Sardine Fillets Research Articles

Analysis of cholesterol oxidation products by Fast gas chromatography/mass spectrometry

The aim of the present study was to set-up a Fast gas chromatography/mass spectrometry method for the analysis of cholesterol oxidation products (COPs). A silylated mixture of seven oxysterol standards was injected into a Fast GC/MS system. A capillary GC column (10 m×0.1 mm internal diameter×0.1 μm film thickness) coated with 95% dimethyl- and 5% diphenyl-polysiloxane, was used. The method gave a fast (total analysis time=3.5 min) and satisfactory resolution (R>1.2) of the COPs standards, with a good repeatability and sensitivity, similar to those of conventional GC/MS; recoveries were tested on mice liver. Fast GC/MS method suitability for COPs analysis in food was also tested on an oxidized sardine fillet, which had been previously saponified and purified by NH(2) solid-phase extraction (SPE); a good repeatability and sensitivity was also obtained. The analytical performance of the Fast GC/MS method for the determination of COPs, together with the consequent significant reduction of the analysis time and consumables, demonstrates that Fast GC/MS represents a valid alternative to conventional GC/MS and evinces the great potential of such an analytical technique, which could be applied for both food and biological samples.

Effects of chitosan on the shelf life of marinated sardine (Sardina pilchardus) fillets during refrigerated storage

This study was carried out to evaluate the effect of chitosan on chemical, colour, sensory and microbial changes of marinated sardine (Sardina pilchardus) fillets. Marination solution consisted of 10% sodium chloride +1% chitosan (dissolved in 3% acetic acid) for the chitosan group, and 10% sodium chloride +3% acetic acid solution for the control group. After the marination process, sardine fillets were packed and stored at 4°C for 60 days. Thiobarbituric acid (TBA) values were found to be lower in the chitosan group than the control group (P<0.05). There was no difference in the total volatile basic nitrogen (TVB-N) value between groups and this remained low during storage. pH was under 4.5 in both groups during storage. Chitosan had no statistically significant effect on L*, a*, or b* values of marinated sardine fillets. According to sensory analysis, shelf life of the chitosan group was found to be ten days longer than that of the control group. Total bacteria count of two marinated groups was found to be less than 1 log CFU/g. This study concluded that sardine marination with the addition of chitosan can delay undesirable chemical changes, retard lipid oxidation, improve sensory attributes and extend the shelf life of the product during refrigerated storage.

Effects of rosemary and sage tea extract on biogenic amines formation of sardine (Sardina pilchardus) fillets

SummaryNatural antimicrobials and antioxidants from rosemary (Rosmarinus officinalis) and sage tea (Salvia officinalis) were produced using solvent extraction method. The effect of two extracts on ammonia (AMN) and biogenic amines (BAs) formation in vacuum packed sardine (Sardina pilchardus) fillets stored at 3 ± 1 °C was investigated for 20 days. Although the effect of extracts was dependent on specific amine and storage time, phenolic compounds from rosemary and sage tea generally resulted in lower AMN and BAs accumulation in sardine muscle. Putrescine (PUT) and cadaverine (CAD) were the most abundant amines, while histamine (HIS) concentration ranged from 2.05 to 28.77 mg 100g−1. Rosemary and sage tea extracts significantly reduced HIS, PUT, CAD and trimethylamine accumulation in the fish muscle (P &lt; 0.05) while stimulating effect of extracts was observed on serotonin and agmatine formation. At the end of the storage period, PUT and CAD contents of control were 100‐fold higher than those of treated groups.

The effects of the combination of freezing and the use of natural antioxidant technology on the quality of frozen sardine fillets (Sardinella aurita)

SummaryThe effects of combination of freezing and the use of antioxidant technology on the quality of frozen sardine fillets were investigated in terms of sensory, biochemical [thiobarbituric acid (TBA), total volatile basic nitrogen (TVB‐N), peroxide value (PV) and free fatty acids (FFA)] and microbiological analyses [total viable count (TVC)]. Fish were filleted and divided into three groups. The first group was used as the control (C) without rosemary extract, the second group was treated with 1% rosemary extracts for 2 min (R1) and the third was treated with 2% rosemary extracts for 2 min (R2). All groups were frozen at −18 °C over the storage period of 6 months. The results obtained from this study showed that the combination of antioxidant and frozen storage resulted in significant reduction of bacterial growth and stabilised the biochemical characteristics, especially for R2. However, the use of antioxidant at the level of 2% (R2) gave a bitter taste according to sensory assessment whereas the panellists mostly preferred R1.

