Effect of previous gutting on rancidity development in horse mackerel (Trachurus trachurus) during frozen storage at −20 °C

Gutting was applied to fresh horse mackerel (Trachurus trachurus) to study its effect on rancidity development during a prolonged frozen storage (up to 12 months at −20°C). To do so, chemical (free fatty acids, FFA; peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescence ratio, FR) and sensory (odour and taste) analyses were carried out. The results showed that the gutting of horse mackerel led to a higher degree of oxidation in the frozen product, according to the chemical (PV, TBA-i and FR) and sensory (odour and taste) analyses. However, a lower extent of lipid hydrolysis (FFA formation) was detected at the end of the storage (twelfth month) as a result of gutting. It is concluded that the gutting of a medium-fat fish species such as horse mackerel is not recommended as previous treatment to frozen storage.     

Effect of previous chilled storage on rancidity development in frozen horse mackerel (Trachurus trachurus)

Rancidity development during frozen storage (?20 °C) of an underutilised medium‐fat‐content fish species, horse mackerel (Trachurus trachurus), was studied. Special attention was given to the effect of previous chilled storage (0, 1, 3 and 5 days) on the quality of the frozen fish. For this, chemical (free fatty acid and conjugated diene contents; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compound formation) and sensory (rancid odour and taste) analyses were carried out. Hydrolytic rancidity showed an increase with frozen storage time; however, no effect of previous chilling time was observed on the frozen product. Oxidative rancidity measured by chemical (PV, TBA‐i and fluorescence) and sensory (odour and taste) indices increased with frozen storage time and also with previous chilling time. Satisfactory quality was maintained up to 7 months of frozen storage of horse mackerel provided that a short chilling time (not longer than 3 days) was employed. © 2002 Society of Chemical Industry     

Effect of frozen storage on the quality of whole fish and fillets of horse mackerel (Trachurus trachurus) and mediterranean hake (Merluccius mediterraneus)

 Whole fish and fillets of horse mackerel (Trachurus trachurus) and mediterranean hake (Merluccius mediterraneus) were assessed for quality (physical, chemical and sensory attributes) changes throughout 12 months of frozen storage at −18 °C. The pH, expressible water (EXW), quantities of trimethylamine (TMA), dimethylamine (DMA), formaldehyde (FA), the total volatile base nitrogen (TVB-N) the thiobarbituric acid number (TBA), peroxide value (PV) and amount of free fatty acids (FFA) increased, while sensory attributes (odour, taste, texture) decreased during the frozen storage period. A comparison of quality scores between whole fish and fillets of horse mackerel and mediterranean hake showed that there were no significant differences (P>0.05) in attribute scores. There were, however, significant differences (P<0.05) in pH, EXW, TMA, DMA, FA, TVB-N, TBA, FFA and PV. Received: 19 April 1996/Revised version: 7 September 1996     

An investigation of rancidity inhibition during frozen storage of Wels catfish (Silurus glanis) fillets by previous ascorbic and citric acid treatment

The effect of preliminary ascorbic and citric acid (AA and CA, respectively) soaking treatments on the rancidity development in Wels catfish ( Silurus glanis ) fillets during further frozen storage (−18 °C; up to 6 months) was studied. Rancidity development was measured by biochemical quality indices (formation of free fatty acids, peroxides and secondary oxidation products) and compared with sensory analysis (appearance, rancid odour and consistency) and general chemical analyses (pH, expressible moisture and heme iron contents). When compared with control samples, AA- and CA-treated samples showed a lower ( P  < 0.05) formation of primary and secondary lipid oxidation compounds that was corroborated by a longer ( P  < 0.05) shelf-life time as a result of a lower rancid odour formation. According to these results, control samples showed a higher ( P  < 0.05) heme iron breakdown (months 3–6) and a lower ( P  < 0.05) water-holding capacity (higher expressible moisture value) (month 6).     

