Decomposition of trimethylamine oxide during iced storage of blue whiting (Micromesistius poutassou)

 Products of the decomposition of trimethylamine N-oxide (TMAO) during iced storage of blue whiting were monitored over 15 days. Increasing amounts of trimethylamine (TMA) and dimethylamine (DMA) were found in the white muscle with increasing storage time. The production of TMA was interpreted as a consequence of bacterial growth, while DMA production was due to enzymatic activity of trimethylamine N-oxide demethylase (TMAOase). TMAOase activity was monitored with time in different organs. The highest activities always corresponded to kidney and spleen. Also, TMAOase was found to remain active during the 15 days of iced storage. A relationship was found between TMAOase in kidney and DMA concentrations in white muscle.     

Enzymatic hydrolysis of blue whiting (Micromesistius poutassou); functional and bioactive properties

Functional and biochemical properties of fish protein hydrolysates (FPH) from blue whiting (BW) were studied. FPH (2.5%, 5%, 10%, and 15% degree of hydrolysis [DH]) were made from isolated proteins from headed and gutted BW with Alcalase 2.4 L. The properties of dried BW mince and protein isolate compared to 4 reference proteins (soy and milk protein) were studied: color, solubility, water-holding capacity (WHC), oil-binding capacity (OBC), emulsion capacity (EC), and emulsion stability (ES). The angiotensin I-converting enzyme (ACE) inhibitory activities of the soluble fraction of BW powders were also investigated. Furthermore, the products were characterized by analyzing their chemical composition. Chemical composition, solubility, OBC, and EC of the BW powders was significantly (P < 0.05) different with different DH, while color, ES, and WHC were not significantly (P > 0.05) different. Salt content of the FPH was high (4% to 19%) and increased with increased DH. Protein solubility varied from 10% to 70% and increased with increased DH. WHC of the FPH was around 97% and was higher than that of all the reference proteins tested. OBC decreased with increased DH (from 3.5 to 2.1 g oil/g protein) and was higher than OBC of the soy and milk proteins (1.6 to 1.9 g oil/g protein). EC of FPH was similar or lower than the reference proteins. ES of FPH (60% to 90%) was similar to or lower than soy and whey proteins (60% to 98%) but higher than casein (20%). ACE inhibition activity increased as DH was increased. Practical Application: The results from this study demonstrate that a functional bioactive hydrolysate can be produced from BW, which is an underutilized fish species, and may aid the industry in better utilizing this raw material. The novelty of this research was the use of BW as a raw material where the protein has been isolated with the pH shift method. Furthermore, it was novel that bioactivity and functionality was measured in the same samples.     

Decomposition of trimethylamine oxide during iced storage of blue whiting (Micromesistius poutassou)

Products of the decomposition of trimethylamine N-oxide (TMAO) during iced storage of blue whiting were monitored over 15?days. Increasing amounts of trimethylamine (TMA) and dimethylamine (DMA) were found in the white muscle with increasing storage time. The production of TMA was interpreted as a consequence of bacterial growth, while DMA production was due to enzymatic activity of trimethylamine N-oxide demethylase (TMAOase). TMAOase activity was monitored with time in different organs. The highest activities always corresponded to kidney and spleen. Also, TMAOase was found to remain active during the 15 days of iced storage. A relationship was found between TMAOase in kidney and DMA concentrations in white muscle.     

Lipid and protein changes during the ensilage of blue whiting (Micromesistius poutassou Risso) by acid and biological methods

Fish waste is a potential source of protein for animal nutrition. Ensilage could provide an advantageous means of upgrading these residues. Careful control of the degree of proteolysis and lipid oxidation is required to produce silages of high nutritional value. This paper studies the changes in lipids and protein during storage (15 days) of acid silages (with 0, 0.25 and 0.43%, w/w, of formaldehyde) and biological silages (with 10 and 20% molasses or dehydrated whey) prepared from blue whiting. A remarkable reduction in protein solubilisation values was achieved by adding formaldehyde. However, formaldehyde addition led to an increase in the peroxide value of the oil extracted from the silages. Ensiling by biological methods seems promising. It yielded both a considerable reduction in protein solubilisation and in basic volatile nitrogen when compared with acid ensilage. In addition, the oil from biological silages had lower peroxide values than the oil from acid silages with added formaldehyde.     

