Effect of Delayed Icing on the Microbiological Quality of Tropical Fish: Barracudas (Sphyraena barracuda)

ABSTRACT: Effect of delayed icing on the bacteriological quality of a commercially important tropical fish, barracuda ( Sphyraena barracuda ), was studied. Fish obtained from the fish-landing center of Tuticorin, India, were immediately brought to the laboratory and divided into 2 lots. One lot was immediately iced (II) and the other lot was left at ambient temperature (32 ± 2 °C) for 6 h and then iced (DI). Immediate icing extended the shelf life of barracuda by 6 d. In II fish, the total bacterial count increased from 10³ to 10⁶ colony-forming units (CFU)/g; total lactics and total histamine formers appeared on day 7 and 3, respectively, and the total coliforms were very low. While in DI fish, total bacterial count remained at 10⁶ CFU/g. Total lactics, total histamine formers, and total coliforms were high.     

Effect of ice and cold storage on the chemical and technological characteristics of Egyptian crab meat

Effect of ice and cold storage at 4°C on the chemical and technological characteristics of one of red local Egyptian crab (Carcinw meanas) has been studied. Such studies involved the determinations of pH values, moisture, total nitrogen, protein nitrogen, ether extract, acid value, thiobarbituric acid value (TBA) and total bacterial count (TC). It has been found that the shelf life of ice stored crabs was 2 days. Raw crabs stored at 4°C can be kept without any deterioration for 8 days. Dipping of raw crab in 20 ppm chlorotetracycline (CTC) for 20 min raised the keeping period at 4°C up to 11 days. Cooked crabs can be stored at 4°C without any spoilage for 14 days. However, dipping of cooked crabs in 20 ppm of CTC for 20 min increased the keeping period to 17 days.     

Effect of Early Evisceration on the Keeping Quality of Atlantic Croaker (Micropogon undulatus) and Grey Trout (Cynoscion regalis) as Determined by Subjective and Objective Methodology

Heading and evisceration of Atlantic croaker and grey trout soon after harvest was shown to promote higher quality maintenance during iced but not frozen storage for both species. Fish eviscerated immediately upon landing maintained class 1 quality (FDA) 7–10 days longer than iced uneviscerated fish or fish eviscerated 3 days after harvest. Total volatile nitrogen levels and miccrobial counts (7° and 25°C incubation) increased more rapidly than trimethylamine levels as storage time progressed. Both Torrymeter readings and hypoxanthine levels served as good indicators of “freshness” (time/temperature age). However, of the two tests only Torrymeter values reflected quality differences between fish stored iced for an equal period of time (equal “freshness”) but varying in quality, due to the evisceration treatment.     

Autoproteolysis rate of rainbow trout muscle proteins

Effect of some physicochemical agents (pH, temperature and incubation time) and iced storage of farmed rainbow trout (Oncorhynchus mykiss) on autoproteolysis of muscle proteins and quality (sensory assessment, instrumental texture, total bacterial counts) were determined. The results showed that the autoproteolysis rate proceeded with its highest intensity at pH 4.2 and temperature about 55 degrees C. The rate of protein hydrolysis and protease activity, as well as microbial contamination, gradually increased with prolonged periods of iced storage of fish. Properly iced trout immediately after its evisceration was acceptable in quality for up to 10 days.     

Effect of storage at 0 °C on mantle proteins and functional properties of jumbo squid

Effect of iced storage of jumbo squid mantle with fin on gelling capacity and changes in protein fractions and functional properties of jumbo squid mantle protein during storage at 0 °C were assessed. Most values of texture variables in gels did not significantly change during storage. On average, they were: strength 65.07 ± 4.71 N; elasticity 68.14 ± 5.3%, fracturability 52.97 ± 1.28 N and cohesiveness 36.6 ± 0.1%. Protein solubility increased more than 40%. Whippability increased during storage for 16 days at 0 °C (81–162%), as did foam stability (73–94%). Results suggest that iced squid mantle protein is a suitable ingredient for food products where these functional properties are desirable. Muscle fibres of squid mantle undergo various changes during storage. At 0 °C, they are disrupted, whereas at −20 °C, they aggregate and develop empty spaces in the tissue.     

