Spectrometric method for determination of inorganic metals (Iron, zinc, copper and mercury) in fresh and canned Thunnus tonggol

doi:10.21203/rs.3.rs-1544826/v1

Download PDF

Research Article

Spectrometric method for determination of inorganic metals (Iron, zinc, copper and mercury) in fresh and canned Thunnus tonggol

https://doi.org/10.21203/rs.3.rs-1544826/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

We evaluated the nutritional value of fresh and canned tuna based on the date of production and expiration and measured the concentration of heavy metals in samples. The twenty canned Thunnus tonggol and 5 kg of fresh Thunnus tonggol were prepared from Bahbahan market, Iran. After storage periods of 6, 9 and 11 months, concentration of heavy metals measured. The results showed that the concentration of heavy metals significantly increased in storage periods, but obtained contents were lower than the limits allowed by international standards. Due to changes in water content and analytical issues, the concentrations of heavy and toxic elements in canned tuna changed. Therefore, due to the high consumption of these products, it is desirable that appropriate control programs be provided by the competent authorities at the community level.

Fresh fish

Thunnus tonggol

Canned fish

Tuna

Heavy metals

Ash

Moisture

Tuna fish is found in tropical waters and is scattered around the world. Tuna fish is one of the most important food sources for human consumption, but it can to store large amounts of heavy metals, which is sometimes used to measure environmental pollution (Ikem and Egiebor 2005).

One of the benefits of canned food is its preservation and safety. The main steps in the canning process include cooking, cooling, packaging after adding oil or tomato sauce to cans and sterilizing (Selmi et al. 2008). To prevent the growth of thermophilic bacterial spores, it should be not stored at temperatures above 35°C. Changes in food quality during storage are due to changes in physicochemical and microbiological properties that reduce their nutritional value, taste and safety. Because of easy to use of canned fish, today the distribution and consumption of these products has been widely spread, so that in 2012, 569 million cans of canned tuna were produced by 134 production factories in the countries (Fisheries Research Institute of Iran). Because of the high consumption of this product due to the use of metal cans for packaging, this product may be contaminated (Bonyadian et al. 2012). On the other hand, due to the increasing pollution of aquatic ecosystems, there is a possibility of quality problems and pollution in this valuable food source (Cheung and Chan 1999).

Velayatzadeh and Askari (2014) investigated on the accumulation of heavy metals such as mercury, cadmium, tin, nickel, zinc and iron in canned samples of tuna in Iran. The results showed that the levels of the heavy metals of nickel, mercury, zinc and tin in canned Hoover fish were lower than those allowed by the WHO and FDA, but cadmium levels were high. In another study conducted by Velayatzadeh et al. (2010), the accumulation of heavy metals in canned tuna in the cities of Shushtar, Isfahan and Hamedan in Iran was compared. He showed that the concentrations of metals such as mercury, cadmium, tin and nickel were below the permissible levels and international standards. Rahimi et al. (2014) investigated the determination of arsenic concentration in canned tuna in Isfahan and Shahrekord in Iran. In his study, the concentration of arsenic in 60 canned tuna was measured. Arsenic concentrations in canned tuna samples were lower than the EU standard. Ghazi Khansari and Afshar (1996 (studied the concentration of heavy metals in tuna fish. Their results showed that the amount of accumulation of metals such as cadmium, arsenic, lead, mercury and tin was lower than global standards. Lashkari Moghadam et al. (2010) conducted a study on the accumulation of heavy metals in canned tuna fillets and oil and found that the amount of nickel in tuna muscle was low but its amount was high in canned fish oil. The amount of cadmium in the product was more than the standard.

Emami Khansari et al. (2002) evaluated the amount of heavy metals in canned tuna. Their results showed that the amount of metal toxins in canned tuna in Iran was less than the permitted level by FAO (2003), and will not pose a danger to consumers. The study results of Qomi Behbahani and Javaheri Baboli (2014) showed that the percentage of protein and fat in the canned fish increased compared to fresh fish (control) and the percentage of moisture decreased significantly. Naseri et al., (2011) studied the changes in fat and chemical composition under different conditions of sterilization in canned silver carp. Their results showed that the amount of fat, protein, moisture and ash in fresh silver carp was significantly different from the canned fish. In this experiment, the percentage of moisture and fat decreased during the sterilization process and the percentage of protein and ash increased.

