Quality assessment of whole and gutted sardines (Sardina pilchardus) stored in ice

The quality and shelf life of whole ungutted and gutted sardines ( Sardina pilchardus ) stored in ice were studied. The changes in the fish were investigated by sensory assessments, chemical analyses and microbiological analyses. The sensory scores of uneviscerated and gutted sardines stored in ice at +4 °C were 7 days. The chemical indicators of spoilage, total volatile basic nitrogen and trimethylamine values of gutted sardine increased very slowly, whereas for whole ungutted samples higher values were obtained reaching a final value of 15.03–29.23 mg per 100 g and 2.36–4.16 mg per 100 g, respectively (day 9). Peroxide and thiobarbituric acid values remained lower for whole ungutted sardine samples until day 9 of storage, whereas for gutted fish were higher. The level of histamine exceeded the legal limit in whole ungutted sardine after 7 days of storage in ice, during which sardines were rejected by the sensory panel. Mesophilic aerobic bacteria count, H₂S-producing bacteria, sulphide reducing anaerobe Clostridias, Enterobacteriaceae count of whole ungutted sardine samples are higher than gutted sardine samples during the storage. Psychrotrophic bacteria counts of the two groups were not different. The limits of microbiological data were not exceeded throughout the storage in both the groups' samples.     

Quality changes in soup from deboned chicken frames at refrigerated (4 ± 1 °C) and frozen (−18 ± 1 °C) storage

Chicken soup was made from the broth collected after the pressure cooking of deboned chicken frames (bones). The quality of stored chicken soup (S1) was compared with the soup prepared from the stored chicken broth (S2) at refrigerated (4 ± 1 °C) and frozen (−18 ± 1 °C) storage up to 12 and 90 days, respectively. Thiobarbituric acid reactive substances values and microbial counts were significantly ( P  < 0.01) higher in stored soup (S1) compared with fresh soup (S2). Psychrotrophs and coliforms were not detected. Appearance and odour scores of broth were satisfactory throughout the storage. Sensory attributes were rated better for fresh soup (S2) made from stored broth than stored soup (S1) but all the attributes were decreased with increasing storage period. The stored soup was acceptable up to 9 and 90 days in refrigeration and frozen storage respectively, while the soup made from refrigerated stored broth was acceptable for 12 days.     

Quantitative changes in bacteria, amino acids and biogenic amines in sardine (Sardina pilchardus) stored at ambient temperature (25–28°C) and in ice

Freshly caught sardines contained high levels of bacteria located mainly on the skin and the gills. These bacteria invaded and grew rapidly in sardine muscle, reaching 5x10⁸ c.f.u. g^-1 and 6x10⁸ c.f.u. g^-1 respectively after 24h at ambient temperature and 8 days in ice.
Histidine, arginine, lysine, tyrosine and methionine levels decreased during storage. The other amino acids, except proline and taurine, accumulated in the fish muscle, indicating an extensive proteolysis.
Histamine, cadaverine and putrescine accumulated to levels of 2350ppm, 1050ppm and 300ppm respectively, after 24h storage at ambient temperature. Histamine and cadaverine reached similar levels after 8 days storage in ice, whereas putrescine formation was insignificant. Spermidine and spermine levels increased slightly under ambient conditions.
Salting the fish at 8% delayed bacterial and chemical changes but only in iced sardines.
The high content of free histidine found in sardines and the susceptibility of its muscle to histamine and cadaverine formation could explain its increasing implication in incidents of histamine poisoning.     

Physical,chemical and sensory analysis of sardine (Sardina pilchardus) stored in ice

The shelf-life of iced sardine (Sardina pilchardus) was studied. The main changes which take place in raw fish were investigated by means of organoleptic assessments, chemical analyses (total volatile nitrogen (TVB-N), trimethylamine (TMA-N), trimethylamine oxide (OTMA-N) and hypoxanthine) and physical measurements (GR Torrymeter readings and pH). The influence of both seasonal changes and fat deterioration were also considered. The results obtained indicate that TVB-N and TMA-N parameters are not good freshness indicators for this species, but Torrymeter readings and hypoxanthine values can be used as indicators of freshness. However, they must always be confirmed by a sensory evaluation. From the different combinations tried, the most highly significant degree of correlation was obtained between sensory evaluation and Torrymeter readings.     

