Saturday, June 18, 2011

Fish Dehydration Process & Market

Fish normally contains 65 to 80% of water content depending on species of fish that are being dehydrated. Prawns contain about 80% water whereas Mackerel contains 65% water. Percentage of water in fish also varies depending on how they are stored in raw condition. If stored in ice naturally water content goes up but if preserved in cold storage keeping humidity at best possible level fish carries natural water content. Depending on water content entire process cycle has to be determined.

SFVL proposes to dehydrate following types of fish/prawns in its high-tech continuos process plant.

a. Mackerel
b. Salmon
c. Pomphret
d. King fish
e. Sardines
f. Prawns
g. Cod fish
h. Silver belly


A. Cleaning
B. Deheading
C. Deskinning and cutting
D. Blanching in salt water
E. Steaming
F. Dehydration
G. Packing


a. Cleaning

Raw fish is contaminated by inorganic elements. Before starting any process fish has to be cleaned under high pressure water in batches in cleaning machine. High presesure water nozzels are mounted in cleaning chambers from different angles. Outlets are provided so that dirt water is flushed out. The washed batch is brought to the next chamber where enough time is allowed to drip all water.

b. Deheading:

Cleaned fish is coveyed to deheading machine first where head and tails are removed by auto-deheading machine. Heads and other waste is carried separately out to bio-plant.
Deheading is must because any way heads are not used in food preparations and also intestines etc. has to be removed skilfully without harming base materials. Manual check has to be maintained during this process.

c. Deskinning and cutting:

Deheaded fish are shipped on conveyer belts to deskinning section where skin of the fish is removed. After removing the skin (Or shells in case of prawns) fish is brought to cutting machine where fish is cut in desired shapes. Benefit of cutting is not only that facilitates end consumer but it increases dehydration speed as compared to the full-size fish. Especially Pomphrets, salmons, are preferred in sliced forms.

d. Blanching:

To maintain specific flavor of dried fish it is essential to blanch fish in salt enriched water for 15 minutes per batch. Here conveyer belt moves through salt-rich water chamber in specific speed so that blanching process is complete. No chemical additives like sulfur is used in this process because sulfur though enhances final look of the product but is health hazardous. So instead of sulphication steaming is highly recommended by our technical collaborator.
Due to salting (Not to that ridiculous level of conventional dryers) not only flavor is added but also it helps in drying process.

e. Steaming:

After blanching fish is brought to steaming chambers where high degree temperature steam is applied on the fish. Steaming is usually done only to kill bacteria’s that are inherently are present in flesh of the fish. So that after drying even if fish is kept in open air for long time no formation of fungus or bacteria’s is possible. Also due to steaming the quality of dried fish is enhanced. Aesthetics of end product too are maintained.

Steaming is not done to the level of cooking. Normally a batch takes five to seven minutes for steaming.

d. Dehydration:

Ready to dehydrate fish/prawns is brought to continous tunnel dryers. The speed of belt is determined by SCADA and Process Audit software depending on input materials moisture content. Since the length of the dryers is predetermined, to remove moisture content to desired level i.e. 8 to 10% To determine moisture content in the raw material censors are mounted on conveyer belt as well as throughout the dryer at various stages moisture removal ratio is counted, supervised and controlled. Determining moisture content becomes highly essential because depending on that:

a. Speed of belt
b. Temperatures at different stages
c. Air circulation rates
d. Moisture removal rates
e. Moisture enriched airs removal rate

Has to be predetermined. If some mistake is there it not only drying speed may come down but ultimately either end product is dried beyond desired levels or still it may need drying. Re-drying always is harmful because it loses the desired flesh texture, harms to proteins and flavor. So it becomes impertinent that when fish comes out of dryer in ambient temperature there should not be necessity of redrying.

Here sensors and their direct connection with intelligent software helps to control entire drying process. After reading moisture content software immediately calculates the moisture removal ratio, dehydration time and coordinates entire process activity and commands through instrumentation to the individual equipment involved in drying process. For example if air flow required is high, software commands to air-flow machine. If temperature requirement varies even by single degree software commands heating machines. Speed control and air-flow control within the dryer is also done by software. If this done manually it will take longer time to calculate process imperatives and till that time entire damage is done.

Dryer has five different zones. Dryer is made of stainless steel so that no food-contamination is possible. The raw fish is automatically spread on stainless steel mesh-conveyer that hangs halfway in the chamber so that hot air circulation is easy and helping dry the input material homogeneously. Speed of the belt varies from 1 inch per minute to 1.5 inch per minute and speed control naturally has to be that exact accuracy depending on moisture content in the input raw material.