Shelf life of ice-stored redfish, Sebastes marinus and S. mentella

Redfish ( Sebastes marinus and S. mentella ) were caught by an Icelandic trawler, stored at about 0°C in boxes in the hold and landed in a German fishing harbour. Boxed redfish, differing in storage time on board, were subsequently stored in melting ice in the chill store of the laboratory at a temperature of +4°C until the borderline of saleability was reached. the quality loss of the ice-stored redfish was monitored by a number of chemical, physical and microbiological parameters including volatile base nitrogen (TVB-N), trimethylamine (TMA), trimethylamine oxide (TMAO), creatine, ethanol, Fishtester readings and number of cfu. AH parameters were correlated with sensory analysis and time in ice.
The rate of deterioration of iced redfish depended on the conditions of storage. Sensory analysis was the most accurate indicator of the limit of saleability of redfish. Iced redfish, stored mainly in a chill store (4–5°C) onshore, had a shelf-life of 16 to 19 days from catching. Fish stored at 0.5°C in the hold of the fishing vessel had a shelf-life of 22 days: These results reflect the different storage temperatures and the effects of handling, transport and storage damage on the quality of the fish. the Fishtester proved to be very useful for the determination of deterioration. Measuring ethanol, TVB-N and TMA gave no information about quality changes during the first 12 days of storage.     

Quality of rainbow trout chilled-stored after post-catch holding

The shelf-life of headed and gutted rainbow trout (Salmo gairdneri) was evaluated over period of storage at 0°C. There were three groups of samples: (i) fish held at 10°C for 6h and iced, (ii) fish held at 20°C for 6h and iced and (iii) fish held at 30°C for 6h and iced. Quality was assessed over the period of iced storage by measurements of total volatile bases (TVB), hypoxanthine, thiobarbituric acid, pH, water holding capacity (WHC) and tissue compressibility (TC). The results indicated that holding at various time/temperature periods before icing influences quality over the period of iced storage. Deterioration in quality was most pronounced when the fish had been held at high ambient temperatures of 30°C. Hypoxanthine values appeared to give an accurate indication of quality of freshwater fish. There was a linear increase in hypoxanthine values over the period of iced storage for all samples. However, for trout held at 30°C for 6 h before icing the values appeared to be highest. The coefficients of linear regression for fish iced immediately on receipt were lowest per day. It is suggested that hypoxanthine values may be used as chemical indicators of quality of freshwater trout.     

Chemical and Sensory Assessment of Nonspawning Capelin (Mallotus villosus) Subjected to Long Term Frozen Storage

Nonspawning capelin (Mallotus villosus) were processed immediately after being caught, after 5 days of iced storage or after being frozen at sea and later thawed. Fish from all variables were stored at ?23°C for up to 21 months. Both pre-processing treatment and frozen storage time significantly (P ≤ 0.05) affected all sensory variables except appearance. Regardless of treatment, the sensory quality was very stable during early and intermediate stages of frozen storage; capelin processed at sea was superior to that of the other two treatments. Appearance, dimethylamine, timethylamine, moisture and thiobarbituric acid values were dependent upon an interaction between pre-processing treatment and frozen storage time. Hypoxanthine concentration had the greatest potential as an index of sensory quality.     

