Frozen Fillets Research Articles

Thaw rigor in Atlantic salmon (Salmo salar) fillets, as affected by thawing rate and frozen storage time

The influence of stress, storage time and thawing regimes was investigated with respect to rigor development and other related physical traits, on farmed Atlantic salmon. The fish were sampled from a commercial slaughterhouse production line, filleted, vacuum packaged and quickly frozen, pre-rigor. The investigated parameters were selected to maintain fresh-like quality.No significant (p > 0.600) effects were seen between rigor contraction and stress parameters measured at time of slaughter. Frozen storage time significantly (p = 0,003) affected contraction, while no effect of thawing method (p = 0.824) was detected. The liquid loss of the frozen groups was significantly (p = 0.019) affected by thawing method, while frozen storage time had no significant (p = 0.087) effect. Further, drip loss was not affected by fillet contraction (p = 0.075). Increasing frozen storage time significantly (p = 0.042) decreased the redness and thawing in air rather than water significantly (p = 0.015) decreased the yellowness of the fillets. Fillet stored for 1 month had significantly (p = 0.004) lower F-break force, while no significant (p > 0.227) effect of storage or thawing was seen on hardness. Frozen fillets were comparable to 7 days old vacuum packaged fresh fillets stored on ice for seven days, albeit with some increase in drip loss and some differences in texture, but with comparable color and fillet contraction.

Effects of freezing method on water distribution, microstructure, and taste active compounds of frozen channel catfish (Ictalurus punctatus)

AbstractEffects of freezing method and frozen storage duration (16 weeks) at −18 °C on water distribution, microstructure, and taste active compounds of channel catfish fillets were investigated. Results showed that freezing and frozen storage resulted in increase in thawing loss, extracellular space, and loss of some taste active free amino acids and inosine monophosphate (IMP). After 16 weeks of storage, the total content of free amino acids decreased to 77.68% (static air freezing), 78.92% (air‐blast freezing), and 83.13% (liquid nitrogen immersion freezing) of their initial value, while IMP decreased by 45.06% (static air freezing), 25.08% (air‐blast freezing), and 24.11% (liquid nitrogen immersion freezing), respectively. Low‐field 1H NMR T2 relaxation data showed an increase in relaxation time of T21 and T22, and a decrease of T21 population with concomitant increase in T22 population during frozen storage. Compared with the other two freezing methods, liquid nitrogen immersion frozen fillets with rapid freezing rate showed a less alteration of quality, exhibiting more compact fiber arrangements, less thawing loss and better retention of taste active compounds.Practical applicationsFrozen storage has been widely used to preserve meat products for a long time, but it inevitably caused undesirable physical, chemical, and structural changes, thus leading to quality loss in texture, flavor, and color. And the degree of quality deterioration of frozen food varies depending on materials, freezing process, and frozen storage conditions. Frozen fillet is one of the main processed fish products. The study of the influence of freezing method and frozen storage on the quality of fillets in terms of water distribution, structural changes, and taste active compounds is of importance to better control the quality of frozen fish products in the industry.

Effect of precooking and polyphosphate treatment on the quality of microwave cooked catfish fillets.

In the U.S. market place, there are many examples of precooked poultry products designed to be reheated in a microwave oven and, to a lesser extent, fish products such as tilapia. However, few U.S. catfish products are designed to be microwave cooked or reheated. The first objective of this study was to examine the properties of microwave cooked raw frozen catfish fillets and oven precooked (to 62.8°C) frozen fillets and then reheated by microwave cooking. The second objective was to evaluate changes in properties as a consequence of treatment with a commercial polyphosphate blend (Individually Quick Frozen [IQF]). The sample analysis included weight loss, proximate content, color (CIE L*a*b*), pH, mechanical texture (hardness), and lipid peroxidation (TBARS) measurements. Frozen fillets which contained polyphosphate showed <4% moisture loss after microwave cooking, relative to a 12% moisture loss for fillets without polyphosphate. A large cooking loss of ~40% was observed for precooked fillets after microwave cooking, correlated with a higher percent moisture loss (11% and 13% for fillets with and without polyphosphate, respectively) to comparable samples that were not precooked. For both types of fillets, an increased amount of yellow color was observed for precooked fillets after microwave cooking, relative to comparable fillets that were not precooked. Fillet hardness determined by peak force revealed an overall harder texture (~1.1–1.8 times) for fillets without polyphosphate than fillets with polyphosphate. This study will be used to develop precooked catfish products that can be reheated in a microwave oven.

