and may perhaps result in the development of a practical means to eliminate or reduce the risk of PSP intoxication associated with shellfish consumption. [Copyright &y& Elsevier]

Abstract: The rubicund pigmentation in salmon and trout flesh is unique and is due to the deposition of dietary carotenoids, astaxanthin and canthaxanthin in the muscle. The present study was undertaken to determine which protein was responsible for pigment binding. Salmon muscle proteins were solubilized by sequential extractions with non-denaturing, low ionic strength aqueous solutions and segregated as such into six different fractions. Approximately 91% of the salmon myofibrillar proteins were solubilized under non-denaturing conditions using a protocol modified from a method described by Krishnamurthy et al. [Krishnamurthy, G., Chang, H.S., Hultin, H.O., Feng, Y., Srinivasan, S., Kelleher. S.D., 1996. Solubility of chicken breast muscle proteins in solutions of low ionic strength. J. Agric. Food Chem. 44: 408–415.] for the dissolution of avian muscle. To our knowledge, this is the first time this solubilization approach has been applied to the study of molecular interactions in myofibrillar proteins. Astaxanthin binding in each fraction was determined using an in vitro binding assay. In addition, SDS-PAGE and quantitative densitometry were used to separate and determine the relative amounts of each of the proteins in the six fractions. The results showed that α-actinin was the only myofibrillar protein correlating significantly (P <0.05) with astaxanthin binding. Alpha-actinin was positively identified using electrophoretic techniques and confirmed by tandem mass spectroscopy. Purified salmon α-actinin bound synthetic astaxanthin in a molar ratio of 1.11:1.00. The study was repeated using halibut α-actinin, which was found to have a molar binding ratio of astaxanthin to α-actinin of 0.893:1. These results suggest that the difference in pigmentation between white fish and Atlantic salmon is not due to binding capacity in the muscle, but rather differences in the metabolism or transport of pigment. [Copyright &y& Elsevier]