Effect of handling treatment on fillet yields and quality of tropical fish

The effect on fillet yields and quality of the cold shock reaction of tropical fish when they are iced immediately following death was investigated. Tilapia ( Oreochromis moss-ambicus/niloticus hybrid) were subjected to three handling treatments: filleting immediately following death; icing the whole fish immediately following death and filleting after 3 days; ageing the fish for 6 hr at ambient temperature prior to icing and then filleting after 3 days. All fillets were stored on ice until 9 days after death. Pre-rigor filleting resulted in the highest filleting yields with the least drip loss and gaping on storage but the shortest shelf life. This was accompanied by the highest post-mortem metabolic rate. The lowest yields and highest drip loss were obtained by icing the fish immediately at death followed by filleting after 3 days. A 6-hr delay before icing gave yields and drip loss which were between these two extremes and also the slowest post-mortem metabolism. The two post-rigor filleting procedures produced fillets with increased gaping but a longer shelf life compared with pre-rigor filleting. The implications of the cold shock reaction in terms of recommended codes of practice and handling operations in tropical fisheries are discussed.     

Inhibition of bacterial growth in thawed cake and rapid evaluation methods for microbiological quality

The inhibition of bacterial growth in thawed cake kept under refrigeration and rapid evaluation methods for microbiological quality of the cake were investigated. The effects of the freezing temperature and the addition of ethanol or emulsifier on bacterial numbers in a cake model after storage for 72 hr at 10 degrees C following the thawing process were also studied. Bacterial growth in the cake model was inhibited by the additives under various freezing conditions. In addition, rapid evaluation methods for estimating bacterial numbers in the cake model after incubation for 72 hr at 10 degrees C were studied. High correlations were found between bacterial numbers in the cake model incubated for 24 hr at 20 degrees C and for 6 hr at 35 degrees C with tryptic soy broth and that of the cake model incubated for 72 hr at 10 degrees C. This result indicated that rapid evaluation by incubation for 24 hr at 20 degrees C or for 6 hr at 35 degrees C with tryptic soy broth can be used to predict the bacterial numbers in a cake model after incubation for 72 hr at 10 degrees C. Furthermore, the ATP-bioluminescence method was applied to shorten the testing time, because culture on an agar medium was not necessary.     

Effects of Selected Commercial Phosphate Products on the Natural Bacterial Flora of a Cooked Meat System

Four commercial phosphate blends and a neutral pyrophosphate were used at three levels (0.30–0.65%) in the preparation of cooked sausage. Control treatments contained no phosphate. Vacuum-packaged sausage was stored at 5°C for 21 days or held at room temperature (20–22°C) for up to 48 hours after 7 days of refrigerated storage. Mesophilic and facultative anaerobic bacterial counts were highest in control treatments after 14 and 21 days at 5°C and after 24 and 48 hr at 20–22°C. For each phosphate, the level of addition was the determining factor in bacterial inhibition, since the highest phosphate level resulted in the lowest bacterial counts in sausage held at 5°C and 20–22°C. The level of phosphate was more important in prolonging shelf life than was the type of phosphate.     

STORAGE TEMPERATURE EFFECTS ON THE PROTEOLYTIC ACTIVITY OF RADIATION-SURVIVING BACTERIA IN OYSTERS

ABSTRACT— The activity of 2 radiation-surviving and strongly proteolytic strains of Pseudomonas and Achromobacter were compared to the activity of 2 lesser active strains of Neisseria and Bacillus in fresh oysters during iced (32°F) and refrigerated (40°F) storage for 15 days. Radiation doses used for the oysters were 100 and 800 krad. The activity of the former bacteria was higher than that of the latter 2 at both temperatures and radiation doses. Neither the nonirradiated nor the irradiated uninoculated oysters displayed significant increases in proteolytic activity when they were ice-stored for 15 days, but storage at 40°F for the same period resulted in significant activity increases in the nonirradiated. This emphasizes irradiation and storage temperature as related factors. A slight decrease in pH at 15 days in both nonirradiated and 100 krad-irradiated oysters corresponded to the increase in bacterial numbers.     