In the dryer there are different zones varying in temperatures, speed and airflow rates. In first zone temperature is as high as 85 to 90 degree Celsius. In first zone moisture removal rate is higher so the care has to be taken that moisture enriched air is continuously pumped out maintaining free air that can remove moisture at higher rates. Here all rules of thermo-dynamics and aerodynamics are applied so that moisture removal process is fast but it does not damage the raw material.

In second zone temperature is brought slightly low because surface moisture is entirely removed and if same temperature continues it will start burning raw material. This is not desired. Till second stage moisture content in raw material is brought to 25 to 30% various air-vents and sensors keep on tracking moisture content not only in product but in inside air as well. This makes easy to determine in next stage what temperature is required. In third stage temperature is further brought down to the level of 50 degree Celsius. Here whatever moisture is existent in core of the product too is removed.
Till the product reaches last chamber it is hotter. If same material directly is introduced to open air it has tendency to catch moisture prevalent in ambience. And since fish drying plants normally are located about seashore humidity is higher than other areas. Catching again moisture is dangerous in this process for it not only defeats original purpose but destroys entire texture of the product. Hence it becomes essential that product is brought to normal temperature in controlled atmosphere where no moisture is prevalent.

For this fifth stage is used where no moisture that has been removed in chamber is existent. Where vacuum is maintained to 650 to 700 mm, product should be brought to ambient temperature. Such product does not catch moisture from ambiance.


Processed fish is periodically rested in the lab for moisture content, texture of flesh, protein and carbo-hydrate contents, bacteria/or fungus and nutrient values as compared with natural.

a. Moisture content should be less than 10%
b. Nutritional values should be above 95%
c. Color should be faint brown.
d. NO ash content should be existent
e. No foreign material should be existent
f. Flavor should not be abnormal
g. Re-hydration should not take more than 20 minutes.
h. Quality should be consistent
i. No shrinkage or brittleness in final product should be existent.

These checks are done in the lab periodically, every hour, manually as well as through chemical lab facilities.


As soon product sufficiently has dried, periodically tested should be packed immediately. Packing, as the proposed product is intended for mass markets should be packed in nitrogen purged Tetra-pack in desired quantities. Due to nitrogen there can not be any development of fungus or bacteria because Nitrogen is an inert gas. It does not allow any bio-chemical reaction to take place. This increases shelf life of the product dramatically. Tetra-packed fish has shelf life of more than five years. Domestically sun-dried has shelf life of 2 to 3 months. If not tetra-packed, hygienically processed and dried under controlled atmosphere fish has shelf life of two years. But as we know in today’s dynamic consumer oriented market quality and style of packaging holds merit. Also for export where product has to go through different weather conditions it always is advisable to pack the end product in tetra-pack.

The vacuum-packed material is again packed in cartons for easy count and transport.



What dilutes nutrition values in foods? It is simple to answer. It is water. In almost all fresh meat and food water content is higher than 65% Drying is a process in which all water is skillfully removed to form a concentrate that always is rich in nutrition values. Also it occupies lesser space to store, it is light weight to make transportation cheaper and when cooked it gives same flavor as fresh vegetables or meat would give.

The same theory is applied to fish as well. First of all except coastal areas no fresh fish in its true sense is made available to off-coast areas. Traders in auctions at very low prices buy fresh catch that is harbored. As fish is highly perishable needs cold storage and transportation too in cold-storage trucks or ice-filled trucks. That naturally adds to the costs. For an example all that fish that is sold as fresh in Pune, the city that only is 200 km away from coast, is stale not less than by 15 to 20 days. Normally fish is stored at the temperature of minus four degree Celsius but that temperature does not help formation of certain bacteria’s. That is why even so called fresh fish smells a lot. Coagulation of blood in veins and rotten material in intestines again makes the so-called fish uneatable if considered international food guidelines. Also the costs that one has to pay are phenomenal. For example in Pune fish mongers sale small size pomphret at the average rate of Rs. 200 to 275/- a Killo. This rate amounts to 4 time higher than what they are bought originally at source.

International study on nature of meat preservation by cold methods suggest that unless any meat or fish is preserved below sub-zero level we can not stop formation of unhealthy bacteria and fungus. Minus four temperature in cold storage at the most can save meat or fish for 4-5 days from the day they are preserved. But apparently facts are different. NO care of keeping food meant to sell to the desirous class of the society in desired conditions is found even in western countries. That makes scenario little macabre.