The effects of soluble gas stabilisation on the quality of packed sardine fillets (Sardina pilchardus) stored in air,VP and MAP

Sardine (Sardina pilchardus) is a species that for its abundance assumes great importance in the Portuguese fishing sector. In order to contribute for a better utilisation of this species, the aim of this study was to investigate the effect of the pre‐treatment with soluble gas stabilisation (SGS) (100% CO₂ at 2 bar, during 15 and 30 min) on the quality and shelf‐life of sardine fillets, packed in air (AP), vacuum (VP) and modified atmosphere (MAP: 5% O₂/35% CO₂/60% N₂). During the chilled storage, the quality changes were evaluated by sensory evaluation, chemical and microbiological analysis. The total volatile basic nitrogen content remained almost constant, between 16 and 19 mg N/100 g muscle, during the storage period, for all samples. The TBARs values increased with storage time, for all batches and storage conditions. The application of SGS treatment to sardine fillets, resulted in a bacteriostatic effect, contributing to the improvement of the microbiological quality of fillets. Considering a sensory criteria, the shelf‐life of SGS pre‐treated sardine fillets was found to be 5 days in AP and MAP while in VP‐treated fillets a shelf‐life of 8 days was reported. At sensory rejection, sardine fillets presented a K‐value of 30% in AP and MAP batches and 40% in VP batch.     

Spoilage and shelf life of sardines (Sardina pilchardus) packed in modified atmosphere

The effect of modified atmosphere packing (MAP) (O₂/CO₂/N₂, 5/35/60 (%) and O₂/CO₂/N₂, 5/70/25 (%)) on the quality of sardine stored in refrigerator was investigated in terms of sensory, chemical and microbiological analysis. Although chemical and microbiological analyses indicated that modified atmosphere packing prolonged the shelf life of sardine compared with that of air packing, sensory analysis showed that the extension of shelf life was (condition: O₂/CO₂/N₂, 5/70/25 (%)) 8 days and in air (condition: O₂/CO₂/ N₂, 5/35/60 (%)) 6 days. The results showed significant differences (p <0.05) between air and MAP storage conditions.     

Biogenic amine changes in barramundi (Lates calcarifer) slices stored at 0 °C and 4 °C

The biogenic amines formation in barramundi (Lates calcarifer) slices kept for 15 days at 0 °C and 4 °C were investigated using nine biogenic amines, total plate counts and biogenic amines formers. Significant differences in biogenic amines concentrations of barramundi slices stored at 4 °C and at 0 °C after 3 days of storage were observed. All amines, except tryptamine, 2-phenylethylamine, tyramine and agmatine in the slices increased with time during storage at both temperatures. At the end of the storage period, histamine concentrations were 82 mg/kg and 275 mg/kg for samples kept at 0 °C and 4 °C, respectively. At day 15, the total plate count was approximately 8.6 log CFU/g for sample kept at 0 °C and 9.7 log CFU/g for samples kept at 4 °C. Histamine-forming bacteria (HFB) in all samples ranged from 5.4 to 6.1 log CFU/g at 0 °C and 4 °C, respectively. The observed shelf-life of barramundi slices were 6–9 days.     

Chemical,enzymatical and textural changes during marination and storage period of sardine (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) marinades

In this study frozen fillets of sardine (Sardina pilchardus) were used to make marinades. The marinating process was performed in 7% acetic acid and 14% sodium chloride in barrels. The fish:solution ratio was (1.5:1). After the marination process, sardine fillets were packed in glass jars in two different formulations fish:solution ratio of (1.5:1); the first formulation contained 2% acetic acid and 4% sodium chloride with tomato sauce and spices and the other was 2% citric acid and 4% sodium chloride with lemon and also the same spices. Pasteurization process had been applied on half of the jars at 70 °C for 20 min. Chemical, enzymatical and textural changes during marination and 6 months storage period of sardine marinades were determined. The results obtained in proteolytic activities correlated well with the observed texture measurements according to time of storage. A decrease in the histidine content and an increase in glutamic acid and aspartic acid contents of marinated sardines were determined. Histamine levels were lower than the toxic limit (100 mg/kg) during the marination and storage period of sardine marinades.     

Optimisation of oil extraction from sardine (Sardina pilchardus) by hydraulic pressing

The aim of this study was to evaluate the influence of the processing conditions (pretreatment temperature: 5–55 °C, pressure: 60–120 bar and number of pressing stages: 1–3) on the yield and quality (free fatty acids, peroxide value, p‐anisidine and Rancimat induction period) of the oil extracted from whole sardine by hydraulic pressing. Experimental factors were investigated by a designed experiment and optimised by response surface methodology. A maximum yield of oil, 12.47%, was obtained at 55 °C, 60 bar and two pressing stages. Regarding oil quality, it was found minimum values for acidity (0.25% oleic at 55 °C, 60 bar and one pressing stage) and for peroxide value (0.29 meq kg^?1 oil at 5 °C, 60 bar and one pressing stage). Hence, the opposite effect of pretreatment temperature and number of pressing stages on the yield of oil and on its oxidation parameters suggested applying the weighted‐sum method as multiobjective optimisation technique.     

