Banana Shrimp, Penaeus merguiensis, Quality Changes During Iced and Frozen Storage

Shelf life of banana shrimps, Penaeus merguiensis, were studied along with formaldehyde changes in their muscles during iced and frozen storage. K-value, timethylamine oxide nitrogen (TMAO-N), trimethylamine nitrogen (TMA-N), volatile basic nitrogen (VB-N) and sensory quality were determined. Shelf life was 4 days in ice, 6 days at -3°C and 9 wk at ??10°C. They remained acceptable after 6 mo at ?20°C. Formaldehyde was a good indicator in shrimp shelf life assessment.     

Application of partial autoproteolysis to extraction of protein from Antarctic krill (Euphausia superba). Part 3. Changes in and yield of nitrogen substances during autoproteolysis of fresh and frozen krill

Respective utilities of the fresh and frozen (after a 10-month storage at ?21 °C) krill for precipitate production by means of partial autoproteolysis within 10–60 °C were compared. The highest yield of the precipitate was found at about 20 °C, regardless of the raw material used, although the optimal temperature ranges for the fresh and frozen krill were 20–30 °C and 10–20 °C, respectively. The main factors assisting the protein extraction during partial autoproteolysis were enzymatic protein hydrolysis in the fresh krill and the loosening of tissues brought about by water crystallization in the frozen krill.     

PROTEIN INSOLUBILIZATION IN FROZEN GREENLAND HALIBUT (REINHARDTIUS HIPPOGLOSSOIDES)

Frozen storage of minced Greenland halibut (Reinhardtius hippoglossoides) at -10°C resulted in a rapid loss in salt solubility of “my ofibrillar proteins” (approximately 50% in 15 days) and in a gradual loss in water solubility of “sarcoplasmic proteins” (approximately 40% in 120 days). The water and salt inextractable protein from frozen mince (R) was completely soluble in 4% sodium dodecylsulfate (SDS) when a disulfide bond reducing agent such as mercaptoethanol (ME) was present. Other reagents, including urea and Triton X 100, were less effective in solubilizing the protein from mince after frozen storage. Evidence presented supports the thesis that disulfide bond formation contributes to the observed loss in protein extractability during frozen storage of mince. Addition of various thiol reagents to mince prior to freezing was effective in minimizing protein insolubilization. An estimated 50% of the reduced cysteine associated with protein is oxidized in mince after long time storage at -10°C. However, the kinetics of disulfide bond formation do not parallel the time course of protein insolubilization; accordingly, the possibility that disulfide bond formation is a secondary event cannot be excluded. Other lines of evidence indicate that additional covalent or strong bond interactions contribute to the formation of(R). Solubilization and boiling of(R) in SDS/ME does not dissociate high molecular weight aggregates (500–1000 Kdaltons) although these aggregates are disrupted by sodium borohydride reduction. In addition, the degree of hydrolysis of proteins in frozen mince by certain proteolytic enzymes is lower then that of fresh mince despite the complete solubilization of the mince protein by these proteolytic enzymes. The mince protein from frozen fish contains substantially more fluorescence than that of fresh fish. Fluorescence is associated with the high molecular weight peptide fraction after pepsin catalyzed hydrolysis. The amino acid composition of mince proteins after HCl or formic acid/HCl hydrolysis did not change appreciably as a result of frozen storage. The data indicate that covalent bond formation by sulfhydryl residues and other borohydride and acid labile linkages contribute to the loss in solubility of the protein in Greenland halibut mince during frozen storage at -10°C.     

