Preparation of microbial silage from fish of underutilized species

Fish silage was produced by microbial means from a mixture of several fish species which are not used for human consumption, and form part of the shrimp by-catch. The fish was mixed with a carbohydrate source (molasses) and a starter culture of Lactobacillus plantarum 8014. The mixture was fermented at 30 +/- 2 degrees C. Several tests were undertaken to determine the optimal conditions and concentration of molasses (5, 10 and 15%) and Lactobacillus (0.5, 1.0, 2.5, 5.0 and 10.0%). Results indicated that 1% of microorganisms and 15% of molasses were the optimal proportions to produce a stable fish silage. The production process and stability study of fish silage were followed through chemical, physical and microbiological tests. As findings revealed, the first six days of the process are related to acid production, pH reduction and microbial control, while after this period the process is basically related to protein hydrolysis. In addition, sensory tests of flavor and color were performed. The results of this study suggest the feasibility of utilizing this marine resource at present discarded, through a technological scheme, to produce fish silage for animal feed.     

Preparation of a spread from shrimp by-catch fish

The composition of shrimp by-catch fish from the Central-Western region of Venezuela at different periods of the year was studied, as well as mean size and weight of same, and the yields obtained during processing, until the edible portion (pulp) was reached. The pulp was also analyzed from the physical, chemical and microbiological (pH, basic volatile N, trimethylamine, thiobarbituric acid test, moisture, fat, protein, ashes content and mesophyll and psychrophilic counts) points of view. The purpose of these studies was to determine its quality and freshness, since said pulp was utilized for the preparation of a canned and sterilized bread spread. Results obtained indicated the pulp to have an acceptable freshness, a fact which reflected in a final product with adequate characteristics. The bread spread was also analyzed from the physical, chemical, microbiological and sensory viewpoints (objective analyses of color and texture, pH, rancidity and sterility tests, moisture, fat protein, ashes, carbohydrates, sodium chloride contents, and sensory evaluation). In addition, these analyses were repeated monthly during the three-month storage period at two temperatures. On the basis of the above-mentioned findings, it was possible to determine that the bread spread had adequate acceptability and stability during storage. Furthermore, raw material variations did not affect the final product characteristics, which resulted in a product with commercial potential.     

Fish silage from shrimp by catch fish: I. Preparation and biological evaluation

Fish silage was prepared from some fish species of the shrimp by-catch caught in Golfo Triste, Carabobo, Venezuela. Fish were ground until a particle size that would guarantee the liquefaction process was achieved. The process was accelerated by the incorporation of a 3.5% w/w acid mixture, formed by diluted sulfuric acid (1:3) and concentrated formic acid, in a proportion of 1:4. The silage process occurred spontaneously at room temperature during 17 days. Chemical, physical and microbiological tests were conducted in order to characterize both the raw material and the final product. The raw material used had adequate levels of freshness, so that it was suitable for use, thus producing a first-grade silage. A first biological evaluation was carried out in rats in order to estimate the protein quality of the silage by means of certain biological parameters such as PER, NPR and apparent digestibility percentage of the protein. The results of the first experimental period demonstrated that the fish silage protein was of optimal quality, since the biological response in rats was similar to that of the control group fed the casein diet.     

Processing and evaluation of fish silage from accompanying fauna of shrimps

Fish silage for animal feed was produced from a mixture of several fish species belonging to the shrimp by catch. All of them were ground and mixed with formic and sulfuric acids, 3.5% w/w at 1:2; 1:3 and 1:4, respectively, and stored at room temperature for 15 days, to complete liquefaction. The pH, exuded liquid, consistency, soluble nitrogen, total volatile bases, trimethylamine, lipid oxidation by thiobarbituric acid test and microbial count were measured during the 60 days of the storage period. Fish silage was dried and used for biological tests in chicken fed a diet with 6% of silage as a substitute of fish meal. Results of proximal analysis, amino acid profile and mineral content, as well as of the biological test with the dried product, indicated the feasibility of using fish silage as a substitute of traditional fish meal for the chicks included in the trial. This fact, coupled to its simple processing technology, make fish silage adequate for utilization as animal feed.     

