The influence of storage conditions of tuna viscera before fermentation on the chemical, physical and microbiological changes in fish sauce during fermentation

Effect of storage condition of tuna viscera on chemical, physical and microbiological changes of its sauce were monitored. Results based on microbial counts, protein degradation products, total volatile base (TVB), and trimethylamine (TMA) contents, showed that tuna viscera stored at room temperature underwent more deterioration than that kept in ice, especially with increasing storage time. As a result, fish sauce obtained from tuna viscera stored at room temperature for a longer time rendered the greater amino nitrogen, TVB, TMA contents as well as browning intensity. However, storage conditions had no marked effect on overall changes in chemical, physical and microbiological characteristics of sauce generated during fermentation. Additionally, fish sauce produced from tuna viscera kept at room temperature comprised lower histamine content than that prepared from fresh or ice-stored viscera. Therefore, tuna viscera stored at room temperature for up to 8h could be used for the production of fish sauce with no detrimental effect on the quality.     

Characterization of Volatile Compounds in Astraeus spp.

Astraeus spp. is consumed in several regions of Southeast Asia. C₈ compounds, including 1-octen-3-ol, are the main volatile compounds in fresh Astraeus spp. Other compounds typical of edible mushrooms, such as terpenoids and sulfur-containing compounds, were not detected in fresh Astraeus spp. The amounts of fatty acids, including linoleic acid, substantially decreased after homogenization of fresh Astraeus spp. This high metabolic activity possibly correlates with formation of the C₈ volatiles. Heating the mushrooms produced cyclohexene compounds, 2-n-pentyl-furan, furanyl compounds, and benzaldehyde.     

Diverse migration strategy between freshwater and seawater habitats in the freshwater eel genus Anguilla

The freshwater eels of the genus Anguilla, which are catadromous, migrate between freshwater growth habitats and offshore spawning areas. A number of recent studies, however, found examples of the temperate species Anguilla anguilla, Anguilla rostrata, Anguilla japonica, Anguilla australis and Anguilla dieffenbachii that have never migrated into fresh water, spending their entire life history in the ocean. Furthermore, those studies found an intermediate type between marine and freshwater residents, which appear to frequently move between different environments during their growth phase. The discovery of marine and brackish-water residents Anguilla spp. suggests that they do not all have to be catadromous, and it calls into question the generalized classification of diadromous fishes. There has been little available information, however, concerning migration in tropical Anguilla spp. Anguilla marmorata, shows three fluctuation patterns: (1) continuous residence in fresh water, (2) continuous residence in brackish water and (3) residence in fresh water after recruitment, while returning to brackish water. Such migratory patterns were found in other tropical species, Anguilla bicolor bicolor and Anguilla bicolor pacifica. In A. b. bicolor collected in a coastal lagoon of Indonesia, two further patterns of habitat use were found: (1) constantly living in either brackish water or sea water with no freshwater life and (2) habitat shift from fresh water to brackish water or sea water. The wide range of environmental habitat use indicates that migratory behaviour of tropical Anguilla spp. is facultative among fresh, brackish and marine waters during their growth phases after recruitment to the coastal areas. Further, the migratory behaviours of tropical Anguilla spp. appear to differ in each habitat in response to inter and intra-specific competition. The results suggest that tropical Anguilla spp. have a flexible pattern of migration, with an ability to adapt to various habitats and salinities. The ability of anguillids to reside in environments of various salinities would be a common feature between tropical and temperate species without a latitudinal cline. Thus, the migration of Anguilla spp. into fresh water is clearly not an obligatory behaviour. This evidence of geographical variability among Anguilla spp. suggests that habitat use is determined by environmental conditions in each site.     

Relationship among fecal coliforms, Escherichia coli, and Salmonella spp. in shellfish.

