Sardine Muscle Research Articles

The ACE Inhibitory Dipeptide Met-Tyr Diminishes Free Radical Formation in Human Endothelial Cells via Induction of Heme Oxygenase-1 and Ferritin

Food sources such as soybeans and fish contain angiotensin I converting enzyme (ACE) inhibitory peptides with antihypertensive properties. Methionine-tyrosine (Met-Tyr) is an ACE inhibitory dipeptide derived from sardine muscle. The present study investigates the effect of Met-Tyr on the expression of the antioxidant stress proteins, heme oxygenase-1 (HO-1) and ferritin, in endothelial cells derived from the human umbilical vein and their contribution to the decrease in radical formation that occurs under the influence of this dipeptide. Preincubation of endothelial cells with Met-Tyr (10–300 μmol/L) followed by washout markedly diminished subsequently induced NADPH-mediated radical formation. This indirect protection was associated with a significant increase in protein expression of HO-1 and ferritin and abolished by the HO inhibitor zinc deuteroporphyrin IX 2,4-bis-ethylene glycol (ZnBG). The HO product bilirubin produced antioxidant effects comparable to those of Met-Tyr. Met-Tyr raised HO-1 mRNA levels by enhancing mRNA stability. Antioxidant effects were specific for Met-Tyr and not observed with other methionine-containing dipeptides or ACE inhibitory agents. Our results demonstrate that Met-Tyr protects endothelial cells from oxidative stress via induction of HO-1 and ferritin but independently of its ACE inhibitory properties. This pathway represents a novel, potentially antiatherogenic mechanism of Met-Tyr and dietary proteins releasing Met-Tyr during gastrointestinal digestion.

Characterisation of myoglobin from sardine ( Sardinella gibbosa) dark muscle

Myoglobin from the dark muscle of sardine ( Sardinella gibbosa) with the molecular weight of 15.3 kDa was isolated and characterised. The different myoglobin derivatives exhibited varying thermal unfolding characteristics. Deoxymyoglobin showed a single distinct endothermic peak at 74.5 °C, whereas two transition temperatures were noticeable for oxymyoglobin (64.5 and 78.4 °C) and metmyoglobin (59.0 and 76.0 °C). The spectrum of deoxymyoglobin and oxymyoglobin had absorption bands at 739, 630, 575, 500 and 405 nm, while the disappearance of the peak at 575 nm was found in the spectrum of metmyoglobin. The soret peak of all derivatives was noticeable at 405 nm. The autoxidation of myoglobin became greater at very acidic or alkaline conditions as evidenced by the formation of metmyoglobin, the changes in tryptophan fluorescence intensity as well as the disappearance of soret absorption. The higher temperature, particularly above 40 °C, and the longer incubation time induced the higher metmyoglobin formation as well as the conformational changes.

Physicochemical properties, gel-forming ability and myoglobin content of sardine (Sardinella gibbosa) and mackerel (Rastrelliger kanagurta) surimi produced by conventional method and alkaline solubilisation process

Characteristics and gel properties of sardine and mackerel surimi produced by conventional washing process and alkaline solubilising process were investigated. The decrease in Ca2+-ATPase activity with the changes in the surface hydrophobicity was found in surimi produced by alkaline solubilising process (p<0.05), suggesting the denaturation of protein induced by this process. The alkal-ine solubilising process with prewashing could remove myoglobin most effectively from sardine muscle, whereas the process without prewashing resulted in the greatest myoglobin removal in mackerel muscle (p<0.05). Surimi conventionally prepared by water or NaCl washing showed the gel with greater breaking force and deformation than that from alkaline solubilising process (p<0.05). The hig-her expressible moisture was found in the gels of surimi pre-pared by alkaline process, indicating the poor water holding capacity of the gel matrix. The highest whiteness was found in the gel of sardine surimi produced by alkaline process with prewashing but the highest whiteness was obtained in the gel of mackerel surimi washed with distilled water.