Experimental research and prediction of the effect of chemical and biogenic sulfuric acid on different types of commercially produced concrete sewer pipes

New equipment and procedures for chemical and microbiological tests, simulating biogenic sulfuric acid corrosion in sewerage systems, are presented. Subsequent steps of immersion and drying, combined with mechanical abrasion, were applied to simulate events occurring in sewer systems. Both chemical and microbiological tests showed that the aggregate type had the largest effect on degradation. Concrete with limestone aggregates showed a smaller degradation depth than did the concrete with inert aggregates. The limestone aggregates locally created a buffering environment, protecting the cement paste. This was confirmed by microscopic analysis of the eroded surfaces. The production method of concrete pipes influenced durability through its effect on W/C ratio and water absorption values. In the microbiological tests, HSR Portland cement concrete performed slightly better than did the slag cement concrete. A possible explanation can be a more rapid colonisation by microorganisms of the surface of slag cement samples. A new method for degradation prediction was suggested based on the parameters alkalinity and water absorption (as a measure for concrete porosity).     

Nutritional Value of Various Ray Fish Liver Oils to the Pacific White Shrimp <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

A 32-day comparative feeding trial was performed to evaluate the nutritional value of four different ray fish liver oils to the Pacific white shrimp Litopenaeus vannamei. Four feeds were prepared with liver oil extracted from Dasyatis brevis, Rhinoptera steindachneri, Aetobatus narinari, and R. bonasus. A control feed was prepared with Menhaden fish oil. Ray fish liver oils were mainly composed of poly- and highly unsaturated fatty acids and contained levels of 20:5n-3 and 22:6n-3 comparable in magnitude to those of Menhaden fish oil, except for A. narinari liver oil, which had moderately low concentrations of 20:5n-3 and 22:6n-3 but showed a particularly high level of 20:4n-6, more than six times greater than that of Menhaden fish oil. Dietary fatty acids significantly influenced the fatty acid composition of shrimp muscle tissue, e.g., the diet with Menhaden fish oil elicited significantly higher shrimp muscle DHA level than diets with oil from D. brevis, and A. narinari, but not than diets with oil from R. steindachneri and R. bonasus. In spite of these differences, all four ray fish liver oils evaluated were as efficient in promoting growth and survival of L. vannamei as Menhaden fish oil, an ingredient known for its adequate nutritional quality to shrimp and fish. This study demonstrated one of the many possible applications of a locally-available resource that is currently being wasted.     

The Free Fatty Acid Content of Fish Oil-An Analysis of Anchovy Lipids at Different Stages in the Manufacture of Anchovy Meal and Oil

The quality of fish oil, as reflected by its free fatty acid (FFA) content, was studied in relation to the processing conditions of fish meal manufacture from anchovy (Engraulis capensis). Six samples of anchovy lipids were isolated from consecutive stages of the process and analysed for fatty acid composition, FFA, phosphorus and choline content. Results indicated that no significant oxidation of polyunsaturated fatty acids takes place in the fish meal manufacturing process. Only minimal amounts of FFA, generated as a result of chemical breakdown, are accumulated in the fish meal, rather than the press oil.     

Assessment of the nutritional value of novel proteins

Methods of determining the nutritive value of novel proteins or derived food products such as proteins from fish, algae, leaf or microbiological sources, are reviewed. The use of physical (solubility) or chemical (amino acid analysis) methods, feeding tests in rats and other animals for the determination of biological value, digestibility and protein efficiency ratios, rate of enzymatic hydrolysis or retention of enzymatic activity are among the procedures surveyed. The safety of new food sources must always be a first consideration. Presented at AOCS-AAOC Short Course on Oilseed Proteins: Chemistry, Technology and Economics, French Lick, Indiana, July 1969.     

