Nutritional quality and safety of cooked edible crab (Cancer pagurus)

Edible crab (Cancer pagurus) is one of the most important crustaceans consumed in Southern European countries, either as boiled or steamed cooked product. So far, the majority of studies assessing health benefits and risks associated to seafood consumption have been carried out in raw products, despite being generally cooked before consumption, and mostly in muscle tissue. Therefore, the aim of this study was to assess the effect of steaming and boiling on the chemical safety and nutritional value of C. pagurus caught in spring and summer. Generally, chemical and elemental composition of brown meat (tissue in the body cavity comprising mainly gonads and hepatopancreas) differed significantly from muscle (white meat in claws and legs). Additionally, the same tissue revealed differences in chemical and elemental composition of raw and cooked C. pagurus, likely due to water leaching. In contrast, few variations between seasons were observed. The results revealed that the consumption of cooked edible crab muscle should be promoted, whereas brown meat ingestion should be done parsimoniously.     

Effect of temperature on the spoilage rate of whole, unprocessed crabs: Carcinus maenas, Necora puber and Cancer pagurus

Shelf life of whole, initially live, crabs depended primarily on the storage conditions and the time at which death occurred. Large differences in the time that individual crab species survived particular storage conditions resulted in wide variations in shelf-life. Bacterial spoilage of Carcinus maenas, Necora puber and Cancer pagurus, measured using aerobic plate counts, indicated that on ice at 4 degrees C whole unprocessed crabs had a shelf life approximately 9-11 days, at 4 degrees C approximately 13-29 days, in simulated supermarket conditions of sale approximately 5-7 days and at 20 degrees C approximately 2-16 days. Storage of whole unprocessed crabs chilled at 4 degrees C considerably extended shelf life compared to crabs stored on ice. Live crabs stored on ice died within 24h, most likely due to thermal shock and their early death was responsible for their more rapid increase in bacterial numbers compared to crabs stored at 4 degrees C. No growth of bacteria occurred in the flesh of live crabs stored at 4 degrees C for between 128 and 504 h. Crab flesh quality deteriorated prior to maximum shelf-life (defined as the time at which bacterial load reached log 5 cfu/g crabmeat) in some instances. The best compromise between high crabmeat yield and long shelf-life is likely to be to transport crabs at 4 degrees C live to market where they could be stored live at 4 degrees C without spoilage for 2 weeks before placed on ice at 4 degrees C, with a potential maximum shelf life of approximately 24 days.     

EFFECT OF PROCESSING VARIABLES ON MICROBIAL QUALITY AND SHELF-LIFE OF BLUE CRAB (CALLINECTES SAPIDUS) MEAT

The effects of cooking time, cooking method, season, and storage condition on the microbiological quality, sensory characteristics, and shelf-life of crabmeat were determined under commercial processing conditions. Microbial flora content of the meat was inversely proportional (p 0.05) to the cooking time in both total aerobic and anaerobic plate counts after 6 and 9 days at 2.2C during summer. Boiled cooked crabmeat showed higher microbial count (1–2 log cycle) and shorter shelf-lives than 10 and 12 min retort cooked meat. During summer, the shelf-life of the meat as determined by a sensory evaluation, was: 15.5 days at 0.0C; 12.5 days at 2.2C; and 8.5 days at 5.6C.     

A comparison of different processing methods for picked blue crab (Callinectes sapidus)

Five methods for producing picked crab meat from cooked blue crab (Callinectes sapidus) were evaluated for internal food temperatures and bacterial numbers at various process points. Whole shell-on crabs, crab cores ("backed" crabs with carapace removed), and crab meat samples were analyzed for standard plate count, total coliforms, fecal coliforms, Escherichia coli, and Staphylococcus aureus. For three of the processes, crabs were backed and washed a substantial time before picking; one of the processes used an ice slush dip to cool cooked crabs. Except for a single crab sample, bacteria were not isolated from crab and core samples. Standard plate count, E. coli, and S. aureus in crab meat samples from the different processes were statistically the same. Bacterial numbers in fresh picked crab meat samples exposed to an ambient temperature of 20 to 21.1 degrees C for 1.5 and 3.5 h and stored at 1 degrees C for 3 to 4 days and 7 to 8 days did not significantly differ (P < 0.05).     

