An Evaluation of the Suitability of Selected Waste Products in Feeds for Three Fish Species

ABSTRACT

Five types of aquatic food industry waste products (carp offal, carp roe, fish frames, trout offal and surimi processing waste) together with fish meal were evaluated for their suitability as potential fish meal replacements, partially or wholly, in diets for three species (rainbow trout, Murray cod and shortfin eel) cultured in Australia, using a number of criteria.

The proximate composition of the ingredients on a dry matter basis including protein content, lipid and ash, varied considerably. The essential amino acid (EAA) contents of the waste products and fish meal decreased in the order: carp roe > fish meal > carp offal > ‘surimi’ processing waste > fish frames > trout offal. The results of cluster analysis of A/E ratios of waste products and fish whole body fell within three clusters. The EAAI of whole body tissue of Murray cod, rainbow trout and Australian shortfin eel however, were closest to fish meal, followed by fish frame waste and/or ‘surimi’ waste. The results on A/E ratios and EAAI did not conform to the raw data on TAA and EAA. Therefore, the study emphasizes the need to have a multi-prong approach to determine the suitability of ingredients for incorporation into fish feeds.     

胶州湾及其邻近海域鱼类群落结构及与环境因子的关系

 为了进一步研究胶州湾及其邻近水域鱼类群落结构及与环境因子的关系, 本文根据2011年冬季(2月)、春季(5月)、夏季(8月)和秋季(11月)在胶州湾及其邻近海域进行的渔业资源和环境调查数据, 应用相对重要性指数、生态多样性指数和多元分析方法等研究了胶州湾鱼类群落结构及其季节变化, 并分析了胶州湾鱼类群落结构与主要环境因子的关系。结果表明: 本次调查共捕获鱼类57种, 隶属于2纲10目31科46属, 种类组成以暖温性和暖水性鱼类为主。主要优势种有方氏云鳚(Pholis fangi)和六丝钝尾虾虎鱼(Amblychaeturichthys hexanema)等。胶州湾鱼类群落物种丰富度指数D的季节变化范围为1.02~1.65, 多样性指数H’变化范围为1.36~1.73, 均匀度指数J′变化范围为0.61~0.76。方差分析表明, 丰富度指数的季节变化显著, 而均匀度指数J′和多样性指数H′无显著性季节变化。单因子相似性(ANOSIM)分析表明, 胶州湾鱼类群落结构和种类组成存在明显的季节更替现象。相似性百分比分析(SIMPER)表明, 方氏云鳚、六丝钝尾虾虎鱼、细纹狮子鱼、斑、赤鼻棱鳀和皮氏叫姑鱼等是造成群落结构季节变化的主要分歧种。典范对应分析表明, 影响胶州湾及其邻近海域鱼类群落结构的主要环境因子为水温、盐度和pH, 其次是底质类型, 条件效应分别为0.310、0.084、0.176和0.256。本研究旨在通过分析胶州湾鱼类群落结构和多样性特征及其与环境因子的关系, 为胶州湾渔业资源的保护和可持续利用提供科学依据。

     

PCR amplification and sequence analysis of the major capsid protein gene of megalocytiviruses isolated in Taiwan

Viruses belonging to the genus Megalocytivirus in the family Iridoviridae are one of the major agents causing mass mortalities in marine and freshwater fish in Asian countries. Outbreaks of iridovirus disease have been reported among various fish species in Taiwan. However, the genotypes of these iridoviruses have not yet been determined. In this study, seven megalocytivirus isolates from four fish species: king grouper, Epinephelus lanceolatus (Bloch), barramundi perch, Lates calcarifer (Bloch), silver sea bream, Rhabdosargus sarba (Forsskal), and common ponyfish, Leiognathus equulus (Forsskal), cultured in three different regions of Taiwan were collected. The full open reading frame encoding the viral major capsid protein gene was amplified using PCR. The PCR products of approximately 1581 bp were cloned and the nucleotide sequences were phylogenetically analysed. Results showed that all seven PCR products contained a unique open reading frame with 1362 nucleotides and encoded a structural protein with 453 amino acids. Even though the nucleotide sequences were not identical, these seven megalocytiviruses were classified into one cluster and showed very high homology with red sea bream iridovirus (RSIV) with more than 97% identity. Thus, the seven iridovirus strains isolated from cultured marine fish in Taiwan were closer to the RSIV genotype than the infectious spleen and kidney necrosis virus genotype.     