The relationship of fecal coliforms, Escherichia coli, and Salmonella spp. was examined in freshly harvested and stored shellfish. In 16 of 40 freshly collected oyster samples, fecal coliform levels were above the recommended wholesale level suggested by the National Shellfish Sanitation Program (less than or equal to 230/100 g), and Salmonella spp. were present in three of these samples. Salmonella spp. were not, however, present in any sample containing less than 230 fecal coliforms per 100 g. Analysis of the data suggests that low fecal coliform levels in both fresh and stored oysters are good indicators of the absence of Salmonella spp., but that high levels of fecal coliforms are somewhat limited in predicting the presence of Salmonella spp. E. coli levels correlated very strongly with fecal coliform levels in both fresh and stored oysters and clams, suggesting that there is no advantage in replacing fecal coliforms with E. coli as an indicator of shellfish quality.     

Relationship among fecal coliforms, Escherichia coli, and Salmonella spp. in shellfish

The relationship of fecal coliforms, Escherichia coli, and Salmonella spp. was examined in freshly harvested and stored shellfish. In 16 of 40 freshly collected oyster samples, fecal coliform levels were above the recommended wholesale level suggested by the National Shellfish Sanitation Program (less than or equal to 230/100 g), and Salmonella spp. were present in three of these samples. Salmonella spp. were not, however, present in any sample containing less than 230 fecal coliforms per 100 g. Analysis of the data suggests that low fecal coliform levels in both fresh and stored oysters are good indicators of the absence of Salmonella spp., but that high levels of fecal coliforms are somewhat limited in predicting the presence of Salmonella spp. E. coli levels correlated very strongly with fecal coliform levels in both fresh and stored oysters and clams, suggesting that there is no advantage in replacing fecal coliforms with E. coli as an indicator of shellfish quality.     

The microbial flora of herring fillets after storage in carbon dioxide, nitrogen or air at 2°C

Herring fillets from the Baltic Sea were stored in glass vessels in air, nitrogen or carbon dioxide (CO₂) at 2°C and the microbial development was studied. The microbiological shelf-life of the herring (the time to reach 10⁷ organisms/g) was prolonged by a factor of 3.5 in CO₂ as compared to air. The corresponding factor in nitrogen was 1.5. The microflora of fresh and spoiled herring was classified. The initial microflora was dominated by coryneforms, Flavobacterium spp., Moraxella -like organisms and Pseudomonas spp. The spoilage-flora in air (after 9 d) was dominated by Pseudomonas spp. and Moraxella -like organisms, and in nitrogen (14 d) Enterobacteriaceae, Vibrionaceae and Lactobacillus spp. were dominant. Homofermentative Lactobacillus spp. were the only organisms isolated from fillets stored in CO₂ (28 d). It was concluded that storing fresh fish in pure CO₂ at low refrigeration temperatures is a method with industrial potential. The method (1) improves the microbiological stability and (2) reduces the microbiological health hazards of the fish.     

Development of a combined PCR-culture technique for the rapid detection of Arcobacter spp. in chicken meat

A combined PCR-culture technique was developed to detect Arcobacter spp. in fresh chicken meat. Following a short selective enrichment of chicken samples, bacterial DNA was extracted and amplified using primers targeted at the genes encoding 16S rRNA of Arcobacter spp. The selected primers amplify a 181-bp fragment from all Arcobacter spp., whereas no PCR product is generated for other bacteria, including the closely related Campylobacter and Helicobacter species. The assay was used to screen 96 retail-purchased chicken samples for the presence of Arcobacter spp. Fifty-three percent of the samples analysed were positive for this micro-organism. The assay is simple and sensitive and reduces the amount of time required to positively detect Arcobacter spp. in poultry meat.     

Incidence of Acinetobacter spp. and other gram-negative, oxidase-negative bacteria in fresh and spoiled ground beef

A total of 1,409 gram-negative bacterial colonies were randomly selected from 19 samples of fresh and spoiled ground beef plated on six media. Only 137 (9.7%) were oxidase negative, and 20 (14.6%) of these were Acinetobacter spp., all of which were recovered from fresh meat samples. The importance of this group in both fresh and spoiled beef is less than is generally believed.     