Fish, as explained above needs far more better treatment than what it receives today for it is a fact that fish has been and will be an important source of not only food but of nutrition as well.

As discussed in other chapter about 15% fish goes waste only because either it doesn’t find buyer at the right time or can not be preserved by conventional drying methods. The species of fish that are not popular in food recepies have too many other usages but unfortunately all that fish that falls in nets of the fishermen has to be thrown away. But these species too can be used for productive purpose. For example undesired species by human consumers can be utilized as animal feed. But so far except western countries no thought has been given to these aspects of fishing business.

When we say 15% fish is waste we have to think to what it amounts to. India has recorded annual catch of ……..million tons and we know if we include unorganized sector it will be even higher, but even if we take government figures as a base …..million tonns of fish is a waste. This not only is waste of human efforts but of great natural resource.

It is a fact that masters of ancient past invented drying as a good medium of preserved food. Fish drying can be dated back to 5000 years BC. But conventional drying has too many restrictions. With conventional drying you simply can not dry every species of fish. More is the bulk lesser are the chances of sundrying. For example you can not sundry pomphret or salmon. Successful drying is in the case of Bombay Ducks and small size prawns. Other species that are dried are Mackerel or Surmai. But then there are tremendous limitations for both of above specis need drying time not less than six days. So driers use tremendous salt that disturbs everything. And not only this, there are lot many problems are associated with conventional drying. For example:

a. Entirely dependent on Mother Nature.
b. Variable temperatures during day and night
c. Humidity in air
d. No control over dust and unhygienic foreign materials
e. No control over food values
f. NO checks on quality.
g. NO proper packing ( We can see heaps of gunny bags loaded with smelling dry fish in local markets catching even more pollution.
h. This business is done in smaller quantities.

But to our wonder even taking in to consideration all limits that conventional drying methods have total business that they do is over RS. 1800.00 crore.

This is for very simple reason. Dry fish have been a desired staple food in India. In rural areas where no fresh sea-water fish is available they are contended with dry fish. The liking for dry fish is not limited to rural areas but in cities too. For example our survey tells us that only in Pune city total market for dry fish is over Rs. 20 crore per annum and it is growing.

Considering the facts about fresh fish and conventionally dried fish, another fact remains that people are having in the name of fish a health hazardous food that they are having.

The fish that is dehydrated in controlled conditions has following advantages.

a. Fish can be prepared for food as good as fresh fish
b. All nutrient values are preserved unlike other preservation methods. For example in canning nutritional values are just 40%. In Freezing they are 60% . But with drying the values are over 95%.
c. In other food preservation methods weight is increased. Hence it occupies more storage space and also the added transportation and energy costs. With drying weight is reduced about 1/5th and so the storage space required is less and so less are the transportation and energy costs.
d. Shelf life is far more larger than any other method of food preservation.
e. NO additional preservation costs.
f. NO odor is prevalent.

This makes dry fish produced in controlled atmosphere a value-added product. That does not only save natural resources but provides end-user high-quality product at equivalent rates to so-called fresh fish.

Fish dehydrated in controlled conditions has following characteristics.

a. Looks like oven-fresh, slightly brown.
b. It does not smell
c. Available in ready-to-cook form.
d. Rehydration takes just 15 minutes.
e. Nutrition values are enriched and tastes as good as prepared fresh fish.
f. Can be stored as long as five years.
g. No seasonal bindings.
h. From soups, pickles, chutney etc. (Recipes are described elsewhere) to regular food preparation is possible and easy.

So this is all about dehydrated fish in controlled conditions. But when we say controlled conditions to produce dry fish of high quality these are not as easy as they are anticipated. That’s why till today, even after wake of new economic policy no plant is established to produce dehydrated fish


Frozen fish is another medium to preserve fish for longer time. Comparison between two processes is as follows:

Frozen fish needs continuous low temporature atmosphere, from processing to storage till it is brought to end use. This needs high energy consumption. If anywhere temperature couldn’t be maintained or electricity is off for some time thawing process begins that leads to decomposition hence damages the fish making it unusable.

Dehydrated fish doesn’t need cold storage to preserve it after processing. It remains preserved at ambient temperature without any additional storage costs.

Due to abopve frozen fish is highly costlier than even fresh fish that is available in remote areas. Added to this transportation costs frozen fish is costlier because it needs:

Special vans
Weight of frozen fish is always higher than original weight so adding to transportation costs.

Whereas dehydrated fish is 1/5th by original weight, hence transportation costs are far below than fresh or frozen fish. Selling outlets need not to make special freezing provisions till the goods are sold.

