Value addition to fish in the context of NE India
- Part 2 -

Ranendra K Majumdar *

Annual Fish Fair / Fish Crop Competition at Hapta Kangjeibung on 26th October 2022 :: Pix - Shanker Khangembam

Preservation of fish by fermentation

The NE region is a treasure on indigenous knowledge systems pertaining to agriculture, medicine, food and natural resources management. Several fermented fish products are traditional to the North East, important of which includes 'Shidal', 'Ngari' and 'Hentak'. However, amongst these the popularity and turn-over of Shidal is maximum and it is available in almost all the States of the North East.

Especially Assam and Tripura is the major producer of Shidal amongst the North East States. Tripura is one of the largest producers of Shidal in the North East next only to Assam. Shidal is exported from Tripura to the States like Mizoram, Meghalaya, Nagaland, Manipur and Arunachal Pradesh. According to the estimate provided by the manufacturers, the present annual production of Shidal in Tripura State is about 750 tons.

But these fermented fish products have a potential to grow into a small or medium size industry, if scientific and technological support is extended to the existing practices. Shidal is considered as the only source of animal protein to the tribal communities as well as to the people living below poverty line of NE region.

The quality deteriorates very fast after continuous exposure to air due to absorption of moisture which invites spoilage microorganisms and non-enzymic browning reaction is responsible for deterioration of colour of the product. Study has been conducted in the College and found that addition of 2% of common salt to the Shidal enhances its storage life in ambient temperature.

Traditional Shidal technology

Shidal is a salt-free fermented fish product indigenous to the North East sector of India. It is popularly called as seedal, sepaa, hidal, verma and shidal in Tripura, Assam, Mizoram, Arunachal Pradesh and Nagaland. It is very much popular due to its strong flavour. This product is usually prepared from Puntius sp. Although, recently shidal is also produced from another estuarine fish Setipinaphasa known as 'phassyashidal'. At present phassyashidal is commercially produced in Tripura and Manipur.

In Manipur it is known as Thum-thakpi, thumnga Ngari, Samudra ngari etc. The appearance of 'shidal' is solid, bilaterally compressed and pasty and shape of the fish remains almost unchanged except little disintegration near belly and caudal portion.

The colour of best quality product is dull white that gradually becomes slight brownish to deep brownish on continuous exposure to air. However, studies made in the College compared the quality f shidal of Tripura with that produced in Bangladesh and reported that quality-wise shidal of Bangladesh was superior. Preparation of shidal is somewhat complex and usually dried Puntius spp. is used. The raw material (dried Puntius spp.) comes from Gujarat and Chennai via Jaggi Road (Assam), the largest whole sale dry fish market in Asia.

Shidal is usually prepared in the month of November to February. The dried Puntius spp. after sorting and cleaning are washed thoroughly in running water preferably in the evening time. The duration of washing depends on the moisture content of the dry fish. Earthen pear-shaped container (locally called 'matka') with neck diameter 8-inch, diameter of middle expanded part 24 inch and height 36 inch are generally used. Matkas are oil processed before use. This is an important step to close the micropores present in the container.

The inner side of the matkas are rubbed thoroughly with oil followed by drying under sun. This process is repeated for 5-6 times in case of new matka and 2-3 times in case of old matka. Oil extracted from Puntius sp. is usually used to get a yield of a good quality shidal. In absence of puntius sp. is usually used to fill up the matka.

After washing the wet fish are spread at a thickness of about 6 inch over a cemented platform or a bamboo mattress for about 10-12 hours. The matka is placed in the ground by digging a hold. Then the partially dried fish are placed layer by layer. Each layer is packed tightly by pressing with feet till the layer each near to neck. Then wooden stick is used along with feet for almost air tight packing.

Then wooden the neck is sealed airtight by a paste prepared from dust of dry fish. The thickness of the cover layer is 2-2.5 inch. Finally, the matka is sealed by a layer of wet mud. This layer is checked on and often for any crack and is repaired immediately by wet mud again. The packed matkas are left undisturbed in a shade for maturation. The usual period of maturation is 4-6 months but it may be extended to one year. About 40-42 kg shidal is obtained from each matka.

Critical factors in the manufacture of shidal

o Washing of dried fish
o Drying of washed fish
o Oil processing of matka
o Packing of fish in the matka
o Sealing of matka
o Storing of matka

Requirements for better quality shidal

o Freshness of raw fish
o Proper drying
o Adequate water soaking and partial drying
o Compaction during packing
o Proper sealing
o Safe storing for fermentation

Shortcomings in the present technology

o Inferior in quality than the shidal of Bangladesh
o Unhygienic condition in the production area
o Fermenting container (matka) is breakable during transportation
o Short shelf-life after maturation due to lack of proper packaging
o Adulteration of different types (both in the process and raw materials), which are:
o Insufficient fermentation period by the manufacturers for early return
o Addition of spoiled and old dried sea fish along with Puntius during fermentation to reduce the cost of production for more profit

Scopes for intervention in the traditional shidal technology

o Hygienic production
o Improvement of quality
o Reduction of fermentation period (without compromising the characteristic properties of shidal especially its flavour and texture)
o Increase of shelf-life of shidal through packaging
o Replacement of traditional fermenting container by reusable one
o Checking adulteration in the technology
o Decentralization of monopoly of technology by encouraging micro-enterprises
o Step towards gradual automation of the processes
o Improvement in the marketing of the product
o To explore export possibility to Southeast Asian countries
o To study medicinal value (if any) of shidal

Traditional ngari technology

Ngari, a fermented fish product has been most widely used by the people of Manipur. It is one of the essential ingredients of every household in the area accounting to its taste, therapeutic properties and strong appetizing nature. Due to its ever-growing popularity, its value as a food ingredient has grown into other States of the North Eastern region. Ngari is locally prepared from some fish species mainly the Puntius species. Ngari is a major ingredient in 'iromba' preparation, a pungent vegetable and bamboo-shoot stew.

In Ngari preparation the fishes used are of comparatively small sizes ranging from 5-10 cms. In texture Ngari is comparatively softer than Shidal which has a comparatively hard solid texture. Puntius sophore (locally known as Phabounga) is exclusively used for Ngari preparation. The method of manufacture is almost similar with shidal technology with few differences.

The dried fish are soaked in water for a period of 10-15 minutes and then allowed to drain for 8-10 hours. The fish are now of soft texture with dry surface skin. In the next step, fish are smeared with vegetable oil and then another drying under the sun for an hour is done. The amount of oil added decides the texture of the final product.

The fish are then stamped or rolled by rollers to make the fish soft and tender. The fish are now ready to be packed in the chaphus (matka/jar of 40-50 kg capacity). Now the pre-processed chaphus are buried in the pits excavated earlier and layered with moist sacks with half or one-third of the belly underground. Initially, 5-6 kg of the fish is put in each jar and they are pressed under feet until wet liquid is released from the fish.

The process is continued until the jars are fully filled with the fish. The jars are then sealed with wet mud and are kept for maturation for 4-6 months. After the maturation, the top layer of fish in the jars (locally called as Phmai, a inferior quality fermented fish) is removed and the rest are used for human consumption which we call as "Ngari".

Besides its good taste, ngari also has got strong appetizing properties. In order to keep away from fungal attack, the product is usually packed in tight containers or sometimes partially fried in oil. Endowed with its precious food value and medicinal qualities this fermented product is getting more popularised day by day. Due to its wider acceptance, there is a great market demand of the product. But the ngari still prepared by traditional way. So, there is a great scope for scientific intervention in production of hygienic product, which will help provide a consumer-friendly product.

To be continued....