INVESTIGATION OF PROTEIN DENATURATION AND PIGMENT FADING IN FARMED STEELHEAD (ONCHORHYCHUS MYKISS) FILLETS DURING FROZEN STORAGE

The present experiment was conducted to measure the extent and nature of quality loss in farmed steelhead fillets during frozen storage, to determine the possible causes of steelhead pigment fading as a result of frozen storage and to suggest some methods for improving storage conditions in order to obtain good‐quality frozen steelhead. This two‐part study confirms the importance of frozen temperature and appropriate storage conditions on the extension of product shelf life. The fading phenomenon of steelhead fillets during 10 months of frozen storage at ?20C was subsequently studied in detail over a 6‐week period for fillets stored at both ?5 and ?30C. Associated protein denaturation, tough/dry texture and rancidity were also examined. Temperature had a stronger effect on the development of rancidity in steelhead fillets than the duration of the storage period for fillets stored for up to 6 weeks. Highest levels of oxidation products were observed in the fillets stored at ?5C even in the short‐term storage experiment while extensive lipid oxidation, toughening, expressible fluid loss on thawed fillets and apparent pigment fading took place during long‐term storage at ?20C. The results from sensory evaluation of texture, color and flavor agreed well with the chemical assessment of rancidity. Flavor scores from the fillets stored at ?5C revealed a slightly oily/rancid taste as compared to the samples at ?30C after 6 weeks of storage. The expressible fluid results indicated that the binding of water to protein decreased significantly in fillets stored at ?5C as compared to the matching fillets at ?30C and during long‐term storage at ?20C. The increases in expressible fluid correlated positively with fading (L*) and negatively with redness (a*). The quantity of extractable protein nitrogen (EPN) decreased drastically over the 6‐week period in both temperature groups (?5 and ?30C), but during this relatively short experiment, the EPN levels between temperature treatments were not significantly different. In both experiments, fillet redness faded dramatically as a result of frozen storage. Abusive cold storage at ?5C resulted in far more fading than at ?30C even after 6 weeks. Fading was measured both subjectively and objectively using reflectance colorimetry, and an increase in whiteness value was concomitant with a decrease in redness. It is suggested that whiteness may be used as an accurate subjective parameter for color fading in frozen storage. Redness values were significantly higher in the fillets at ?30C. The study showed that pigment fading was not a result of a decrease in carotenoid concentration but may be related to protein denaturation, which causes muscle tissue appearance to change from translucent to opaque, thereby giving the illusion of pigment fading.     

Damage Inhibition During Frozen Storage of Horse Mackerel (Trachurus trachurus) Fillets by a Previous Plant Extract Treatment

ABSTRACT: We investigated the effect of a commercial plant extract, Rosmol-P (RP) on the stability of fish during frozen storage. Horse mackerel ( Trachurus trachurus ) fillets were soaked in water (water control) and 2 RP concentrations (RP-1 = 0.333%; RP-2 = 1.333%) and compared with untreated fillets (blank control). Fluorescence detection and thiobarbituric acid index showed a lower oxidation development for both RP treatments than for both controls, especially in the case of the highest concentration (RP-2). The decrease in glutathione peroxi-dase activity was found to be slower in the case of the RP-2 treatment. The sensory analysis showed an increased shelf-life according to the sequence blank control < water control > RP-1, RP-2.     

Extra-Cold Storage of Hake and Mackerel Fillets and Mince

Extra-cold storage (?30 and ?40°C) of mackerel (Scomber scombras) mince and fillets showed lower free fatty acid formation. Extra-cold storage (-30°C) of white hake (Urophycti tenuis) fillets produced fish with better quality based on sensory and chemical indices. The colder the storage temperature, the less firm the hake mince and fillets. Ascorbic acid accelerated cohesiveness development of mackerel mince and fillets. Over time, the quality of the hake and mackerel decreased according to sensory and chemical indices. They became tougher and generally more cohesive.     

Effect of pre-soaking whole pelagic fish in a plant extract on sensory and biochemical changes during subsequent frozen storage