Effects of rosemary and sage tea extracts on the sensory, chemical and microbiological changes of vacuum‐packed and refrigerated sardine (Sardina pilchardus) fillets

SummaryThe effect of the natural antioxidants and antimicrobials from ethanol extracts of rosemary and sage tea on sensory, chemical [Total volatile basic nitrogen (TVB‐N), thiobarbituric acid reactive substances (TBARs), peroxide value (PV), free fatty acid (FFA)] and microbiological (total viable count‐TVC and total coliform count) changes of vacuum‐packaged sardine (Sardina pilchardus) fillets stored at 3 ± 1 °C was investigated for 20 days. The fish fillets were divided into three groups: untreated group (control, C) and treated groups that were immersed in a 1 L of distilled water containing 10 g rosemary (R group) or sage tea (S group) extracts for 4 min. The shelf life of sardine fillets was found to be 13 days for control (C), 20 days for R and S groups according to sensory assessment results, whose corresponded microbiological assessment showed a shorter shelf life (5 days for C group, 9 for R and S groups). At the end of storage period, TBARs values were 0.98 mg malonaldehyde kg−1 for C group, 0.66 malonaldehyde kg−1 for R group and 1.44 mg malonaldehyde kg−1 for S group. Microbiological results showed that natural compounds from rosemary and sage tea resulted in a lower bacterial growth in fish fillets during the storage period.

Study of moisture and salt transfers during salting of sardine fillets

The objectives of this work are to study the effect of salting time, salt concentration and temperature on moisture and salt transfers within Sardinella aurita fillets. Temperature rise as well as brine concentration increase (from 5 to 20 °C and from 15 to 26.5% NaCl, respectively) accelerated water exudation and salt diffusion in the sardine fillets. Salt and moisture apparent diffusivities evolution as a function of concentration were determined by a mathematical treatment without fixing any mathematical relationship between values of diffusivity and concentration. Moisture apparent diffusivity increased from 2.40 × 10 −10 to 1.90 × 10 −8 m 2/s with fillets moisture content increase (from 0.35 to 3.00 g/g db, i.e. 25.9–75% w/w). For a salt content range from 0.16 to 12.80 g NaCl/100 g water, salt apparent diffusivity was relatively constant. Hence, sardine fillets water diffusivity is more related to moisture content than salt diffusivity to brine concentration.

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

SummarySardine (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.

Effect of controlled lactic acid bacterial fermentation on the microbiological and chemical qualities of Moroccan sardines(Sardina pilchardus)

Lactic acid bacteria (LAB) strains were assayed for the conservation of fresh sardine "Sardina pilchardus". Lactobacillus delbrueckii subsp. delbrueckii was used for inoculation of sardine fillets in a solution of NaCl (5%, w/w) and glucose (4%, w/w) concentration in water. Microbial counts including Standard Plate Count (SPC), LAB, yeasts, coliforms, Salmonella, staphylococci and Clostridium were followed during two weeks of storage at 30 degrees C. Determinations of chemical parameters including pH, dry matter, fat, ash, total nitrogen (NT), total volatile basic nitrogen (TVBN) and trimethylamine (TMA) were carried out under the same conditions. Chemical determinations showed a net pH decrease from an initial value of 6.05 in raw sardine fillets to 4.3 after 16 days of fermentation. Increases in TMA content and TBVN were observed. Microbiological control showed that LAB counts reached a level up to 3.10(9) cfu/g after 4 days of fermentation. After two weeks, fermented fish was free of coliforms and Salmonella. The inhibition of pathogenic microflora including staphylococci and Clostridium was also observed. The results indicated that controlled LAB fermentation could be used as a successful process for biopreservation of sardines produced in huge quantities in Morocco.

