Small-Scale Processing of Fish (ILO - WEP, 1982, 140 p.): CHAPTER II. SALTING - DRYING - FERMENTING: III. DRYING: III.1. Basic principles

Small-Scale Processing of Fish (ILO - WEP, 1982, 140 p.)

(introduction...)

Acknowledgements

Preface

CHAPTER I. INTRODUCTION

(introduction...)

I. FISH SPECIES

II. PROCESSING METHODS

III. PREVENTION OF LOSSES AND SPOILAGE OF FISH

(introduction...)

III.1. Prevention of spoilage of fish before processing

III.2. Prevention of spoilage of fish during processing

III.3. Prevention of spoilage of fish after processing

CHAPTER II. SALTING - DRYING - FERMENTING

(introduction...)

I. FISH PREPARATION

(introduction...)

I.1. Equipment for fish preparation

I.2. Gutting and splitting methods

II. SALTING

(introduction...)

II.1. Kench salting

II.2. Pickle curing

II.3. Brine salting

II.4. Salt quality

III. DRYING

III.1. Basic principles

III.2. Natural drying

III.3. Artificial drying

III.4. Solar drying

IV. PACKAGING AND STORAGE

V. METHODS OF PREPARATION

(introduction...)

V.1. Dried/salted fish

V.2. Dried-unsalted fish

V.3. Dried/salted shark

VI. GENERAL PLAN FOR A FISH CURING YARD

VII. FERMENTED FISH PRODUCTS

(introduction...)

VII.1. Products which retain substantially the original form of the fish

VII.2. Fish paste products

VII.3. Liquid fish products

VII.4. Packaging

CHAPTER III. FISH SMOKING AND BOILING

(introduction...)

I. SMOKING

(introduction...)

I.1. Fish preparation prior to smoking

I.2. Cold smoking

I.3. Hot smoking

I.4. Fuel

I.5. Smoking kilns

I.6. Preparation of some smoked fish products

I.7. Packaging and storage of smoked fish

II. BOILED FISH PRODUCTS

(introduction...)

II.1. Traditional processing methods

II.2. Quality of boiled fish products

CHAPTER IV. THERMAL PROCESSING

(introduction...)

I. RAW MATERIALS

II. ENERGY AND MANPOWER REQUIREMENTS

III. PROCESSING OPERATIONS

III.1. Filling and sealing

III.2. Sterilisation

III.3. Cooling

IV. QUALITY CONTROL

V. POSSIBLE ALTERNATIVES TO THE USE OF METAL CANS

(introduction...)

V.1. Reusable container

V.2. New developments in aseptic (retortable) pouches

CHAPTER V. ALTERNATIVE TECHNOLOGIES: EVALUATION, EMPLOYMENT GENERATION AND MANPOWER TRAINING

(introduction...)

I. ASSESSMENT OF COSTS

II. SALTING AND DRYING

III. SMOKING

IV. THERMAL PROCESSING

V. EMPLOYMENT IMPACT OF ALTERNATIVE FISH PROCESSING TECHNOLOGIES

VI. ASSISTANCE TO THE SMALL-SCALE FISHERIES SECTOR: MANPOWER TRAINING AND SUPPORTING SERVICES

(introduction...)

VI.1. The socio-economic framework

VI.2. Infrastructural requirements

VI.3. Organisation of production and marketing of fresh and cured fish

VI.4. Extension services and training

CHAPTER VI. IMPACT OF SMALL SCALE FISH PROCESSING OPERATIONS ON THE ENVIRONMENT

(introduction...)

I. FISH RESOURCES

II. WASTE DISPOSAL

III. AIR POLLUTION

IV. CONCLUDING REMARKS ON ENVIRONMENTAL IMPACT

APPENDICES

APPENDIX I. Codex Codes and Standards issued by the Secretariat of the Joint FAO/WHO Food Standards Programme, FAO, Rome.

APPENDIX II. Bibliographical references

QUESTIONNAIRE

OTHER ILO PUBLICATIONS

BACK COVER

III.1. Basic principles

During drying, water is removed from the fish by evaporation in two phases. During the first phase, only water on the surface of the fish or very close to the surface evaporates. The rate at which the fish dry depends on the surface area of the fish, the air temperature, the speed of the current of air passing over the fish and the relative humidity or wetness of the air. The drying rate during the first phase may be increased by:

- Increasing the fish surface area by splitting the fish and scoring them.
- Choosing a drying site where the air is dry and to avoid, if possible, marshy areas and places where the air has blown over water.
- Choosing a drying site where the wind is strong.

Once the surface is dry, water will evaporate at the rate at which it rises from inside the flesh to the surface of the fish. This rate slows down as the fish gets drier.

During the second phase, the drying rate is function of:

- The type of fish. For example, the rate at which water rises to the surface is slower for fatty fish.
- The thickness of the flesh.
- The temperature of the fish.
- The water content of the fish, and
- The wetness of the surrouding air.

If moisture is removed from the fish surface sufficiently quickly, the drying rate is independent of the level of humidity contained in the air. It depends only on the rate at which water reaches the surface of the fish. If drying is very fast during the early period, the surface may dry too quickly, thus producing a hard layer which will slow down the rise of the water to the surface. This is known as case hardening. When case hardening occurs, the centre of the fish could spoil even though the fish may look as if they have been well dried.

The drying rate during the second phase may be increased by:

- Reducing the thickness of the flesh by splitting and scoring the fish before drying starts, and
- Raising the temperature of the fish.