Quality Changes in Gamma Irradiated Marinades of Anchovy (Engraulis anchoita) During Refrigerated Storage

The effect of gamma irradiation (0, 1.8, and 3.3 kGy) on the microbiological, chemical, and color characteristics of marinated (7% acetic acid and 10% NaCl) and vacuum-packed anchovy fillets was analyzed during 20 months of refrigerated storage (4 ± 1°C). Acidity, pH, water activity (a_w), total volatile basic nitrogen (TVBN), lipid oxidation, and color parameters were determined. Mesophilic and psychrotrophic bacteria, sulphite-reducing clostridia, total and fecal coliforms, Staphylococcus spp., yeasts, and molds were investigated. Gamma irradiation reduced the initial mesophilic bacterial counts and inhibited mesophils growth during 20 months. As a result, the production of TVBN during storage was lower in irradiated samples than in control. Also, lipid oxidation was lower in irradiated samples than in nonirradiated. The color of anchovy fillets was not affected by the irradiation treatment. Even if nonirradiated anchovy fillets presented a high stability in comparison with the traditional product (in flasks with vegetable oil and spices), gamma irradiation improved the microbiological and chemical quality of anchovy fillet marinades without inducing changes on its characteristic color for 20 months.     

Reflecting on the Recent Publisher's Report

Research was conducted to determine the effects of potassium sorbate applications (0, 1, 3, and 5% w/v) on the shelf life of pearl mullet (?nci Kefali; Chalcalburnus tarichi) fillets packaged with vacuum. Fillets kept at 4 ± 1°C were subjected to microbiological (total aerobic mesophilic bacteria, psychrotrophic bacteria, lactic acid bacteria, Enterobacteriaceae, molds, and yeasts) and chemical (pH, thiobarbituric acid—TBA, total volatile base nitrogen—TVB-N, water activity, and biogenic amines) analyses on certain days (0, 3, 6, 9, and 12 days) of storage. It was determined that potassium sorbate had effects on total aerobic mesophilic bacteria, psychrotrophic bacteria, Enterobacteriaceae, mold-yeast counts, TVB-N values, phenylethylamine, putrescine, tryptamine, and pH of fillets at a significant (p < 0.01) degree. Retarded bacterial growth was observed as the antimicrobial effect increased with the degree of its concentrations. Storage time had significant (p < 0.01) effects on bacteria count, TBA, TVB-N values, and biogenic amines; all of which were increased by longer storage. It was concluded that application of potassium sorbate, especially at a 5% level, and vacuum packaging helps cold stored fillets maintain their biogenic amines and microbiological and chemical qualities longer.     

带鱼腌制加工过程理化指标、微生物和生物胺的动态变化及相关性

为探明鱼类腌制过程生物胺形成机理,本文研究了带鱼(Trichiurus haumela)在腌制加工过程盐度、水分含量、水分活度(Aw)、pH、蛋白质水解指数(P.I.) 非蛋白氮(NPN) 、游离氨基酸、微生物和生物胺的动态变化及相互关系,结果表明：pH在腌制阶段增加但在干燥阶段下降;盐度、P.I和微生物(菌落总数、乳酸菌、葡萄球菌和微球菌)在整个加工过程持续上升,水分含量和Aw则持续下降。整个加工过程,发生了明显的蛋白质降解反应,NPN 和游离氨基酸在干燥阶段含量显著上升;总生物胺含量增加了2.26倍(p＜0.05),其中尸胺含量显著增加了157倍,其次是组胺。带鱼腌制过程,游离氨基酸与生物胺显著正相关(p＜0.05),作为生物胺前体物质对生物胺的形成影响较大,微生物则起到了促进和抑制生物胺的作用,生物胺的形成还受pH、盐度、Aw等因素的共同影响,是一个极其复杂的过程。     

Effects of Natural and Artificial Colorants on Hot Smoked Garfish—Belone belone (Linnaeus, 1761)—Stored at 4 ± 1ºC

