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Characterization of the Traditional Fermented Fish Product Lona Ilish of Northeast India

Characterization of the Traditional Fermented Fish Product Lona Ilish of Northeast India

Indian Journal of Traditional Knowledge Vol. 9 (3), July 2010, pp. 453-458

Characterization of the traditional fermented fish product Lona ilish of Northeast

RK Majumdar 1* & S Basu 2 1College of (Central Agricultural University), Lembucherra, Agartala, 799 210 2Central Institute of Fisheries Education (Deemed University), Fisheries University Road, Versova, Mumbai 61 E-mail: [email protected]

Received 29 February 2008; revised 9 April 2009

Lona ilish is a traditional salt fermented fish product widely consumed in and Northeast parts of India. It is prepared exclusively from Hilsa , ilisha (Ham-Buch, 1822), a high fat fish. Biochemical composition of market sample of lona ilish has been studied. The moisture, salt and pH of the product have been estimated as 54%, 15% and 5.66%, respectively. The product is stable when remains immersed in brine at ambient temperature. Lowering of water activity due to osmotic action of salt as well as effect of salt on spoilage bacteria are presumed to be the reasons behind this salt technique. High peroxide value is the indicative of lipid peroxidation but, however, did not impart any undesirable rancid taint to the product. The bacterial flora comprised of Micrococcus and Bacillus species. Lack of scientific study to standardize the methods, use of poor quality raw material fish, improper salting, inadequate fermentation period as well as adulteration in the process, etc. are some of the reasons for gradual deterioration of the quality of lona ilish .

Keywords: Fish fermentation, Hilsa , Lona ilish , Fermented food, Traditional fish product

IPC Int. Cl. 8: A61K36/00, A01G1/00, A01G17/00, A47G19/00, A23L1/00

Fermented are important dietary scientific work done on this product. The product is components in the protein deficient Far East sliced hilsa , about 1.50 to 2.00 cm in thickness. A especially in Southeast Asia, the near East and in typical lona ilish has a uniform pink colour with a Africa 1. Preservation of fish by salt is an age old glossy appearance immediately after taking the technology. This method of preservation still enjoys product out of the brine. The texture remains firm and popularity in many developing countries owing to its the flesh does not easily separate from its bone. It has simplicity and low cost of processing. When fatty a characteristic strong aroma mixed with some sweet, fishes are salted, there is usually a certain degree of fruity and acidic notes along with some saltiness. The fermentation involved 2. Fermentation of fish is strong odour permeates the air during storage and brought about by autolytic enzymes from the fish and gives the area a characteristic smell of lona ilish . It is in the presence of high salt kept immersed in saturated brine until consumption. concentrations 3. Lona ilish is a salt fermented product The technology of lona ilish actually originated in prepared from Indian shad (Tenualosa ilisha , Ham- Bangladesh about 100 yrs ago on the bank of river Buch, 1822), a high-fat fish (fat content of adult hilsa Padma and Meghna under Noakhali district. It is ranges from 14-25%)4. This fish is popularly known assumed that the technology evolved during the glut as hilsa due to its earlier generic name Hilsa . Lona period when there were no such preservation ilish is a very popular product and is widely techniques except sun drying and salting was consumed in Northeast India and Bangladesh mainly available. Sun drying was not suitable for hilsa like due to its typical flavour, aroma and texture. high fatty fishes due to rapid development of rancidity Unfortunately, this product has so far not found its on being exposed to the sun. In addition, sun drying due place in the literature among the fermented fish was difficult during continuous spell of rain in July- products of South East Asia mainly due to the lack of August that corresponds to the main glut period. This way of processing might have been started to quickly ______*Corresponding author preserve large quantity of fish in an inexpensive way. 454 INDIAN J TRADITIONAL KNOWLEDGE, VOL 9, NO. 3, JULY 2010

The technology has not changed much since the Methodology earlier days and the practice is still one of the major Biochemical analysis means of preservation of hilsa by the fishermen Samples of lona ilish were collected from local fish community of Bangladesh. Although different market at Agartala and brought to the laboratory for technologies have come into being so far, no other biochemical analysis. Moisture, pH, ash, and salt preservation techniques except salt drying and to contents were measured 8. Ten gm of samples were some extent canning are in use presently. The homogenized with 10 ml of distilled water and the pH technology got entry in to Northeast India through of the homogenate was then measured. Total titratable migrants. The large scale production and consumption acidity (TTA) was measured 8. The acidity was of lona ilish is limited mostly in the Chandpur calculated as per cent lactic acid. Differences in subdivision in Noakhali district of Bangladesh and weight were recorded after drying the sample in hot Northeast India. One of the reasons of localized air oven at 100 ± 2 °C overnight to determine the consumption in India may be due to the practical moisture content. Ashing was done by incineration in difficulties in its transport. However, there is a good a muffle furnace at 550 ± 50ºC until the ash was demand for the product in the fish eating communities in other areas.