加工处理对鲢小清蛋白免疫活性的影响

采用鱼丸加工、烘烤、油炸、高压4种方式对鲢进行加工,并比较在这4种鲢制品中小清蛋白的含量、免疫活性以及体外模拟胃液消化稳定性的变化情况.通过Tricine-SDS-PAGE和Western-blotting分析表明,鱼丸加工、烘烤、油炸、高压等方式处理可降低鲢制品中小清蛋白的含量,但在一定程度上提高了小清蛋白的胃液消化稳定性;高压几乎可完全破坏小清蛋白的IgG结合能力,是较为理想的降低食物过敏原免疫活性的加工方式之一.     

CERTIFICATION OF SHRIMP AND SALMON FOR BEST AQUACULTURE PRACTICES: ASSESSING CONSUMER PREFERENCES IN RHODE ISLAND

This study uses a conjoint experiment to evaluate seafood consumers’ preferences for wild versus farmed seafood in Rhode Island, while providing an option for farmed products to be certified for best aquaculture practices, focusing upon salmon and shrimp. The definition for best aquaculture practices provided to respondents in the survey is broadly based upon standards currently in use by aquaculture certification groups, highlighting sustainability of fish feed, and control of antibiotic use, water quality and stocking density. Using data from an in-person intercept survey, a conditional logit model shows that a sample of 250 seafood consumers in Rhode Island choose wild products over farmed even when farmed products are certified, and by an entity preferred by the consumer. Results warrant both further study of consumer preferences for certified aquaculture products across a broader population, and study of the effect of different explanations of ‘best aquaculture practices’ upon preferences.     

A Comparison of French and English Consumers’ Expectations Regarding Labeled Cod Fillet Products

Consumers in England and France are exposed to different fish products and information at the marketplace. Based on this information and cultural differences, English and French consumers create expectations about fish products. The aim of this study was to compare English and French consumers on: (a) expectations regarding labeling on cod fillet products, (b) important factors when purchasing prepacked and fresh fish, and (c) drivers and barriers to fish consumption. English consumers (n = 120) reported in a survey more positive expectations about thawed products than French consumers (n = 120) due to greater familiarity with relevant labeling information.     

Investigations of dry matter and fat content in carp species smoked by hot and cold methods

In recent years the freshwater fish market has required more processed goods, as young consumers purchase ready-to-cook food products. In Middle European aquaculture systems carp are the main species. The appearance of new species (African catfish, trout, salmon), as well as the improved import possibilities of value-added fish products have introduced new challenges for fish farmers. In order to maintain the share of carps in fish sales, it is indispensable to develop up-to-date products that meet the needs of present generations. It is necessary to find processing methods that remove the fish bone and the off flavours occurring in Cyprinids. Smoking of carp has a strong tradition in the region, thus there are advantages to the development of smoked carp products, mainly in the form of boned fillets. The present study investigates two smoking methods aimed at ensuring basic information for product innovation. Analyses of the variation of weight, dry matter and lipid content during hot and cold smoking are presented for the case of three species: the common, silver, and grass carp. To determine the most acceptable products, the paper details the results of organoleptic tests, in which five characteristics (appearance, consistence, flavour, smell, and succulence) were investigated. Evaluation results indicate that the hot-smoked carp products are more acceptable, therefore it is hoped that these products, packed in a modified atmosphere, will achieve a strong market share in the near future.     

Consumer Attitudes Toward Fresh and Frozen Fish

Studies indicate that many consumers hold a persistent belief that frozen fish is substantially inferior to fresh. Focus group interviews were conducted in two U.S. locations to explore consumer perceptions about frozen fish. The discussion uncovered several fundamental misconceptions; many participants believed that frozen fish is less nutritious than bonier than fresh, and that only the “off cuts: are used for freezing. One way of overcoming these impressions and providing assurance to the consumer, is to sell frozen fish products in vacuum sealed see-trough packages. It is essential to provide clear instructions for handling and to confirm that frozen fish is an nutritious as fresh. This research also highlights the need for concerted efforts to rectify possible misunderstanding about aquaculture fish products.     

Fish Quality and Consumers: How Do Consumers’ Knowledge About and Involvement in Fish Quality Define Factors That Influence Fish Buying Behavior?

ABSTRACT

Despite recommendations, fish consumption is low in several countries. One of the many relevant factors that influence fish consumption is the quality of fish products. However, consumers differ in involvement in and knowledge about fish quality. The aim of this study was to reveal differences in involvement and knowledge about fish quality among consumers and measure how these lead to variations in the importance of factors that influence consumers when buying fresh fish fillets. We aimed to explain these results based on subjective and objective knowledge, fish consumption, and social and demographic characteristics. This study was based on data collected from 738 Norwegian consumers who responded to a questionnaire. The survey included items regarding knowledge and involvement in fish quality, objective and subjective knowledge measures, factors important when buying fish, and finally sociodemographic characteristics. This article suggests that perceived quality is one of the most important factors that influence buying behavior when it comes to fish fillet products in Norway. Consumers can have a high or low involvement with and knowledge about fish quality. However, when confronted with the decision of what fish product they may buy, most consumers reported using fish quality as a main driver.     