The effects of different incubation temperatures on the acetaldehyde content and viable bacteria counts of bio-yogurt made from ewe's milk

Yogurt and bio-yogurt were manufactured from ewe's milk using a starter culture and a probiotic culture. Incubation was carried out at 37°C and 42°C until pH 4.6 was reached and the yogurts were stored at 4 +1°C for 14 days. Analysis after 1, 7 and 14 days showed that incubation temperature and storage time significantly influenced overall properties of the samples. During the storage, whey separation and pH decreased, but titratable acidity, lactic acid and volatile fatty acid contents increased. Viable bacterial counts in all bio-yogurts were above 10⁷ cfu g⁻¹ at the end of storage.     

Bacterial Studies on Irradiated Tropical Fish—Bombay Duck (Harpodon nehereus)

SUMMARY— Gamma irradiation (0.4 Mrad) of Bombay duck ( Havpodon nehereus ) fillets sealed in polyethylene bags brought about alterations in the bacterial flora during storage at 10–12°C. Micrococcus, Pseudomondas, Ackromobacter, Flavobacterium, Microbacterium, Bacillus, Alkaligenes , and Sarcina , which comprised the initial flora of Bombay duck, were predominated by Proteus, Bacillus, Aeromonas, Micro-cocci , and Neisseria in the spoiled samples after four days storage at 10–12°C. In contrast, absence of putrid odors in the irradiated samples stored at 10–12°C for 14 days may be attributed to the biochemically inactive nature of the predominating Micrococci.     

Extending the shelf life of kohlrabi stems by modified atmosphere packaging

ABSTRACT:  Kohlrabi stems (without leaves) were stored under modified atmosphere packaging (MAP) for 60 d at 0 °C. An additional retail sale period of 3 d at 12 °C after each cold storage evaluation (30 and 60 d) was applied. Under high relative humidity (RH) and 0 °C, the stems showed low metabolic activity, as no changes in sugars and organic acids were found. From day 21 at 0 °C, air-stored stems showed a yellowing of stalks and later they fell down. This disorder severely affected the appearance of stems. A gas composition of 4.5 to 5.5 kPa O₂ plus 11 to 12 kPa CO₂ was reached using antimist oriented polypropylene plastic bags of 20-μm thicknesses. The stems in MAP conditions kept a high sensorial quality. It was enough for commercial purpose of 2 mo. The storage of kohlrabi stems in plastic bags, either MA or in perforated (control) packages, provided an additional protection reducing physical damage. The MAP conditions delayed the weight loss and development of bacterial soft and black rot, extending the shelf life of kohlrabi stems to 60 d at 0 °C plus 3 d at 12 °C. Stems are not chilling injury sensitive.     

QUALITATIVE AND QUANTITATIVE CHANGES IN AEROBIC MICROFLORA FROM INTESTINAL CONTENTS OF SOUTH-BALTIC COD DURING STORAGE AT 1-2°C

SUMMARY— The bacterial flora of the intestinal content of cod (Gedus morrhua L) were investigated during a period of 1 year. The quantity of bacteria in recently caught fish was studied during the full period. the quality during only 6 months. 3 groups of fish from the same capture and fishing grounds were analyzed: fresh, and stored at 1–2°C for 5 and 10 days. It was seen that in general gram-positive bacterial flora dominated in recently caught fish, while after 5 and 10 days of storage gram-negative flora our numbered the former. In the intestinal contents of fresh fish the Vibrio species dominated, whereas at storage, Pseudomonas spp. became dominant. In fresh fish, the bacterial flora of stored fish amounted to 3.10% of the total initial quantity after 5 days of storage and 1.5% after 10 days. Also, the gram-positive flora decreased comparatively more rapidly than gram-negative flora. The authors believe that the temperature of 1–27°C may play a part in the decreasing number of flora, as well as some other factors not investigated in the present research.     

