Chilled Storage of High Pressure Processed Black Tiger Shrimp (Penaeus monodon)

The effect of high pressure (HP) treatment (at 100, 270, and 435 MPa for 5 min at 25°C) on microbiological (total viable count and total psychrotrophic count), physical (color, texture, and drip loss), and microstructural characteristics of black tiger shrimp (Penaeus monodon) during storage at 2°C for 35 days was investigated. Pressure treatment increased drip loss, maintained low microorganisms level, imparted cooked appearance to the muscle, and resulted in improved texture. Results of scanning electron microscopy revealed more compact structure in treated samples, confirming the results of texture profile analysis. Pressure treatment of 435 MPa was most effective in preserving the quality of shrimp.     

The Effects of Light Salting on Physicochemical Characteristics of Frozen Cod (Gadus morhua) Fillets

Abstract

The effects of light salting by brine injection and brine immersion on physicochemical and textural properties of cod fillets were evaluated. Light salting significantly increased yield and water holding capacity. Adding brine injection to the process can be used to shorten the process time needed to obtain the desired salt content and increase yield. The effects on chemical composition were most significant in salt content, but water and protein content were also affected. Water content decreased from the tail to head direction of the fillets, both in unsalted and light salted fillets. Changes in protein content were in opposite proportion to changes in water content. This could be seen in the fresh fish and also after freezing, both in unsalted and light salted fillets. Texture of the fish was not significantly affected by salting and freezing.     

Color,Yield, and Texture of Heat and High Pressure Processed Mussels During Ice Storage

High pressure processing (HPP) can shuck (open) shellfish, saving labor while conferring food safety and yield benefits. Mostly male New Zealand Greenshell? mussels (Perna canaliculus) were HPP-shucked (3 min at 500 MPa, 30°C) and assessed during 6-days’ ice storage (0°C) for cooked yield, color, and texture compared with heat processed (1 min at 70°C) and untreated samples. HPP-treated mussels had improved yields but lost more weight during ice storage. Male mussels from all treatments became darker with ice storage. HPP-treated mussels had firmer adductor muscles, while their guts required higher maximum force but less energy to puncture them.     

Effect of Heat Treatment at Different Stages of Rigor on the Quality of Pacific White Shrimp (Litopenaeus vannamei)

Effect of blanching and cooking on the quality of Pacific white shrimp with skeletal muscle severed (by beheading and peeling) at different stages of rigor was evaluated. Peeling and beheading shrimp in post-rigor stage resulted in higher yields compared to shrimp in in-rigor and pre-rigor stages. Weight loss due to blanching/cooking was highest when skeletal muscle was severed in in-rigor stage followed by post- and pre-rigor stages. Highest crude and sarcoplasmic protein contents were found in the shrimp blanched or cooked while in in-rigor stage followed by pre-rigor and post-rigor stages. Hardness, springiness, and chewiness were found to be better in the shrimp blanched in pre-rigor stage. Highest sensory scores for color, appearance, succulence, and odor were found for shrimp blanched or cooked in pre-rigor followed by in-rigor stage. Instrumental analysis of color and texture confirmed the sensory scores.     

Effect of High Pressure Processing on Color,Fatty Acids,and Volatile Compounds of Sea Bass Skeletal Muscle

Changes of color, free fatty acids, triglyceride fatty acids, and volatile flavor compounds in sea bass skeletal muscle (SBSM) with high pressure (HP) treatment were studied. The results indicated that HP could increase the L* value of SBSM and free fatty acid content, but had little impact on total triglyceride fatty acids. Total saturated triglyceride fatty acid content increased with increasing pressure and had a maximum at 100 MPa; total unsaturated triglyceride fatty acid content decreased. The increased free fatty acids might have resulted from phospholipid hydrolysis. High pressure processing was conducive to the generation of alcohols and cooked-like flavor of SBSM and produced more favorable volatile compounds at the pressure of 400 MPa.     

Effects of High Pressure on Myofibrillar Protein and Moisture Distribution of Shrimp (Solenocera melantho) Muscle

ABSTRACT

The effects of high pressure (100–500 MPa) treatment on myofibrillar protein (MP) contents and distribution of water in Solenocera melantho muscle were investigated. The results showed that the shrimp treated with 200 MPa had the highest shelling score, and the solubility of MP in meat of shrimp treated with 300 MPa was significantly reduced. Moreover, the surface hydrophobicity of MP increased with increasing pressure. Treatment of shrimp with 200–300 MPa high pressure partially converted the structure of MP from an α-helix structure to a β-sheet structure, allowing for greater exposure of the tryptophan residues present. Treatment of shrimp with 100–200 MPa led to a significant loss in the amount of immobilized water in shrimp muscle. However, the treatment did not significantly change the moisture distribution. Overall, pressures of 100 to 200 MPa are considered the most suitable for the processing of S. melantho.     

