The current fessiekh industry is based on traditional means of production. Those practices do not seem to have been based on scientific background. This work aims at the effects of various concentrations, through three treatments, for one genus of fresh water fish, on the fessiekh product. Recent efforts have been focusing on the consolidation of positive and as much as possible the minimization of the negative results.
Chemical composition of the two species at different salt concentrations in the three treatments indicated some losses of the nutritive value when compared with fresh state. While the moisture ranged from 80.77 to 69.45% in fresh fish, it dropped to 70.17 to 67.54%D.W. in salted fish. Values for protein, fat, crude fibre and ash were18.20 to17.64%, 1.29 to 1.12%, 1.03 to 0.85% &1.7 to 1.4% in fresh fish, while in salted fish values were19.57 to 16.54%, 1.62 to0.88%, 1.32 to 0.64%, and 10.21 to 13.86% D.W. respectively
Fessiekh is not a truly indigenous Sudanese food product but it is a major fermented product from fish in the Sudan. The product has an immense popularity in Egypt and is also familiar to some regions of the Middle East, (Makie, et al 1971). Fessiekh making is a seasonal activity, which begins in October to November and ends in May ' June with a peak in February and March (Dirar 1993).
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Fessiekh is almost made from one or both of two morphologically very similar fish types. The bulk of the product is made from the fish locally called 'kawara' (Pebbly fish; Alestes Spp .Yousif 1988), the other fish is 'Kass' (Tiger fish; Hydrocynus spp). Both types of fish belong to the family Characidae (Idris, 1981).
Fessiekh of good quality should have light color, and the body of the cured fish should be partially dry but still very flexible (Dirar 1993).
The experienced producers, by tasting and other sensory means evaluate the ripening of the product. A bad quality fessiekh has characteristic strong proteolysis odour, as a sign of spoilage which is usually, due to the use of low salt concentration or to the use of already spoiled fish (El- tom, 1989).
(Dirar 1993) mentioned that fessiekh which is consumed as a source of protein, also furnished fat which is a welcomed addition to the diet in areas where there is shortage in calories. Moreover, fatty fish and fish gonads are useful sources of the fat-soluble vitamins A, D and E as well as the water-soluble vitamins, particularly thiamin and cyanocobalamin (vitamin B12).
2 MATERIALS AND METHODS:
2.1 Samples collection
Fresh fish were brought from El Mowrada fish market (Omdurman city), namely kass (Hydrocynus Spp). Fish were collocated in polyethylene bags and transported (early morning) to the Fisheries Research Center (Shaggara) where samples for chemical and microbiological analysis were immediately collected and carried out to reference labs for analyses.
Commercial fessiekh samples were obtained from El Markzi fish market south of Khartoum city centre.
During processing of fessiekh in the laboratory, samples were withdrawn at random for chemical and microbiological analysis. Sampling was carried out every five days for 7 times (about a month). The salt used in the processing of the experimental fessiekh was obtained form El Mahali market south of Khartoum chty center and also subjected to microbiological analysis.
Fresh fishes for fassiekh processing were immediately washed, eviscerated, washed again and transferred to baskets to dry up while a thin cover was placed in order to keep away insects. Then fishes were weighed to the nearest gram using a dial balance (KRUPS type 875); for the purpose of salting, as three equal groups each (about 3kg). Then the first group was subjected to addition of a total weight of salt amounting to 20% of the fish weight, the second to 25% while the third to 30%. The idea was to get a comparison of the effect of salt concentration. The procedure used was dry salting. In this method hand salting was applied by brushing of the fish surface, the inner lining of eviscerated abdominal cavity and the gills chambers. This procedure was conducted by arranging the fish layers separated by coarse salt layers inside the plastic container.
The steps applied above were repeated three times according to the seasons of the year: summer, autumn, and winter (i.e. at different temperatures, during April, August, and December respectively)
Always on Time
Marked to Standard
2.3 Chemical Analysis
Moisture, protein, fat, fiber and ash contents were determined according to AOAC (1980).
Mineral content: were determined using Atomic Absorption spectrophotometer (8625,UNI cam-UV/VIS, Germany) according to the AOAC (1980).