Changes of lipids in sardine ( Sardinella gibbosa) muscle during iced storage

Changes in lipids of sardine ( Sardinella gibbosa) muscle during 15 days of iced storage were investigated. Lipid deterioration, lipolysis and lipid oxidation, occurred throughout the storage. The progressive peroxide formation was monitored by the increase in the absorbance band at 3600–3200 cm −1 in Fourier transform infrared (FTIR) spectra and increased peroxide values were observed in sardine muscle up to 6 days of iced storage, followed by a continuous decrease from then for 9 days ( P < 0.05). The increase in thiobarbituric acid reactive substances (TBARS) was noticeable throughout the iced storage ( P < 0.05). However, no difference in conjugated diene (CD) of sardine muscle was found within the first 12 days of iced storage ( P > 0.05). Marked decreases in unsaturated fatty acids, especially eicosapentaenoic acid (EPA; C20:5( n − 3)) and docosahexaenoic acid (DHA; C22:6( n − 3)) were observed as the storage time increased. Those changes indicated that lipid oxidation occurred in sardine muscle. A gradual increase in free fatty acid formation, with decreases in triglyceride and phospholipid contents, was found during iced storage ( P < 0.05), suggesting hydrolysis induced by lipases and phospholipases.

Effects of storage in ozonised slurry ice on the sensory and microbial quality of sardine ( Sardina pilchardus)

The use of slurry ice, both alone and in combination with ozone, as compared with traditional flake ice was investigated as a new refrigeration system for the storage of sardine ( Sardina pilchardus). Microbiological, chemical and sensory analyses were carried out throughout a storage period of 22 days. According to sensory analyses, sardine specimens stored in ozonised slurry ice had a shelf life of 19 days, while counterpart batches stored in slurry ice or flake ice had shelf lives of 15 and 8 days, respectively. Storage in ozonised slurry ice led to significantly lower counts of aerobic mesophiles, psychrotrophic bacteria, anaerobes, coliforms, and both lipolytic and proteolytic microorganisms in sardine muscle, and of surface counts of mesophiles and psychrotrophic bacteria in sardine skin as compared with the slurry ice and the flake ice batches. In all cases, the slurry ice batch also exhibited significantly lower microbial counts, both in muscle and skin, than the flake ice batch. Chemical parameters revealed that the use of slurry ice slowed down the formation of TVB-N and TMA-N to a significant extent in comparison with storage in flake ice. A combination of slurry ice with ozone also allowed a better control of pH and TMA-N formation as compared with slurry ice alone. This work demonstrates that the combined use of slurry ice and ozone for the storage of sardine can be recommended to improve the quality and extend the shelf life of this fish species.

Abstracts

Abstracts

Characteristics and gel properties of muscles from sardine ( Sardinella gibbosa) and mackerel ( Rastrelliger kanagurta) caught in Thailand

Dark and ordinary muscle from sardine ( Sardinella gibbosa) and mackerel ( Rastrelliger kanagurta) were characterized. Lipid and myoglobin contents were higher in dark muscle than in ordinary muscle of both species, and higher contents of both constituents were found in sardine muscle than mackerel muscle. The extractable myoglobin contents in sardine dark and ordinary muscle were 14.27 and 2.18 mg/g, while mackerel dark and ordinary muscle contained 4.88 and 1.37 mg myoglobin/g sample, respectively. Alkali-soluble protein and stroma contents were greater in dark muscle than ordinary muscle. Mackerel muscle comprised a higher content of non-protein nitrogenous compounds than sardine muscle. The effect of washing conditions on the myoglobin extractability was investigated. A large amount of myoglobin was removed in the first washing cycle and only a small amount was removed in the second washing cycle. The highest removal of myoglobin from sardine (32.10–46.55%) and from mackerel muscle (103.20–313.66%) was achieved when the mince was washed with 0.2% NaCl and 0.5% NaCl, respectively. Washing media showed the marked effect on the color, expressible drip and textural properties of sardine and mackerel mince gels. The breaking force of directly heated and kamaboko gels from both sardine and mackerel mince washed with NaCl solution was higher than that of unwashed mince and water washed mince. However, no difference in deformation was observed. Washing also resulted in increased whiteness and lowered expressible moisture. In general, sardine surimi showed the superior gel-forming ability and whiteness to mackerel surimi.