Pacific whiting frozen fillets as affected by postharvest processing and storage conditions

Whole fish and H&G (headed and gutted) fish were stored under refrigeration (<4°C) for 0, 2, and 5days and subsequently filleted and frozen at −18°C and −80°C. Frozen fillets were analyzed during 24weeks of storage. The activity of trimethylamine-N-oxide demethylase (TMAOase) decreased more quickly at −18°C than −80°C. TMAOase reduction was distinctively noted at −18°C storage. Formaldehyde (FA) induced by TMAOase increased at all treatments at −18°C as frozen storage extended to 24weeks, but it was near zero at −80°C up to 12weeks of storage. Textural toughening, low water retention ability, and low salt soluble protein resulted from the denaturation function of FA. A sudden decrease in surface hydrophobicity at 24weeks, when stored at −18°C, resulted from FA-induced unfolding and subsequent aggregation. FA concentration appeared to affect protein aggregations and textual toughening of fillets during frozen storage.

Assessment of Color and Sensory Evaluation of Frozen Fillets from Pangasius Catfish and Nile Tilapia Imported to European Countries

The current study was designed to assess the color and sensory evaluation of frozen fillets of Pangasius catfish and Nile tilapia imported to Poland, Germany, and Ukraine in order to evaluate the possible impact of negative media image of these fish fillets on the sensory expectations of the consumers. The study used two trials of sensory evaluation: Blind and informed, on a group of untrained respondents and additional color analysis using the Commission Internationale de l’Éclairage (CIE) L*a*b* scale. The lowest grades during sensory evaluation in all measured parameters were given to Pangasius imported to Ukraine and Poland. The grades of Pangasius and tilapia imported to Germany were similar and significantly higher than of other Pangasius groups. Generally tilapia fillets were marked as better than Pangasius fillets. Moreover the present study found that there was considerable percentage of customers which are susceptible to various commercial frauds since they marked Pangasius higher when they thought they are consuming turbot. This study also showed that the negative image of Pangasius presented through various mass-media might have a negative impact on consumer’s perspective of Pangasius consumption.

Comparison of fatty acid content of fresh and frozen fillets of rainbow trout (Oncorhynchus mykiss) Walbaum

The aim of this study was to evaluate and compare the percentage content of fatty acids (FA) of 54 rainbow trout fresh and frozen fillets. Frozen fillets were stored at -15ºC for 45 and 90 days. Saturated (SFA), monounsaturated (MUFA), polyunsaturated (PUFA), omega-6 (n-6) and omega-3 (n-3) fatty acids were determined by gas chromatograph coupled to mass spectrometry. The results indicated that during frozen storage, SFA and MUFA content increased by 32.63 and 9.25%, respectively, while PUFA content decreased by 25.3%, n-6 by 12.4% and n-3 by 32.55%. These changes were more significant (P ≤ 0.05) during the first 45 d of storage. It was concluded that the frozen storage had a negative impact on meat quality of rainbow trout due to the reduction of PUFA, n-3/n-6, polyene index and PUFA/ SFA and the increase of the SFA, and atherogenic and thrombogenic indexes, which meant a substantial loss of nutritional value in the fillets of rainbow trout.

Qualidade microbiológica e vida útil de filés defumados de tilápia-do-nilo sob refrigeração ou congelamento

O objetivo deste trabalho foi avaliar a qualidade microbiológica e a vida útil de filés de tilápia-do-nilo, submetidos a diferentes métodos de defumação e condições de armazenamento. Foram utilizados dois processos de defumação (a frio ou a quente), em filés com ou sem pigmentação. Os produtos foram armazenados sob refrigeração ou congelados, e monitorados por 28 dias para avaliação da vida útil. Os filés congelados foram monitorados continuamente por 146 dias, apenas para a análise de ácido tiobarbitúrico (TBA). Defumação a quente e a frio reduziram a quantidade de coliformes, respectivamente em 99,78% e 97,80%. O armazenamento do produto sob refrigeração permitiu a redução de 99,73% dos coliformes, e o armazenamento sob congelamento os reduziu em 99,83%. Os valores encontrados de coliformes fecais estiveram dentro do limite permitido. Os valores de TBA nos filés atingiram o máximo no 14o dia de armazenamento. Os valores de TBA nos tratamentos sob refrigeração foram superiores aos daqueles sob congelamento e, também, em filés defumados a frio, em comparação aos defumados a quente. O processo de defumação a quente, com posterior armazenamento sob congelamento, é a técnica mais apropriada para assegurar qualidade e maior período de vida útil para os filés de tilápia-do-nilo, independentemente do processo de pigmentação.

Effect of glaze and selected herbal extracts on lipid oxidation and sensory properties of frozen Atlantic herrings (Clupea harengusL.)

Frozen fillets of Atlantic herrings (Clupea harengus) were used to evaluate the effect of glaze with or without addition of selected herbal extracts on lipid oxidation and sensory properties during 8 months of freezing storage under −14 °C. Fillets were divided into four groups: control non-glazed group, glazed group without addition of herbal extracts, and glazed groups with addition of hawthorn (Crataegus oxyacantha L.) extract (0.3%) and agrimony (Agrimonia eupatoria L.) extract (0.3%). The antioxidant activity and total phenolic content in hawthorn and agrimony extracts, and their effect on lipid deterioration expressed as thiobarbituric acid reactive substances were measured. The results showed that the herbal extracts of hawthorn and agrimony are effective antioxidants and good sources of total phenols. Significant influence of herbal extracts added into glaze on the extent of lipid oxidation changes has been obvious within 4 months storage of herring fillets under freezing conditions. Finally, positive influence of glaze and herbal extracts on organoleptic characteristics of fish fillets was found.