In this study, the effects of natural and artificial colorants on the shelf life of hot smoked garfish were investigated in terms of its chemical, microbiological, and sensory quality. Turmeric and Sunset Yellow FCF were used as the natural and artificial colorants, respectively. The amount of total volatile basic nitrogen (TVB-N) and thiobarbituric acid (TBA), counts of total mesophilic aerobic bacteria, total psychrophilic aerobic bacteria, total yeast and molds increased during the storage (p < 0.05). The results showed that turmeric and Sunset Yellow FCF had a significant effect on pH value and salt content of hot smoked garfish samples during storage (p < 0.05). According to the sensory analysis results, the shelf life of hot smoked garfish stored at 4 ± 1ºC was determined as 17 days.     

Microbiological Quality of Farmed Tropical Freshwater Prawn (Macrobrachium rosenbergii de Man)

ABSTRACT

The objective of this study was to determine the microbiological quality of farmed giant freshwater prawn (Macrobrachium rosenbergii) collected from four freshwater farms located in Kerala (India). Microbiological counts on whole, deheaded, and deheaded and deveined prawn as well as on head and intestine were determined. Average counts (log₁₀ cfu g^?1) on whole prawn were 6.9 (total mesophilic counts (TPC) at 37°C) and 4.1 (psychrotrophic count at 7°C). The results indicated that the aerobic counts were within the acceptable limit. The levels of enterococci and faecal coliforms in farmed M. rosenbergii were high. There was an increase in the numbers of enterococci and Staphylococcus aureus after deheading. The major groups of bacteria comprising the flora of M. rosenbergii were Aeromonadaceae, Enterobacteriaceae and Pseudomonas. Farmed M. rosenbergii carried pathogenic bacteria such as Enterococcus spp., S. aureus, Aeromonas hydrophila, A. veronii biovar sobria and Clostridium perfringens. The results of the study suggest adoption of good farming and post harvest practices to improve the microbiological quality of farmed freshwater prawn.     

Effects of Modified Atmospheric Packaging Conditions on the Quality Changes of Pasteurized Oyster (Crassostrea belcheri) Meat during Chilled Storage

ABSTRACT

The effects of different atmospheric conditions on the quality and the shelf life of pasteurized oyster meat in chilled storage were investigated. The alternatives tested for pasteurized oyster meat were normal air (Control), 75% CO₂/25% N₂ (MAP-1), 75% CO₂/25% O₂ (MAP-2), 75% CO₂/5% O₂/20% N₂ (MAP-3), and vacuum packing (VP). The various observations of microbiological (total viable count (TVC), Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria (LAB), and hydrogen sulfide–producing bacteria), physical (color coordinates L*, a*, and b*, and cutting strength), chemical (moisture, pH, total volatile basic nitrogen (TVB-N), peroxide value (PV), and thiobarbituric acid reactive substances (TBARS)) and sensory properties were performed every 3 days over a total of 27 days. During storage across all the treatments, L*, a*, cutting strength, pH, moisture content, and sensory scores decreased; whereas, b*, TVB-N, PV, TBARS, and microorganisms increased. However, among the various alternatives, MAP-1 had the best retention of oyster quality during storage. Based on sensory and microbiological qualities, the shelf lives in chilled storage were 9 days for control, 15 days for VP, 21 days for MAP-2 and MAP-3, and 24 days for MAP-1-treated cases.     

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.     