Domoic acid accumulation in the sardine Sardina pilchardus and its relationship to Pseudo-nitzschia diatom ingestion

Planktivorous fish are key potential vectors for the phycotoxin domoic acid (DA), pro- duced naturally by diatoms from the genus Pseudo-nitzschia. The diet of the Atlantic sardine Sardina pilchardus is largely dominated in number by microplanktonic species such as chain-forming diatoms, making the accumulation of this toxin and its transfer to the higher trophic levels likely. DA concentration in sardine tissues and Pseudo-nitzschia ingestion were monitored fortnightly during 2002 and 2003 off the NW coast of Portugal, where seasonal upwelling events are responsible for the occurrence of algal blooms. Sardine stomach content analysis showed that Pseudo-nitzschia prey reached concentrations as high as 7.8 × 10 6 cells g -1 ; in some cases this diatom genus represented more than 99% of the phytoplanktonic prey identified in the stomachs. Four different diatom species were distinguished using scanning electron microscopy (SEM): P. australis, P. pungens, P. pseudodel- icatissima and P. delicatissima. DA accumulation in sardines was linearly dependent on P. australis consumption. Toxin content per individual cell was estimated by comparing DA and P. australis con- centrations in the stomach contents. DA production by P. australis was significantly higher in the summer months than during the spring. In both years, DA in sardine guts was initially detected in May and peaked several times until late summer. Toxin distribution in the different tissues was also determined, with the highest DA levels detected in the intestine. The maximum toxin concentration observed in sardine guts was 128.5 µg DA g -1 . No DA was found in the sardine muscle; consequently implications for human health appear minimal.

Lipase activity in different tissues of four species of fish: rohu (Labeo rohita Hamilton), oil sardine (Sardinella longiceps Linnaeus), mullet (Liza subviridis Valenciennes) and Indian mackerel (Rastrelliger kanagurta Cuvier)

AbstractLipase activity in stomach and pyloric caeca, liver, intestine and red muscle of rohu (Labeo rohita Hamilton), oil sardine (Sardinella longiceps Linnaeus), mullet (Liza subviridis Valenciennes) and Indian mackerel (Rastrelliger kanagurta Cuvier) was studied. Distinct differences in lipolytic activity in different tissues of these fish were observed. Rohu showed the highest activity in all tissues in comparison with the other three species of fish. Among the three size groups of mullet, medium‐sized mullet showed higher activity than the other two groups in all tissues except intestine. Rohu hepatopancreatic lipase exhibited more hydrolytic activity on fish oil than rohu intestinal lipase. Copyright © 2003 Society of Chemical Industry

Preliminary Characterization of European Sardine Transglutaminase

The significant role of transglutaminase (TGase) in the setting of surimi led us to perform its preliminary characterization in sardine muscle. The time course of the reaction and the effect of enzyme level were studied. The temperature optimum was around 35°C and the thermal stability was studied in the 15-55°C range. Higher TGase activity was measured in sardine dark muscle than in the white muscle. A slow decrease of TGase activity during ice storage of sardine was recorded, but after eight days in ice it was about 50% of its initial activity. Cold storage of sardine for a short period did not affect TGase activity.

食品タンパク質由来機能性ペプチドによる血圧降下作用 イワシペプチド（Ｖａｌ‐Ｔｙｒ）による降圧食品の開発を中心として

The procedures for preparing a food material with antihypertensive efficacy from sardine muscle have been reviewed. Hydrolysis of sardine muscle by pepsin yielded angiotensin I-converting enzyme (ACE)-inhibitory peptides. Further studies aimed at preparing a hydrolyzate with potent ACE-inhibitory activity as well as having good flavor were carried out using Bacillus licheniformis alkaline protease. After 17h of hydrolysis of 0.3wt% sardine protein, the 10wt% ethanol fraction obtained with ODS resin showed some excellent properties, including strong ACE-inhibitory activity (IC50=0.015mg protein/mL), high digestive resistance, no bitterness, and no antigenicity. In addition, this fraction was confirmed to have a significant in vivo depressor effect in mildly hypertensive volunteers (n=29), who showed a 9.3mmHg reduction in systolic blood pressure and 5.2mmHg reduction in diastolic blood pressure after 4 weeks of oral administration of this peptide drink (4g of the ODS fraction/200mL/day).

Postmortem Biochemical and Functional Characteristic of Monterey Sardine Muscle Stored at 0 °C

ABSTRACT:Postmortem changes of sardine muscle during 15 d storage at 0 °C were studied to evaluate its quality and functionality. No microbial deterioration was detected since trimethylamine and histamine concentration remained low with final values of ≤ 1.62 mg/100g and 0.00018 ppm, respectively. A final proteolytic activity ≤ 20 μg Tyrosine/min/g protein was detected. Lipid oxidation from moderate to advanced was detected after day 5 with values of 31.8 to 33.9 meq/kg and 26 mg/kg for peroxide value and thiobarbituric acid value respectively. Muscle protein showed no gel‐forming ability. Extraction of myofibrillar protein decreased 45% and 81% at day 5 and 15 respectively. Overall results indicated that good quality was maintained during the storage period with a final K value of 50.7% when proper handling practices were implemented.