Plant extract treatments have largely shown a positive effect on inhibiting the quality loss during the frozen storage of minced and filleted fish products. In the present case, the effect of a plant extract on a whole fish product was checked. For it, whole fresh horse mackerel was soaked in a commercial extract solution during 60 min and then kept frozen up to 12 months at −20 °C. Sampling was carried out on the initial material and at months 1, 3, 5, 7, 9 and 12. Two parallel experiments consisting on untreated fish (Blank Control) and water treated fish (Water Control) were carried out in the same conditions. Lipid damage was measured by lipolysis development (free fatty acid formation), rancidity development (conjugated dienes (CDs), secondary oxidation compounds, fluorescent compounds and cholesterol oxides) and sensory (odour, firmness and colour) analyses. As a result of the previous plant extract treatment, better odour and colour scores were obtained that led to a larger shelf-life time (7 months) than in the two controls (5 months), according to the sensory analysis. Water treatment of fish (Water Control) also showed some better results in sensory (odour and colour) analysis than the Blank Control, that could be related to the elimination of some prooxidant molecules included in fish. Some biochemical indices (CDs and free fatty acids) also provided a damage inhibition (P<0.05) in the 9-12 months period as a result of the plant treatment and water treatment; however, fluorescence and cholesterol oxide detections did not show differences (P>0.05) when compared to the Blank Control. The present experiment provides promising results for soaking a pelagic whole fish in an aqueous plant extract as a previous step to its commercialization as a frozen product.     

Storage Life of Frozen Blocks of Patagonian Hake (Merluccius hubbsi) Filleted and Minced

Relevant parameters that reflect quality loss during frozen storage in filleted and minced Patagonian hake at two different temperatures were determined. Cooked sensory assessment, oxidative rancidity, dimethylamine, formaldehyde, salt soluble protein, free and expressive drip, refractive index, pH and total volatile bases, were evaluated over a lo-month period. Salt soluble protein decreased as formaldehyde and dimethylamine increased. Sensory evaluations and total volatile bases indicated that minced hake remains acceptable after 6 months at −20°C and 12 months at −30°C and fillets remain acceptable for over 12 months both at −20°C and −30°C.     

Superchilled,chilled and frozen storage of Atlantic mackerel (Scomber scombrus) fillets – changes in texture,drip loss,protein solubility and oxidation

Changes in quality characteristics in relation to protease activity and protein oxidation in chilled, superchilled and frozen mackerel fillets during storage were studied. The solubility of sarcoplasmic proteins was quite stable in mackerel samples for all storage experiments, whereas the solubility of myofibrillar proteins decreased in both superchilled and frozen samples. A significant correlation (r = 0.983, P < 0.05) between the increased activity of cathepsin B+L in chilled fillets and softening of the fish flesh during storage was revealed. Contrary with chilled samples, the texture of superchilled mackerel fillets became tougher along the storage period, which can be explained by a higher rate of myofibrillar oxidation (r = 0.940, P < 0.05). The hardness and drip loss decreased slightly at the end of frozen storage. Superchilling preserved the quality of mackerel fillets with the least side effects in relation to protein solubility, drip loss and softening of the fish tissue as compared to chilled and frozen storage.     

Changes in Fatty Acids and Sensory Quality of Fresh Water Prawn (Macrobrachium rosenbergii) Stored Under Frozen Conditions

The effects of frozen storage and packaging methods on the oxidation of fatty acids and rancidity development in fresh-water prawn Macrobrachium rosenbergii were studied. The lipids of these fresh prawns contained 23% saturated, 46% monounsaturated, and 31% polyunsaturated fatty acids. The fatty acids, especially the unsaturated ones decreased during frozen storage for 6 months at -18°C, regardless of the packaging procedure employed. No objectionable rancid flavor was detected in these prawns during the 6-month frozen storage study.     

Effect of gamma irradiation and frozen storage on chemical and sensory characteristics of rainbow trout (Oncorhynchus mykiss) fillet

The present study was conducted to evaluate the combined effect of low‐dose gamma irradiation (1, 3 and 5 kGy) and frozen storage (5 months at ?20 °C) on chemical and sensory characteristics of rainbow trout (Oncorhynchus mykiss) fillet. Our statistical analysis showed that irradiation process and frozen storage time had a significant effect (P < 0.05) on total volatile nitrogen (TVN), peroxide value (PV), thiobarbituric acid (TBA) and pH. The level of all of these factors increased with increasing frozen storage time. At the end of the fifth month of frozen storage, the lowest and the highest level of TVN, PV and TBA were corresponding to the irradiated samples at 3 and 5 kGy, respectively. In terms of the overall acceptability of their texture, odour, colour and taste, irradiated samples at 3 kGy had the best quality and remained acceptable after 5 months frozen storage. The optimum dose of gamma radiation of rainbow trout fillets according to chemical and sensory analysis was obtained at 3 kGy.     

