Authored by Adel A El Lahamy*
Abstract
Fish and fish products are subject to enzymatic, microbiological and chemical changes during fish processing. Canned fish products stable at ambient temperature, have long shelf life and in consequence are eminently suitable for world-wide distribution. Therefore, this study aimed to conclude the alterations in proximate chemical composition, Quality characteristics, nutritional quality and microbiological safety of fish during canning process. Also following changes in these parameters during storage period of canned fish.
Keywords: Canning process; Chemical composition; Storage period
Introduction
Canning is a well-established and traditional means of providing food which is stable at ambient temperatures, has long shelf life and in consequence is eminently suitable for world-wide distribution. Canned fish is therefore exported from countries all over the world into the consumer markets. The manufacturing of canned fish has provided, and continues to provide much-needed employment, individual incomes and the means for foreign currency exchange for developing countries, particularly in Southeast Asia, South America and the Indian Ocean. [1] Canned fishery products are formally canned in vegetable oils and now available in water packs. Preservation methods such as freezing, and canning are technologies that used basically due to cost and non-availability of equipment and cold storage system [2]. The advantages of canned food are such as their preservation, safety and convenience. The major steps in canning process include cooking, cooling, packing with a covering oil or tomato sauce in sealed cans and sterilized to achieve commercial sterilization by the heat. Oxidation of lipids and formation of nitrogenous compounds can occur during the cooling step of fish cooking [3]. during storage temperature (above 35°C) must be avoided to prevent the growth of thermophilic bacterial spores. Changes in the food quality during storage period result from a change in physicochemical and microbiological properties that decrease their nutritional value, palatability, and safety.
Chemical Composition
Slabyj and Carpenter [4] stated that raw mussel meat contained 81.2% moisture, 3.29% protein, 0.81% lipid, 0.41% ash, and 0.75% carbohydrate, steamed mussel meat contained 74.6% moisture, 2.73% protein, 0.62% lipid, 0.24% ash, and 0.32% carbohydrate, and canned mussel meat contained 75.7% moisture, 2.90% protein, 0.72% lipid, 0.27% ash, and 0.20% carbohydrate. El-Sherif (2001) [5] stated that the moisture contents of shrimp canned with vegetables and those canned with tomato sauce were lower by 12.6 and 10.8% respectively as compared with moisture content of raw shrimp. Also, he found that protein content in shrimp and found that protein contents of raw shrimp, samples canned with vegeta-bles and samples canned with tomato sauce were 76.90, 60.85 and 68.11 (on dry weight basis), respectively. These values indicated that heat treatments applied in canning process resulted in losses of protein which were accounted by 20.9 and 11.4 in samples canned with vegetables and tomato sauce respectively. Chemical analysis of canned shrimp showed that crud fat, crud ash and carbohydrate content were higher than of raw shrimp [5]. The chemical composition of smoked mussels of (Mytilus galloprovincialis L) were 20.4±0.45, 4.9, 1.30, 2.4±0.02 and 69.4±0.23 for Protein, lipid, ash and moisture respectively. After caning process these values changed to 12.7±0.46, 8.1±0.14, 3.1±0.14 and 70.2±0.62 for Protein, lipid, ash and moisture respectively [6]. Also he reported that chemical composition of mussels (Mytilus galloprovincialis L) were 17.3±0.04, 4.0±0.28, 1.8±0.19 and 73.0±0.07, after caning process these values changed to 12.2±0.47, 10.6±0.57 2.8±0.01 71.1±0.29 for Protein, lipid, ash and moisture, respectively. Shakila, et al., (2005) [7] have observed a reduction of 6% moisture content in cooked tuna. Also, Garcia-Arias et al., (2003) [8] have reported that moisture content decreased and fat content increased in cooked