Effect of modified atmosphere and vacuum packaging on microbial, chemical and sensory quality indicators of fresh, filleted Sardina pilchardus at 3 °C

AbstractThe self‐life, quality and safety of refrigerated sardine fillets (Sardina pilchardus) were determined at 3 °C in atmospheric air, vacuum and modified atmosphere (50% CO2/50% N2) packaging conditions. Microbiological, physico‐chemical and sensory parameters were utilised as quality indicators. The microbial flora of sardine comprised—according to order of occurrence—Shewanella putrefaciens, pseudomonads, Brochothrix thermosphacta, lactic acid bacteria and, finally, Enterobacteriaceae. Bacteria grew most quickly in sardines stored in air, followed by those in vacuum packaging, and the lowest counts were found in modified atmosphere packaging. The concentrations of moisture, ash, protein, fat and polyunsaturated fatty acids were not affected during the storage period compared to the pH values and the concentrations of lactate and ammonia that showed significant differences. Copyright © 2007 Society of Chemical Industry

Chemical, enzymatical and textural changes during marination and storage period of sardine (Sardina pilchardus) 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.

The determination of the shelf‐life of pasteurized and non‐pasteurized sardine (Sardina pilchardus) marinades stored at 4 °C

SummaryIn this study the shelf‐life of sardine marinades was investigated. After the marination process, sardine fillets were packed into glass jars with 2% citric acid, 4% sodium chloride and spices. The effect of pasteurization at 70 °C for 20 min on the shelf‐life of the sardine marinades was determined. At the end of 6 months storage the differences between thiobarbituric acid, free formaldehyde (FA(ex)), free and bound formaldehyde (FA(dest)) and peroxide value of pasteurized and non‐pasteurizated marinades were not significantly (P &gt; 0.05) different, while the difference between total volatile basic nitrogen, trimethylamine, pH, total plate count and lactic acid bacteria count of pasteurized and non‐pasteurized marinades were. The shelf‐life of both pasteurized and non‐pasteurized sardine marinades was found to be 5 months at 4 °C.

Effect of different levels of sodium chloride and glucose on fermentation of sardines (Sardinella brasiliensis) by Lactobacillus sakei 2a

Lactobacillus sakei 2a is a bacteriocin producer strain. In this study, it's effects as a starter culture in the curing process of sardine (Sardinella brasiliensis) fillets were studied at different concentrations of NaCl (2, 4, 6%) and glucose (2, 4%). After 21 days of fermentation, the spoilage microorganisms population reached 9.7 Log10 CFU g-1 corresponding to 6% NaCl and 4% glucose. With no addition of glucose and starter culture, sardine fillets began spoilage 72 hours after fermentation, even when 6% NaCl was used. Little differences were observed in lactic acid production when 2 and 4% glucose were added, since total acidity was 1.32 and 1.34% respectively, the experiments with 6% NaCl presented the best results. Initial pH of sardine fillets was 6.0 and after 21 days pH values were 3.8, 3.9 and 4.0 for the experiments with 2, 4 and 6% NaCl respectively. This could have been due to the inhibitory properties of NaCl over the spoilage microorganisms. After 21 days of the fermentation, the levels of lactic acid bacteria (LAB) were 14.5 Log10 CFU.g-1.

Chemical characteristics and lipid fraction quality of sardines (Sardina pilchardus W.): influence of sex and length

An experimental investigation was carried out on sardines (Sardina pilchardus W.) with the aim to evaluate the influence of sex and total length (TL) on total weight (TW) and fillet weight (FW), chemical composition, and lipid fraction quality. Special emphasis was given with respect to the content of polyunsaturated fatty acids (PUFA), which are considered important from a dietary, nutritional, and functional point of view. Sardines were subdivided as a function of TL and sex. Four groups were obtained: (i) males, TL 130–155 mm, (ii) males, TL 155–180 mm, (iii) females, TL 130–155 mm, (iv) females, TL 155–180 mm. Fatty acid composition and chemical analyses were subsequently carried out on the sardine fillets; results showed higher TW and FW in female sardines and higher percentage value of FW/TW ratio in male sardines, indicating a higher incidence of viscera and other non-edible parts in females than in males. Moreover, total lipids were on average significantly higher (P < 0.05) in longer specimens (TL = 155–180 mm) than in shorter ones (TL = 130–155 mm). Finally, total saturated fatty acids (SFA) and total mono-unsaturated fatty acids (MUFA) values were found to be significantly higher in females than in males; such values increased significantly (P < 0.01) only for total SFA from shorter to longer sardines. As for total PUFA, both ω6 and ω3 were found to be higher in male than in female sardines and significantly higher (P < 0.001) in larger than in smaller sizes. Total PUFA/total SFA ratio were in all cases close to 1, with higher values in male than in female sardines and in larger than in smaller specimens.