Microbial Growth Models in Gilthead Sea Bream (Sparus aurata) Stored in Ice

ABSTRACT

This study analyzes microbiological changes in whole, ungutted farmed gilthead sea bream (Sparus aurata) stored for an 18-day period in ice using traditional methods for mesophilic aerobic bacteria, psychrotrophic, Pseudomonas spp., Aeromonas spp., Shewanella putrefaciens, Enterobacteriaceae, sulphide-reducing Clostridium (Clostridia), and Photobacterium phosphoreum in muscle, skin, and gills, evaluating their seasonal differentiation. Two different statistical models were used to analyze microbiological growth. Simultaneously, physicochemical parameters such as the temperature, pH, biological oxygen demand (BOD), total dissolved solids, salinity, ammonia nitrogen, and total phosphorus content of growing waters were analyzed. The results showed that by the end of the storage time, specific spoilage bacteria (SSB) such as Pseudomonas spp., Aeromonas spp., and S. putrefaciens as H₂S-producing bacteria were dominant in sea bream harvested in temperate water in the Canary Islands. Muscle tissue had the least contamination, followed by skin and gills. The values of the analyzed seawater parameters were constant during the four seasons, except that the temperature showed a small difference between winter and summer. Seasonal effects were observed among the fish analyzed, suggesting that the lower levels of contamination detected in winter may have been due to the slight difference observed in water temperature in that season.     

Biochemical,Physical, Chemical,and Microbiological Assessment of Blue Shrimp (Litopenaeus stylirostris) Stored in Ice

Postmortem changes in blue shrimp (Litopenaeus stylirostris) muscle were studied on the basis of biochemical, chemical, physical, and microbiological changes during an 18 day storage period at 0°C. Adenosine 5′-triphosphate (ATP) content, breakdown products, K-value, pH, trimethylamine nitrogen (TMA-N), total volatile basic nitrogen (TVB-N), water holding capacity (WHC), color, and texture (shear force) changes were examined. Also, total mesophilic and psychrophilic bacterial counts were measured. K-value increased linearly (r² = 0.98) from an initial value of 1.37 ± 0.59 to 59.42 ± 6.05% at Day 18. Spoilage indicators TVB-N and TMA-N increased from 29.56 ± 1.33 and 0.69 ± 0.25 to 39.04 and 2.04 ± 0.59 mg of N/100 g at Day 18, respectively; meanwhile, the total viable counts of mesophilic and psychrophilic bacteria increased from 3.48 ± 0.44 and 2.61 ± 0.29 log CFU/g to 6.27 ± 0.21 and 7.14 ± 0.39 log CFU/g, respectively, which indicated spoilage at the end of the storage period. The pH, texture, WHC, and color were affected (p < 0.05) during the storage period. Overall, results indicate that blue shrimp muscle quality was maintained for 12 days of storage in ice.     

Microbiological quality of Litopenaeus vannamei culture using conventional and biofloc systems

Shrimp farming is a fast‐expanding activity that has supported the growth in the supply of these crustaceans to consumers around the world. However, the end product is vulnerable to contamination at all stages of the process, including the rearing tanks, where current practices prioritize to raise stocking densities and the minimization of water renewal. It is thus important to evaluate the potential of these systems for the proliferation of undesirable microorganisms, which may render the product unfit for human consumption. In the present study, the presence of coagulase‐positive Staphylococcus, Salmonella spp., Vibrio spp., and total and thermotolerant coliforms was verified in biofloc tank and conventional pond systems used for the rearing of Litopenaeus vannamei in Pernambuco, Brazil, and the results were compared with the legislation regulating the marketing of fresh shrimp. Samples were collected from two biofloc tanks with a density of 375 shrimp m^?2, and two conventional ponds with 12 shrimp m^?2. None of the samples tested positive for either Salmonella spp. or coagulase‐positive Staphylococcus, which is consistent with the legislation. While no standards are defined legally for Vibrio spp. or coliforms, very low concentrations were recorded in both systems, in comparison with other studies. While some variation in bacterial contamination was observed over the rearing process, the end product of both systems was fit for human consumption. The results of the study indicate that, while the water is not renewed in the biofloc system, the development of undesirable microorganisms can be controlled, with no adverse effects for the end product.     