A comparative study of consumer preference for blue whiting (Micromesistius poutassou) and whiting (Merlangius marlangus) before and after incorporation into products

Good quality blue whiting and whiting fillets were compared by taste panels before and after incorporation into five products. In the plain cooked form, blue whiting was liked by assessors but whiting was preferred marginally. In product form, both fish were well liked and there was no significant preference for either species.     

Frozen storage of high-pressure- and heat-induced gels of blue whiting (Micromesistius poutassou) muscle: rheological, chemical and ultrastructure studies

This paper examines the influence of frozen storage over 34 weeks on the rheological properties as well as the chemical and microstructural characteristics of gels made from muscle of blue whiting (Micromesistius poutassou) subjected to different gelling treatments entailing three combinations of pressure, temperature and time: 200 MPa, <10°C, 10 min (lot L), 375 MPa, 38°C, 20 min (lot H) and atmospheric pressure, 37°C, 30 min and then 90°C, 50 min (lot T). Freezing at –40°C caused certain changes in rheological parameters. In heat-induced gels, breaking deformation, elasticity and cohesiveness increased. Of the high-pressure-induced gels, breaking force increased and cohesiveness decreased in the gel formed at lower pressures, while the only change in the gel formed at higher pressure was some loss of elasticity. There was a general fall in water holding capacity (WHC) values. Lightness remained stable. In terms of protein solubility, there was an increase in covalent bonds in lot L. As for the ultrastructure, all gels matrixes were more disorganized as a result of freezing. In the course of frozen storage, the greatest changes in rheological parameters generally took place during the first 8 weeks, and in all the gels there was a decrease in WHC. In the heat-induced gel the changes were less marked over the storage period compared with those in the high-pressure-induced gels, but the heat-induced gel was more brittle and did not maintain maximum folding test scores. Covalent bonds increased and hydrophobic interactions decreased in all lots. The general appearance of the structure of gel T remained more homogeneous, while the pressurized gels exhibited more and larger cavities.     

Application of nisin,CO2 and a permeabilizing agent in the preservation of refrigerated blue whiting (Micromesistius poutassou)

Gram‐negative bacteria are mainly responsible for spoilage of refrigerated fish. Nevertheless, to preserve refrigerated fresh fish no additives are permitted and only packaging as in a modified atmosphere can be used. Despite the fact that the present‐day application of nisin has been extended to dairy and meat products, its ineffectiveness against Gram‐negative bacteria complicates application to fresh fish unless combined with other additives such as chelators. With this aim, agents that increase the permeability of the membrane and facilitate the diffusion of many hydrophobic antimicrobial agents were screened for their combined activity with nisin against different genera of Gram‐negative bacteria. Quantification of the synergistic effects has shown sodium hexamethaphosphate (SMP) and ethylenediaminetetraacetic acid (EDTA) were the most effective. Further studies were done on the combined effects of nisin, SMP and CO₂ in the preservation of fresh fish. A factorial experimental design was used to determine synergism between these variables. Logarithmic values of total viable counts and total volatile bases after 12 days of storage were described by empirical equations. Analysis of the results showed a marked effect of CO₂ in decreasing both variables. Whereas CO₂ interacted positively with nisin and SMP, a non‐significant interaction was observed between nisin and SMP. It is concluded that CO₂ interacts readily with SMP, and may offer an additional advantage for CO₂‐rich atmospheres in food preservation. Copyright © 2005 Society of Chemical Industry     

Chilled storage of high pressure and heat-induced gels of blue whithing (Micromesistius poutassou) muscle