High pressure processing pretreatment of Chinese mitten crab (Eriocheir sinensis) for quality attributes assessment

The present study evaluated high pressure processing (HPP) pretreatment effects on the quality attributes of Chinese mitten crab (Eriocheir sinensis). Process parameters were optimized (300 MPa for 5 min) and the effects of HPP pretreatment on the total edible part of Eriocheir sinensis were investigated. The results showed that steamed loss has no significant difference and water holding capacity of inner meat was increased by approximately 51.33% with HPP pretreatment. HPP pretreatment can also decrease hardness value of crab carapace and preserve texture properties of crab leg meat. Compared with raw inner meat, results of DSC analysis of inner meat with HPP pretreatment has revealed that the denaturation temperature and the enthalpy of protein were decreased remarkably. The results of water distribution indicated that HPP pretreatment reduced the loss of entrapped water in inner meat. Finally, compare with the conventional steamed crabs, it has been detected that the aroma of the edible viscera of crabs has a significant difference with HPP pretreatment. Above findings indicated that HPP pretreatment retains quality attributes of Eriocheir sinensis well, in the meantime improves the processing efficiency since steaming time can be reduced by applying HPP pretreatment.Industrial relevanceHPP is a novel non-thermal technique widely used in the field of food production. Compared with conventional thermal processing, it is important for assessing the impact of HPP pretreatment on the quality attributes of crab in order to obtain high-quality products. According to recent studies, HPP pretreatment has been confirmed to be able to improve the quality of hot processed crabs. By applying 300 MPa for 5 min on Eriocheir sinensis, the total edible part was improved, and the water holding capacity of crab inner flesh was increased. Moreover, HPP pretreatment can also decrease hardness value of crab carapace and preserve sensorial properties of crab leg meat. These results indicated HPP pretreatment retains high quality characteristics of Eriocheir sinensis and reduces steaming time by which means the processing efficiency can be improved. This work provided further support for the use of HPP in Eriocheir sinensis.     

Irradiated vacuum-packed lamb meat stored under refrigeration: Microbiology,physicochemical stability and sensory acceptance

Reducing spoilage and indicator bacteria is important for microbiological stability in meat and meat products. The objective was to evaluate the effect of different doses of gamma radiation on the shelf-life of lamb meat, vacuum-packed and stored under refrigeration, by assessing the microbiological safety, physicochemical stability and sensory quality. Lamb loin cuts (Longissimus dorsi) were irradiated with 1.5 kGy and 3.0 kGy. The samples, including control, were stored at 1 ± 1 °C during 56 days. Samples were analyzed on zero, 14, 28, 42 and 56 days by their microbiological and physicochemical characteristics. Sensory quality was carried out on day zero. The results showed a reduction (p < 0.05) in the microbial load of the irradiated samples. The acceptance of lamb loins was not affected (p > 0.05) by the radiation doses. Thus gamma irradiation at 3.0 kGy was effective in reducing the content of microorganisms, without harming the physicochemical characteristics evaluated.     

Evaluation of hygiene practices and microbiological quality of cooked meat products during slicing and handling at retail

Cooked meat ready-to-eat products are recognized to be contaminated during slicing which, in the last years, has been associated with several outbreaks. This work aimed to find out possible relation between the hygiene practice taking place at retail point during slicing of cooked meat products in small and medium-sized establishments (SMEs) and large-sized establishments (LEs) and the microbiological quality of sliced cooked meat products. For that, a checklist was drawn up and filled in based on scoring handling practice during slicing in different establishments in Cordoba (Southern Spain). In addition, sliced cooked meats were analyzed for different microbiological indicators and investigated for the presence of Listeria spp. and Listeria monocytogenes. Results indicated that SMEs showed a more deficient handling practices compared to LEs. In spite of these differences, microbiological counts indicated similar microbiological quality in cooked meat samples for both types of establishments. On the other hand, Listeria monocytogenes and Listeria inocua were isolated from 7.35% (5/68) and 8.82% (6/68) of analyzed samples, respectively. Positive samples for Listeria spp. were found in establishments which showed acceptable hygiene levels, though contamination could be associated to the lack of exclusiveness of slicers at retail points. Moreover, Listeria spp presence could not be statistically linked to any microbiological parameters; however, it was observed that seasonality influenced significantly (P < 0.05) L. monocytogenes presence, being all samples found during warm season (5/5). As a conclusion, results suggested that more effort should be made to adequately educate handlers in food hygiene practices, focused specially on SMEs.     