Bacterial microflora associated with farmed freshwater prawn Macrobrachium rosenbergii (de Man) and the aquaculture environment

The initial counts of bacteria associated with farmed giant freshwater prawn (Macrobrachium rosenbergii de Man) as well as with the water and sediment from two farms located at Kottayam district in Kerala (India) were determined. A total of 367 randomly selected isolates were characterized and identified. Prawn samples yielded mean microbiological counts of 4.92 log CFU g^?1 of shell with muscle and 7.78 log CFU g^?1 of intestine at 30°C. Bacterial numbers in the intestine of prawn were much higher than those in the pond water. Motile and non‐motile aerobic Gram‐negative bacteria together with Enterobacteriaceae accounted for 60–70% of the mesophiles isolated from water and prawn. However, the microorganisms isolated in significant numbers from shell with muscle and intestine of prawn were not recovered from the growing waters. Among Gram‐positive bacteria, Micrococcus, Bacillus, coryneforms, and Arthrobacter were found. Faecal coliforms and enterococci were found in significant numbers in M. rosenbergii. The rearing practices such as feeding and pond fertilization could have influenced the microflora in prawn. The commensal microflora of freshwater prawn included opportunistic pathogens such as Aeromonas spp. and Streptococcus spp. Storage of prawn at elevated temperatures can permit their survival and growth leading to quality loss. Care should be exercised during handling and processing to prevent contamination of edible meat.     

Effect of the UV-C Radiation on Shelf Life of Vacuum-Packed Refrigerated Pirarucu (Arapaima gigas) Fillets

The effect of Ultraviolet radiation type C (UV-C) radiation (0.100 ± 0.010 J/cm²) on shelf life of Arapaima gigas fillets stored at 4 ± 1°C for 18 days was investigated. The samples were analyzed for total aerobic mesophilic bacteria (TAMB) counts; total aerobic psychrotrophic bacteria (TAPB) counts; Enterobacteriaceae; purge loss; pH; lipid oxidation; total volatile bases (TVB-N); ammonia; biogenic amines (BAs); and L*, a*, and b* values. UV-C radiation increased (P < 0.05) the generation time of all bacterial groups evaluated, increasing the shelf life by 2 days. UV-C-treated fillets showed lower (P < 0.05) L* values, purge loss, pH, TVB-N, ammonia, and BAs levels than their control counterparts throughout the storage period. Moreover, UV-C treatment did not result (P > 0.05) in detrimental effects on lipid oxidation or a* and b* values. UV-C at 0.100 J/cm² demonstrated a good potential for use in A. gigas fillets and, therefore, it could be applied at industrial scale.     

Effects of the Depuration Process on Microbiological Quality and Nutritional Composition of Mediterranean Mussel (Mytilus galloprovincialis Lamarck, 1819)

In this study, the effects of the depuration period on Mediterranean mussel (Mytilus galloprovincialis L., 1819), collected from Band?rma Harbor Area by the Sea of Marmara, were investigated. Distinctive changes were found to exist in the percentage of moisture, protein, fat, and ash content. The process of depuration was determined to have an effect on the number of total aerobic mesophilic/psychrophilic bacteria. Salmonella spp., Listeria monocytogenes, Vibrio parahaemolyticus, Vibrio cholera, Escherichia coli, and Staphylococcus aureus could not be identified during the study. The substances of aluminum, iron, zinc, copper, manganese, nickel, cadmium, chromium, lead, and potassium were determined to decrease in the Mediterranean mussel from the baseline to the end of the depuration. It was found that the process of depuration has a positive effect on alanine, phenylalanine, lysine, tyrosine, valine, leucine, and isoleucine; a negative effect on aspartic acid, glutamic acid, threonine, proline, and arginine and no effect on methionine, histidine, glycine, and serine. The total saturated fatty acids, total monounsaturated fatty acids, and total polyunsaturated fatty acids at the end of depuration were found to be 29.29%, 12.51%, and 45.57%, respectively, and the change in the amount of polyunsaturated fatty acids was found to be significant (p < 0.05).     