The Effects of On-Board Handling and Frozen Storage on Gaping in Hoki (Macruronus novaezelandiae)

Abstract

Hoki were trawl-caughl under commercial conditions and subjected to one of five treatments before heading and gutting and freezing to ?35°C. Fish were either processed within 1 hour of capture, held at ambient temperatures or in ice until rigor was established or held at ambient temperatures or in ice until rigor was resolved. Fish from each treatment were then stored at ?20°C for periods of up to 56 weeks and tested for gaping, pH and other related physical and sensory properties. Fish frozen post-rigor showed the most gaping and fish frozen pre-rigor had less than those frozen in rigor. The temperature of storage before freezing had little effect on gaping other than extending the time taken to proceed through rigor. Extended time in frozen storage resulted in decreased water-holding capacity but had little effect on gaping. Gaping was not related to pH levels and did not affect the texfural properties of the cooked fish.     

Comparison of Stunning Methods on the Physicochemical Properties of Frozen Nile Tilapia (Oreochromis niloticus) Fillets

This study compares how CO₂ narcosis and thermal shock affect the physicochemical aspects of Nile tilapia fillets held frozen (?18°C) for up to 6 months. The characteristics of tilapia fillets subjected to CO₂ narcosis were those of higher lightness and whiteness and lower redness. The hardness values of fillets of tilapia subjected to thermal shock were lower than those subjected to CO₂ narcosis. During frozen storage to both treatments, the drip loss, denaturation of myosin, and lipid oxidation increased, while fillet water holding capacity and hardness decreased. The physicochemical properties of frozen fillets of tilapia stunned by CO₂ narcosis were considered more desirable; therefore, the method can be a potential replacement to thermal shock.     

Quality Index Method (QIM) Scheme Developed for Whole Nile Tilapias (Oreochromis niloticus) Ice Stored under Refrigeration and Correlation with Physicochemical and Microbiological Quality Parameters

ABSTRACT

A quality index method (QIM) scheme was optimized to evaluate the freshness of whole tilapias (Oreochromis niloticus) ice stored under refrigerated conditions, which is the most common format of commercialization between primary producers and retailers. QI showed a high prediction accuracy, estimating a rejection point of 10.8 days. Principal component analysis showed the influence of the storage time on sensory, physicochemical (instrumental color and texture profile, total volatile base nitrogen, thiobarbituric acid-reactive substances, pH), and microbiological (total aerobic mesophilic count and total aerobic psychrotrophic count) quality parameters and the correlations between them. The suitability of the QIM scheme for assessing the freshness of whole tilapia was demonstrated to be a fast and accurate tool to maintain proper quality control along the production chain.     

Quality Changes and Browning Developments During Storage of Dried-Seasoned Squid (Dosidicus gigas and Ommastrephes bartrami)

ABSTRACT

The physicochemical changes—moisture, water activity, crude protein, total volatile basic nitrogen (TVB-N), trimethylamine oxide (TMAO), dimethylamine (DMA) and formaldehyde, reducing sugar and amino acid; microbiological changes—aerobic plate count (APC) and coliforms; and browning development (browning intensity and color) in dried-seasoned squids (Dosidicus gigas and Ommastrephes bartrami) during storage at 25°C were investigated. After the storage, the moisture and water activity decreased significantly. The content of crude protein decreased, accompanied by progressive accumulation of TVB-N and slow increase of APC. The high level of TMAO in dried-seasoned squid gradually decreased, whereas DMA and formaldehyde increased significantly during the whole period of storage. The browning intensity and b* value significantly increased, which revealed the occurrence of browning in two squid products. The dominant reducing sugar, lactose, and glucose, and the total amino acid including lysine and proline, decreased remarkably, which were well-correlated with the browning development. The quality deterioration in jumbo squid was more rapid than in neon flying squid partially due to the high level of reducing sugar in the former product. To improve quality and resist browning reaction of dried squid product during storage, the addition of extrinsic reducing sugar became a control factor.     

Effects of Long-Term Feed Deprivation on the Development of Rigor Mortis and Aspects of Muscle Quality in Live-Stored Mature Atlantic Cod (Gadus Morhua L.)