Quality changes in sardines (Sardina pilchardus) stored in ice and at ambient temperature

The keeping times of sardines were 21–27 h (average 23 h) at ambient temperature (T_amb) and 8–11 days (average 9.5 days) in ice. The muscle pH increased from 6.15 to 6.85 atT_amband from 6.24 to 6.55 in ice. Trimethylamine–nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) accumulated rapidly atT_ambto reach 11.2 mg 100 g⁻¹of fish and 57.3 mg 100 g⁻¹of fish, respectively at spoilage. In ice, the rate was rapid for two trials (2.72 mg TMA-N 100 g⁻¹of fish per day and 5.20 mg TVB-N 100 g⁻¹of fish per day) and slow for three trials (0.21 mg TMA-N 100 g⁻¹of fish per day and 3.7 mg TVB-N 100 g⁻¹of fish per day). Likewise, the histamine development rate was rapid during one trial (5.4 per day atT_amband 0.313 per day in ice), slow (average rate 3.503 per day during four trials atT_amb, 0.305 per day during one trial in ice) and zero during the other three ice-trials. Bacteria multiplied rapidly atT_amb; psychrotrophs multiplied slowly, and represented 10–68% of mesophiles at rejection point.In ice, bacteria multiplied slowly after lag phases of up to 120 h, but reached levels of rejection similar to those observed forT_ambstorage, H₂S-producing bacteria represented 0.5–7% of the initial fish flora and 3–10.1% at rejection point. They grew with a shorter lag phase as was the situation with the total flora.     

A study on the lipid fraction of Adriatic sardine filets (Sardina pilchardus)

Sardine (Sardina pilchardus Walb.) is an important Mediterranean commercial fish species. In this study, the lipids of sardine filets, fished in the Adriatic Sea at different times, were examined. In function of their total lipid (TL) content, sardine filet samples were grouped into lean (TL < 4%) and fat (TL > 4%). It was demonstrated that the differences of TL were exclusively due to a seasonal cyclical increase of neutral lipids. In fact, during moderate-hot months, sardines accumulated reserve fat that was metabolised during the winter months. The fatty acid composition was similar in both sardine sample groups and the fatty acid profile was equally distributed among saturated fatty acids, on average 38.3%, 31.2% monounsaturated, and 30.4% polyunsaturated. The polyunsaturated fatty acid n3 (PUFA-n3) represented on average 20.9%, always higher than PUFA-n6. C20:5n3 eicosapentaenoic acid, (EPA) and C22:6n3 docosahexaenoic acid (DHA) were the must abundant PUFA-n3. Under nutritional aspects, the lipids of 100 g of fat-sardines provided PUFA-n3 quantities, in particular EPA and DHA, significantly higher than human daily requirements. In lean-sardines, the PUFA-n3 input drastically decreased and was estimated that EPA and DHA inputs in 100 g of sardines covered around 17% and 50% of daily requirements, respectively. Finally, cholesterol was equal to 93 mg/100 g of sardines, ranging from 67 to 131 and it did not increase in relation to the total lipid content. In conclusion, this study has highlighted that, under nutritional aspects, regarding EPA and DHA inputs, it is preferable to consume sardines with at least 4% total lipids.     

Effects of brine concentration on shelf-life of hot-smoked tilapia (Oreochromis niloticus) stored at 4 °C

This work evaluated the effect of brine concentration on the shelf-life of hot-smoked tilapia (Oreochromis niloticus) stored at 4 °C. The fish were brined in solutions of 5%, 10%, and 15% NaCl and unsalted fish were used as controls. The fish were then smoked, cooled and stored at 4 °C. Oxidative rancidity measured by the peroxide value (PV), and thiobarbituric acid number (TBA) showed increases with the storage time and also as a result of the increasing salt content in fish muscle. Hot smoked tilapia can be stored safely under refrigerated conditions for over 35 days, and 5% brine was found to be optimal for storage.     

Behaviour of egg white and starch in gelation of sardine muscle (Sardina pilchardus)

Response surface methodology was used to determine the role played by egg white and starch in gelation of minced and washed sardine muscle. There was no detectable interaction, either positive or negative, between the effects of the two ingredients. Both egg white and starch significantly affected gel strength. Egg white had a direct, positive influence on hardness and adhesiveness. Starch had a direct, positive influence on cohesiveness and the ability to retain water.     

