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Assessment of Microbiological Counts and pH level of Wet-salted Fermented Fish Product (Terkin) in Sudan

O. A. O. Aidam H. M. Adam K. M. Elamin
Vol 2(1), 126-134
DOI-

A wet-salted fermented fish product (locally called Terkin) is one of the traditional fish product normally made and consumed in Sudan. This study was conducted to assess and compare total bacterial count (colony forming unit per gram) and pH level in two products collected from different factories; Jebel Al-aulia dam (Khartoum State, 45km south of Khartoum) and Wadi Halfa (lied in Sudanese-Egyptian border in the north of Sudan) in order to ensure the hygienic situation, according to the Sudanese Standards and Metrology Organization (SSMO), SDS 3767/2007. The results of this a study revealed that there is a highly significant difference (p ≤ 0.01) in pH level , highest value recorded for Jebel Al-aulia Terkin and the lower value for Wadi Halfa Terkin(6.7). The results also showed that there was no significant difference (p > 0.05) in Total Bacterial Count among treatments investigated.


Keywords : Alestes species Kass Hydrocynus species Kawara Tiger fish

Introduction

Although its meat spoils rapidly, Fish remain an important source of dietary animal protein worldwide. Fish meat that is not boiled, salted, dried, smoked or preserved in some other way will get spoiled quickly. In South-East Asia, fermentation is the most important way of preserving fish. Fermented fish pastes and sauces have a must more important place in the daily diet than salted or dried fish (Brigitte et al., 2004). During the fermentation process fish proteins are broken down in high salt concentration. The fish proteins are broken down mainly by enzymes that come from fish itself.

Brigitte et al (2004), mentioned that, fermentation methods are traditional and the fermentation process is allowed to take place by chance and is only guided by experience. No control is exerted over the fermentation. Dirar (1993) mentioned that, there are four major fermented fish products in Sudan (Fessiekh, Kejeik, Mindeshi and Terkin), the fifth, Batarikh, is prepared in the homes of a few families of Egyptian origin. The product is made by fermenting fish roe or milt and is better known in Egypt than in the Sudan.

Yokotsuka (1982) suggested that the Sudanese fish product called Fessiekh fell in the category of South-East Asia fermented fish sauces. Actually, as should have become apparent Fessiekh falls in the class of salted whole fish. The Sudanese fish product which falls in the category of sauces is the one called Terkin. It becomes clear that perhaps Terkin is even more akin to paste than to sauces. It is actually very difficult to group Terkin solely with either sauces or pastes. So it can be argued at this stage that Terkin is related to sauces such as nuoc-mam, nam-pla, and bubu as well as to pastes such as bagoong, pra-hoc and shiokara (Avery, 1952; Van, 1953; Hesseltine, 1965; Mackie et al., 1971; Steinkraus, 1978; Sundhagul and Somachai, 1978; Beddows et al., 1979; Beddows et al., 1980; Food and Agriculture Organization, 1981a Beddows, 1985).

While Fesseikh is considered of Egyptian origin, the product called Terkin is regarded locally as hundred percent Sudanese. The area famous for its production and consumption is centred around Dongola, the ancient town of upper Nubia. The region has a long tradition in fish products (Besyuni, 1979) and Terkin seems to carry a tag of antiquity.

Traditional methods of fish fermentation are three: fermentation with salting and drying, fermentation and drying without salting and fermentation with salting but without drying (FAO, 1992a).

The word “Terkin” itself is considered a Dongolawi word, and its full pronunciation, in language of Dongola (people of Dongola), is ‘Terkinj‘. Terkin is probably not the only paste in this part of Africa and the Arab world, as Hesseltine and Wang (1979) mentioned that a number of apparently similar products are known in the Near East.

The objective of this a study is to determine the Microbial load (Total Viable Count) and pH values of Wet-salted Fermented Fish product (Terkin) Produced in Jebel Al-aulia dam and Wadi Halfa Town.

Materials and Methods

General Experimental Strategy

Thirty-six Terkin (wet-salted fermented fish product) samples were purchased from Commercial Sources of two Manufacturing compasses; Elhuda Fishing Establishment located in Jebel Al-aulia dam – Khartoum State 45km south of Khartoum and Mohammed El-halfawi Manufactory located in Wadi Halfa Town, lied in Sudanese-Egyptian border in the north of Sudan and subjected to laboratory.