Fresh Atlantic cod is available in large amounts in Norway during the first 5 months of the year. Live-storage of cod may extend the marketing period of fresh cod products throughout the year. In addition, this concept makes pre-rigor processing possible. The main problem of keeping wild cod in captivity is that it does not easily accept formulated dry feed. The purpose of this study was, therefore, to investigate how long-term live-storage of mature Atlantic cod in the absence of feed (79 days) affects the onset and development of rigor mortis, as well as fillet quality by assessing hardness and water-holding capacity of the muscle, pH, protein, and water content. The results showed that starvation of Atlantic cod for 23 days reduces the pre-rigor time from 29 to 17 h. Further starvation did not decrease this period significantly, suggesting that live-stored cod deprived of feed for 79 days may still be industrially processed before the onset of rigor mortis. More than 51 days of starvation reduced protein concentration and increased water content of the muscle. After 51 days, the muscle texture was softer than in fish starved for a shorter period.     

Effects of Potassium Lactate and Acetate on Listeria monocytogenes Inhibition,Physicochemical and Sensory Properties of Smoked Catfish Fillets

The objective of this study was to evaluate the effects of liquid and wood smoking with a potassium lactate (PL) and acetate (PA) combination on the quality and inhibition of L. monocytogenes growth in ready-to-eat (RTE) smoked catfish fillets. Catfish fillets were tumbled with PL and PA, and treated with no smoke (NS), wood smoke (WS), liquid smoke 1 (LS1), and liquid smoke 2 (LS2). Wood smoke with antimicrobials (WSWA) showed greater inhibition (p < 0.05) of L. monocytogenes growth than other treatments with the exception of the LS1 treatment with antimicrobials. Consumers preferred (p < 0.05) smoked catfish fillets treated with WS to LS1 with respect to appearance, odor, flavor, texture, and overall acceptability. In conclusion, the use of PL and PA did not have a negative impact on the quality and sensory properties of smoked catfish fillets but had a synergistic effect with wood smoke constituents that inhibited the growth of L. monocytogenes.     

Comparative Properties of Bluefish (Pomatomus saltatrix) Gels Formulated by High Hydrostatic Pressure and Heat

High pressure was applied at levels of 300 to 3,742 atm for 30 min to formulate gels from bluefish meat paste, and the properties of the resulting gels were compared with those of heat-induced gels formulated at 90°C for 20 min, or at 60°C for 60 min. The moisture content of the pressure-induced gels was similar to that of the heat-induced gels, while protein contents and pH values of pressurized gels were slightly lower than those formulated by heat. Gels formed by pressure were more translucent as compared with those formulated by heat. Texture measurement indicated that there were no significant differences between the elasticities of the gels obtained under various pressures, although gel firmness increased with pressure. Overall, the heat-induced gels formulated at 90°C for 20 min were firmer but had similar elasticities to pressure-induced gels, while gels formulated at 60°C for 60 min were comparatively softer and had lower elasticities. The salt-extractable protein and protein digestibility studies indicated that pressure treatment formed gels with less protein denaturation and which were more digestible than the fish gels formulated by heat. The results from proteolytic activity studies showed that the pressure range used in this study was less effective in inactivating the endogenous proteases in the fish flesh than heat.     

Effects of Lactic Acid Bacteria and Citrus Essential Oil on the Quality of Vacuum-Packed Sea Bass (Dicentrarchus labrax) Fillets During Refrigerated Storage

The preservative effect of refrigerated and vacuum-packed sea bass (Dicentrarchus labrax) fillets inoculated with four mixtures of lactic acid bacteria (LAB) (Lactococcus lactis, Lactobacillus plantarum, and Carnobacterium piscicola) and incorporated with citrus essential oil (CEO) was evaluated on the basis of microbiological and biochemical analysis.

Initially, sea bass fillets showed high nutritional quality. During refrigerated storage, lipid contents did not show a significant decrease in any fish fillets; meanwhile, important proteolysis was observed in untreated control. In addition, results indicated that both CEO and LAB strains exhibited antimicrobial activity against spoilage, pathogenic, and fungi flora. Moreover, the total volatile bases (TVB-N) values were higher in control fillets, and the lowest TVB-N values were observed in Control CEO and C3 + CEO (30.47 ± 0.00 and 32.29 ± 1.12 mg TVB-N/100 g, respectively). Also, the levels of biogenic amines increased in all fillets without exceeding the upper limit of acceptability except for untreated control (sum of about 1396.63 ppm). Furthermore, this combined treatment ameliorated the muscle liquid-holding capacity, which improves technological properties.