 Microbiological, rheological and chemical characteristics were examined in gels made from the muscle of blue whiting (Micromesistius poutassou) and subjected to three different combinations of pressure, temperature and time: 200 MPa at 3  °C for 10 min (lot L), 375 MPa at 38  °C for 20 min (lot H) and atmospheric pressure at 37  °C for 30 min followed by 90  °C for 50 min (lot T), and kept in chilled storage for 20 days. The microorganism content dropped at the outset as pressurizing took effect, the highest microbial content being found in lot L; however as the effect was not lethal, the total load increased over the following days. Microbial load was significantly lower in lot T. During chilled storage, the values of breaking deformation, breaking force and cohesiveness of lot L were higher than those of the other lots, although they did decrease with storage. The heat-induced gel was much harder, had greater water-holding capacity and was considerably more stable than the high-pressure-induced gels. The lightness value was higher in lot H than in the other two lots. In general, changes in protein solubility tended towards the cleavage of strong bonds as a result of microbial action. The electrophoretic profiles evolved differently in each of the lots over the chilled storage period. However, all of them exhibited large numbers of bands of lower molecular mass which could have been the result of degradation. This was particularly evident in lot H. The heat-induced gels exhibited a highly porous ultrastructure, quite different from the high-pressure-induced gels; these had a more compact matrix which expanded as storage progressed. Received: 26 May 1997     

The storage life of iced southern blue whiting (Micromesistius australis)

The storage life of iced southern blue whiting (Micromesistius australis) was studied. Pre- and post-spawning characteristics were investigated by means of organoleptic assessments of raw and cooked fish, total volatile bases, reduced viscosity of high ionic strength muscle extract and GR Torrymeter readings. Results show a great influence of the biological condition on the keeping time in ice.
The results suggest that in pre-spawning condition the whole fish can be stored up to 12 days while in post-spawning condition the keeping time cannot exceed 6 days.
The gutting of the fish could lengthen the possible storage time in the post-spawning condition for up to 2 days. Nevertheless the post-spawning fish quickly loses its quality 2–3 days after catching.
The possibility of utilizing standard white fish processing machines and the influence of parasites are also discussed.     

Effect of a two‐step natural organic acid treatment on microbial activity and lipid damage during blue whiting (Micromesistius poutassou) chilling

Quality loss inhibition in chilled blue whiting (Micromesistius poutassou) was investigated. For it, a natural organic acid‐mixture including ascorbic, citric and lactic acids was applied in a two‐step processing strategy: (i) as an aqueous dipping medium previous to chilling storage and, (ii) included in the flake ice employed as chilling system. As a result of the acid‐mixture addition, a partial inhibition of microbial and biochemical mechanisms involved in the quality loss was obtained. Thus, aerobe and psychrotrophe counts in treated fish showed lower ranges (2.07–4.15 and 2.43–4.39 log CFU g^?1, respectively) than control fish (2.64–5.83 and 2.30–5.30 log CFU g^?1, respectively). Sensory analysis revealed that treated fish was still acceptable at the end of the experiment (day 9), while control fish was rejected at this time. Lipid hydrolysis (free fatty acid formation) proved to be more limiting of fish quality than lipid oxidation (peroxide and thiobarbituric acid‐reactive substance formation).     

In vitro evidence for gut hormone stimulation release and dipeptidyl-peptidase IV inhibitory activity of protein hydrolysate obtained from cuttlefish (Sepia officinalis) viscera

Two cuttlefish (Sepia officinalis) viscera protein hydrolysates were obtained with different enzymes extracted from cuttlefish and smooth hound (Mustellus mustellus). Their ability to stimulate the secretion of cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1), using the enteroendocrine STC-1 cell line, and to inhibit the DPP-IV activity during a simulated gastrointestinal digestion was assayed. The physico-chemical parameters of hydrolysates and their effects on intestinal cell viability were also determined. The hydrolysate obtained with cuttlefish enzymes (CVPH1) appeared to be the most promising for all assessed bioactivities. Thus CVPH1 was able to stimulate CCK and active GLP-1 releasing activities of enteroendocrine cells without any cytotoxicity and to inhibit DPP-IV activity. Moreover, these actions were enhanced after gastrointestinal digestion and CVPH1 was also able to inhibit the intestinal DPP-IV activity of Caco-2 cells. These very promising findings highlight, via two different mechanisms, the positive effect of CVPH1 on GLP-1 actions.     