The use of nisin as a preservative in fish sausage stored at ambient (28 ± 2 °C) and refrigerated (6 ± 2 °C) temperatures

Summary The efficacy of nisin at three different concentrations, 12.5, 25 and 50 ppm, on the keeping quality of fish sausage in synthetic casing at ambient (28 ± 2 °C) and refrigerated (6 ± 2 °C) temperatures was assessed. Gel strength, expressible water content, total volatile base nitrogen, total plate count and aerobic spore counts were affected by the storage temperatures and nisin concentrations used. Fish sausage treated with 50 ppm of nisin was acceptable after storage at ambient temperature for 20–22 days compared with the control, which were acceptable only for 2 days. The keeping quality of the sausages, at refrigerated temperature, varied from 30 days in the control to 150 days in 50‐ppm nisin‐treated samples. The residual nisin decreased slowly in samples stored at refrigerated temperature, whereas, in fish sausages stored at ambient temperature, the decrease was rapid. Nisin at 50‐ppm level showed a significant effect (P ≤ 0.05) on the gel strength and overall acceptability scores both at ambient and refrigerated temperature.     

Effect of previous slurry ice treatment on the quality of cooked sardine (Sardina pilchardus)

The use of slurry ice was evaluated as a technological treatment prior to cooking processing of fish. Thus, sardine (Sardina pilchardus) was stored in slurry ice for 2, 5 and 8 days. At such times, sardine specimens were taken and subjected to steam cooking, and the results were compared with those from a parallel control batch previously stored in flake ice. Quality assessment of lipid damage in cooked fish was performed by measuring the formation of free fatty acids, peroxides, thiobarbituric acid-reactive substances and interaction compounds. The volatile amines–total and trimethylamine–assessment was also carried out. A significant (p<0.05) inhibition of lipid damage–peroxides and fluorescent compounds assessment–and trimethylamine formation was observed in cooked sardine as a consequence of the preliminary treatment in slurry ice. This work opens the way to the use of slurry ice as a preliminary treatment of fish material prior to its thermal processing.     

Seasonal changes and preliminary characterization of cathepsin D-like activity in sardine (Sardina pilchardus) muscle

The seasonal changes of cathepsin D-like activity in white and dark muscle of sardine were followed and maximum activity was found in April and October, which could be related to the spawning period of this species. Higher catheptic activity was measured in dark muscle and females. The crude extract of this muscle enzyme had an optimum pH and temperature of 3.2 and 55 °C, respectively, and the activity was strongly inhibited by low levels of NaCl (6%). The thermal stability was lower at pH 3.2 than at pH 6.5 and the enzyme was stable in the pH range 3–4.5. The activity of this protease was detected during the ripening process of salted sardine which suggests its participation in this process.     

Development of a multilayered antimicrobial edible coating for shelf-life extension of fresh-cut cantaloupe (Cucumis melo L.) stored at 4 °C

The objective of this study was to develop a multilayered edible coating with antimicrobial agent to extend the shelf life of fresh-cut cantaloupe stored at 4 °C. Three different sets of experiments were designed to test the effect of different concentrations of chitosan (0.5, 1, 2 g/100 g), pectin (0.5, 1, 2 g/100 g), and encapsulated trans-cinnamaldehyde (1, 2, 3 g/100 g), on the quality of fresh-cut cantaloupe. The first set (chitosan concentrations) provided the optimum concentration of chitosan based on preferences by the panelists. The second set (pectin concentrations) produced an acceptable coating that maintained shelf life. The third set (antimicrobial concentrations) helped establish the optimum concentration of trans-cinnamaldehyde in the coating. Changes in fruits texture, color, moisture, acidity, and pH were monitored. Sensory testing was carried out to support the objective quality data and microbiological analysis helped verify the antimicrobial effectiveness of trans-cinnamaldehyde. Uncoated fresh-cut cantaloupes stored at 4 °C served as controls. To test for the antimicrobial activity of chitosan alone, a second set of controls consisted of samples coated only with chitosan.     

The presence of bioactive peptides in hydrolysates prepared from processing waste of sardine (Sardina pilchardus)

A proteolytic enzyme, Alcalase®, was used to produce partly digested proteins from cooked wastes of sardine (Sardina pilchardus). The presence of biologically active molecules was investigated in these hydrolysates prepared under various conditions of time and enzyme/substrate ratio. By means of radioimmunoassays and mitogenic and radioreceptor assays, the presence of molecules related to secretagogue peptides, growth factors and calcitonin gene‐related peptide (CGRP) respectively was detected in the hydrolysates. Exclusion chromatography permits the conclusion that the biological activity of the different fractions is related to their size. © 2001 Society of Chemical Industry