Use of Electrolyzed Oxidizing Water for Quality Improvement of Frozen Shrimp

The bactericidal effect of electrolyzed oxidizing (EO) water was evaluated on Escherichia coli O157:H7‐inoculated and Salmonella‐inoculated shrimp. The shrimp were inoculated on day 0 and stored frozen at ‐20°C. Bacterial enumeration was done on days 0, 24, 49, and 119 of frozen storage. Acidic EO water at 40 ppm free available chlorine was as effective as aqueous chlorine of the same concentration and was significantly more effective (P < 0.05) than tap water in reducing pathogen load on the inoculated shrimp. Further reduction of pathogen numbers was observed after each frozen storage period. Prewashing with alkaline EO water did not enhance the bactericidal activity of the acidic EO water on the shrimp. The washed acidic EO water of the inoculated shrimp had a nondetectable bacterial population compared with treated aqueous chlorine, alkaline EO water, and tap water. Non‐inoculated shrimp subjected to similar treatments were served cooked or uncooked to a minimum of 10 experienced panelists for sensory evaluation on days 0, 24, 49, and 119 of frozen storage. The cooked shrimp were evaluated for the presence of off‐odor, juiciness, tenderness, shrimpy flavor, aftertaste, and overall acceptability; whereas the raw shrimp were evaluated for color, firmness, presence of off‐odors, melanosis, and overall acceptability. Raw shrimp thawed from each frozen storage period were stored at refrigeration temperature (4 °C) for 3 d to observe for melanosis. No difference of sensory attributes was detected among the various treatment groups. Therefore, acidic EO water can be used as an effective disinfectant to replace aqueous chlorine for thawing shrimp blocks.     

Freezing and Freezing-Thawing Cycles on Textural and Biochemical Changes of Meagre (Argyrosomus regius,L) Fillets During Further Cold Storage

The effects of freezing and freezing-thawing cycles during cold storage have been studied in meagre (Argyrosomus regius) fillets. Fillets were subjected to three conservation protocols: fresh, freezing at –20°C, and repeated freezing-thawing cycles. Fresh fillets were stored (4°C, 15 days), and the same protocol was followed for freezing and freezing-thawing after the freezing period. Freezing and freezing-thawing fillets were softer and presented lower water holding capacity than fresh, mostly attributable to collagen solubilization, and partial myofibrillar protein degradation. Cold storage (4°C) during 15 days caused softening in fresh and frozen fillets attributable to myofibrillar protein hydrolysis. Freezing-thawing cycles increased proteolysis, this leading to unacceptable softening even from early stages of further cold storage, and this was also revealed by SDS-PAGE.     

Enrichment of Chicken Nuggets with Microencapsulated Omega-3 Fish Oil: Effect of Frozen Storage Time on Oxidative Stability and Sensory Quality

This work studies for the first time the elaboration of frozen chicken nuggets enriched with microcapsules of omega-3 fatty acids using fish oil. Three types of chicken nuggets were prepared: control (C), enriched in bulk fish oil (BFO), and with added microencapsulated fish oil (MFO). Effect of length of frozen storage after pre-frying and before domestic frying was studied. The pre-fried nuggets were stored during 24 h at refrigeration temperature (0–2 °C) (T0) or during 1 month (T1M) or 3 months (T3M) in a domestic freezer at ?18 °C before frying. Length of frozen storage after pre-frying and before domestic frying promoted lipid and protein oxidative reactions in omega-3-enriched nuggets. Microencapsulation showed a protective effect against lipid and protein oxidation, especially during the first month of storage. In MFO, sensory traits were not affected by enrichment. In BFO-T0, a higher juiciness and saltiness and a less intense meat flavor in comparison with C-T0 and MFO-T0 was found. Time of frozen storage did not influence the sensory quality of chicken nuggets enriched with omega-3. Microencapsulation seems to be a promising method for enrichment of pre-fried frozen meat products with fish oil, improving the oxidative shelf life and preserving the sensory quality characteristics of the enriched products.     

Oxidative Effects of Meat Grinder Wear on Lipids and Myoglobin in Commercial Fresh Pork Sausage

Pork ground before and after the replacement of worn meat grinder plates and knives was formulated as commercial fresh pork sausage containing antioxidants and processed into 454-g chubs. The sausage was frozen at ^?15°C for 4, 8, 12, and 16 wk and monitored for oxidation after 1 day, 2 wk and 3 wk of postfrozen refrigeration at 1°C. Estimated average grinder metal in sausage was 136 ppb. Meat temperature rise during grinding was higher (P<0.05) with the worn hardware (2.3°C vs 1.6°C). Hunter “a” values were greater (P<0.05) with the sharp than with the worn equipment. 2-Thiobarbituric acid (TBA) numbers did not differ with equipment state of wear. Significant correlations (P<0.05) indicated in inverse relationship between the oxidation of lipids and myoglobin.     