Functional properties of fish protein hydrolysates from Pacific whiting(Merluccius productus) muscle produced by a commercial protease

Pacific whiting (Merluccius productus) muscle was used to produce hydrolysates with 10%, 15% and 20% degree of hydrolysis (DH) using the commercial protease Alcalase^® and were characterized at pH 4.0, 7.0 and 10 according their solubility, emulsifying and foaming properties. Protein recovered in soluble fractions increased proportionally with the hydrolytic process, yielded 48.6 ± 1.9, 58.6 ± 4.1 and 67.8 ± 1.4 of total protein after 10%, 15% and 20% DH, respectively. Freeze-dried hydrolysates presented almost 100% solubility (p > 0.05) at the different pHs evaluated. Emulsifying properties (EC, EAI and ESI) were not affected by DH as most samples showed similar (p > 0.05) results. Higher EC (p ? 0.05) than sodium caseinate, used as control, were obtained at pH 4 for most hydrolysates. Hydrolysates showed very low foaming capacity not affected by pH; but foam stability was equal or even better (p > 0.05) than bovine serum albumin (BSA), except at pH 4.0. Results suggest that hydrolysates from Pacific whiting muscle can be produced with similar or better functional properties than the food ingredients used as standards.     

In vitro antioxidant activity of papain‐treated grass carp (Ctenopharyngodon idellus) protein hydrolysate and the preventive effect on fish mince system

Antioxidant activities of papain‐treated grass carp protein hydrolysate (HP) were investigated using in vitro methods and in grass carp mince system. Lipid oxidation, colour changes and cooking loss in grass carp mince added with 0% (control), 0.5%, 1.0%, 2.0% and 4.0% HP during refrigerated storage (4 °C) for 8 days was studied. HP could chelate 50% of Fe²⁺ and scavenge 50% of hydroxyl radicals at the concentration of 0.81 and 8.12 mg mL^?1, respectively. And HP could effectively decrease peroxide values and inhibit the formation of thiobarbituric acid reactive substances in fish mince throughout storage (P < 0.05), at the application level range from 0.5% to 4.0%. In HP‐treated samples the formation of conjugate dienes (CDs) was retarded 5–30% at day 6 of storage compared to control. In addition, HP could significantly decrease cooking loss of fish mince samples, at the application level range from 1.0% to 4.0%.     

Acceptability of crackers ('Keropok') with fish protein hydrolysate

Proteins from Oreochromis mossambicus , a freshwater fish, were hydrolysed, using alkalase 0.61, to produce a soluble, spray-dried hydrolysate. The hydrolysis was carried out at 50°C, using a ratio of one part water and one part fish mince, an enzyme:substrate ratio of 1:50 at pH 8.0. Reaction was terminated by heating to 90°C for 20min. After neutralization, the soluble fraction obtained after centrifugation was spray dried in a mini spray-drier, at an air inlet temperature of 170°C and a feed rate of 41⁻¹. The spray-dried hydrolysate was incorporated into crackers which are fried before eating. Ten per cent hydrolysate was found to give maximum linear expansion. Sensory evaluation with 20 experienced assessors showed that in terms of appearance, crispiness and colour, crackers with hydrolysate had the highest scores, compared to crackers made with O. mossambicus and Sciaena sp. (Jewfish). There were no significant differences in overall acceptability in all three samples. Crackers with hydrolysate also had the highest nitrogen content.     