Insights for the Development of a Functional Fish Product: Drivers and Barriers,Acceptance, and Communication of Health Benefits

This study aims to explore consumer acceptance of a new functional fish burger using a qualitative approach based on four focus group discussions conducted in selected major Italian cities. Results show that the development of functional fish products may bypass fish consumption barriers, combining convenience and health benefits delivered by functional ingredients. The acceptance of new functional fish products seems to be influenced positively by the enrichment of functional ingredients naturally present in fish, particularly omega-3 fatty acids. Consumer acceptance of this new product is also influenced by the use of different nutritional and health claims. Implications for marketers and policy makers and insights for further research are discussed in the conclusions.     

热塑挤压蒸煮处理对鱼肉蛋白分子影响的研究

用热塑挤压蒸煮加工技术与传统食品加工技术比较了不同加工技术对鱼肉蛋白分子的影响.通过采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳对原料鱼肉,3种传统加工方法即常规蒸煮、热力杀菌和鱼糜加工处理的鱼肉制品及热塑挤压蒸煮的鱼肉制品进行蛋白质分子量的测定,分析比较各种鱼肉制品的蛋白质分子量的测定结果,初步探索了热塑挤压蒸煮对鱼肉蛋白质分子量的影响.研究结果表明,热塑挤压蒸煮对鱼肉蛋白质的分子量有一定的影响.     

Microbiological aspects of common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis>) and its processing—relevance for final product quality: a review

The aquaculture production of common carp (Cyprinus carpio) is one of the biggest on a global scale, although European production represents a minor part. Thus, common carp is a little-exploited, low-cost, and highly nutritious food source. For development of new quality products that have customers’ appeal and are safe, a combination of traditional and novel technologies can be used. However, good quality raw material is of basic importance for further processing and final product quality. Fish microbiota have a major role in fish spoilage and as potential human pathogens. To diminish the negative impact of the microbiota on fish, different methods and technologies can be used. The important steps before the final product processing in the production of common carp products include purging, transport, pre-slaughter storage, slaughter method, bleeding, cleaning, desliming, descaling, and gutting. The most important factor in fish spoilage prevention is chilling, although to assure longer freshness and shelf-life, the concept of hurdle technology should be used. Many preservation and packaging techniques have been developed for fish products, but not all have been researched for common carp products. This review aims to identify the gaps in research, knowledge, and practice for the microbiological aspects that impact upon the production of high-quality common carp food products.     

The nutritional properties of co-dried fish silage in rainbow trout (Salmo gairdneri) dry diets

Feed ingredients containing fish silage and liquefied fish made from ground, whole Pacific whiting and co-dried in a vacuum dryer with mixtures of soybean meal and feather meal to facilitate drying were prepared. An additional batch of fish silage was co-dried with the other dry ingredients in the diet formulation that was used, Abernathy diet S8-1. Fish meal, made by vacuum drying Pacific whiting, was used in the control diet. Co-dried fish meal was made by co-drying Pacific whiting with a soybean meal-feather meal mixture. Fish meal was entirely replaced by the co-dried products in the experimental diets, which were fed to rainbow trout (Salmo gairdneri) for 32 weeks. The best growth and food conversion values were obtained by feeding the fish meal control diet or the diet in which the fish meal was replaced with co-dried liquefied fish. No significant differences in final weights were found between trout fed diets containing co-dried fish meal or co-dried fish silage (fish products were 25% of the diet), but these fish were significantly smaller than fish fed the fish meal control or the co-dried liquefied fish diets. Reducing the fish silage to 12.5% or increasing it to 50% further reduced weight gains in the trout. Food conversion values, protein efficiency ratios, and net protein utilization values generally followed the same trends between diets as did the final weight values. Apparent digestibility coefficients for the co-dried products were lower than for the fish meal, possibly because they contained soybean meal-feather meal mixtures. Organoleptic properties of the fish were not affected by diet.     