FROZEN STORAGE QUALITY CHANGES IN WHOLE JONAH CRABS

The Jonah crab is an underutilized species in the mid-Atlantic region, and use of the whole, frozen crab would broaden marketing options for this seafood product. We monitored quality changes in whole cooked crabs held in a blast freezer for up to 50 weeks. A sensory evaluation panel determined the point at which detectable differences appeared in the product. Microbiological testing was conducted at selected intervals to assess bacterial content. In a triangle test, frozen experimental samples of leg meat were first differentiated from frozen controls at approximately 24 weeks. No significant difference was defected in body meat for up to 33 weeks’ storage. Microbial quality was acceptable throughout the experiment.     

Prevalence, characterization and sources of Listeria monocytogenes in blue crab (Callinectus sapidus) meat and blue crab processing plants

Seven blue crab processing plants were sampled to determine the prevalence and sources of Listeria spp. and Listeria monocytogenes for two years (2006–2007). A total of 488 raw crabs, 624 cooked crab meat (crab meat) and 624 environmental samples were tested by standard methods. Presumptive Listeria spp. were isolated from 19.5% of raw crabs, 10.8% of crab meat, and 69.5% of environmental samples. L. monocytogenes was isolated from 4.5% of raw crabs, 0.2% of crab meat, and 2.1% of environmental samples. Ninety-seven percent of the isolates were resistant to at least one of the ten antibiotics tested. Eight different serotypes were found among 76 L. monocytogenes isolates tested with the most common being 4b, 1/2b and 1/2a. Automated EcoRI ribotyping differentiated 11 ribotypes among the 106 L. monocytogenes isolates. Based on ribotyping analysis, the distribution of the ribotypes in each processing plant had a unique contamination pattern. A total of 92 ApaI and 88 AscI pulsotypes among the 106 L. monocytogenes isolates were found and distinct pulsotypes were observed in raw crab, crab meat and environmental samples. Ribotypes and serotypes recovered from crab processing plants included subtypes that have been associated with listeriosis cases in other food outbreaks. Our findings suggest that molecular methods may provide critical information about sources of L. monocytogenes in crab processing plants and will augment efforts to improve food safety control strategies such as targeting specific sources of contamination and use of aggressive detergents prior to sanitizing.     

Quality changes in oyster (Crassostrea belcheri) during frozen storage as affected by freezing and antioxidant

Changes in physical, chemical, microbiological and sensory qualities of individual quick frozen (IQF) and contact plate frozen (CPF) oyster (Crassostrea belcheri) meat, treated and untreated with butylated hydroxyanisole (0.02% BHA suspension) during storage at −20 °C for 12 months were investigated. Increase in expressible drip of IQF oyster was slower than that of CPF oyster, due to the fact that quick freezing (IQF) resulted in less tissue damage than slow freezing (CPF). Neither freezing method nor antioxidant treatment caused significant changes in chemical qualities, i.e., pH, moisture, crude protein, crude fat and total volatile basic nitrogen (TVB-N), nor in microbiological qualities, i.e., total viable count (TVC), psychrotrophic bacteria, Escherichia coli and Vibrio parahaemolyticus. During frozen storage, TVC and psychrotrophic bacteria of both BHA-treated and untreated CPF oyster decreased with storage time increases (p < 0.05) at a slower rate than in IQF oyster. Antioxidant treatment could minimise sensory quality changes, especially the colour of frozen oyster during storage.     