Hydrogen ion concentration ( pH)
One gram of fish sample added to ten ml of distilled water and put into Heraeus CHRIST for digestion of the sample and then put into the buffer tube of pH meter (JENNAY 3015) for reading.
2.4 Microbiological examination
Microbiological examination of the stored fessiekh was carried out by the following standard methods.
Total Viable Counts (TVC): using pour plate technique as described by Harrigan and MacCance (1976), dilution from
10-1 to 10-6 in. Nutrient agar and incubated at 37oC for 24 hours. Colonies were counted by making the colony on the opposite side of the plate on its position colonies counter apparatus.
Isolation and identification Of Colonies:
The samples of fish were first inoculated in nutrient broth medium and incubated at 37oC for 24 hours. In MacConkey's agar and blood agar were cultured from broth medium by streaking method and incubation at 37oC for 24 hours of the samples were done to isolate a single colony. The identification of purified isolates was carried out according to Cowan and Steel (1974).
2.5 Statistical analysis
The data obtained were analysis as a completely randomized design and the means were tested for significance using Duncan Multiple test described by SPSS soft word (Version 13).
The results obtained from this study focus mainly on a number of issues considering the effect of seasonality (i.e.temperature), salt concentration, the time of fermentation for treatment and microbiological development on the quality of the final product. The main biochemical components have been investigated and used as indicators to monitor, these effects, as given in the following.
3.1 Microbiological analysis
One genus of Nile fish was used in fessiekh making namely Kass (Hydrocynus Spp) which is common traditional and highly accepted.
Fish treated with, 20%, 25%, and 30% salt (by weight) within different seasons(summer,average temperture 37oC,Autumn, average temperture 30oC and winter average temperture 27oC)
Microbial content of fresh fish (used as raw material in fessiekh preparation): -
From the results presented in table (1) it can be seen that there are no significant differences in the microbial loads with the Hydrocynus Spp during different seasons. It could be noticed that there are substantial differences in the microbial contents of the three samples from gills, viscera & whole fish. The viscera contains much higher viable count, than either the whole fish or the gills.
Bacterial content of salted fish processed under laboratory conditions:
The microbiological examinations of Hydrocynus Spp were carried out every 5 days for a curing period of 30 days.
Table (2) shows the microbial count of Hydrocynus Spp at fermentation time during different seasons. It can be seen from the results shown in the same table the total viable counts of Hydrocynus Spp treated with different salt concentrations had higher viable counts of bacteria in winter seasons than in other two seasons(i.e.temperture37o and 30oC).
From the results presented in table (2) it could be seen that the initial total viable count was slightly higher during the first five days of the fermentation. Furthermore the count steadily decreased as the curing progressed, at different salt concentrations.
3.2 Chemical properties of fessiekh.
Chemical analysis of fresh fish (Hydrocynus Spp) is presented in table (3). The results show there seems marked differences with different seasons, especially moisture content and iron. Also the same table shows highly significant differences (P<0.05) of chemical composition of salted fish (Fessiekh) at different seasons.
The effect of different salt concentration on the chemical composition of experimentally prepared 'Fessiekh' specimens, It is shown in table (4) that there were significant differences (p<0.05) of all parameters over all experiments at different salt concentrations.
Commercial samples: -
The comparison of the viable counts of laboratory prepared samples in three treatments, shows highly significant differences at different salt concentration (table 5)
Table (6) shows the chemical composition of commercial fessiekh collected from EL-Markzi market. It appears that there are highly significant differences (P<0.05) in chemical composition of commercial salted fish during time of fermentation. There is a general trend of slight decline of chemical composition with time (days).
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From the results illustrated in table (7), there were no significant differences (P>0.05) between commercial fessiekh and experimental one, except calcium at salt concentration 20% & 30%, sodium at salt concentration 25% & 30% and potassium at different salt concentrations.
Table (1): Viable count of different parts of the fish body (fresh kass) cells/ml in different seasons.
Whole Gills Viscera
A = autumn season. S = summer season.W = winter season.
Table (2): show the viable count of bacteria throughout fermentation days at different salt concentrations
in different seasons for Hydrocynus Spp.