Biochemical and Microbiological Assessment of Crucifix Crab (Charybdis feriatus) Stored at 4°C

Charybdis feriatus is a highly prized crab in the local and international markets of East Asian countries. In local markets, crabs are sold live, iced, or refrigerated at 2°C – 4°C. The present study was carried out to determine the shelf life of whole crab stored at 4°C for 192 h using a set of biochemical, microbiological, and sensorial parameters. Biochemical indicators such as the total volatile base nitrogen (TVB-N) and trimethylamine nitrogen (TMA-N) increased significantly during storage and within an acceptable limit up to 144 h. Regarding the biogenic amines, cadaverine and spermidine increased significantly (p < 0.05) during the storage period. Among them, cadaverine could be proposed as a useful spoilage indicator for this crab species. The mesophilic and psychotropic bacterial count exceeded the limit of acceptance after 144 h of storage. Sensory attributes were gradually diminished with the storage time. Sensory scores were found to correlate well with both mesophiles and psychrotrophs. Based on the results of this study, the meat quality of Charybdis feriatus can be maintained up to 144 h when properly stored at a temperature of 4°C ± 1°C.     

Preservation of Black Tiger Shrimp Penaeus monodon Spermatophores by Chilled Storage

Chilled storage of spermatozoa in fish has been extensively investigated for many years, but limited research was focused on crustacean species. Chilled storage of spermatophores of black tiger shrimp Penaeus monodon is needed to generate consistent and reliable supply of spermatozoa for subsequent use. The objective of this study was to develop a protocol for the chilled storage of black tiger shrimp spermatophores and to evaluate bacterial propagation during chilled storage of spermatophores. In the first experiment, spermatophores were selected and preserved using four different extenders, namely mineral oil, Ringer's solution, phosphate buffer and 0.85% sodium chloride, and stored at low temperature (2‐4 C) for 42 d without antibiotic supplementation. Results showed that mineral oil was the best extender for chilled storage of spermatophores, since the highest percentage of viable sperm (58.3 ± 2.9%) was observed with this extender at the end of experiment (day 42). Bacillus sp., Staphylococcus sp., and Pseudomonas aeruginosa were identified as the predominant bacteria occurring during chilled storage, and the total bacteria count gradually increased during the experiment. In the second experiment, spermatophores were preserved in the mineral oil with four concentrations of the antibiotic, penicillin‐streptomycin (0.1%,1%, 2%, and 3%). There was no significant difference (P 0.05) in the percentage of viable sperm among treatments with 0.1%,1 %, 2%, and 3% antibiotics. The total count of Bacillus sp., Staphylococcus sp., and P. aeruginosa in the antibiotic treated groups significantly decreased (P < 0.05) to undetectable levels by day 14 of the experiment. Fertility studies from artificial insemination indicated that P. monodon spermatophores preserved with mineral oil for 7‐8 d at 2‐4 C were capable of fertilizing eggs with hatching rates similar to the controls. This study suggests that chilled storage of spermatophores is a feasible approach for the management and spawning of black tiger prawn broodstock or other Invertebrate species that produce spermatophores.     

The use of probiotics during the nursery rearing of the pink shrimp Farfantepenaeus brasiliensis (Latreille, 1817) in a zero exchange system

The present work evaluated the use of probiotics during the nursery rearing of the pink shrimp Farfantepenaeus brasiliensis, in a zero exchange aerobic heterotrophic culture system during 30 days. Three replicate tanks were randomly assigned to the following treatments: (1) Bacillus spp. mixture (Sanolife Pro‐‐W^®), (2) Bacillus sp., Enterococcus sp., Lactobacillus spp. mixture (Biomin Start‐grow^®), (3) Bacillus cereus var. toyoi and (4) control treatment (without probiotic addition). Bacteriological analysis monitored the abundance of presumptive Vibrio spp. in the water of experimental tanks. For the immunological analysis, shrimp haemolymph was collected to determine the granular haemocyte count and total protein concentration. Results showed that mean final weight and specific growth rate of shrimp in the probiotic treatments were significantly higher. Furthermore, shrimp reared in the probiotic treatments showed higher levels of total protein and granular haemocyte. The bacteriological analysis showed that the concentration of Vibrio spp. measured in probiotic treatment tanks was lower than that recorded in the control tanks.     