Overall, this treatment may open new promising opportunities for the biopreservation of fish products by enhancing the period of storage of refrigerated and vacuum-packed sea bass fillets.     

Quality and Shelf Life Assessment of Puffer Fish (Lagocephalus guentheri) Fillets during Chilled Storage

The aim of the study was to quantify the shelf life and quality characteristics of puffer fish, Lagocephalus guentheri, fillets on chilled storage at 2 ± 1°C. The puffer fish muscle contains 16.14% protein, 80.76% moisture, 0.99% ash, and 0.17% fat. The mouse bioassay proved the absence of tetradotoxin in muscle, liver, skin, and gonads of the fish. The polyunsaturated fatty acid to saturated fatty acid (P/S) ratio of puffer fish was found to be 1.3, with n-3 to n-6 ratio of 3.27. The puffer fish had hypocholesterolemic/hypercholesterolemic ratio (H/H) value of 2.68, artherogenicity index of 0.43, and thrombogenicity index of 0.29. Beheaded and deskinned fishes were filleted and were studied for 10 days of chilled storage. The physical, chemical, sensory, and microbiological parameters showed significant (p < 0.05) changes during the entire storage period. While the hydrolytic rancidity was significantly correlated to springiness, gumminess, and chewiness of fillets, the peroxide value (PV) correlated with the color attributes and pH. The hardness of the samples decreased significantly and was evident in both sensory and instrumental analysis. With storage time, the yellowness of the fillets increased steadily. The results of this study can help in improving processing, preservation, and marketing aspects and enhance the utility of puffer fish.     

Synergic Effects of Light Salting,Vacuum Packaging,and Onion Extract on the Quality Retention of Refrigerated Rainbow Trout (Oncorhynchus mykiss) Fillets

This experiment investigated the synergistic effects of vacuum packaging, light salting, and onion extract on the shelf life of rainbow trout (Oncorhynchus mykiss) fillets stored under refrigeration. The chemical, microbial, and organoleptic changes were monitored for up to 18 days in fillets. Total volatile basic nitrogen (TVB-N) and free fatty acid (FFA) values were evident in the order: control (without salting, vacuum packaging, and extract) > air packaged, salted (APS) > vacuum packaged, salted (VPS) > and vacuum packaged, salted, containing 2% and 4% (v/w) onion extract (2% and 4% VPSOE) throughout the storage period. Thiobarbituric acid values in APS groups were higher than control groups. Data from microbial assay showed that treatment with 2% and 4% VPSOE decreased total viable microbial count (TVC) compared with other treatments. APS, VPS, and VPSOE samples remained acceptable for up to 8, 12, and 15 days, respectively. The most suitable indices for determining shelf life of rainbow trout fillets are TVC.     

Effects of Dietary Vitamin E Enrichment on Frozen Channel Catfish, (Ictalurus punctatus) Fillets

The storage quality of channel catfish (Ictalurus punctatus), following long term frozen storage, fed diets containing 5 and 10 times the normal level of vitamin E for 45 or 60 days prior to harvest, was evaluated. There were no unusual effects of treatment on fish weight, survival or feed conversion ratios. Muscle vitamin E content was higher (P < 0.05) from fed diets containing supplemental vitamin E than in the control. Oxidation as measured by TBARS and sensory analysis values did not differ (P > 0.05) in response to vitamin E supplementation. Lipid oxidation increased as storage time increased. Lack of change in phospholipid and neutral lipid fractions during storage indicated that autoxidations was the major cause of oxidation in catfish. Vitamin E levels up to 10 times the normal amount did not improve the overall quality of catfish fillets.     

Quality Characteristics of High Pressure-Induced Hake (Merluccius capensis) Protein Gels with and without MTGase

The effects of microbial transglutaminase (MTGase; 0.5%, w/w) and high hydrostatic pressure (HHP) on the quality of protein gels from unwashed mince of hake (Merluccius capensis) trimmings were studied. MTGase incorporation improved texture. Protein solubility was lower for those gels containing MTGase, as a result of myosin heavy chain cross-linking. HHP improved texture. Pressure level was the most important HHP parameter, since higher levels (300 vs. 100 MPa) augmented gel strength (GS). A positive synergistic effect of MTGase and HHP was found for some properties, such as GS, yielding improved gels from a raw material that otherwise shows poor gelation.     

高温对鱼类的影响及其预防研究

鱼类是水生变温动物,其生长繁衍与生活环境条件密切相关,其中环境温度是鱼类生长发育最重要的环境因子之一.水温影响着鱼类的摄食、生长、免疫和生殖等活动,具有多方面生态作用.