Oxidative stability of fish oil‐enriched mayonnaise‐based salads

The oxidative stability of fish oil‐enriched mayonnaise‐based salads and the influence of different vegetables in shrimp and tuna salads were evaluated. Moreover, the lipid oxidation in the presence of 1% oregano, rosemary, or thyme in fish oil‐enriched tuna salad was assessed. The results obtained showed that the mayonnaise itself was more oxidatively stable without vegetables and tuna or shrimp, in spite of the higher oil content in mayonnaise (63 and 6.3% fish oil, respectively) compared to salads (～24 and 2.4% fish oil, respectively). Surprisingly, the fish oil‐enriched mayonnaise was only significantly different from the standard mayonnaise in the volatile concentration during the end of storage. In fish oil‐enriched shrimp salad, asparagus had an anti‐oxidative effect and shrimp a pro‐oxidative effect, where the anti‐oxidative effect of asparagus was strong enough to prevent the pro‐oxidative effect of shrimp. The effect of ingredients in tuna salads was inconclusive, possibly due to a high content of volatiles in the vegetables themselves. However, the addition of spices increased the oxidative stability of tuna salad (oregano>rosemary>thyme).     

Homarine as a feeding deterrent in common shallow-water antarctic lamellarian gastropodMarseniopsis mollis: A rare example of chemical defense in a marine prosobranch

The common bright yellow antarctic lamellarian gastropodMarseniopsis mollis was examined for the presence of defensive chemistry. Proton nuclear magnetic resonance (NMR) spectroscopy indicated that a major component of ethanolic extracts purified by reversed-phase column chromatography was homarine. Further high-performance liquid chromatography (HPLC) analysis of the mantle, foot, and viscera verified the presence of homarine in all body tissues at concentrations ranging from 6 to 24 mg/g dry tissue. A conspicuous macroinvertebrate predator of the shallow antarctic benthos, the sea starOdontaster validus, always rejected live individuals ofM. mollis, while readily feeding on pieces of fish tail muscle. Filter paper disks treated with shrimp elicited a broad range of feeding behaviors in the sea starO. validus (movement of disc to mouth, extrusion of cardiac stomach, humped feeding posture). Shrimp disks treated with homarine (0.4 and 4 mg/disk) were rejected byO. validus significantly more frequently than control disks treated with solvent carrier and shrimp or shrimp alone. The highest concentration of homarine tested not only caused feeding deterrence, but in several sea stars a flight response was noted. Homarine was not detected in the tunic of the antarctic ascidianCnemidocarpa verrucosa, a presumed primary prey ofM. mollis. Nonetheless, crude extracts of the epizooites that foul the tunic (primarily the bryozoans and hydroids) contain homarine, suggestingM. mollis may ingest and derive its chemistry from these organisms. This appears to be only the third example of chemical defense in a member of the Order Mesogastropoda. As the vestigial internalized shell ofM. mollis is considered a primitive condition, the findings of this study lend support to the hypothesis that chemical defense evolved prior to shell loss in shell-less gastropods.     

Classification of feeding fats by FT‐IR spectroscopy

In this paper, a technique useful for the classification of different food oil co‐ and by‐products of potential use for feed preparation is shown. The proposal is based upon a Fourier transform infrared evaluation of different classes of compounds, and its elaboration was carried out starting from the knowledge of the chemical composition of each feedstock category. Using this technique, a sure classification of fatty acid calcium soaps, fully hydrogenated fatty acids, lecithins, acid oils from chemical refining, acid oils from physical refining and fish oils can be easily done. The remaining categories of animal fats, fried oils and oils recovered from exhausted bleaching earth can be differentiated by using one or two additional chemical tests. The scope of this paper is to provide a quick, easy and non‐expensive tool for a correct classification of feedstock, in order to allow the choice of correct and applicable analytical tests for the evaluation of the quality and of the composition of each sample.     

Influence of MHC on sibling discrimination in Arctic char,Salvelinus alpinus (L.)

The preference of juvenile Arctic char [Salvelinus alpinus (L.)] for odors from siblings and nonsiblings with different major histocompability complex class II (MHC) genotypes was studied in two-choice fluviarium tests. In the first part of the study, test fish demonstrated no preference for water scented by a sibling with a MHC genotype different from its own versus water scented by a MHC identical nonsibling. When both donors were siblings with different MHC genotypes, however, the test fish chose the water scented by the fish with the same MHC type as the test fish. The results suggest that odors with information about kinship are dependent on MHC but also on other, unknown factors. In the second part of the study, we observed that fish isolated since fertilization did not show any behavioral discrimination towards siblings, based on MHC genotype. One reasonable explanation for this result is that Arctic char learn to discriminate between odors from individuals of different MHC types.     