Determination of epsilon-N-pyrrolylnorleucine in fresh food products.

epsilon-N-Pyrrolylnorleucine was determined in different fresh food products to study its presence as a normal component of food proteins. Twenty-two different products were screened: cod, cuttlefish, salmon, sardine, trout, beef, chicken, pork, broad bean, broccoli, chickpea, garlic, green pea, lentil, mushroom, soybean, spinach, sunflower, almond, hazelnut, peanut, and walnut. Foods were homogenized, their proteins were precipitated with trichloroacetic acid and hydrolyzed with 2 N NaOH for 20 h, and the epsilon-N-pyrrolylnorleucine content was determined by capillary electrophoresis. The epsilon-N-pyrrolylnorleucine, which was identified by HPLC/MS in sardine muscle hydrolysate, ranged in the 22 foods analyzed from 0.24 to 6.36 micromol/g. This concentration was correlated with the protein content of the food (r = 0.687, p = 0.00041). In addition, the epsilon-N-pyrrolylnorleucine/lysine ratio was found to be a function of the lipid, iron, and protein contents of the food (r = 0.881, p < 0.0001) and was directly correlated with lipid and iron contents and inversely correlated with the protein content. These results are in agreement with the oxidative stress origin proposed for epsilon-N-pyrrolylnorleucine and suggest that the epsilon-N-pyrrolylnorleucine/lysine ratio is a characteristic of each food. In addition, epsilon-N-pyrrolylnorleucine seemed to be a normal component of many fresh food products, in which it may be acting as a natural antioxidant.

Chemical and functional properties of sardine (Sardina pilchardus W.) dark and light muscle proteins during frozen storage. Effect of washing on mince quality / Propiedades químicas y funcionales de las proteínas del músculo oscuro y claro de sardina (Sardina pilchardus w.) durante el almacenamiento en congelación. Efecto del lavado en la calidad del músculo picado

This paper examines the effects of eight months of frozen storage on the protein conformation and functionality of whole, light and dark sardine muscles, and washed mince. The variation in protein surface hydrophobicity and Ca-ATPase activity was different in dark muscle from that in whole muscle over the storage period. The dark muscle lacked gel forming capacity because of its higher fat content and a greater presence of low molecular weight proteins, and it also became insoluble faster than the light muscle. The Ca-ATPase activity of the actomyosin extracted from the dark muscle was higher than in light or whole muscle during the first three months. Washing the minced muscle induced conformational changes in the myosin molecule which, together with the added cryoprotectants, contributed to greater functional stability of the washed mince at least during the first three month's storage, at which stage gels were somewhat softer and more elastic than with unwashed mince.

Isolation and identification of peptidic alpha-glucosidase inhibitors derived from sardine muscle hydrolyzate.

We report here the isolation of alpha-glucosidase (AGH) inhibitory peptides derived from sardine muscle hydrolyzate, which was prepared by digestion with Bacillus licheniformis alkaline protease. As a result of reversed-phase HPLC purification, two AGH inhibitory peptides were isolated from a DEAE-Sephadex A-25 column eluate. The peptides were identified as follows: Val-Trp (IC50 = 22.6 mM) and Try-Tyr-Pro-Leu (IC50 = 3.7 mM). AGH inhibitory studies of Try-Tyr-Pro-Leu and its derivatives demonstrated the importance of the tri-peptide chain length as well as the hydrophobic aromatic amino acid tyrosine at the N-terminus, aliphatic amino acids at the C-terminus, as well as an amide proton from the peptide chain at the middle position of the tri-peptide to develop AGH inhibition activity.

Desmin Degradation in Postmortem Fish Muscle

ABSTRACTThe degradation of desmin was studied in postmortem white dorsal muscle from sea bass, brown trout, turbot and sardine, stored at 0–4°C. Based on desmin specific antibody tests, results showed that the extent and rate of desmin degradation in postmortem fish muscle varied considerably among species. There was no degradation of desmin during the first 4 days postmortem storage of sea bass and brown trout, whereas 10 to 20% of muscle desmin was degraded during the first 4 days of postmortem storage of turbot. Sardine muscle presented a very complex pattern of desmin degradation products and aggregated desmin fragments detected within the first 24h. Most polypeptides were larger than the nondenatured desmin. Desmin degradation would not be a suitable marker for evaluation of postmortem changes of stored fish.