Lona ilish is traditionally prepared by dry salting the diagonally cut hilsa chunks followed by fermentation in saturated brine (previously boiled and cooled) in metal container till appearance of the characteristic flavour and texture (Figs 1-3). It is kept immersed in the fermenting medium (saturated brine) till consumption. The fermentation period is usually 4-6 months. The reports on biochemical composition of hilsa are scanty. The fat content of hilsa of different water bodies such as river (19.28%), Saurastra coast (16.73%), Padma river (14.40%), (7.17%) and (5.40%) was investigated 5. The taste of the fish seems to be largely dependent on the fat content. The biochemical composition of the muscles of adult hilsa from the Calcutta market contain moisture (78.38%), dry matter (21.62%), protein (12.44%) and fat (18.01%) 6. Adult hilsa is a fatty species with fat content varying from 11.8% (small fish) to 18.91% (large fish) 7. The traditional methods of preparation of lona ilish and evaluation of some of its important biochemical and microbiological quality have been discussed (Fig. 4). Fig. 4—Preparation of Lona ilish by traditional method

Fig. 1—Hilsa ( Tenualosa ilisha ) Fig. 2—Lona ilish Fig. 3—Traditional tin container used for fermentation MAJUMDAR & BASU: TRADITIONAL FERMENTED FISH PRODUCT OF NORTHEAST INDIA 455

obtained. The salt content was determined by titrating through the process of osmosis. Such transfer of excess silver nitrate with ammonium thiocyanate moisture from the fish due to osmosis resulted using ferric alum as indicator 8. Total nitrogen was decrease of moisture content with simultaneous measured by using the micro-kjeldahl method 8. Ten increase of ash and salt content of the final product. per cent trichloroacetic acid (TCA) extract was used The role of salt is highly significant to guarantee the to estimate non-protein nitrogen (NPN), total volatile quality and stability of the finished products in this basic nitrogen (TVBN) and free α-amino nitrogen category. The preservative action of salt lies in the (FAN) by using micro-kjeldahl method, Conway's reduction of water activity (a w) of a system thus micro-diffusion method and by copper method, renders a condition less favourable for the microbial 8-10 14-16 respectively . Protein nitrogen was estimated by life . To achieve a w of 0.90, which inhibits most subtracting non-protein nitrogen from the total bacteria, a salt solution of approx 15.5% is required 17 . nitrogen. Total lipid was measured from dried sample In general, food borne pathogenic bacteria are by soxhlet extraction with petroleum ether 8. The inhibited by a water activity of 0.92 or less that is peroxide value (PV) and the content of free fatty acids equivalent to NaCl concentration of 13% (w/v) 18 . It (FFA) were determined on the chloroform extracts of was proposed to explain the preservative action of tissues 2,11 . salt, that it exerts a poisonous action; makes moisture unavailable for the microorganisms; prevents bacterial Microbiological analysis growth by dehydrating the cells by plasmolysis, and An amount of 10 gm of muscle from different destroys bacterial protoplasm 19 . Salt content of dry locations of a sample was aseptically collected and salted and pink stored at ambient macerated with 90 ml sterile saline (5% NaCl). After temperature were reported as 17.5% and >21.0%, making serial dilution in the same diluents, pour respectively 20 . Salt content of salt fermented plating was done using nutrient agar fortified with 5% was found 19.40% 21 . Salt content of lona ilish was NaCl. Total viable count (expressed as log cfu ) was found to be less than most of the other fermented fish made after 96 hrs of incubation at 37 °C and was products which is significant from the view point that expressed as log cfu (colony forming units). Bacterial high dietary salt pose a severe health risk. The pH and identification was made up to the generic level using total titratable acidity (TTA) of lona ilish were found biochemical tests 12,13 . as 5.66% and 0.98%. The reason of low pH value of the product may be attributed to the fact that samples Results and discussion were undergoing fermentation and not spoilage. In the The proximate composition of lona ilish is given same analogy, the high value of TTA seemed to be (Table 1). The mean values (as % muscle) of due to production of different organic acids. This moisture, salt and ash were found as 54.35, 15.75 and implies that the fish underwent sufficient fermentation 16.73, respectively. The process however, includes with endogenous and/or exogenous (microbial) diffusion of salt into the fish and elimination of water enzyme systems.

Table 1—Proximate composition of lona ilish (n=5) A series of complex biochemical processes including proteolysis, lipolysis and lipid oxidation Biohemical Parameters Value (mean ± s.d.) take place during fermentation (also known as ripening stage). The ripening stage renders a product ± Moisture (%) 54.35 5.06 with a firm consistency having characteristic pleasant Ash (%) 16.73 ± 1.13 pH 5.66 ± 0.06 aroma and taste. The physical and chemical changes Total titratable acidity (TTA)) 0.98 ± 0.04 that occur during ripening determine the overall 22 Total nitrogen (%, muscle) 3.35 ± 0.42 sensory qualities of this salt fermented fish product . Protein nitrogen (%, muscle) 2.81 ± 0.29 These changes are induced by enzymes, which break Non protein nitrogen (%, muscle)) 0.540 ± 0.06 down both proteins and fats. Despite leaching out in α Free -amino-nitrogen (mg %) 163.5 ± 32.4 brine during transfer of moisture and salt, the contents ± Lipid (%) 9.41 0.74 of non-protein nitrogen, free α-amino nitrogen and Total volatile basic nitrogen (mg %) 48.0 ± 6.08 Salt (%) 15.75 ± 1.16 total volatile basic nitrogen of lona ilish were found Peroxide value (meq O 2/Kg lipid) 40.0 ± 4.5 as 540 mg, 163 mg and 48 mg, respectively. Free fatty acid (% oleic acid) 18.22 ± 1.26 Accumulation of such low molecular weight 456 INDIAN J TRADITIONAL KNOWLEDGE, VOL 9, NO. 3, JULY 2010