fish fillets. Selmi, et al. (2008) [3] the lipid contents found in tuna (Thunnus thynnus) and sardine (Sardina pilchardus) contents dropped significantly (P<0.05) after the caning process. In cooked tuna, the moisture content decreased significantly (p<0.05) with an increase in the duration of heat process giving up to 16% reduction [9]. Canning process reduced the protein content for Orcynopsis unicolor, But, increased in protein content for Euthynnus affinis. El-Dengawy, et al. (2012) [10] determined the chemical composition of Sixteen samples of canned fish products imported (canned tuna, canned sardine, canned Mackerel) and observed that moisture percentages in all canned fish samples ranged between 52.41±0.035 to 78.53±0.142 %. It could be observed that all canned fish samples had high values of water activity (0.990-0.999). Meanwhile, NaCl content ranged between 0.13±0.000 to 1.20±0.042%. Czerner, et al. (2015) [11] determined that the chemical composition of fresh anchovy were 77.65±0.67, 16.24±0.82, 4.25±0.09 and 1.16±0.06 for moisture content, protein content, lipid content and ash content respectively. In canned fish, chemical composition were 64.82±0.06, 26.74±0.74, 6.23±0.38 and 2.21±0.01 respectively. Sajib (2015) [12] Studied the effect of canning process on the chemical composition of chela (Laubuka dadiburjori) and determined that moisture content, protein content, lipid content, ash content and carbohydrate content of fresh fish were 76.56±1.62, 13.74±1.22, 4.25±0.85, 2.37±0.56 and 1.41±0.79 respectively. After canning process these values changed to 67.15±1.69, 16.68±0.88, 5.46±0.34, 8.15±0.83 and 1.35±0.07 for Moisture, Protein, Lipid, Ash t and Carbohydrate respectively.
Fatma Arfat (1994) [13] found that the moisture, sodium chloride and protein contents of canned sardine and mackerel were decreased after 24 months storage at room temperature while, total lipids contents was increases. Ghaly (1995) [14] pointed out that chemical composition of canned shrimp was affected by storage at room temperature for 6 months and the kind of filling medium. Moreover, moisture, protein and carbohydrates were decreased while, fat and ash were increased in canned bosr and shrimp packed by dry method. On the other hand the moisture, fat and ash contents were increased. Abd El-Ghafour (1999) [15] found that moisture contents of Tilapia fish fillets slightly decreased while crude protein contents was considerably reduced but crude fat and ash contents were progressively and gradually increased during storage of ambient temperature. Ibrahim (1999) [16] mentioned that moisture, protein and fat contents of canned sardine showed a gradual decreasing as a period of storage at room temperature extended up to 12 months while, ash and salt contents showed a noticed increase. The chemical composition of canned chela (Laubuka dadiburjori) fish were 76.56±1.62, 13.74±1.22, 4.25±0.85, 2.37±0.56 and 1.41±0.79 at zero time of storage period. After 30 day of storage period these values changed to 68.13±2.06, 15.15±0.95, 5.51±0.56, 10.43±0.91 and 1.36±0.09. At the end of storage 60 days these values were 68.88±1.89, 15.62±0.45, 5.96±0.48, 12.60±1.12 and 1.39±0.07 for moisture content, protein content, lipid content, ash content and carbohydrate content respectively [12].
Quality Characteristics
Total volatile basic nitrogen (TVB-N) and Trimethyleamin (TMA-N)
TMAO can be degraded during the thermal processing to disagreeable molecules such as TMA and DMA [5,17]. The cooking process had no significant effect on the TVB-N levels (P<0.05), while TMA-N levels in sardine increased to reach 6.32 mg/100g [3]. El-Dengawy, et al. (2012) [10] determined the quality characteristics in Sixteen samples of canned fish products imported (canned tuna, canned sardine, canned Mackerel) and observed that TVN values in canned fish samples ranged between 7.01±0.254 mg N/100g sample to18.04±0.593 mg N/100g sample. The TVB-N in fresh chela (Laubuka dadiburjori) fish recorded 7.10 mg N/100g, these values increased to 15.50 mg N/100 g after caning process [12].