Incidence of Acinetobacter spp. and other gram-negative, oxidase-negative bacteria in fresh and spoiled ground beef.

A total of 1,409 gram-negative bacterial colonies were randomly selected from 19 samples of fresh and spoiled ground beef plated on six media. Only 137 (9.7%) were oxidase negative, and 20 (14.6%) of these were Acinetobacter spp., all of which were recovered from fresh meat samples. The importance of this group in both fresh and spoiled beef is less than is generally believed.     

A preliminary study of parasite diversity in the anadromous Kamchatkan mikizha Parasalmo mykiss mykiss (Osteichthyes: Salmoniformes: Salmonidae)

The study of parasites associated with the anadromous mikizha from several rivers of the Western Kamchatka has revealed 44 parasite species. The majority of parasites (59%) belong to marine and estuarine-marine species. Lecithophyllum bothryophorum, Echinorhynchus leidyi and plerocercoids of the family Litobothriidae were found for the first time in anadromous fish entering into Asian continental watersheds. It has been revealed that only a few specimens of the anadromous mikizha feed in fresh waters. Most of feeding fish consume a minor amount of food, and this feeding is occasional. Young forms of intestinal parasites of the freshwater and estuarine-freshwater groups (Neoechinorhynchus spp., Crepidostomum spp., Cucullanus truttae, Eubothrium salvelinf) come into anadromous fishes mainly before their entering in fresh waters.     

Distribution and antibacterial drug resistance ofAeromonas spp. from fresh and brackish waters in Southern Turkey

The frequency of antibiotic resistance was compared inAeromonas spp. isolated from fresh and brackish water in Southern Turkey. A total of 97Aeromonas spp. strains were isolated from four zones (three from fresh and one from brackish water). Most of the strains isolated from all samples wereAeromonas hydrophila (79.4%), while the amount ofAeromonas sobria andAeromons caviae, were rather lower in the samples examined (17.5% and 3.1% respectively). A high proportion of isolates from all water sources showed resistance to cephalotin (86.6%) and trimethoprim-sulphamethoxazole (69%). On the other hand, a low proportion of bacteria showed resistance to tetracycline (14.4%), chloramphenicol (11.3%), gentamicin (7.2%) and nitrofurantoin (6.8%). Only one strain showing resistance to amikacin was found. Multiple Antibiotic Resistance Index (MARI) to at least two antibiotics was highest in brackish water (zone 4), followed by fresh water (zone 3). MARI values ranging from 0.2 to 0.8 for the bacteria isolated from brackish water. This study suggest that, multiple antibiotic resistantAeromonas spp., especiallyA. hydrophila, can be easily recovered from fresh and brackish water sources in Turkey and these sources may play as a reservoirs responsible for disease pathogen aeromonads.     

酱油中黄曲霉毒素B1的风险评估

黄曲霉毒素B1(AFB1)是已知毒性最强的天然物质,在我国的酱油产品中普遍存在,对人体的危害及其严重,其安全性受到消费者的密切关注。为了解我国酱油中黄曲霉毒素B1的安全现状,建立我国酱油中黄曲霉毒素B1的应急对策,本文采用酶联免疫法(ELISA)对我国203个酱油样品中的AFB1含量进行了检测,并就现有的污染状况,从危害识别、危害描述、暴露评估和风险特征描述等方面对酱油中的AFB1进行了风险评估。     

Antihypertensive and natriuretic effects of less-sodium soy sauce containing gamma-aminobutyric acid in spontaneously hypertensive rats

We investigated the mechanism of the antihypertensive effect of less-sodium soy sauce containing gamma-aminobutyric acid (GABA) in spontaneously hypertensive rats (SHRs). When SHRs were given a diet with less-sodium soy sauce containing GABA (GABA-rich soy sauce group) for 6 weeks, the systolic blood pressure decreased as compared with that in rats fed diets with less-sodium soy sauce or a solution of salt. Renal sympathetic nerve activity (RSNA) and positive Na balance were reduced, and the urinary Na excretion tended to increase in the GABA-rich soy sauce group. Vascular hypertrophy of the thoracic aorta and the coronary and renal interlobular arteries tended to reduce in the GABA-rich soy sauce group. These results suggest that inhibition of Na retention by natriuresis, as a result of inhibition of RSNA by the GABA in the soy sauce contributed to the antihypertensive effect of GABA in the SHRs. Intake of less-sodium soy sauce containing GABA might help to reduce overall cardiovascular risk.     