In India frozen fish is not widely accepted by consumers because then they prefer fresh fish available in local markets for costs are many fold higher. Whereas dehydrated fish is cheaper than fresh and frozen fish and needs no preservation arrangements and there already are established markets for them.

Moreover, which is highly important, nutrition values in frozen fish are just 60% whereas in dehydrated fish the same amounts to more than 95%

For frozen fish thawing takes more than 3 to 4 hours whereas dry fish can be rehydrated in 20 minutes, saving cooking time.

Dehydrated fish has many functions. Since all that is removed is the liquid, the natural flavor and nutrients remain as they were in highly concentrated form.

Taste of the dry fish is far more intense than of the original raw fish but when it is cooked in water again it forms the original flavor as if cooked as fresh. But with frozen fish when already high water content exists that is enhanced by freezing, when cooked it further dilutes taste and nutritional values.

So above deliberation proves that any other food preservation method does not help much in terms of costs, flavor which is highly desired by the end consumer and nutritional values that are most important.


Processed in controlled conditions, dry fish is globally is in use as a food from last century, and if we look at historical times smoked fish or sundried fish has been in use from known history of mankind. So there has been global acceptance for dry fish. In India though there is market for sundried fish for over Rs. 18,00 crore, it can be enhanced to over Rs. 5000 crore if processed in controlled atmosphere and made available in tetra pack. Global market for dry fish is estimated over $1.23 billion in the year 1999. (Source: Survey conducted by Minnesota University)

Other interesting fact is most of the fresh fish in western countries is imported from Sri Lanka, India, Pakistan, Bangla Desh and Asia pacific rim. Due to weather over six months there is almost no fishing activity in European countries. Countries like Russia have far more limitations in fishing due to the geographical limitations. USA has longer coastline but then there are many species of fish that are not available in their coastal regions. China is a major fishing country after India in Asia and is a large exporter of fresh fish. But if we look at ground realities large quantities of fish still is wasted due to the bad storage conditions, immediate off-take of fresh catch by the traders etc.

Out of total catch (Globally) 15 to 18% goes waste.(Converted to manure)
Only 3 to 4% of selected species are frozen.
Only 10 to 11% fish is dried limited to certain species.
Only about 55 to 60% can reach the end consumer.

As discussed in other chapters now only 2% of total global catch is dehydrated by new technology. Rest of the drying has its own limitations, that is why out of 10 to 11% of fish that is taken for drying only 5 to 6% finally is a marketable fish. So total loss goes even further.

Hence it becomes impertinent that enhance the capacities of modern plants to dehydrate fish and thus make available consumer the right quality of fish as well as save the huge wastage.

If we look at the quantities in totality the facts are startling.



Global: Global market for dehydrated fish though is unorganized, Minnesota Universities study tells us it is somewhere above $21.25 billion in the year 1999 ( Source: World Fisheries Statistics) and it is growing by 7 to 8% per annum.

India: India’s present market for sun-dried fish is above Rs. 1800 crore and is moving up by 4 to 5% p.a.

The detailed figures are mentioned in this chapter at different junctures.


Dry fish of different variety has different usages. But we have categorized the usage as below.

a. Staple food
b. Food preparations
c. Sausages
d. Readymade soups
e. Chutneys
f. Pickles
g. Sausages
h. Animal food

Market segments:

Market for dry fish can be divided in following segments:

a. Consumer marketing
b. Army
c. Hospitals
d. Exports

These market segments can be elaborated as follows:

a. Consumer Market:

As described above India’s consumer existing market for dry fish is above Rs. 1800 crore. Concept of dry fish is known to Indian’s from thousands of years and they have developed their taste for dry fish though many othe varieties of fish is not available in dry form due to the limiting factors. The limiting factors are:

a. many species can not be sundried due to lack of drying know-how and dependency on mother nature
b. Lot of salt is used that makes taste bitter and consumer has to use them only as staple food.
c. Lower shelf life because of excessive use of salt. Salt catches atmospheric moisture very fast and that helps growth of fungus and makes dry-fish unusable.
d. No proper packaging is done in sundried fish because mainly lot many fishermen dry fish in smaller quantities and are sold in auctions to traders. Being this sector entirely unorganized no attention has been given to the consumer orientation. Present packing is in sodden gunny bags, lot of foreign material is existent in sundried fish such as dust, skulls etc.
e. No hygienic conditions are maintained.