Increasing the total volatile basic nitrogen was attributed to the degradation of nitrogenous compounds resulting in an increase in both trimethylamine nitrogen (TMAN) and ammonia nitrogen (NH3N) which were considered the principle fractions of the TVBN [13]. The total volatile nitrogen contents of canned shrimp and bosr packed by dry method and in 3% salt solution, slightly increased during storage at ambient temperature for 6 months [14]. Abd El-Ghafour (1999) [15] recorded a gradual increase in the TVBN content of canned Tilapia fish fillets products as the storage period was extended. At the end of 12 months storage, samples steamed and canned in oil or tomato sauce showed an increasing of TVBN determined by 15.58 and 17.05% respectively while, the increasing rates were 18.71 and 20.61% in samples fried and canned in the same filling media respectively. Fatma Arfat (1994) [13] observed a gradual increase in TMA contents of canned mackerel and sardine samples as the time of storage at ambient temperature was extend ed which was attributed to tri-methyl nitrogen oxide that natural present in fish tissue which chemically reduced by SH group existing in fish protein or by zinc present in C-Enamle used for varnishing the cans. Ibrahim (1999) [16] found that the highest increased observed in TMAN content of sardine during storage was found in samples canned with sauce comparing with those packed in oil or spices. The total volatile basic nitrogen of canned sardine packed in different media gradually increased as the period of storage at room temperature was progressed [16]. In the first period of storage (3 months), TVB-N and TMA-N values increased significantly to attain 23.85 and 18.42 mg/100 g, and 7.95 and 8.11 mg/100 g in sardine and tuna, respectively, and remained statistically constant (P<0.05) until the end of the storage period [3]. The TVB-N values of canned chela (Laubuka dadiburjori) fish was 15.50 mg N/100 g, at zero time of storage period. It increased up to 17.68 mg N/100 g after 30 days. After that it continued to increase to 21.95 mg N/100 g after 60 days of storage period [12].
Thiobarbituric acid (TBA) and Peroxide value (PV)
Primary (peroxide value; conjugated dienes) and secondary (TBA and carbonyl values) lipid oxidation detections did not afford accurate methods for testing quality differences in canned products [18]. Chia, et al. (1983) [19] reported that canning process of rainbow trout pollok and shrimp resulted in reduction of thio-barbituric acid by about 50% of its initial value in the raw materials. The evaporation of water and loss of juiciness during cooking might have also contributed to an increase in TBA-RS values after cooking [20]. Koizumi, et al. (1987) [21] have also reported that TBA-RS values increased during cooking of fish at 100°C for 30 min, but they were below 1 μg of malonaldehyde/g of fat. Thio-barbituric acid determined as malon aldhyde slightly increased from 0.40 mg/kg of raw shrimp to 0.44-0.48 mg/kg of the canned samples. This could be attributed to slight oxidation of unsaturated fatty acids found in shrimp during heat treatment of canning process [5]. El-Dengawy, et al. (2012) [10] determined the quality characteristics in Sixteen samples of canned fish products imported (canned tuna, canned sardine, canned Mackerel) and observed that acid value of canned fish samples had the highest value of AV being 20.39±0.000 mg KOH/g oil in CM.
It is well-known that the quality of canned products has a very close relationship with their lipid content and composition. Canned fishery products are especially susceptible to flavor and other changes due to the high levels of polyunsaturated fatty acids [22]. Ghaly (1995) [14] observed a gradual increase in TBA value of canned Suez Shrimp and elongated boor samples as the period of storage at ambient temperature was prolonged. Ibrahim (1999) [16] who noticed that TBA values of canned sardine products were gradually decreased as storage period extended and samples canned with sauce showed the lowest TBA values. Abd El-Ghafour (1999) [15] reported that a progressive increment in the TBA value of canned Tilapia fish fillets during storage at ambient temperature for 12 months. Selmi, et al. (2007) [3] studied the effect of local canning process and storage time (up to 6 months) on tuna and sardine canned in olive oil and tomato sauce and found that the PV and TBA index increased significantly in tuna.
pH
pH values of raw shrimp, canned shrimp with vegetables and canned shrimp with tomato sauce were 6.27, 6.61 and 6.48 respectively. The higher PH values observed in canned samples may by due to the formation and accumulation of some dibasic amino acid and volatile basic nitrogenous compounds such as NH3 as a result of breakdown and proteolysis of proteins during heat treatment [5]. The pH value of fresh chela chela (Laubuka dadiburjori) fish was 6.8. Drop off pH value after caning process to 5.9 in canned fish [12]. Czerner et al. (2015) [11] studied the effect of canning process on physicochemical of anchovy (Engraulis anchoita) and determined that pH value of fresh fish was 6.07, after canning slightly increased to 6.12.
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