BIOCHEMICAL AND MORPHOLOGICAL CHANGES IN GRASS SHRIMP (PENAEUS MONODON) MUSCLE FOLLOWING FREEZING BY AIR BLAST AND LIQUID NITROGEN METHODS

Grass shrimp (Penaeus monodon) at prerigor stage were frozen at rates ranging from 3.41 to 16.1 cm/h by using an air blast freezer at –35C or a liquid nitrogen freezer at – 80, – 100 and – 120C. Immediately after freezing, the spacing between muscle fiber bundles was larger (21.3 ± 5.7 μm) in shrimp frozen at 3.4 cm/h than in shrimp frozen at 8.6 ～ 16.1 cm/h (6.0 ± 0.6 to 8.8 ± 1.1 μm, respectively). The spacing between fibers increased during frozen storage at – 20C and remained different for slow and fast frozen samples within 4 weeks. The lysosomal fraction from fresh shrimp had more cathepsin D-like activity (187 units/mg protein) than that from shrimp frozen at 10.2 cm/h (179 units/mg protein) and at 3.4 cm/h (86 units/mg protein). During frozen storage at – 20C the cathepsin D-like activity of intact lysosomes decreased and was negligible after 4 weeks. The solubility of muscle protein in 0.6 M KCl was not consistently different in samples frozen by different methods and stored at – 20C for 4 weeks. Liquid nitrogen freezing produced frozen shrimp of higher muscle integrity than air blast. But the differences disappeared after one-month storage at – 20C.     

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

Fillets 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.     

Chilled (5°C) and Frozen (−18°C) Storage Stability of the Purple-Hinge Rock Scallop, Hinnites multirugosus Gale

Purple-hinge rock scallops (Hinnites multirugosus), native to northeast Pacific Coast waters and under evaluation for commercial aquaculture, were harvested wild and analyzed for storage stability. Over 2 wk of chilled storage at 5°C or 5 months of frozen storage at ?18°C, scallops showed no appreciable lipid oxidation, proteolytic change, and ammonia development. Hypoxanthine fluctuated throughout fresh storage. Bacterial numbers were unchanged at ?18°C but sharply increased during the second week at 5°C. Odor of raw scallops deteriorated somewhat at week 2 of chilled storage and month 4 of frozen storage. However, when cooked, scallops showed no significant differences for most sensory characteristics or for acceptability. Cooking losses were variable. Textural shear parameters changed with weight and frozen storage.     

Phosphorous Levels in Peeled and Deveined Shrimp Treated with Sodium Tripolyphosphate

Using volumetric and spectrophotometric methods for the determination of phosphorous, untreated shrimp were shown to have high and variable phosphorous content. When peeled and deveined shrimp were treated with 0.5% and 1.0% sodium tripolyphosphate (STP) solutions, the STP uptake was shown to be low. At these low treatment concentrations the phosphorous content in the treated shrimp did not exceed the range of natural phosphorous found in untreated shrimp. When higher treatment concentrations were used, treated thrimp could be identified. The stability of STP in treated shrimp during frozen storage was investigated using a P³² STP isotope. After 2 wk of frozen storage at –26°C only 12% of the total activity could be attributed to STP. At the same time, pyrophosphate was present at a level of 25% and orthophosphate at 27%. During further frozen storage, the STP concentration remained at approxinately 12%, pyrophosphate dropped down to as low as 2% while orthophosphate gradually increased reaching 45% of total activity at the end of 10 wk storage period.     

Storage Stability of a Processed Ginger Paste

A processed paste was prepared from fresh ginger so that a convenient, shelf-stable product with the odor characteristics of fresh ginger could be manufactured from ginger produced in excess of fresh market demand. The paste was sampled periodically for color by Hunter YI index, odor by trained panel and (6)-gingerol (the major pungent component) by HPLC. This product was found to have a fair shelf-life under refrigeration, but degradation of color, odor and (6)-gingerol made the paste unacceptable after 8 wk storage at 25°C or 37°C.     

