Improving Farmed Fish Quality and Safety

Øyvind Lie

• Publisher: Woodhead Publishing
• Year: 2008
• ISBN:
  9781845694920
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Global aquaculture production has grown rapidly over the last 50 years. It is generally accepted that there is limited potential to increase traditional fisheries since most fish stocks are well or fully exploited. Consequently increased aquaculture production is required in order to maintain global per capita fish consumption at the present level. Fish farming enables greater control of product quality and safety, and presents the possibility of tailoring products according to consumer demands. This important collection reviews safety and quality issues in farmed fish and presents methods to improve product characteristics.The first part of the book focuses on chemical contaminants, chemical use in aquaculture and farmed fish safety. After an opening chapter discussing the risks and benefits of consumption of farmed fish, subsequent contributions consider environmental contaminants, pesticides, drug use and antibiotic resistance in aquaculture. Part two addresses important quality issues, such as selective breeding to improve flesh quality, the effects of dietary factors including alternative lipids and proteins sources on eating quality, microbial safety of farmed products, parasites, flesh colouration and off-flavours. Welfare issues and the ethical quality of farmed products are also covered. The final part discusses ways of managing of product quality, with chapters on HACCP, monitoring and surveillance, authenticity and product labelling.With its distinguished editor and international team of contributors, Improving farmed fish quality and safety is a standard reference for aquaculture industry professionals and academics in the field.

• Reviews safety and quality issues in farmed fish and presents methods to improve product characteristics
• Discusses contaminants, persistent organic pollutants and veterinary drug residues and methods for their reduction and control
• Addresses important quality issues, genetic control of flesh characteristics and the effects of feed on product nutritional and sensory quality

Part I

Chemical contaminants, chemical use in aquaculture and farmed fish safety

Outline

Chapter 1: The risks and benefits of consumption of farmed fish

Chapter 2: Environmental contaminants in farmed fish and potential consequences for seafood safety

Chapter 3: Pesticide contamination in farmed fish: assessing risks and reducing contamination

Chapter 4: Veterinary drug use in aquaculture

Chapter 5: Assessing the human health implications of new veterinary drugs used in fish farming

Chapter 6: Antibiotic resistance associated with veterinary drug use in fish farms

Chapter 7: Improving disease immunity to reduce antibiotic use in farmed fish

Chapter 8: Different methods to reduce antibiotic use in farmed fish

1

The risks and benefits of consumption of farmed fish

J. Tuomisto, KTL National Public Health Institute, Finland

L. Frøyland, National Institute of Nutrition and Seafood Research (NIFES), Norway

Publisher Summary

Fish has long been considered excellent food. There are clear benefits, but there are also some problems partly different from other food items. This chapter provides the information on the benefits and risks of consuming farmed fish. Most of the benefits and risks are not restricted to fish, but often they are more prominent in fish than meat or dairy products. Fish and other seafood contain relatively high levels of many different nutrients and based on an assessment of nutritional factors, they are good sources of protein, fat, especially the long, polyunsaturated marine n-3 fatty acids, vitamin D, vitamin B12, selenium, and iodine. Much of the information benefits of fish consumption are based on epidemiological studies or clinical trials. Epidemiological studies can be based on exposure, a typical such arrangement is a cohort study. Different health indicators are determined over a defined period and correlated with the exposure. Risk factors can be derived from the data for the exposed group as compared with the non-exposed or less exposed group. Farmed fish has every possibility of achieving at least as good a quality as wild fish. Farmed fish is controlled in regard to both quality and safety to ensure the consumer safe and healthy food.

1.1 Introduction: the human health implications of consumption of farmed fish

The aim of this chapter is to give information on benefits and risks of consuming farmed fish. A major part of relevant published information is based on studies dealing with fish in general, or using pure compounds such as n-3 polyunsaturated fatty acids. Therefore it is necessary to outline first the benefits and risks based on studies of fish in general. Then findings will be extrapolated to farmed fish utilising the information on health-promoting compounds and contaminants of farmed fish compared with wild fish, as well as specific health studies available on the consumption of farmed fish.

Fish has long been considered excellent food. There are clear benefits, but there are also some problems partly different from other equivalent food items (Table 1.1). Most of these benefits and risks are not restricted to fish, but often they are more prominent in fish than, e.g., meat or dairy products.

Table 1.1

Examples of some benefits and risks of fish consumption

Benefits	Risks
• Nutritional value (e.g., good quality protein)	• Microbiological problems (requires good hygiene and ice-cold storage)
• Essential n-3 fatty acids (cardiovascular and nervous system benefits, anticarcinogenicity)	• Toxins (e.g., botulinum toxin, certain algal toxins)
• Certain vitamins (e.g., vitamin D) and minerals (e.g., I, Se)	• Chemical contaminants (e.g., Hg, As, PCBs, dioxins, organochlorine pesticides)
• Replaces hard fats in diet

1.2 Nutrients in fish and other seafood

Fish and other seafood contain relatively high levels of many different nutrients, and based on an assessment of nutritional factors, they are good sources of protein, fat, especially the long, polyunsaturated marine n-3 fatty acids, vitamin D, vitamin B₁₂, selenium and iodine.

1.2.1 Fat

Fat is not distributed equally in fish, and the fat content decreases from the head to the tail. In fatty fish the fat is contained in the muscle (fillet), while in lean fish the fat is located primarily in the liver. For this reason, the oil is extracted from the cod liver. Farmed salmon is fatty, whereas wild salmon in general contains less fat, in part because wild salmon have a limited food intake on their journey from the open sea to the rivers for spawning. In addition, during the process of sexual maturation, fat is transferred from the muscle for use in the development of reproductive glands (with the products roe and milt), which further reduces the fat content of the fillet. Because sexually mature salmon are not considered to be of top quality, this process of fat transfer is avoided in the production of farmed salmon. Most fish species are leaner immediately prior to spawning, but they regenerate the fat content in the period up to the next spawning.

Because lean fish, such as cod, stores its excess fat in the liver, the amount of fat in the fillet does not depend on the amount of fat in the feed. However, the composition of fatty acids in the fillet (and liver of cod fish) does reflect the fatty acid profile of the feed, and the composition of fatty acids in the blood lipids of those who eat fish (farmed and wild) and other seafood. This is especially the case for fatty fish or when consuming fish liver. A recently published article documents the correlation between the fatty acid profile of salmon feed, the fatty acid composition of salmon fillet, and the blood lipids of those who eat the salmon (Seierstad et al., 2005).

People and animals can synthesise most of the fatty acids they need, except for linoleic acid (LA, 18:2 n-6) in the n-6 series and α-linolenic acid (ALA, 18:3 n-3) in the n-3 series. As a result, these two fatty acids are called essential and must be supplied through the diet. Many plant oils, especially soy oil, are rich in LA, and because of the widespread use of soy oil and soy beans as food and in animal feed, this is the dominant polyunsaturated fatty acid in the Western diet.

Some plant oils contain signific...

Table of contents

• Cover image
• Title page
• Table of Contents
• Related titles
• Copyright
• Contributor contact details
• Preface
• Part I: Chemical contaminants, chemical use in aquaculture and farmed fish safety
• Part II: Improving farmed fish quality
• Part III: Managing farmed fish quality and safety
• Index