Effect of high pressure on the microbiological quality of cooked chicken during storage at normal and abuse refrigeration temperatures

Vacuum-packaged cooked poultry meat was treated at a range of pressures (400–600 MPa) and hold times (1, 2 and 10 min), followed by storage at 4°, 8° or 12 °C for up to 35 days. Weissella viridescens was found to be the dominant microorganism in the pressure-treated meat, constituting 100% of the microflora identified at 500 and 600 MPa. None of the pressure-treated samples had obvious signs of spoilage during the 35 day storage period, even when the Weissella count was >7 log₁₀ cfu/g. Studies on a typical W. viridescens isolate showed it to be relatively pressure-resistant in poultry meat, with <1 log reduction in numbers after a treatment of 2 min at 600 MPa. Agar diffusion assays showed that the isolate also caused the inhibition of a number of Gram-positive and Gram-negative pathogens, including strains of Clostridium botulinum, Listeria monocytogenes, Bacillus cereus and Escherichia coli. The selection of a pressure-resistant organism, such as this Weissella sp. could be advantageous in extending the shelf-life, and also microbiological safety, of the cooked meat, as it could give protection in addition to the pressure treatment itself.     

Thawed Chilled Barents Sea Cod Fillets in Modified Atmosphere Packaging-Application of Multivariate Data Analysis to Select Key Parameters in Good Manufacturing Practice

The purpose of the present study was to select key parameters in good manufacturing practice for production of thawed chilled modified atmosphere packed (MAP) cod (Gadus morhua) fillets. The effect of frozen storage temperature (−20 and −30 °C), frozen storage period (3, 6, 9 and 12 mo) and chill storage periods up to 21 d at 2 °C were evaluated for thawed MAP Barents Sea cod fillets. Sensory, chemical, microbiological and physical quality attributes were evaluated and multivariate data analysis (principal component analysis and partial least-squares regression) applied for identification of key parameters in good manufacturing practice for this product. Frozen storage of up to 12 mo had no significant effect on quality attributes and shelf-life at 2 °C was above 14 d irrespective of the time of frozen storage. As compared to a previous study with Baltic Sea, cod drip losses during chill storage was low for thawed MAP Barents Sea cod and this fish raw material seemed the more appropriate for production of thawed chilled MAP products. Frozen storage inactivation of the spoilage bacteria of Photobacterium phosphoreum was modest in Barents Sea cod, possibly due to high trimethylamine oxide (TMAO) and NaCl contents.     

Carotenoids in crabs from marine and fresh waters of India

Quantitative and qualitative distribution of carotenoids in meat and shell of major marine crab (Charybdis cruciata) and fresh water crab (Potamon potamon) from Indian waters was assessed. The total carotenoid content was low in both species of crabs analysed, highest being 11.0 μg/g in shell of marine crab. Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) of carotenoid extracts indicated that the marine crab contained astaxanthin and its esters as major carotenoids and zeaxanthin was major carotenoid in fresh water crab extract. Astaxanthin and its esters contributed 67.6 and 65.5 g/100 g of total carotenoids in meat and shell of marine crab. The zeaxanthin content (g/100 g) in the carotenoid extract of meat and shell of fresh water crab was 42.0 and 74.8 of total carotenoids. The carotenoid extracts from both the crabs had higher level of unsaturated fatty acids. Oleic acid (C18:1) and palmitoleic acid (C16:1) were the predominant unsaturated fatty acid in carotenoid extract from meat of marine and fresh water crab, respectively. In the carotenoid extract from shell, eicosenoic acid (C20:1) in marine crab and linolenic acid (C18:3) in fresh water crab were the major unsaturated fatty acids.     

A microbiological perspective of raw milk preserved at room temperature using hyperbaric storage compared to refrigerated storage

The effects of hyperbaric storage (HS, 50–100 MPa) at room temperature (RT) on endogenous and inoculated pathogenic surrogate vegetative bacteria (Escherichia coli, Listeria innocua), pathogenic Salmonella enterica and bacterial spores (Bacillus subtilis) were assessed and compared with conventional refrigeration at atmospheric pressure for 60 days. Milk stored at atmospheric pressure and refrigeration quickly surpassed the acceptable microbiological limit within 7 days of storage, regarding endogenous microbiota, yet 50 MPa/RT slowed down microbial growth, resulting in raw milk spoilage after 28 days, while a significant microbial inactivation occurred under 75–100 MPa (around 4 log units), to counts below 1 log CFU/mL throughout storage, similar to what was observed for B. subtilis endospores. While inoculated microorganisms had a gradually counts reduction in all HS conditions. Results indicate that HS can not only result in the extension of milk shelf-life but is also able to enhance its safety and subsequent quality.Industrial relevanceThis new preservation methodology could be implemented in the dairy farm storage tanks, or during milk transportation for further processing, allowing a better microbial control, than refrigeration. This methodology is very promising, and can improve food products shelf-life with a considerable lower carbon foot-print than refrigeration.     