热塑挤压蒸煮对鱼肉蛋白质营养价值的影响初探

采用胃蛋白酶—胰酶复合处理法对原料鱼肉、蒸煮和罐藏处理的鱼肉产品,以及热塑挤压蒸煮的鱼肉制品进行蛋白质体外消化率的测定,分析比较各种鱼肉制品的蛋白质体外消化率的测试结果;结果表明,挤压蒸煮对鱼肉蛋白质的消化率有一定的影响。     

An evaluation of open and closed systems for in vitro protein digestion of fish meal

The availability of a rapid, cost-effective, accurate and reliable method of assessing fish meal protein digestibility would greatly enhance and standardize quality-control procedures in both the fish meal and fish feed industries. However, while several in vitro digestibility tests have been developed, few have been adopted by industry due to their time-consuming nature, problems surrounding reliability and/or inconsistencies in predictive ability. The present investigation was undertaken to evaluate the utility and predictive qualities of two in vitro digestion assays of distinct design. Methods examined included a novel open system, wherein on-line removal of digestion products was attainable, and a closed system, which permitted analysis of products following completion of the digestion process. Results provided by the two systems were compared using four differentially processed fish meals. The open system supplied information based upon the detected quantity of products below 10 kDa. The closed system provided measurement of free amino groups. Both methods were in agreement with respect to assessing the presence of hydrolysed product. Both systems furnished complementary data with respect to the characterization of fish meal protein quality. The closed and open systems provided insight upon digestibility and digestion kinetic profiles respectively.     

Studies on the effect of temperature and pH on the inactivation of fish viral and bacterial pathogens

Disposal of fish by‐products in the European Community must comply with Regulation (EC) No 1069/2009 which categorizes animal by‐products according to risk, and specifies methods of disposal of by‐products according to that risk. There is provision under the regulation for composting or ensiling to be used for by‐products from aquatic animals. Biosecurity considerations require knowledge of the parameters of time and temperature, or time and pH, required to inactivate any fish pathogens that may be present. To provide those data, we undertook laboratory studies on the inactivation of a number of fish pathogenic viruses and bacteria at 60 °C, pH 4.0 and pH 12.0 as a preliminary to conducting subsequent trials with the most resistant viruses and bacteria in fish tissues. The most resistant bacterium to 60 °C, pH 4.0 as well as pH 12.0 was Lactococcus garvieae. Its concentration was reduced to the level of sensitivity of the test after 24–48 h exposure to 60 °C, but it survived for at least 7 days at pH 4.0 and 14 days at pH 12.0. The most resistant virus to 60 °C was infectious pancreatic necrosis virus, and to pH 12.0 was infectious salmon anaemia virus. The majority of the viruses tested survived exposure to pH 4.0 for up to 28 days. The results suggest that the process of acid ensiling alone is not an effective method for the inactivation of many viral and bacterial pathogens, and fish by‐products would need further treatment by a method approved under the regulation following ensiling, whereas alkaline or heat treatment are likely to provide an increased degree of biosecurity for on‐farm processing of mortalities.     

鱼肉蛋白质挤压过程中操作参数对挤出物水分含量及堆积密度的影响

研究了鱼肉蛋白质在双轴挤压蒸煮处理过程中,主要操作参数末段腔体温度,螺杆转速和供料水分含量对挤出物的水分含量和堆积密度两个物理性质的影响。研究的3个操作参数每一个变量设5个水平,测量相应挤出产物的水分含量和堆积密度,分别建立挤出物水分含量与操作参数,挤出物堆积密度与操作参数的回归拟合方程。结果表明,供料湿度明显影响挤出物的水分含量。供料水分含量、腔体温度和螺杆转速对挤出物的堆积密度都有影响;水分含量与操作参数,堆积密度与操作参数的回归拟合方程的相关系数R²分别是1.000和0.926,拟合的统计模型可信度高。     

Fatty Acid Composition and Oxidative Stability of Fish Oil Products in Turkish Retail Market

The fatty acid composition and oxidative stability of fish oil and syrups available in the Turkish retail market were examined in this study. The major saturated fatty acids in capsules and syrups were palmitic acid (16:0) and stearic acid (18:0). The monounsaturated fatty acid contents of fish oil products have very different results (10.71–50.46%). The results show that the label claims for total omega-3, eicosapentaenoic acid, and docosahexaenoic acid presented a reasonable accuracy for the examined products, but it was noted that some of the results showed a considerable difference with the labels.

The free fatty acid level in fish oil products was generally low (0.13–1.95% of oleic acid). Peroxide value of all examined products was below the limit of 10 meq kg^?1 oils for edible oil as indicated in Codex (1999). It was detected that the p-Anisidine value of fish oil capsules (5.36–8.90) was considerably lower than for fish oil syrups (21.86–26.74). According to our results, the totox value of fish oil capsules evaluated in this study (7.08–17.35) was within acceptable limits. However, fish oil syrups (34.72–38.06) highly exceeded the upper tolerable limit (26).