S A W S A W S A W
0 day 2'103 4'103 12.5'103 5'103 2'103 7.5'103 3'103 1'103 8.5'103
5 1.5'103 4.5'103 15'103 3.5'103 3'103 12.5'103 2.5'103 2'103 7.5'103
10 1'103 4.5'103 14.5'103 1'103 1'103 10'103 0.5'103 1'103 7.5'103
15 4.5'103 2.5'103 14'103 3.5'103 1'103 5'103 4.5'103 0.5'103 4.5'103
20 3.5'103 1'103 10'103 1.5'103 2'103 5'103 1.5'103 0.5'103 2.5'103
25 1.5'103 0.5'103 3.5'103 0.5'103 2'103 3.5'103 0.5'103 0.5'103 1.5'103
30 0.5'103 0.5'103 2'103 0.5'103 1'103 1.5'103 0.5'103 0.5'103 1.5'103
A = autumn season.
S = Summer season.
W = winter season
Table (3) show the effects of different seasons (three treatments) on chemical composition of salted fish.
Seasons Moisture Ash Fat Protien Fiber Na
S A W S A W S A W S A W S A W S A W
Fresh fish 69.45 80.77 76.69 1.4 1.43 1.7 1.6 1.83 1.9 19.5 18.9 19.5 1.0 1.5 1.7 174.5 177 170.1
Treated fish 67.57 70.86 68.40 12.88 11.63 10.71 1.16 1.16 1.26 16.69 17.80 19.09 0.92 0.88 0.98 529.60 515.75 469.02
P Fe Ca K pH
S A W S A W S A W S A W S A W
1.8 1.7 1.9 60 63 73 8.8 8.9 8.8 6.8 6.5 6.8 6.8 6.5 6.8
1.28 1.21 1.49 58.11 59.02 67.35 8.27 8.18 8.42 5.38 5.71 6.05 6.01 6.7 6.82
A = autumn season.
S = Summer season.
W = winter seaso
Table (4): Chemical composition%of fermented fish treated by different salt concentrations.
Species salt Moisture Ash Protein Fat Fiber Na P Fe K Ca PH
Hydrocynus Spp 20% 67.75c 10.68a 19.15a 1.31a 1.01a 316.38c 1.53a 68.24a 6.07a 8.47a 6.8a
25% 68.39b 10.71a 19.04a 1.25b 0.957a 472.10b 1.45a 66.91a 6.03a 8.42a 6.82a
30% 69.05a 10.74a 19.08a 1.22b 0.981a 618.57a 1.50a 66.90a 6.05a 8.37a 6.7a
*Values represent pooled means of triplicate determinations of dry weight.
**Values with different superscript letters vertically in column are significantly different (P<0.05).
Table (5) comparison between viable counts of bacteria in commercial fessiekh and
experimental at different concentrations with one month fermentation
Salted fish fessiekh Mean of viable count T- Test Sign
Hydrocynus spp 20% salt
Commercial fessiekh 2714.29
Hydrocynus spp 25% salt
Commercial fessiekh 1428.57
Hydrocynus spp 30% salt
** High significant differences
Table (6) chemical composition% of commercial fessiekh
Date Moisture Ash Protein Fat Fiber P Fe Ca Na K Ph
0 63.60a 10.67c 18.17a 1.47a 1.20a 1.33a 60.33a 8.00a 365.00a 5.43a 6.7ab
5 62.74a 10.93c 17.90a 1.10b 1.10a 1.30a 56.67a 8.10a 335.00b 5.17b 6.3c
10 60.42b 10.86c 17.33b 1.06b 0.93b 1.23ab 54.00a 7.90ab 329.00b 5.00bc 6.6b
15 57.30c 12.14b 17.20b 0.96bc 0.90bc 1.13bc 51.33a 7.73b 326.67b 4.90cd 6.7ab
20 54.54d 12.22b 16.67c 0.80cd 0.77cd 1.03cd 46.67a 7.43c 318.33bc 4.73de 6.8ab
25 53.58d 12.38b 16.00d 0.77d 0.70de 0.93de 45.00a 7.17d 296.00cd 4.53e 6.90a
30 44.52e 12.96a 16.10d 0.63d 0.60e 0.83e 28.33b 6.87e 283.33e 4.17f 6.89a
*Values represent pooled means of triplicate determinations of dry weight.