不同气调包装对熟制蟹肉蟹黄贮藏品质的影响

熟制蟹肉蟹黄由于蛋白质和脂肪含量较高,暴露在空气中极易被氧化,腐败变质,使货架期大大缩短,严重限制了产品生产和销售规模。本文以熟制蟹肉蟹黄为研究对象,探讨不同气调包装方式（空气,60% CO₂+40% N₂和40% CO₂+60% N₂）在4℃贮藏条件下对其品质的影响,分析风味物质变化规律和货架期,最后确定产品最优气调包装方式。研究结果显示,与空气组比较,气调包装组的菌落总数、pH、挥发性盐基氮及丙二醛含量明显降低,且40% CO₂+60% N₂组效果最佳;40% CO₂+60% N₂组样品挥发性风味物质随时间变化损失较少,呈味核苷酸腺苷酸（AMP）含量显著减少,肌苷酸（IMP）、肌苷（HxR）及次黄嘌呤（Hx）显著增加（P<0.05）,感官评价得分最高,货架期可达到28 d左右,比空气包装组延长了8 d。因此在4℃贮藏条件下采用40% CO₂+60% N₂气调包装能有效提高熟制蟹肉蟹黄的风味品质和货架期限,是一种较好的冷藏保鲜方式。     

SENSORY AND MICROBIOLOGICAL QUALITY EVALUATION OF VACUUM-PACKED SLICED COOKED CHICKEN BREAST. SHELF-LIFE ESTIMATION

Abstract The shelf-life of vacuum packed, sliced, cooked chicken-breast based on sensory and microbial changes as a function of temperature (2.3, 6.5, 10, 13.5 and 17.7C) was determined. Sensory evaluation and a microbiological study charted the development of lactic acid and psychotropic bacteria and of Brochothrix thermosphacta. Six different sensory methods were used to estimate product shelf-life; of these, the method based on average smell and taste was deemed the most suitable, since these parameters had a greater impact on shelf-life. From a microbiological point of view, mean shelf-life times were estimated at each temperature and compared with the estimates of the tasting panel. In the samples stored at the three lowest study temperatures (2.3, 6.5 and 10C), lactic acid and psychotropic bacteria counts of 10⁷–10⁸ cfu/g were not achieved; this agrees with the absence of sensory rejection at the end of the experiment. At 13.5 and 17.7C, mean shelf-life estimated microbiologically was shorter than that estimated using sensory methods. This difference, which here amounted to at least 8 days, is due to the so-called "delayed change", reported in previous experiments with cooked meat products.     

Microbiological and Sensory Changes in Minced Beef Treated with Potassium Lactate and Sodium Diacetate during Refrigerated Storage

The effect of potassium lactate and sodium diacetate on the microbiological changes and sensory properties of vacuum-packaged minced beef was investigated. The meat samples both with a preservative (in the amounts 0.65% and 1.3%) and without were stored at temperatures of 0–1°C and 5–6°C. The influence of storage time on changes in total bacteria count (TBC), lactic acid bacteria (LAB), Brochothrix thermosphacta, and the microbes of the Enterobacteriaceae family was investigated, as well as changes in pH and sensory quality. It was found that the addition of the preservative to the minced meat caused a significant extension (p < 0.05) of the lag phase and an inhibition of microbial growth rate, depending on temperature, storage time, and its concentration. The antibacterial effect was significantly higher (p < 0.05) at a temperature of 0–1°C than at 5–6°C and most susceptible to it were the bacteria belonging to the Enterobacteriaceae. The study results showed that the minced beef containing the preservative which had been vacuum stored at 0–1°C, presented a better sensory quality and had a shelf-life of about 6 days longer, in relation to the quality and shelf-life of the control samples. For each of the refrigeration storage temperatures however, there was no statistically significant change (p < 0.05) in the pH for the various storage periods and preservative quantities present.     