不同虾壳部位中的甲壳素和壳聚糖

用EDTA的方法分别从虾壳的不同部位:虾头、虾身、虾足和虾头内容物三部分制备甲壳素和壳聚糖,对三组试样的性能参数如脱乙酰度和相对分子量等进行分析研究。得出结论:由虾壳不同部位所制得的甲壳素和壳聚糖结构基本一致,但其脱乙酰度和相对分子量有较大差别,其物化性质也有所不同。在三组试样中,以从虾头壳制备的甲壳素和壳聚糖的相对分子质量为最大;而脱乙酰度则以从虾足和虾头内容物中制得试样较高。     

虾壳制备甲壳素和壳聚糖的研究

用EDTA的方法分别从虾壳的不同部位:虾头、虾身、虾足和虾头内容物三部分制备甲壳素和壳聚糖,对三组试样的性能参数如脱乙酰度和相对分子量等进行分析研究。得出结论:由虾壳不同部位所制得的甲壳素和壳聚糖结构基本一致,但其脱乙酰度和相对分子量有较大差别,所以其物化性质也有所不同。特别值得一提的是,在三组试样中,以从虾头壳制备的甲壳素和壳聚糖的相对分子质量为最大;而脱乙酰度则以从虾足和虾头内容物中制得试样较高。     

Achieving clean technology in the fish-meal industry by addition of a new process step

Fish-meal processing plants use large volumes of seawater to unload the fish from ships. Water to fish ratios range from 5 to 10 (m³ tonne⁻¹), producing an effluent high in chemical oxygen demand (COD) load, which is discharged to the sea. Alternative treatments were studied from economic and environmental aspects. The selected treatment involved two sequential steps: recycling of water during unloading and salvaging of reusable organic matter by chemical coagulation of soluble proteins with FeCl₃ followed by centrifugal separation. The recovered sludge was incorporated into the fish-meal process. Technical feasibility and cost implementation at industrial-scale were assessed. Results obtained at one plant demonstrated overall COD removal efficiencies of 93% for the clarified effluent (91% for proteins and 93% for fats and oil). Incorporation of the precipitated organic matter into the process increased productivity by approximately 7%.     

食用海产品中亚硝酸盐含量的分析

根据食品中亚硝酸盐测定的国家标准,针对食用海产品的特点,应用分光光度法,对海虾皮、海蜒、淡菜干、海虾米、海带、海蜇、紫菜等十多种海产品进行检测,并对检测数据进行统计分析,得出上述海产品中亚硝酸盐的含量情况。结果表明:海虾皮、凤尾鱼干、对虾干中亚硝酸盐含量相对偏高,已超过国家标准GB2762—2005中鱼肉的限量指标(3 mg/kg),但仍低于上述国标中酱腌菜的限值(20 mg/kg)和GB2760—2011中腌腊肉制品类的限量指标(30 mg/kg);正规渠道经销的大部分海产品亚硝酸盐含量低于国家标准允许的范围。     

Evaluation of fish silage prepared by microbiological route as a proteinic supplement in diets for fattening chickens]

A bioassay in broilers was carried out during a six-week period, to evaluate, as a protein source, the quality of fish silage produced by microbiological means and to compare it with that of fish flour and soybean flour. A total of 28 broilers of the Cross by Cross strain were used, sexed and assigned at random. Additionally, the fish silage was subjected to moisture (8.1%), ash (18.4%), protein (59.5%), fat (7.55%), carbohydrates (6.47%), and pH (4.2) determinations for its inclusion in the diets formulation. The results obtained did not permit establishment of significant differences between the weight increments presented by chicks fed with fish flour, and those fed with fish silage. Nevertheless, the food conversion index of the chicks consuming the diet prepared with fish silage proved to be better that the conversion index of the diet prepared with fish and soy flours. No lesions in the organs of the animals studied were observed, and the sensory trials indicated that chicks fed with the fish silage did not present differences with those commercially acquired.     