Differentiation of fresh and frozen/thawed fish, European sea bass (Dicentrarchus labrax), gilthead seabream (Sparus aurata), cod (Gadus morhua) and salmon (Salmo salar), using volatile compounds by SPME/GC/MS

BACKGROUND: A simple method based on solid phase microextraction/gas chromatography/mass spectrometry (SPME/GC/MS) was applied for studying the volatile profiles of whole fish samples of European sea bass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) and fillets of cod (Gadus morhua) and salmon (Salmo salar) during frozen storage in order to be able to differentiate a fresh product from one that has been frozen. Analysis of volatile compounds was performed on these two product types, fresh and after freezing/thawing following storage at ? 20 °C for 30 and 90 days. RESULTS: More than a hundred volatile compounds were found by SPME/GC/MS. Statistical processing by principal component analysis and ascending hierarchical classification was used to classify the samples into categories and verify the possibility of separating fresh samples from those that had been frozen and thawed. The compounds to be used as differentiators were identified. Four compounds were common to all species: dimethyl sulfide, 3‐methylbutanal, ethyl acetate and 2‐methylbutanal. Not only were they found in larger quantities after thawing but they also increased with the duration of storage at ? 20 °C. CONCLUSION: These four compounds can therefore be considered as potential markers of differentiation between a fresh product and one that has been frozen. Copyright © 2012 Society of Chemical Industry     

Characteristics of mince from pond-bred silvercarp (Hypophthalmichthys molitrix) and preliminary experiments on its use in sausages

The quality of fresh, chilled and frozen mince made from the flesh of pond-bred silvercarp (Hypophthalmichthys molitrix (Val)) was evaluated. Flavour panel scores for all minces were acceptable and this quality did not deteriorate during storage for one week in a domestic refrigerator (5–6°C) or for one year at ?20°C. The levels of oxidative rancidity (2-thiobarbituric acid analysis) in the minces were consistent with this maintenance of quality. Aerobic plate counts at 25°C of fresh mince rose from 7–9 × 10⁴ to 1.1 × 10⁵ after 6 days' storage at 5–6°C. Coliform and psychrotroph counts rose from 1.0 × 10¹ and 7–8 × 10³ to 5–4 × 10² and 1.3 × 10⁴, respectively. The functional and textural properties of pond-bred silvercarp mince in terms of salt-soluble protein content, water binding capacity and penetrometer values were measured on fresh, refrigerated and frozen samples. All-fish sausages and frankfurters developed from pond-bred silvercarp mince were assessed in laboratory and consumer tests against commercial beef sausages and frankfurters. The fish products competed well and achieved levels of acceptance similar to those of the beef-containing products. Texture measurements revealed slight changes in the fish products during storage for 7 days at 5–6°C. No spoilage was detected in any of the products after a week at 5–6°C. The nutritional advantages of the fish sausages and frankfurters are discussed.     

Effect of Phosphate Blends on Stability of Cod Fillets in Frozen Storage

Atlantic cod fillets were dipped in commercial tripoly or metaphosphate solutions, frozen and stored at either –12 ° 0.5°C or –30°C (constant or with daily programmed fluctuations to ?26°C) for up to 26 wk. Phosphate treatments at both storage temperatures decreased thaw drip and cooked drip and yielded a product with higher raw and cooked moisture. Protein content of cooked drip from fillets stored at –12°C was reduced by phosphate treatment; no significant difference was found between treated and control samples at –30°C. Although salt extractable protein was lowered, phosphate treatment did not affect dimethylamine/formaldehyde formation. Sensory evaluation of treated fillets stored at –30°C (with daily fluctuation to –26°C) revealed phosphated fillets to be the most tender and, after 26 wk storage, the most highly acceptable. Tripolyphosphate treatment significantly retarded the increase of expressible fluid under abusive conditions of frozen storage.     

Shelf Life and Clostridium botulinum Toxin Development during Storage of Modified Atmosphere-packaged Fresh Catfish Fillets

Shelf life (onset of sensory spoilage) and potential for toxin production by Clostridium botulinum type E in retail type packages of fresh catfish fillets in high barrier film were investigated under selected atmospheres when stored under refrigeration and temperature-abuse conditions. Shelf life of fillets in all atmospheres decreased with increase of storage temperature from 4°C to 16°C. Trimethylamine content associated with onset of spoilage was different for each storage temperature and atmosphere. Surface pH and K-values were not good indicators of onset of sensory spoilage. Toxin development coincided with sensory spoilage at 16°C storage for fillets packaged in either atmosphere. At 4°C, none of the MA-packaged fillets became toxic, even after 37 days of sensory spoilage.     