IL-10 is an effector molecule mediating urocanic acid-induced immunosuppression

Urocanic acid (UCA) has been reported to be a mast cell degranulator and has also been suggested as a complementary agent in implicated scombroid fish poisoning. In this research, a new method is described to extract, clean up and perform simultaneous ion-pair chromatographic analysis of trans- and cis-urocanic acid (UCA) in fish samples. UCA was extracted using 0.05 M HCl and protein was removed from the extract by precipitation with 10% trisodium citrate and 10% citric acid. The HPLC method that is developed showed a rapid, precise and sensitive method with short retention time for simultaneous separation of UCA isomers in fish samples. Estimation of trans- and cis-UCA in the muscle of Indian mackerel, tuna and sardine showed that, as expected, no cis-UCA existed in fish muscles and the highest concentration of trans-UCA was found in Indian mackerel with 118.8 mg kg−1 while the highest concentrations of trans-UCA in tuna and sardine were 12.1 and 17.5 mg kg−1, respectively.

Detección de fluorescencia en sistemas modelo conteniendo aldehídos: relación con la alteración de pescado

In previous studies interaction compounds formation was accomplished by fluorescence detection at different excitation/ emission wavelength maxima during fish processing. A fluorescence shift towards higher wavelength maxima was then obtained as a result of damage increase. In the present work, different aldehydes were tested in order to compare their ability in producing fluorescent compounds with similar properties to the ones obtained during fish processing. Aldehydes (formaldehyde, FA; acetaldehyde, AcH; propanal, Pr; hexanal, Hex; 2-hexenal Hx; benzaldehyde, BzH) were reacted in model systems with sardine ( Sardina Pilchardus ) muscle and with n-propylamine at 30°C in dark during 25 days. A fluorescence shift was detected for all the aldehydes investigated as long as the reaction time increased. Great differences were observed between aldehydes, according to their chemical structure and reactivity. A sharp shift was detected for Hx and AcH, while little changes were observed in the cases of FA and BzH. As in the case of fish processing, Pr and Hex showed an increasing ratio between fluorescences detected at 393/463 nm and 327/415 nm as long as the reaction time increased.

Histamine Quantification in Monterey Sardine Muscle and Canned Products from Northwestern Mexico

Histamine production and pH changes in Monterey sardine muscle were monitored for a 15-day storage period at 0°C. Postmortem muscle pH fluctuated from 5.75 to 6.1, while histamine did not exceed 0.00018 ppm (0.0018 mg/100 g of fish). Histamine data was compared with those obtained from three commercial brands of canned sardines to evaluate time/temperature abuse during postcatch handling and processing. Histamine in canned products fluctuated from a minimum value of 0.05 mg/100 g sample for brand B2 to a maximum of 7.03 mg/100 g sample for brand B1. Only one of the analyzed samples exceed the new FDA action level for histamine of 5 mg/100 g sample. The results suggested that hygienic quality of canned sardine could be improved by implementing more strict time/temperature controls during commercial processing.

Development of a bienzymic graphite–Teflon composite electrode for the determination of hypoxanthine in fish

A bienzymic amperometric graphite–Teflon composite biosensor, in which xanthine oxidase and peroxidase, together with the mediator ferrocene, are incorporated into the electrode matrix, was developed for the determination of hypoxanthine in fish samples. These biosensors were fabricated by simple physical inclusion of the enzymes and the mediator in the bulk of the graphite–Teflon matrix. A Teflon content of 60%, a working potential of 0.00 V, a temperature of 30 ± 1 °C and a pH of 7.4 were selected as the optimum working conditions. The composite bioelectrode operated over long periods owing to the renewability of its surface by polishing. Reproducible amperometric responses were achieved with different electrodes fabricated from different composite matrices, and no significant loss of the enzyme activity was observed after more than 6 months of storage at 4 °C. A detection limit for hypoxanthine of 9.0 × 10–8 mol l–1 was obtained by amperometry in stirred solutions. An interference study of different substances which may be present in samples together with hypoxanthine demonstrated very good selectivity for the determination of this analyte. The bienzymic composite biosensor was applied to the determination of hypoxanthine in sardine muscle tissue, and the method was validated by comparing the results with those obtained by applying a recommended reference method.