Determination of the shelf life of sardine ( Sardina pilchardus) marinades in tomato sauce stored at 4 °C

In this study the shelf life of sardine marinades in tomato sauce was investigated. After the marination process, sardine fillets were packed into the glass jars with 2% acetic acid and 4% sodium chloride with tomato sauce and spices. The effect of pasteurization at 70 °C for 20 min on the shelf life of the sardine marinades was determinated. At the end of 6 months storage the differences between TBA, FA(free), FA(total) and pH value of pasteurized and non-pasteurizated marinades were not significantly ( p > 0.05) different, while the difference between TVB-N, TMA-N, total plate count and lactic acid bacteria count of pasteurized and non-pasteurized marinades were significant ( p < 0.05). Shelf life of pasteurized and non-pasteurized sardine marinades in tomato sauce was found to be 6 months at 4 °C.

Chemical, microbiological and sensory changes in thawed frozen fillets of sardine ( Sardina pilchardus) during marination

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). The marination was carried out at 4 °C until the end point of marinating was assessed by sensory texture analysis. The complete marinating of sardine fillets required 22 days at 4 °C. According to statistical analysis at the beginning and at the end of the storage in barrels there were no significant differences ( p>0.05) in chemical analytical results. After the sardine fillets were put into the barrels, total viable count, lactic acid bacteria count, psychrotrophic bacteria count, yeast and mould counts were reduced.

Bacteriocinogenic effect of Lactobacillus sakei 2a on microbiological quality of fermented Sardinella brasiliensis

Lactobacillus sakei 2a is a bacteriocin producer strain and, in this work, it's effects as a starter culture in the fermentation process of sardine (Sardinella brasiliensis) fillets were observed at different concentrations of NaCl (2, 4 and 6%) and glucose (2 and 4%), to determine it's ability to produce organic acids and consequent pH reduction. Experiments were carried out independently, with only one parameter (NaCl or glucose) varying at a time. After 21 days of fermentation the deteriorative bacteria concentration reached 9.7 Log10 CFU. g-1 corresponding to 6% NaCl and 4% glucose. Little differences were observed in lactic acid production when 2 and 4% glucose were added, since total acidity was 1.32 and 1.34% respectively, the experiments with 6% NaCl presented the best results. Initial pH of sardine fillets was 6 and after 21 days pH values were 3.8, 3.9 and 4 for the experiments with 2, 4 and 6% NaCl. This may have been due to the inhibitory properties of NaCl over the deteriorative bacteria. After 21 days of the fermentation process lactic acid bacteria concentrations were 14.5 Log10 CFU.g-1. The ratio protein nitrogen and total soluble nitrogen was typical of a cured fish.

Grilling of sardine fillets. Effects of frozen and thawed modality on their protein quality

Sequential freezing, thawing and cooking may affect the protein quality of fish fillets. Fillets of fresh raw sardine (R) were stored frozen, thawed at 4°C in a refrigerator (RR) or in a microwave oven (MR), and subsequently grilled (G). Proximate and amino acid compositions, solubility in sodium dodecylsulphate+ β-mercaptoethanol, –SH group content and amino acid chemical score were determined. Freezing–thawing increased ( p<0.05) (in wet matter basis) fat and decreased protein content in RR samples and ash content in RR and MR samples. Grilling produced a drip-loss phenomenon that causes loss of moisture that was more prominent after thawing (RG and MG samples). Thawing in refrigerator decreased the protein solubility, but grilling reversed that effect increasing and decreasing it in RG and MG samples, respectively. Every step of all processes caused a decrease in –SH group, cyst(e)ine and methionine giving rise to the lowest chemical score in RG and MG samples. The cholesterolemic index given by the arginine/lysine ratio and the smallest changes in the protein quality suggest that consuming grilled fresh raw sardine fillets is better than consuming refrigerator or microwave thawed–grilled sardine fillets.