Jebel Al-aulia Terkin Preparation

This Terkin product is made by Elhuda Fishing Establishment. This company was located in Jebel Al-aulia Dam; it was specialized in production of Fermented Fish products namely; Fesseikh and Terkin.

In this Company, Terkin was prepared from small-young fish namely; Kass (Tiger fish; Hydrocynus spp.) and Kawara (Alestes spp.) both types of fish (Nile carp; labeo niloticus). The steps followed in order to produce Terkin was; firstly, whole unwashed fish (ungutted) were placed in plastic sac and sprayed by little salt and then closed tightly, left for 1 – 2 days until fermentation signs appeared. Then, placed in boiled-water and left till it ripened (about 5 minutes). The Product was stirred continuously through this period until completely pasted. Then cooled in steel-vessel. After cooling, 10% of salt was added. And the mixture was then transferred to burlap, placed in clean, sandy and slope place for drainage. After drainage completed, the mixture was then transferred to a large closed-plastic-barrel and let to ferment till the desired flavour was occurred (usually 3 – 4 days in summer and more time in winter). Now the product (Terkin) is ready for human use. Finally, Terkin was packed in packs “250g/pack” and sold in the markets in this form. Shelf-life of Jebel Al-aulia Terkin was 6 months. This product aged one month.

Wadi Halfa Town Terkin Preparation

Wadi Halfa Terkin was made by Mohammed El-halfawi Manufactory, which is small Manufactory located in Wadi Halfa state, near to fish plant (Smaco Investment Company – Nubian fisheries). It was specialized for production of Terkin and Fesseikh. Fish species that subjected to Terkin preparation was the same fish species as in Jebel Al-aulia Dam, but large in size, so it had large bones. According to the information obtained from processors; the large fish sizes of Kass and Kawara were collected from fishermen eviscerated and packed by little salt. Then the fishes were placed in boiled water and stirred continuously until the fish were completely pasted, and let cooled. After that, the mixture was packed in large plastic jerricans (about 30 kg/Jerrican) and finally, sealed tightly with its covers. In this stage Terkin was ready to eat. Terkin was sold in the market in this form. Shelf-life of this product was 6 months too. This product aged one month.

Sampling Method

Generally, the large representative samples were collected according to Sudanese Standards and Metrology Organization (SSMO), SDS 3767/2007.

Analytical methods

Plate Count Agar, Physiological Saline and Serial Dilution as well as Sterilization (Dry Heat, Moist heat and disinfection) were done according to description of Barrow and Feltham (1993).

Total Bacterial counts

Total bacterial counts were performed as described by International Standard, ISO No: 4832/2006.

pH values measurement

The pH values were determined with a glass-electrode of a newly calibrated Digital pH-meter (JENWAY-3015 pH-meter).

Statistical Analysis

The data was analysed by using One-way ANOVA, performed by using statistical package (IBM SPSS version 19.0) to compare pH values and Total Viable Count (TVC) in Terkin product between Jebel Al-aulia and Wadi Halfa. A P-value of <0.05 was considered indicative of a statistically significant difference.

Results

There is no significant difference (p > 0.05) in the microbial load of wet-salted fermented fish product (Terkin) of Jebel Al-aulia Dam and Wadi Halfa town, table (I). But there was a highly significant difference (p ≤ 0.01) in pH levels among treatments (II).

Discussion

Micro-organisms are important causes of food spoilage because they break down food into compounds that they can utilize. Therefore, food quality decrease as spoilage start and quality of food product relies on quantification of total number of micro-organisms. Hence, the growth of bacteria in fermented fish product may sometimes cause problems.

This study was conducted to assess and compare total bacterial count (colony forming unit per gram) and pH level in two products collected from different factories; Jebel Al-aulia dam (Khartoum State, 45km south of Khartoum) and Wadi Halfa (lied in Sudanese-Egyptian border in the north of Sudan) in order to ensure the hygienic situation, according to the Sudanese Standards and Metrology Organization (SSMO), SDS 3767/2007.