Listeria monocytogenes incidence and evaluation of the sanitary quality of filleted fresh fish from the Metropolitan Area of San José

Fish constitutes a very important part of human diet due to its protein content. The poor commercialization system existing in Costa Rica for this product causes an important secondary contamination that may include microorganisms such as fecal coliforms, Staphylococcus aureus and even pathogens such as Listeria monocytogenes. There is a lack of recent information about the microbiological quality of the fish that arrives to the Metropolitan Area of San José, Costa Rica, so the aim of this work was to study it through the detection of microbiological indicators and the incidence of L. monocytogenes. Five different samplings were realized to 27 fisheries located in two different areas from San José, Costa Rica: the Central Market and the rest of the Metropolitan Area. Each time, a 500 g sample of fresh filleted fish was taken and transported to the Food Microbiology Laboratory, Universidad de Costa Rica, for performing the different analysis, which included the presence/absence of L. monocytogenes, total plate count, total and fecal coliforms count and Most Probable Number of Staphylococcus aureus. Also, a hygiene evaluation of the different fisheries was performed. According to this, 22.2% of the fisheries were classified as excellent, 14.8% as good, 40.8% as regular and 22.2% as bad. Fisheries hygiene is independent of the incidence of L. monocytogenes with a 95% confidence level, and there is no significant relationship between hygiene and the other indicators analyzed. There is a significant relationship between the incidence of Listeria sp. and the hygiene of the Central Market area. It was determined that 96.3% and 29.6% of the fisheries accomplish with the microbiological limits established by ICMSF for S. aureus and total plate count, respectively. Listeria sp. was found in 65.2% of the fish samples analyzed. From these, 52.3% was L. monocytogenes, 43.2% L. innocua, 3.4% L. ivanovii and 1.1% L. seeligeri. In 88.9% of the fisheries the presence of L. monocytogenes was positive at least once.     

Microbiological controls and control points in a hake fillets manufacturing process for exportation

Indicator and foodborne pathogen microorganisms in the "for export" hake fillets manufacturing were investigated in this study. Critical control points were identified and prevention activities and control were proposed during seafood elaboration process. 45 samples of hake from sequential processing operation stages, 15 ice samples and 12 water samples from utensil washing, were collected. The samples were analyzed for their content of aerobic mesophilic bacteria, psychrotrophic bacteria, enterobacteria, total and fecal coliform bacteria, Staphylococcus aureus and the presence of Escherichia coli, Salmonella and Shigella. The analysis of the samples collected from the factory revealed that the amounts of aerobic mesophile bacteria increased during manual filleting and packaging, in comparison with raw material. Psychrotrophic bacteria were the predominant microorganisms, specially in hake samples. In addition, high levels of enterobacteria, which do not occur normally in fish, were detected in raw hake samples. Staphylococcus aureus, Escherichia coli, Salmonella and Shigella, were not isolated from any samples in this study. The goal of this work is to establish microbiological risks in the hake fillets manufacturing process and, therefore to make possible corrective and control actions to assure the quality and safety of seafood.     

Microbial lipid production as biodiesel feedstock from N‐acetylglucosamine by oleaginous microorganisms

BACKGROUND: The byproducts from shrimp processing are heads and shells which contain a wealth of carbon and could be converted into oils via oleaginous microorganisms. The objective of this investigation was to determine the feasibility of using oleaginous microorganisms to convert N‐acetylglucosamine (GlcNAc), the major carbohydrate of the hydrolysate of shrimp processing waste, to triacylglycerols as a biodiesel feedstock. RESULTS: Screening experiments were conducted among Rhodotorula glutinis, Rhodococcus opacus and Cryptococcus curvatus using GlcNAc as sole carbon and energy source at 30 °C. All three microorganisms were found to grow well on GlcNAc, but the lipid contents in the cells were consistently low (lower than 5%) in the growth phase. However, lipid accumulation by C. curvatus was greatly enhanced upon entering the death phase in the absence of GlcNAc and the lipid content increased to 28.4% at 167.7 h. This indicated that C. curvatus was the optimal tested microorganism for the production of microbial oils from GlcNAc. Phosphate was further evaluated on the growth and lipid production by C. curvatus from GlcNAc. Results indicated that the yields of both biomass during growth phase and lipids at death phase increased with the increase of the ratio of C to P. But the fatty acid profiles of the accumulated lipids did not change significantly. CONCLUSION: Results indicated that shrimp processing waste could be utilized to produce oils as a biodiesel feedstock. The results could be applied to maximize production of oils from shrimp processing waste. Copyright © 2011 Society of Chemical Industry