Partial inhibition of cholesterol oxides formation in frozen fish pre-treated with a plant extract

The formation of cholesterol oxide products (COPs) in frozen horse mackerel ( Trachurus trachurus ) fillets was studied. The effect of pre-treating the fish by soaking (45 min) in either of two concentrations of the aqueous solution of an antioxidant plant extract prior to the freezing step was determined. The fish fillets were sampled immediately after freezing and at intervals along 12 months of frozen storage (−20 °C). Two control groups consisting of untreated and water-treated fish were stored and sampled under the same conditions. During the experiment, qualitative analysis revealed the formation of the following COPs: 7α-hydroxy-cholesterol, 7β-hydroxy-cholesterol and 7-keto-cholesterol. All treatment groups showed an increase ( P  < 0.05) in the content of all three COPs with storage time. As a result of pre-freezing antioxidant treatment, COPs formation was reduced ( P  < 0.05) in comparison with both control samples. This partial inhibition was consistent with a longer shelf-life time as revealed by sensory analysis.     

紫苏水提物联合蒸煮处理对脆肉鲩鱼片冻藏过程中品质的影响

为了研究蒸煮处理及紫苏水提物对脆肉鲩鱼片冻藏品质的影响,以紫苏水提物浸泡的生鱼片（生鱼片组）、紫苏水提物浸泡再进行蒸煮制备的熟鱼片（熟鱼片组）、蒸馏水浸泡的生鱼片（对照组）为研究对象,研究这3 组鱼片在冻藏过程中质构、持水性、盐溶性蛋白含量、Ca2＋-ATPase活性、硫代巴比妥酸（thiobarbituric acid,TBA）值、挥发性盐基氮（total volatile base-nitrogen,TVB-N）含量和感官评分的变化。结果表明：熟鱼片及生鱼片组通过最大冰晶生成带的时间比对照组长;与对照组和生鱼片相比,熟鱼片在冻藏过程中一直维持较高的硬度、弹性、咀嚼性、TBA值和较低的持水力、盐溶性蛋白含量、TVB-N含量;与对照组相比,生鱼片组的质构特性、持水力、盐溶性蛋白含量和Ca2＋-ATPase活力更高,而TBA值和TVB-N含量更低,冻藏300 d后,生鱼片TBA值是贮藏初始时的3.85 倍,TVB-N含量低于20 mg/100 g;感官评价结果进一步表明,3 组样品感官品质在冻藏过程中不断下降,其质地、口感以及汤汁浑浊度评分从高到低依次是熟鱼片、生鱼片和对照组。研究结果证明了紫苏水提物联合蒸煮处理更有利于冻藏过程中脆肉鲩鱼片品质的维持。     

Some comments on the usefulness of 2-thiobarbituric acid (TBA) test for the evaluation of rancidity in frozen fish

Rancidity of frozen fish (Baltic cod and herring, mackerel, horse mackerel and hake) was determined by means of TBA value, organoleptical scoring and peroxide value. The correlation between the rancid odour sensory assessment and TBA test results proved insignificant (r = 0.53). Model experiment was undertaken in which promine D with addition of papain was incubated at 50°C over 44 h. It was shown that as accumulation of protein hydrolysis products proceeded the increase of TBA value has taken place without development of rancid odour and with peroxide content below sensibility of sulphocyanide method. With regard to fish, therefore, it seems that the TBA test applied by means of techniques in which the reaction with TBA proceeds in the presence of interfering substances should be treated as a ?freshness test”? rather than a strictly rancidity one.     

Effect of essential oils treatment on the frozen storage stability of chub mackerel fillets

The effect of bay leaf (BLO), thyme (TO), rosemary (RO), black seed (BSO), sage (SO), grape seed (GSO), flaxseed (FSO) and lemon (LO) essential oil from vegetable extracted on lipid oxidation and some other quality parameter of frozen chub mackerel during frozen storage at ?20°C were examined over a period of 11 months. Taste, odour, texture and overall acceptability of control samples were given ‘unacceptable’ scores by the sixth month. Based primarily on sensory data, the shelf-lives of frozen chub mackerel were found 6 month for samples treated with oil of TO, RO, BSO, SO and LO and 7 month for samples treated with BLO, GSO and FSO. During the 11-months storing process of chub mackerel, the values of pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) both in control group samples and samples treated with oils did not reach to deterioration levels. Thiobarbitüric acid (TBA) and free fatty acid (FFA) values for all treatments remained lower than TBA and FFA values of control samples throughout the 11 month storage period. Particularly, thyme oil treatment is effective in delaying lipid oxidation. Bay leaf, rosemary, sage, lemon, flaxseed and grape seed oils were fallowed.     