Evidence of in vivo satietogen effect and control of food intake of smooth hound (Mustelus mustelus) muscle protein hydrolysate in rats

Protein hydrolysates are of a significant interest, due to their potential application as a source of bioactive peptides in nutraceutical and pharmaceutical domains. The present study was focused on the effect of protein hydrolysate from smooth hound (Mustelus mustelus) (SHPH) in the regulation of components of the food intake control such as satiety. SHPH was produced by intestinal digestive proteases from the same species. The amino acid analysis by GC/MS showed that the hydrolysate was rich in leucine, alanine, glycine, threonine, serine, lysine and glutamate. The molecular weights of peptides in SHPH were estimated by ESI-MS to be between 200 and 2500 Da. Biological in vivo capacities of SHPH in rats were evaluated by determination of the CCK-like peptides and insulin content using a clinical human radioimmunoassay. The food intake and the body weight of rats were measured during the period of treatment. Rats treated with SHPH showed a significant decrease in body weight at the end of treatment, as well as a decrease of food intake. Our findings revealed a possible mechanism of the beneficial effects of SHPH in appetite regulation, and this might be important to prevent the risk of a number of medical conditions including type II diabetes.     

Gaping studies in blue whiting (Micromesistius poutassou)—The effect of prefreezing treatments

Blue whiting caught in January and April were stored in ice, iced sea water and at ambient temperature for varying lengths of time before freezing on board. Thawed fish samples were scored for gaping. The results indicate that storage in iced sea water before freezing reduced both gaping and the seasonal variability of the degree of gaping in the blue whiting.     

Quality assessment of laminated fillet blocks from blue whiting (Micromesistius poutassou)

Laminated fillet blocks made from blue whiting (Micromesistius poutassou) caught in February and April were assessed for quality. The total protein nitrogen value in February-caught fish was greater than the April-caught fish. The bone content, water content and pH values were consistently lower in the February fish than the April fish. Measurement of the acceptability of deep fried, breaded fingers made from the fish and compared with cod fingers produced from fish caught at the same time of year showed a consistent difference between the cod and blue whiting. In addition, the fish fingers from fish caught in February scored consistently higher than those caught in April. The implications of the findings are discussed.     

Isolation and characterization of three antioxidant pentapeptides from protein hydrolysate of monkfish (Lophius litulon) muscle

In the current study, an efficient method had been developed to acquire the antioxidant hydrolysate of monkfish muscle protein (MPH) using trypsin by an orthogonal (L₉(3)⁴) test. Under the optimum conditions of enzymolysis time 4 h, enzyme-to-substrate ratio (E/S) 2%, enzymolysis temperature 40 °C and pH 8.0, the DH (Degree of hydrolysis) and hydroxyl radical scavenging activity of MPH reached 19.83 ± 0.82% and 58.05 ± 3.01%, respectively. By using ultrafiltration, gel filtration chromatography and reversed phase high performance liquid chromatography (RP-HPLC), three antioxidant pentapeptides were isolated from MPH, and their amino acid sequences were identified as Glu-Trp-Pro-Ala-Gln (MPH-P1), Phe-Leu-His-Arg-Pro (MPH-P2), and Leu-Met-Gly-Gln-Trp (MPH-P3) with molecular weights of 629.68 Da, 668.80 Da, and 633.77 Da, respectively. MPH-P1, MPH-P2, and MPH-P3 exhibited good scavenging activities on hydroxyl radical (EC₅₀ 0.269, 0.114 and 0.040 mg/ml), DPPH radical (EC₅₀ 2.408, 3.751, and 1.399 mg/ml), and superoxide anion radical (EC₅₀ 0.624, 0.101, and 0.042 mg/ml) in a dose-dependent manner. MPH-P3 was also effective against lipid peroxidation in the model system. The antioxidant activities of MPH-P1, MPH-P2, and MPH-P3 were due to their small sizes and the presence of antioxidant and hydrophobic amino acid residues within their sequences. The results of this study suggested that the protein hydrolysate and/or its isolated peptides might be effectively used as food additives for retarding lipid peroxidation occurring in foodstuffs.