An Intermediate Moisture Product from Mackerel (Rastrelliger kanagurta) Using Salt Curing,Fermentation, and Drying

Intermediate moisture products were prepared from mackerel (Rastrelliger kanagurta) using salt curing in 20% or saturated brine for 20 hr and fermentation with an inoculum level of l0⁸ cells/mL of Pediococcus acidilactici followed by sun drying (28- 33C) for 23 hr or drying in an electric oven (45-50C) for 14 hr to an 18% moisture level. The chemical and microbiological studies correlated with the organoleptic results, suggesting a shelf-life of 4 months for salted and dried products and 7 months for salted, fermented, and dried products.     

Effect of dietary inulin and oligosaccharides as prebiotics for weaning turbot, Psetta maxima (Linnaeus, C. 1758)

Preliminary experiments were undertaken to investigate the effect of dietary inulin (Raftiline ST), oligofructose (Raftilose P95) and lactosucrose on the growth and intestinal bacteria of the marine carnivorous turbot, Psetta maxima. Turbot larvae were weaned on compound diets containing 2% Rafiline ST, 2% Raftilose P95 or 2% lactosucrose; 2% cellulose was the carbon source in the control group. The final mean weight of the group weaned with Raftilose P95 was significantly higher than those observed with the other diets. The bacterial load was highly variable in weaning turbot, especially with respect to the putative Vibrio spp. growing on TCBS agar which, in general, seemed to be dominant. Of the total load of bacterial isolates from turbot weaned on oligofructose, 14% consisted of a strain of Bacillus spp. This strain could use Raftilose P95 as a single source of carbon, and it might play a role in the beneficial effect of oligofructose on turbot growth, since Bacillus spp. have been documented as probiotics in fish.     

Chemical Parameters for Traceability of Raw Material Freshness of Tropical Surimi

ABSTRACT

Changes in chemical parameters of tropical fish used for surimi production—namely, threadfin bream (TB; Nemipterus spp.), lizardfish (LZ; Saurida spp.), and goatfish (GF; Upeneus spp.)—during ice storage and their respective washed mince were investigated. Total volatile basic nitrogen (TVB-N), trimethylamine (TMA), hypoxanthine (Hx), and total biogenic amine (BA) content of mince increased with storage time. Crude protein of fish and their respective washed mince reduced as storage time of fish was prolonged. Principal component analysis (PCA) revealed that washed mince produced from fish stored in ice for 7–12 days showed chemical characteristics that were distinct from those of washed mince prepared from spoiled fish. The TMA, TVB-N, and Hx content of washed mince appeared to be sufficient raw material freshness indicators in these three species.     

基于16SrDNA分析的浒苔外生细菌多样性研究

为研究浙江近海浒苔Ulva spp.(Enteromorpha spp.)外生细菌多样性,采用传统的形态学和16S rDNA测序分析的方法,从舟山朱家尖、宁海国华电厂和奉化南沙3个地区分离到可培养的浒苔外生细菌及其周围海水细菌65株。根据细菌菌落特征和革兰氏染色结果等将分离到的细菌分为26种表型。16S rDNA序列测序比对发现:菌株与不动杆菌属(Acinetobacter)、交替单胞菌属(Alteromonas)、弧菌属(Vibrio)、假交替单胞菌属(Pseudoalteromonas)、微小杆菌属(Exiguobacterium)、芽孢杆菌属(Bacillus)、赤细菌属(Erythrobacter)、微球菌属(Micrococcus)、假单胞菌属(Pseudomonas)、深海杆菌属(Idiomarina)、Phaeobacter、Roseivirgaj和Silicibacter等23个属相应菌株具有较高同源性。对不同地区浒苔外生细菌进行了Shannon-Wiener多样性指数分析。研究表明:(1)宁海国华电厂的浒苔外生细菌多样性最丰富,多样性指数为93.98%;(2)浒苔外生细菌与其生活地区密切相关,其群落组成具有地域差异,其优势类群也不尽相同,但均归属于变形菌门。