Looking at above limiting factors it is obvious that end consumer gets entirely uneatable food in the name of dry fish. But even then due to the following reasons dry fish still remains only source to make available fish in every part of country.

a. Fresh seafood is not available in all parts of our country except coastal regions.
b. Fresh seafood is seasonal. In monsoons no fish is available
c. As farther you go from coastal areas costs tend to go up, making it highly unaffordable to end consumers.
d. Peculiar highly concentrated taste of dried fish and availability throughout the year at reasonable prices helps consumers to have necessary food item in their meals.
e. Dry fish doesn’t require special storage or is highly less perishable than fresh fish.
f. In Rural areas where there are not even outlets for fresh fish, dry fish makes major sales.

But the fact can not be neglected that as it has already happened in western countries where smoked fish is slowly losing the grounds due to hygienic conditions in processing methods, large educated class is moving away from dry fish. The reasons are:

a. It doesn’t make suitable hygienically for food.
b. It gives intense odor that is not accepted by educated classes.
c. It can not be used for longer time and ultimately results in wastage
d. It is available in selected outlets where only brave-hearts can enter.
e. All dry-fish are stored in entirely unaccepted norms of food and drugs administration laws.

So though there is already existent market and has scope to reach the tops dry-fish markets are growing just by 5 to 6% p.a. This growth is only because of growing population and lack of substitutes to fresh fish.

Also dry-fish market is entirely disorganized. Millions of fishermen dry fish in small quantities in winters and summers and sale them to the traders. Mumbai, Chennai, Trivendram, Kochin, Calcutta are the major centers from where dry fish is marketed in rest of the country in large quantities besides many sub-centers. Mumbai market alone records about Rs. 450 crore (Figures gathered from major dry-fish traders.)

However still this segment can not meet growing expectations of the market. Reasons we already have discussed. Still larger segment of society has been away from present dry-fish products that can be attracted with fish produced by applying modern techniques.

In the process of determining potential market for vacuum-packed, processed under natural condition fish products SFVL contacted several distributors of food products those never had marketed dry fish. The enclosed letters for applying packed dry-fish product are enclosed to prove that huge potential does exist for proposed product. The detailed report on each state is also enclosed separately with region wise expected sales figures.

To describe the market potential per segment can be read as following:

a. Consumer marketing

India’s huge population is in want of highly nutrient staple food. Dry fish is a very good option for them. Fresh fish is not available through out the year and in all parts of the country. There is special liking for the dry fish unlike dehydrated onions or vegetables. In custom-packed offering highly hygeinic qualities with making it available at all possible outlets can bring dry-fish in easy reach of consumer.

Already this segment is deriving turnover of Rs. 1800 crore or even more which can go up to Rs. 3000 crore if right quality is delivered.

b. Army: We all are aware that in army demand of fresh as well as frozen meat is huge. Army spends over Rs. 2.5 billion on food supplies and share of meat is about Rs. 800 million. Most of the meat products are canned or frozen since it is almost impossible to provide soldiers who are stationed at difficult borders or in remote areas with fresh supplies. Not only that canned food lacks in nutrition values but also has lesser shelf life. As yet Fish is not in supplies for the army, neither fresh nor dried as they hardly match the defense standards. Dry fish can be a very good substitute for many canned meat items for it is very low in the weight, have longer shelf life and can be used as food without any pre-treatment.
c. Hospitals: In hospitals where patients need high nutritional foods dry fish is a very excellent option. SFVL already has received a very good enquiry from sangali based distributor who excels in marketing the food in hospitals. Per his statistics he can bring business about Rs. 300/- lakh per annum from Maharashtra only. Hence this too is a potential market.

d. Hotels and Restuarants: Dry fish processed in controlled conditions can directly used as a fresh fish. Most of the restaurants today serve customers fish depending upon the seasons. Also dry fish can be used as an ingredient for soups, Chinese varieties like fish Manchurian etc.

e. Exports:

Export potential can be segragated in following regions:

a. Gulf Countries
b. Europe
c. USA and Canada
d. North Asian countries
e. Northern pole countries like Greenland, Iceland etc.


  1. Sir, Thanks for above writings. You have detailed the drying process and even pointed out many aspects of dehydration. You explained the critical importance of stage dehydration. Your writing has assured me that this business proposal makes sense.

    Sir, where can i get the details of modern process and machinery? May be MSME can be help. However i request your guidance.

    Mahadev Ghadi

  2. Just want to say your article is striking. The clearness in your post is simply spectacular and i can take for granted you are an expert on this field. Well with your permission. humidity chamber manufacturer