Cooking–freezing–reheating (CFR) of sardine ( Sardina pilchardus) fillets. Effect of different cooking and reheating procedures on the proximate and fatty acid compositions

The sequential cooking–freezing–reheating (CFR) method was studied. Sardine ( Sardina pilchardus Walb) fillets were cooked by frying, oven-baking or grilling, frozen, and then reheated using conventional or microwave ovens in order to study changes occurring in the proximate and fatty acid compositions. Both cooking and freezing–reheating affected ( P<0.001) the proximate composition. Frying produced the highest water loss and fat gain, followed by grilling, and then by oven-baking. Microwave oven-reheating (MR) induced higher dehydration than conventional oven-reheating (OR), with grilled–frozen–MR samples also loosing fat and ash. Frying significantly ( P<0.001) affects the fatty acid composition of sardine, increasing oleic and linoleic acids and decreasing eicosapentaenoic and docosahexaenoic acids. Oven-baking and grilling minimally affected the fatty acid content. Freezing–reheating significantly affected ( P<0.001) the fatty acid composition with the content of oleic acid increasing and those of the ω-3 fatty acids, decreasing more in MR than in OR. Thus, according to the positive effect attributed to ω-3 fatty acids, cooked samples with no further treatment would be preferred to their respective CFR counterparts. However, OR should be used instead of MR when the CFR system is performed.

Freezing/defrosting/frying of sardine fillets. Influence of slow and quick defrosting on protein quality

AbstractThe effect of sequential freezing/defrosting/frying on protein quality is not well known. With this in mind, fillets of fresh sardine were stored frozen, then thawed, either conventionally at 4 °C in a refrigerator or with the use of a microwave oven, and subsequently deep‐fried. Proximate and amino acid compositions, protein solubility in sodium dodecyl sulphate/β‐mercaptoethanol (SDS/β‐ME), total SH group content and amino acid chemical score were determined. The lowest protein concentration was observed in frozen/4 °C‐thawed sardines (CR), whilst the lowest fat content was found in both fresh/fried sardines (F) and 4 °C‐thawed/fried sardines (CF). Every step of each process studied caused a decrease in cyst(e)ine; the most important loss was recorded in CF samples and in frozen sardines fried without defrosting (Fro‐F). The lowest solubility in SDS/β‐ME and the lowest total SH group content were observed for Fro‐F samples and microwave‐thawed/fried sardines (MF). On the other hand, the lowest chemical score was found for Fro‐F, CF and MF samples. Although weight loss and proximate composition seemed to change less when defrosting sardine fillets using a microwave oven rather than at 4 °C, the results for SDS/β‐ME solubility and total SH group content suggest that a slow defrosting process (refrigerator at 4 °C) is preferable to a much quicker process (microwave oven) for thawing frozen sardine fillets before frying. Copyright © 2003 Society of Chemical Industry

INFLUÊNCIA DO MÉTODO DE CONGELAMENTO EM FILÉ DE SARDINHA MARINADO

Sardine fillets that were frozen at -20°C and that suffered a pre-treatment by immersion in brine for 10 minutes and for 2 hours and, frozen sardine fillets at -20°C, were unfrozen and marinated in a solution with 3,3% of sodium chlorite and 3,5% of acetic acid for 45 minutes at 10°C, being these products stored at the temperature at 2,5°C. During the marinade, the water has been analyzed as to the loss of water and gain of salt; the quality of the sardine fillets has been evaluated; and immediately after the marinade and 2 months of storage it was evaluated the quality of the sardine fillets according to their humidity, salt tenor, pH, water retention capacity, exudation during the cooking process and color analysis by the instrumental method. In this work, the reduction of humidity has been observed and the increase of pH in all the samples after 2 months of storage. A bigger loss of water has also been observed in the sample frozen by cold air during the process of marinade than in the samples frozen by immersion. The frozen samples by different methods didn't present either significant difference of capacity of water retention during the process of marinade or in the storage period. Regarding to the exudation during the cooking process has been observed that there wasn't significant difference between the different samples, but they presented a bigger amount of exuded liquid after 2 months of storage. (Resume d'auteur)