The Significance of Propionibacterium Species and Micrococcus lactilyticus to the Ensiling Process

The fermentation of lactic acid by two Propionibacterium spp. and by Micrococcus lactilyticus was examined in simulated silage. Fermentation occurred in silages which achieved a low pH (<4·0) but this resulted only in a small rise in pH and a secondary clostridial fermentation did not occur. Lactic acid-fermenting organisms resembling Propionibacterium spp. were isolated from authentic silages but not from fresh grass.     

Industrial production of soy sauce

Summary Soy sauce is a seasoning agent with a salty taste and a distinct aroma suggestive of meat extracts. The sauce is made by fermentation of a combination of soy beans and wheat in water and salt. This paper covers the method for production of fermented soy sauce, and that for acid-hydrolysis of defatted soy bean proteins. The microorganisms involved in soy sauce production, and biochemical and chemical changes in soy bean and wheat during fermentation influence greatly the sensory attributes and quality of soy sauce. Recent progress in industrialization of soy sauce manufacture is discussed.This paper is dedicated to Professor Herman Jan Phaff in honor of his 50 years of active research which still continues.     

Value of Coliform Tests for Assessing Meat Quality

The reactions of 171 psychrotrophic coliforms and Aeromonas spp. isolated from meat and the meatworks environment were determined in media used for coliform tests in food. From 22–68% of strains, depending on the medium, gave positive presumptive and confirmed tests at 35°C. As positive reactions in these tests may be due to psychrotrophic and other non-faecal coliforms, and Aeromonas spp., they have no value as indicators of potentially harmful contamination and it is suggested that these tests should not be applied to fresh meat and meat products.     

Decolorization of synthetic melanoidins-containing wastewater by a bacterial consortium

The presence of melanoidins in molasses wastewater leads to water pollution both due to its dark brown color and its COD contents. In this study, a bacterial consortium isolated from waterfall sediment was tested for its decolorization. The identification of culturable bacteria by 16S rDNA based approach showed that the consortium composed of Klebsiella oxytoca, Serratia mercescens, Citrobacter sp. and unknown bacterium. In the context of academic study, prevention on the difficulties of providing effluent as well as its variations in compositions, several synthetic media prepared with respect to color and COD contents based on analysis of molasses wastewater, i.e., Viandox sauce (13.5% v/v), caramel (30% w/v), beet molasses wastewater (41.5% v/v) and sugarcane molasses wastewater (20% v/v) were used for decolorization using consortium with color removal 9.5, 1.13, 8.02 and 17.5%, respectively, within 2 days. However, Viandox sauce was retained for further study. The effect of initial pH and Viandox concentration on decolorization and growth of bacterial consortium were further determined. The highest decolorization of 18.3% was achieved at pH 4 after 2 day of incubation. Experiments on fresh or used medium and used or fresh bacterial cells, led to conclusion that the limitation of decolorization was due to nutritional deficiency. The effect of aeration on decolorization was also carried out in 2 L laboratory-scale suspended cell bioreactor. The maximum decolorization was 19.3% with aeration at KLa = 2.5836 h⁻¹ (0.1 vvm).     

Diet of Rana cancrivora in fresh water and brackish water environments

Rana cancrivora Gravenhorst inhabits both fresh water and brackish water swamps and ditches in Singapore. Food items in the gut of frogs from both habitats have been examined. The diet of frogs collected near brackish water was predominantly crustacean and included crabs ( Sesarma spp.), while the diet of those collected near fresh water comprised mainly insects. Gut contents of frogs included all the small animal species found in the respective environments, the choice of prey appearing to be limited only by size.