The effect of glaze on the quality of frozen stored Alaska pollack (Theragra chalcogramma) fillets under stable and unstable conditions

Frozen fillets (n = 288) of Alaska pollack (Theragra chalcogramma) were used to evaluate the effect of glaze on lipid oxidation and microbiological indicators during 6 months of freezing storage under stable (−18 °C) and unstable temperature (varying from −5 to −18 °C) conditions. The amount of glaze, moisture, fat and protein content were measured. Despite the low fat content in Alaska pollack, a positive effect of glazing and stable freezing conditions of storage on the range of oxidative changes of lipids expressed as thiobarbituric acid reactive substances was found. Total counts of viable cells slightly rose before the end of the storage period in both groups with commercially glazed fish. The average counts of psychrotrophs in each group () were at the same level, ranging from 9.1 ×103CFU·g-1to 1.1 × 104CFU·g-1. According to the microbiological results fillets stored under unstable conditions were considered to be acceptable, but sensory evaluation showed that at the end of frozen storage they could not be consumed because of rancidity. Based on our results, glaze application ranged from 10 to 15% guarantee of final quality, however, prevention of temperature fluctuation during storage is important to keep the quality of the frozen fillets. This is the first similar study in Alaska pollack.

Depletion of florfenicol amine, marker residue of florfenicol, from the edible fillet of tilapia ( Oreochromis niloticus x O. niloticus and O. niloticus x O. aureus) following florfenicol administration in feed

Aquaflor ®, a 50% feed premix containing the broad spectrum antibacterial agent florfenicol is available globally to control mortality associated with economically significant systemic bacterial diseases of fish. Florfenicol (FFC) is effective in controlling mortality associated with Streptococcus iniae in tilapia Oreochromis sp. when administered in medicated feed at a dose of 15 mg/kg bodyweight (BW)/d for 10 consecutive days. Our objective was to characterize the depletion of the FFC marker residue, florfenicol amine (FFA), from the edible tissue of market-weight Nile tilapia O. niloticus x O. niloticus and hybrid tilapia O. niloticus x O. aureus offered feed medicated with FFC at a nominal dose rate of 15 mg/kg BW/d for 12 days. Near market-weight tilapia were obtained from a commercial tilapia farm, distributed to 2 single pass (one for Nile tilapia and one for hybrid tilapia), flow-through systems and maintained at 27 °C under a 15 h light:9 h dark photoperiod over a 41-d pre-dosing period. During the dosing period, tilapia were offered feed medicated with FFC at a concentration of 1.479 g/kg at 1% BW daily divided in three equal offerings. The initial 10-d dosing period was extended to 12 d because one tank did not consume > 75% of the feed offered during the first two dosing days. The total dose consumed by fish in each of the 2 tanks ranged from 147 to 167 mg/kg. Once during the pre-dose period and on days 1, 2, 4, 7, 14, 21, and 28 of the post-dose period, groups of fish were indiscriminately removed from each tank, measured for weight and length, scaled, filleted, and the skin-on fillets stored at <−70 °C. Frozen fillets were individually homogenized, extracted, and FFA concentration was determined by high-performance liquid chromatography with UV detection. Florfenicol amine is rapidly eliminated from tilapia fillet after withdrawal from medication and depletion followed first-order kinetics with an estimated half-life of 2.32 d. The FFA tolerance limit, calculated as the 99th percentile of the potential residue level at 95% confidence, had depleted to less than the 1 µg/g maximum residue level by 6.14 d after the dosing period.

High Dietary Vitamin E Affects Storage Stability of Frozen‐refrigerated Trout Fillets

ABSTRACTFillets were processed from trout fed a diet containing either 200 (low vitamin E [LVE] diet) or 5000 (high vitamin E [HVE] diet) mg a‐tocopheryl acetate/kg for 0, 4, and 9 wk. These fillets were evaluated fresh and after 6 mo of frozen storage. Frozen fillets were thawed and stored 3 d at 1 °C before analyses. Muscle α‐tocopherol of fish fed the HVE diet continuously increased through 9 wk of feeding. Reduced muscle α‐tocopherol and moisture, and increased muscle redness and fat were observed in frozen‐refrigerated fillets compared with fresh fillets. Thiobarbituric acid‐reactive substances were lower in frozen‐refrigerated fillets produced from fish fed the HVE diet. Proportion of unsaturated fatty acids and omega‐3 fatty acids increased as feeding duration increased from 0 to 9 wk.

The Frozen Fillet: The Fish that Changed North Norway?

The Frozen Fillet: The Fish that Changed North Norway?

Fat Hydrolysis in Frozen Fillets of Lingcod and Pacific Gray Cod

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