In this work, the Total Viable Count for Jebel Al-aulia Terkin as shown in table (I) was 3.5×105CFU/g of Terkin, whereas the Total Viable Count (TVC) for Wadi Halfa Terkin was 6.2×105 CFU/g. The findings showed that there was no significant difference in TVC between Terkin of two production sites. However, in spite of there was no significant difference but markedly that, Wadi Halfa Terkin recorded a higher number of total Bacterial Count than that of Jebel Al-aulia (figure 2), so this increase in TVC may be due to the difference in salt concentration as because Jebel Al-aulia Terkin contains 10% salt whereas Wadi Halfa Terkin contain no salt. and as we know, whenever salt concentration take place Total Bacterial Count expected to be low, because, increase of salt lead to increase of pH, and as we know, the preferable medium for Bacteria is neutral and semi acidic one. Dirar (1993) reported that, there was no doubt, however, that bacterial enzymes contribute to flavour development in fermented sauces and pastes. The relative importance of fish and microbial enzymes in Terkin fermentation probably depends on the procedure followed in the preparation. When the method involves an initial fermentation of the unsalted fish, for instance, the bacterial role would be expected to be pronounced as reflected in swelling of fish and the development of strong odour. These results were in agreement with Knochel and Huss (1984), who studied the microbiology of barrel salted herrings, revealed that both aerobic and anaerobic viable counts (in media containing 15 percent sodium chloride) were low, i.e. not more than 3 x 105CFU/g of fish. Also, Dirar (1993) mentioned that, there were no official reports on food poisoning caused by Terkin, but this does not negate the possibility, since that many food poisoning cases in the Sudan do not reach official channels. However, the limits for Total Bacterial Count (CFU/g) in fermented fish products were not found in Sudanese Standards and Metrology Organization (SSMO).

PH values shown in table (II) were 7.2 and 6.7 for Terkin of Jebel Al-aulia and Wadi Halfa, respectively. The results showed a highly significant difference (p ≤ 0.01) in pH between Terkin of the two production sites. However, Jebel Al-aulia Terkin recorded a higher pH value than that of Wadi Halfa (figure 2). So, this increase in pH was suggested to be due to the increase of salt concentration which in turn lead to increased pH, and since salt concentration in Jebel Al-aulia Terkin was 10%, and this percentage is higher than that of Wadi Halfa, so it’s acceptable that pH markedly differed according to the salt. The results were in agreement with Agab and Shafie (1989), who pointed-out that, pH of Fesseikh prepared from Kawara ranged from 6.5 to 6.9. Furthermore, the findings were in agreement with El-tom (1989), who figured-out that, pH of Fesseikh prepared from Kawara ranged from 6.6 to 6.9.

Table (I): Illustrates Mean ± Sd.E and Significance level of Total Viable Count (CFU/g) for Terkin of two regions:

Microorganisms Region Mean ± Sd.E Sign. Level
 

TVC

Jebel Al-aulia 3.5×105 ± 7.7×103  

NS

Wadi Halfa 6.2×105 ± 2×104

CFU/g: Colony Forming Unit per gram.

TVC: Total Viable Count.

NS: No significant Differences (p > 0.05).

Sd.E: Standard Error.

Sign: Significant.

Table (I) showed that, there was no significant difference ((p > 0.05) in Total Viable Count between Terkin of Jebel Al-aulia and that of Wadi Halfa.

Table (II): Illustrates Mean ± Sd.E and Significance level of pH levels for Terkin of two regions:

Parameter Region Mean ± Sd.E Sign. Level
pH Jebel Al-aulia 7.2 ± 0.01  

**

Wadi Halfa 6.7 ± 0.04

**: Highly Significant Differences at p ≤ 0.01.

Table (II) showed that, there was a highly significant difference ((p ≤ 0.01) in pH levels between Terkin of Jebel Al-aulia and that of Wadi Halfa.

Figure (I) showed Total Viable Count (TVC) for Terkin of Jebel Al-aulia Dam and Wadi Halfa Town.

Figure (II) showed pH values for Terkin of Jebel Al-aulia Dam and Wadi Halfa town, the differences were obvious.

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