**Values with different superscript letters vertically in columns are significantly different (P<0.05).
Table (7) comparison between chemical composition of commercial fessiekh &experimental one
Parameters Hydrocynus spp20%
Commercial fessiekh Hydrocynus spp 25%
Commercial fessiekh Hydrocynus.spp 30%
Mean T-Test Sign Mean T-Test Sign Mean T-Test Sign
*** Very high significant difference\** High significant difference \* Significant difference\N.S Non significant difference
As has already been indicated ''Fessiekh'' is not an indigenous product in the Sudan but has probably been introduced from Egypt or Middle East countries. But subsequent to that continuous efforts pertaining to development and improvements have been made and still there are plans ahead for further development.
The practitioners along the stretch of Nile seem to carry-on the job with no scientific background, but are dependent on heritage and tradition. In this way chances for competition in regional or world markets will not definitely succeed. For this reason this research has been intended to lay the foundation based on a scientific knowledge.
4.1 Microbial contents of fessiekh (fermentation):-
From the results, the total viable count of bacteria in fresh fish used as raw material in fessiekh preparation (Hydrocynus Spp), range was 5.5x103 -3x103. The fish is more susceptible to microorganisms after catching. The number of bacterial counts may be explained on the basis of contamination of fish during catching, handling, transportation and exposure to the surrounding environment. It could be noticed that the total bacterial plate counts of the three samples from gills, viscera and whole fish were slightly different. This close range of microbial content among these fish may be due to collection and treatment in the same environment. Shewan (1977) stated that the bacterial flora on newly caught fish depends on the environment, in which it was caught rather than on the fish species.
Among the fish parts viscera contained the highest bacterial counts. High numbers of microorganisms in the gastrointestinal tract of fish, and such numbers are much higher than in the surrounding water; this indicates the presence of a favorable ecological niche for the microorganisms (FAO, 1995a). On the contrary, authors believe that the micro-flora of the gastrointestinal tract is merely a reflection of the environment and the food intake.
Microbial contents of species after salting by different concentrations were changed during time of fermentation. There was a general trend of marked increase in case of total viable counts during the first five days (average temperatures 37oC, and 30oC) and ten days at temperatures 27oC of salting. Then after that the counts begin to decrease as fermentation proceeded. This could be explained on the basis that early increase occurred while fish was wet and the provision of salt promoted the growth of halotolerant and halophilic bacteria in fish. As the fish became drier, there was a decrease in water activity and this together with the accumulated salt in the flesh, resulted in suppression of bacterial growth.
The primary objectives of high levels of salt used in fish fermentation are to select the halophilic organisms, which will affect a controlled degradative process on the organic compounds in the fish muscle to bring about the desired flavours in the product (FAO,1992).
All microbial growth is inhibited at water activity below 0.6.Halophiles grow optimally at high salt concentration but unable to grow in salt-free media. Halotolerant organisms grow best without significant amount of salt but also grow in cocentration higher than that of sea water(FAO, 1992).
The viable bacteria counts of commercial fessiekh were higher when compared to the laboratory prepared sample for the three treatments. This could be explained by the quality of fish, which were used for fessiekh and amount of salts which were added and techniques used in commercial production.
4.2 Chemical properties of fessikh:-
The results of chemical composition of fresh fish used in fessiekh preparation, namely Hydrocynus spp (Kass) are in close agreement with those reported by Mahmoud, (1977) who found that the chemical analysis of common Nile fishes were in the range of 63.29-78.19 , 14.99-22.01% ,0.36-2.50% and 0.45-1.94% for moisture, protein, fat and ash respectively. Clucas, (1981) reported a moisture content ranging from 74.7 to 80.20 % in Hydrocynus vittatus and Omer, (1984) reported a moisture content at 77.49 + 10.21, protein 17.34+ 14.21, fat 1.43+0.42 and ash 1.44+ 0.58 in Hydrocynus forskalii. The present data fall in range of the protein content, at 13.86-19.89 and fat content 0.68-2.12 given by Babiker, (1981), for Hydrocynus spp and Schilbe spp, but a moisture content of 77.64-85.01% was slightly higher than the present data. Minerals content of two species, compared to the results given by Murray and Burt, (1969) is very low specially phosphorus.