Astaxanthin Extraction from Shrimp Wastes and its Stability in 2 Model Systems

Abstract: The objective of this work was to study the stability of astaxanthin, obtained from shrimp wastes, and incorporated to 2 model systems: egg albumin protein solution and sunflower oil. Shrimp wastes were ensiled by a treatment with formic/acetic acids (4%–4% v/w wastes) and stored at 4 °C for 24 h. The pigment was extracted with organic solvents (petroleum ether:acetone:water, 15 : 75 : 10) and concentrated. The storage parameters studied were: illumination (light/dark), temperature (4/20 °C), atmosphere (air/air-free), and storage time (0, 1, 2, 3, 4, 5 wk). Results showed that total xantophylls and astaxanthin were more stable in sunflower oil than in the protein system. Total xantophylls showed more stability than astaxanthin, possibly due to the presence of other, more stable carotenoids quantified together with xantophylls. Astaxanthin concentration was significantly affected by storage time; its degradation followed a first-order reaction rate under all the studied conditions. This pigment was stable only for 17 d, even when stored in air-free flasks, under refrigeration, and in the dark. Practical Application: Shrimp catching and farming generate large amounts of polluting wastes; they can be an important source of added-value red-orange pigments. However, these pigments are highly unstable to various transformation processes and to storage conditions. This research studied the effect of storage on 2 model systems (protein and lipid) on pigment degradation.     

Gilthead seabream (Sparus aurata): suitability for freezing and commercial alternatives

The quality of portion‐size farmed gilthead seabream (Sparus aurata) during frozen storage and the influence of post‐mortem treatments were studied in order to find new ways of marketing this species. Portion‐sized gilthead seabream, fasted for 48 h prior to slaughter, were frozen and stored at ?20 °C for up to one year. Whole fish were frozen immediately after rigor mortis; gutted fish were frozen immediately after rigor and after 5 days of storage in ice. All lots were stored at ?20 °C for up to one year. The myofibrillar protein of this species was very stable and a slight decrease of solubility in salt solutions was found only after one year of frozen storage. A slight decrease in water‐holding capacity and a slight increase in shear strength were observed, but these were lower than in other species. These changes were reflected as increased toughness and reduced juiciness in sensory analysis of the cooked fillets after one year. The main changes in the cooked fillets were observed in odour and flavour. No significant detrimental effect due to the guts was detected during frozen storage. Storage in ice prior to freezing was reflected in sensory assessment of the raw fish, mainly in terms of initial higher demerit points for fishy odour, gills and eyes; however, no effect was observed in the cooked fillets. Copyright © 2004 Society of Chemical Industry     

Quality and Nutritional Changes in Frozen Breaded Shrimp Stored in Wholesale and Retail Freezers

Chemical, microbiological, and sensory changes were monitored in breaded fantail shrimp held in upright and coffin style freezers at two retail markets and in a large warehouse freezer. Quality and nutritional changes in a test lot of shrimp were followed for 13 months. Significant sensory deterioration can be detected as early as 3 - 4 months after production when shrimp are stored in a retail freezer. Minimum retail freezer temperatures reached ≤-20°C between 1% and 36% of the monitored days and had daily temperature variations of 12 - 18°C. Storage at the wholesale level below -20°C with maximum daily temperature variations of 2 - 3°C proved to be an effective method to maintain the quality of frozen shrimp for at least 13 months of storage.     

Protein changes in shrimp (Metapenaeus ensis) frozen stored at different temperatures and the relation to water-holding capacity

To study the effects of freezing temperature on muscle proteins, shrimp (Metapenaeus ensis) were frozen stored at either −18 or −60 °C up to 90 and 210 days. Shrimp frozen at −18 °C had higher thawing and compression loss and poor myofibril water-holding capacity compared with those frozen at −60 °C. In terms of protein characteristics, shrimp frozen at −18 °C had higher levels of carbonyls and reduced sulphhydryls. Moreover, the shrimp frozen at −18 °C had higher surface hydrophobicity and reduced Ca²⁺-ATPase activity, indicating increased protein denaturation. Proteomics revealed that seventy-five proteins were classified as differentially abundant proteins (DAPs) following freezing. There were sixty-four DAPs in the F18-CON comparison group (shrimp frozen at −18 °C vs. control) and thirty-two DAPs in the F60-CON comparison group (shrimp frozen at −60 °C vs. control), suggesting that freezing at −18 °C results in more DAPs than freezing at −60 °C. A comparison between F18 and F60 revealed that ribosomal proteins (L44, L7a) and heat shock protein 21 were downregulated in F18. These results increase our understanding of the variable quality associated with shrimp frozen at different temperatures.