Effect of essential oils treatment on the frozen storage stability of chub mackerel fillets

The effect of bay leaf (BLO), thyme (TO), rosemary (RO), black seed (BSO), sage (SO), grape seed (GSO), flaxseed (FSO) and lemon (LO) essential oil from vegetable extracted on lipid oxidation and some other quality parameter of frozen chub mackerel during frozen storage at −20°C were examined over a period of 11 months. Taste, odour, texture and overall acceptability of control samples were given ‘unacceptable’ scores by the sixth month. Based primarily on sensory data, the shelf-lives of frozen chub mackerel were found 6 month for samples treated with oil of TO, RO, BSO, SO and LO and 7 month for samples treated with BLO, GSO and FSO. During the 11-months storing process of chub mackerel, the values of pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) both in control group samples and samples treated with oils did not reach to deterioration levels. Thiobarbitüric acid (TBA) and free fatty acid (FFA) values for all treatments remained lower than TBA and FFA values of control samples throughout the 11 month storage period. Particularly, thyme oil treatment is effective in delaying lipid oxidation. Bay leaf, rosemary, sage, lemon, flaxseed and grape seed oils were fallowed.     

12‐Lipoxygenase activity in the muscle tissue of Atlantic mackerel (Scomber scombrus) and its prevention by antioxidants

Lipoxygenase was prepared from Atlantic mackerel muscle using differential centrifugation, ammonium sulphate precipitation and gel permeation (phenyl Sephadex G‐50) column chromatography. The crude lipoxygenase enzyme preparation was characterised by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE), which showed two prominent bands with molecular weights of 119 and 125 kDa. Fractions collected from the chromatography column were tested for enzyme activity by reacting with arachidonic acid and determining the production of hydroxyeicosatetraenoic acid (12‐HETE) using reverse phase HPLC and GC–MS. The 12‐HETE peak was absent from the fresh arachidonic acid control sample and from arachidonic acid treated with heat‐inactivated lipoxygenase. Esculetin, a known inhibitor of lipoxygenase, inhibited the production of 12‐HETE from the reaction of lipoxygenase with arachidonic acid, thus confirming that the enzyme was lipoxygenase. The HETE peak was partially reduced in the presence of antioxidants, namely synthetic butylated hydroxytoluene (BHT) and natural antioxidants vitamins C and E. The presence of lipoxygenase in Atlantic mackerel muscle indicates the possibility that the lipid oxidation mechanism is initiated enzymatically in chilled and frozen stored fillets of mackerel and that this oxidative deterioration could be inhibited by antioxidants (BHT, vitamins C and E) which are used widely in the food industry. © 2001 Society of Chemical Industry     

Ocean Pout (Macrozoarces americanus): Nutrient Analysis and Utilization

Ocean pout (Macrozoarces americanus), an underutilized marine species, was subjected to nutrient analysis, frozen storage stability studies and minced fish flesh evaluation. The nutritional quality of protein was higher than the reference casein, based on the protein efficiency ratio. A 3:1 ratio of unsaturated to saturated fatty acids was observed, making the product susceptible to rapid rancidity development. Mineral composition was low in calcium, magnesium and manganese but high in sodium and zinc, in comparison to other species. A decrease in water-holding capacity and an increase in free fatty acid and thaw drip volume of frozen fillets was observed. Mechanically deboned meat was acceptable by sensory evaluation, after 4 wk of frozen storage at –15°C. The effect of washing minced flesh was observed in the semi-fried product.     

Preservation of Grayfish (Squalus acanthias) by Salting

Grayfish (Squalus acanthias) fillets were preserved by an improved salting technique with pre-brining procedure along with ascorbic acid treatment in order to retard rancidity. The protein loss during salting was 2.4% and more than 2/3 fatty acid content of salted fillets decreased over 8 wk of storage at 20°C. The added ascorbic acid had an antioxidative effect for 2 wk of storage, after which the TBA values rose sharply. The organoleptic evaluation indicated no significant decrease in flavor until after 4 wk of storage. Statistical T-test showed no significant differences for appearance, odor, and texture among salted grayfish and salted cod fillets.