Physicochemical and microbiological changes of “Souvlaki” – A Greek delicacy lamb meat product: Evaluation of shelf-life using microbial,colour and lipid oxidation parameters

Fresh Souvlaki-type lamb meat was packaged under vacuum (VP) and modified atmospheres (MAs) and stored under refrigeration (4 °C) for a period of 13 days. The following gas mixtures were used: M1: 30%/70% (CO₂/N₂) and M2: 70%/30% (CO₂/N₂). Identical samples were aerobically-packaged and used as control samples. Quality evaluation of product stored under the above packaging conditions was conducted using physicochemical and microbiological analyses. Of the chemical parameters determined, pH values of product showed no significant differences for all packaging treatments as a function of storage time. Lipid oxidation of lamb meat was enhanced by aerobic storage and gas mixture M1, whereas VP and gas mixture M2 controlled lipid oxidation to a greater extent. Souvlaki colour stability (as determined by a^∗, b^∗ and L^∗ values) was not negatively affected by either VP or MA conditions during the 13 days of storage. Of the two MAs and VP used, gas mixture M2 and VP were the most effective treatments for the inhibition of total viable counts (TVC), Pseudomonas spp., yeasts and Brochothrix thermosphacta in Souvlaki meat. Lactic acid bacteria (LAB) and Enterobacteriaceae were also found in the microbial flora of Souvlaki and increased during storage under all packaging conditions used. Based on microbiological analysis data and on the proposed a^∗ values, the use of VP and MAP (M2: 70%CO₂/30N₂) extended the shelf-life of “Souvlaki” meat stored at 4 °C by approximately 4–5 days compared to aerobic packaging.     

Biochemical intervention of ergothioneine-rich edible mushroom (Flammulina velutipes) extract inhibits melanosis in crab (Chionoecetes japonicus)

We investigated the effects of decreasing phenoloxidase (PO) activity and prophenoloxidase (proPO) gene expression on the inhibition of postharvest melanosis formation in the red queen crab, Chionoecetes japonicus. The cDNA of proPO from hemocytes of C. japonicus was partially cloned and sequenced. Immersion of live crabs in a 1.0% ergothioneine (ESH)-rich mushroom extract (Flammulina velutipes; ME) solution resulted in significant inhibition of haemolymph PO activity and a reduction of the proPO gene expression in hemocytes that consequently controlled melanosis in the crabs during ice storage. Treatments with a 0.05% w/v sodium sulphite solution or a 0.05% w/v 4-hexyl-1,3-benzenediol solution had similar positive effects as the treatment with a 1.0% ME solution in vivo. In vitro experiments showed that authentic l-(+)-ESH inhibited PO activity and decreased proPO gene expression in crab hemocytes. Thus, the application of ESH-rich ME can be a novel alternative to synthetic melanosis-inhibiting agents to control postharvest melanosis in crabs.     

The effects of packaging method (vacuum pouch vs. plastic tray) on spoilage in a cook-chill pork-based dish kept under refrigeration

The effects of two packaging methods on the spoilage of a cook-chill pork-based dish kept under refrigeration were studied. Raw pork cuts and pre-cooked tomato sauce were packed under vacuum “sous vide” in polyamide–polypropylene pouches (SV) or into translucent polypropylene trays under modified atmosphere (80% N₂ + 20% CO₂) and sealed with a top film (PT). Samples were cooked inside the pack at an oven temperature/time of 70 °C/7 h, chilled at 3 °C and stored at 2 °C for up to 90 days. Microbial (psychrotrophs, lactic-acid bacteria, Enterobacteriaceae, moulds and yeasts), physical–chemical (pH, water activity and total acidity) and sensory (colour, odour, flavour, texture and acceptance) parameters were determined. Heat penetration was faster in SV (2 °C/min) than in PT (1 °C/min) (core temperature). Both packaging methods were equally effective in protecting against microbial spoilage for 90 day at 2 °C. Minor counts were only detected for lactic-acid bacteria and anaerobic psychrotrophs in SV. No Enterobacteriaceae growth was found. Slight differences between SV and PT in pH and total acidity were observed. SV and PT had similar effects on the sensory preservation of the dishes. A gradual loss of acceptance of the cooked pork and tomato sauce was observed. Rancid flavour in PT and warmed-over-flavour in SV were noted in the final stages of storage. According to acceptance scores, the shelf-life of both SV and PT was 56 days at 2 °C. Both packaging methods can be used to manufacture sous vide meat-based dishes subsequently stored under refrigeration for catering use.