The low contents of minerals may be due to the fresh water fish and the natural variation of these constituents; it is impossible to give comparable figures (FAO, 1995a).
The water content ranged between 70.86-67.57%. These values are in agreement with Hussien, (2002) who reported a moisture content range (74.94-60.20%), for dry salted Hydrocynus forskalii. Mahmoud,(1977) reported a moisture content of (34.63%+4.94)for dry salted Hydrocynus spp, Omer, (1984) reported a moisture content at 51.79+6.76 in dry salted Hydrocynus spp.
Salama et al., (1977) found that the moisture content of salted sardine ranged from 45-53% (a product meals in Egypt). These three results are slightly low when compared with the present results; this could be attributed to the time of fermentation and amount of salt added to fish.
King et al., (1985) reported that the seven days salted product from sardine has a moisture content of 55.3%. It seems that moisture content was highly reduced in fessiekh samples than fresh state. This can be attributed to the plasmolysis occurring as action of salt applied to the fish. However, the moisture content preferences and limit of microorganisms causing spoilage of cured fish are not known.
The protein content of salted fish ''fessiekh'' ranged between 19.09-16.69. There appears to be no systematic variation in protein content after processing between experimental and commercial samples. These results are in agreement with those reported by Mahmoud, (1977) who found an average protein content of (48.66+5.36% D.W) for dry salted fish ''fessiekh'' from hydrocynus spp, and protein content of (25.88+4.43% W.W) reported by Omer, (1984). But slightly lower than protein content of 18.50-23.4% which was reported for dry salted Hydrocynus vittatus by Clucas, (1981)and 18-23% reported by Salama et al ., (1977) for salted sardine product in Egypt.
On comparing the protein content of fish before and after salting systematic differences were observed. It is evident that the protein content of processed fish has decreased after the course of salting. Loss of protein during processing is extremely variable. In our results, the losses of protein during processing of fessiekh were around 2.40%. Farr, (1965) stated that salting of fish was usually accompanied by protein losses. As water is drawn out a meal brine is formed, some protein is dissolved into the brine (clucas, 1981). Generally the quantity of protein lost depends on the exact nature and duration of the salting process and the conditions of fish when salted (Eltom, 1989).
The fat content of fessickh samples range was 1.62-0.88%. This result is very low compared to the range (6.68+2.26% W.W) which was given by Omer, (1984) for dry salted Hydrocynus spp and values of (1.48-5.97%) given by Hussien (2002). It is clear from the present results that fat content of fessiekh is lower than that of fresh fish. This may be due to the leaching out of some substances during processing. According to Tarr, (1961) fat losses during salting are usually negligible.
Also from the result of chemical composition of ''fessiekh'' ash content ranged between (10.71-12.88%). These results are in agreement with those reported by Mahmoud (1977), who found an average ash content (16.61+2.26%D.W) and (15.87+6.32%D.W); given by Omer, (1984) for dry salted Hydrocynus spp. Salma et. al., (1977) reported that the ash content in salted sardine ranged between 14-18%.
It is known that the oozing of fish juice during salting usually is accompanied with losses of minerals thus the relatively high ash content absorved in fessiekh samples can be attributed to the salt penetration into fish flesh during curing process.
Also from the results minerals content show systematic variation during time of fermentation of three treatments. This change in fish state (i.e. before and after salting) as seen from the following:-
* The higher value of sodium after salting, could be referred to added amounts of sodium chloride from salts. Thus lead to increase, as the result of moisture removed and concentration of nutrient materials. It is evident that the mineral content of salting decreased after the course of salting.
*Three salt concentrations (20, 25, and 30%) did not show marked variation in chemical composition of two species in three treatments, but concentration 20% gave best result than other two concentrations.
It is noticed that the best time for fessiekh making with good quality was during winter (temperate 27oC)
*It could be noticed that the best fessiekh product can be made from zero day until 30 days, because at that time nutritive value of fessikh gave good range of contents