nitrogenous components might have resulted due to volatile fatty acids may be responsible for degradation of tissue protein and to some extent that characteristic flavour and aroma of fermented fish may possibly be responsible for the generation of products 32 . Microorganisms such as Bacillus and typical flavour and aroma of the final product, Staphylococcus which were isolated from nam-pla, lona ilish . The role attributed to tissue enzymes versus bakasang and patis produced a significant amount of microbial enzymes is controversial. Tissue enzymes volatile acids 33 . Bacillus sp in the early stages of patis rather than microbial enzymes are responsible for fermentation was reported 34,35 . Occurrence of ripening of salted anchovy 23 . Microorganisms play an Micrococcus sp in one month old patis indicated the important part on the later stage of fermentation and possible involvement of non-spore-forming protein degradation by these microorganisms leading microorganisms in the early stages of some to the production of volatile compounds from amino fermentation. During ripening of salted anchovy, the acids and small peptides as raw materials 24 . Bacterial microflora was found to be dominated by halophilic proteases play a significant role in the fermentation and halotolerant bacteria like Micrococcaceae , lactic and flavour and aroma producing processes 25 . The acid bacteria and some moulds and yeasts 29 . aroma in fermented fish product has been claimed to be derived from the activity of various types of Conclusion halophilic bacteria 26 . The total lipid content and their The principle of preservation behind this salt degraded products such as peroxides (indicated by fermentation technique has been presumed as peroxide value) and free fatty acids of lona ilish were lowering of water activity and effect of salt on found as 9.41%, 40% and 18.33%, respectively. spoilage bacteria. The process however, basically Since, lona ilish is prepared from hilsa fish which divided into two stages. The first includes diffusion of comes under the high fatty fish group; it is not salt into the fish and elimination of water through the unlikely to find high fat content in lona ilish . The process of osmosis. The second slower stage of observed high PV is due to oxidation of unsaturated ripening which involves a series of complex fatty acids of lipid. Sodium chloride acts as a pro- biochemical processes including proteolysis, lipolysis oxidant 27, 28 . A similar PV (41.3 meq O /Kg fat) and 2 and lipid oxidation. The ripening stage renders a higher FFA (31.84%) have been reported in salted product with a firm consistency and the characteristic anchovy after 9 weeks of fermentation 21 . The PV and pleasant aroma and taste. The physical and chemical FFA contents increased significantly throughout the changes that occur during ripening determine the period of storage of mackerel and pink perch at overall sensory qualities of this salt fermented fish ambient temperature and reached 60 mmole O per kg 2 product. The lona ilish is different from other and 21.1% (as oleic acid), respectively after 35 days fermented fish products. Some distinctive features of of storage 20 . Salt does not inhibit lipases responsible lona ilish are: it does not come under the category of for liberation of free fatty acids 29,30 . An assessment of or fish sauce; exclusively hilsa , Tenualosa changes in FFA could provide an objective method ilisha (Ham-Buch, 1822), a very high fatty fish is for measuring the maturation of 30 . used for its preparation; whole fish is cut in to chunks However, this increased PV did not impart any rancid and remains intact after maturation whereas, in the taint to the product. case of other salt fermented fish products whole fish The total viable count (log cfu ) of lona ilish was is either crushed or dressed as whole and most of found to be 2.3 ± 0.05, comprised of Micrococcus them do not retain original form after maturation; dry (1.38 ± 0.03) and Bacillus (0.92 ± 0.06) species. Both salting is followed by brining whereas either dry Micrococcus and Bacillus constituted 60% and 40% salting or simply brining is done in case of most of the of the total bacterial flora, respectively. It was opined similar type of products; once taken out from the that microbiological and other processes play an brine and exposed to air, deterioration is very fast but important role in the preparation of many fermented this is not happened in case of most of the products. fish products 26 . Halophilic Bacillus sp were reported This is due to high fat content of the lona ilish that from Thai fish sauce was found responsible for the undergo autoxidation by atmospheric oxygen and the production of volatile acids 31 . The complex rate which is further accelerated due to presence of interaction of enzymatic activity and oxidation during prooxidant, i.e. NaCl; unlike some of the fermented the fermentation along with bacterial production of fish products, lona ilish must be cooked before MAJUMDAR & BASU: TRADITIONAL FERMENTED FISH PRODUCT OF NORTHEAST INDIA 457

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