POULTRY PRODUCT QUALITY. 5. Microbiological Evaluation of Mechanically Deboned Poultry Meat

SUMMARY —Samples of deboned meat from broiler necks and backs, whole fowl and turkey racks were obtained from commercial sources and examined for total aerobic counts, fecal coliforms, salmonellae, Clostridium perfringens, coagulase positive staphylococci and psychrotolerant microorganisms. The raw materials were either deboned immediately after birds were processed (conventional processing) or held in the plants at 3–5°C for 5 days prior to deboning (delayed processing). The storage studies were conducted by holding the deboned meat at 3°C for 0, 3, 6 and 12 days and at -15°C for periods of 3, 6 and 9 months. The total aerobic counts of delayed processed samples were shown to be higher than conventionally processed meat and remained the same throughout the storage period. In all instances, the total aerobic counts increased during the storage at 3°C. The MPN fecal coliforms were high for all samples and remained relatively the same throughout the storage period at 3°C. Freezing resulted in a significant reduction of fecal coliforms. Only six out of 54 samples were contaminated with salmonellae while four showed the presence of C. perfringens and none was contaminated with S. aureus. Pseudomonas, Achromobac-ter and Flavobacterium dominated the psychrotolerant genera isolated in this investigation.     

Use of UV-C irradiation to prevent decay and maintain postharvest quality of ripe 'Tommy Atkins' mangoes

Ripe mangoes 'Tommy Atkins' were exposed to UV-C irradiation for 10 and 20 min, prior to storage for 14 days at 5 or 20 °C and a shelf-life period of 7 days at 20 °C. UV-C-treated fruit maintained better visual appearance than unirradiated controls. UV-C irradiation for 10 min was the most effective regime in suppressing decay symptoms and maintaining firmness during storage at 5 or 20 °C. Such fruit (treated with UV-C for 10 min) showed greater levels of putrescine and spermidine after cold storage than controls and those treated with UV-C for 20 min. Higher levels of sugars and lower levels of organic acids were observed in mangoes treated with UV-C for 20 min. However, the most effective UV-C treatment (10 min) for reducing decay maintained sugar and organic acid levels similar to the controls. No UV-damage was observed on treated fruits after storage. These results indicate that UV-C irradiation could be used as an effective and rapid method to preserve the postharvest life of ripe mangoes without adversely affecting certain quality attributes.     

Storage Stability of Nonpackaged Irradiated Indian Mackerel (Rastrelliger kanagurfa) in Ice

The storage stability of eviscerated Indian mackerel (Rastrelliger kanagurta) irradiated at a dose of 1.5 kGy and held under melting ice was examined. Packaging in polyethylene pouches prior to irradiation gave a shelf-life of 25 days, while, nonpackaged, irradiated fish remained in acceptable condition up to 20 days. The nonpackaged irradiated fish has less irradiation odor and better appearance as compared with packaged irradiated fish during the course of ice storage. Uni-radiated and nonpackaged mackerel kept in ice were acceptable only for 14 days. The results suggest that pre-irradiation packaging was not essential for commercially adequate extension in shelf-life of the iced fish.     

Retention of Folate, Carotenoids, and Other Quality Characteristics in Commercially Packaged Fresh Spinach

ABSTRACT: The effect of storage temperature (4 °C, 10 °C, and 20 °C) on retention of folate, carotenoids, and other quality characteristics in commercially packaged fresh spinach were determined. Based on visual color and appearance, spinach was unacceptable after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Color differences (AE), chlorophyll degradation, fresh weight loss, and microbial populations increased at all storage temperatures and occurred more rapidly at higher temperatures. Peroxidase activity increased but was not significantly ( P > 0.05) affected by storage temperature. Lipoxygenase activity was unaffected by storage time or temperature. Substantial losses of nutrients occurred at each storage temperature. Only 53% of folate in packaged spinach was retained after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Carotenoid losses increased with temperature with only 54%, 61%, and 44%, respectively, of initial detected levels remaining. Vitamin and quality changes were unaffected by presence or absence of packaging.