The concentration of elements in different amounts in fish Kharo Chirocentrus nudus in Iran were as follows: Fe > Zn > Pb > Cd > Ni. Results showed that with increase fish length and weight, the amount of toxic and non-toxic elements such as Ni, Pb, Fe and Zn, except Cd, were increased significantly (Aberoumand and Baesi 2018).

Ezzatpanah et al. (2010) studied on the levels of lead and cadmium in canned yellow fin tuna. Lead and cadmium levels were lower than recorded levels by the Institute for Industrial Research and Standards and the European Union Committee. In his experiment, it was found that the lead and cadmium content was significantly reduced during the canning process, including defrosting, cooking and sterilization.

Although the consumption of some nutritious fish is high in the world, due to the bioaccumulation of lead (Pb), cadmium (Cd), mercury (Hg) and other heavy metals that enter the fish muscles from the environment, it can have adverse effects on Have human health. These three metals are considered as one of the most important pollutants in the aquatic environment of fish, which is due to toxicity and accumulation in marine organisms and due to high durability in the environment (Castro-González and Méndez-Armenta, 2008). Although heavy metals are natural pollutants in the aquatic environment, their levels have increased due to industrial activities (Sarmiento et al. 2011). Mercury is one of the most abundant toxic metals and is a particularly important element because its mineral form is biologically converted in aquatic environments and even low concentrations of metals may threaten the health of aquatic organisms and humans (Olmedo et al. 2013). The purpose of this study was to evaluate the nutritional value and the heavy metals in canned tuna during 6, 9 and 11 months storage to determine the best time to consume canned fish.

Preparation of samples

This research has been done at 2021in the fisheries laboratory of Khatam Alanbia University of Technology in Behbahan. To prepare the samples, 15 canned tuna and 5 kg of fresh tuna fish (Thunnus tonggol) were purchased from Behbahan city market. The tuna were placed in completely clean plastic bags. After transferring the samples to the fisheries laboratory, all samples were washed thoroughly with distilled water to remove viscous substances and heavy metals adsorbent particles from the fish's body surface. First, all laboratory dishes are washed with detergent and then the dishes are placed in nitric acid for 24 h which thoroughly cleaned. Finally, it was washed with distilled water and then dried. First, the head, tail and internal organs of the fish were removed with a knife, and then the muscle fillets was separated and transferred to pre-cleaned containers.

Fresh fish and canned fish after 6, 9 and 11 months storage were transferred to laboratory located in Behbahan city, Iran for analysis of heavy metals. The heavy metals such as copper, zinc, iron, and mercury measured.

Measurement of the moisture of the fish

To measure the percentage of moisture in tuna fillets and canned fish fillets, 10 g of the sample weighed, then, it was placed in a container. The prepared samples were placed in an oven at 103 ° C until reaching a constant weight. After leaving the oven, the container were placed in a desiccator for 30 min to cool and then weighed (AOAC 2005). ). Moisture percentage was determined using the following equation:

Percentage of dried matter = (weight of dried sample / initial weight of sample) × 100

Percentage of wet matter - Percentage of dried matter= Percentage of moisture

Measurement of ash percentage

An electric furnace was used to determine the percentage of ash in the samples. The 10 g of the samples already dried in the oven were placed in a container, then placed in an electric oven at 500 ° C for 12 hr. The container was placed in a desiccator for 30 min to cool the samples (AOAC, 2005). The amount of gray sample remaining in the container was the amount of sample ash, which is obtained based on the following equation:

Percentage of ash = (weight of ash/initial weight of sample) × 100

Measurement of heavy metals

In order to chemically digest and measurement of concentration of heavy metals after transferring the samples to the laboratory, all samples were placed in an oven at 65 °C for 150 min until they reached a constant weight. Dry method was used to digest the samples. The 0.5 g of the weighed sample was placed into a 250 ml flask and 25 ml of concentrated sulfuric acid, 20 ml of 7 M nitric acid and 1 ml of 2% sodium molybdate solution were added. For uniform boiling of the solution, several welding stones were placed in a balloon. After cooling, 20 ml of a mixture of concentrated nitric acid and concentrated perchloric acid in a ratio of 1: 1 was added to the sample from the top of the refrigerant. The mixture heated until the white vapors of the acid have completely disappeared. Slowly 10 ml distilled water add to the cooled mixture while the balloon is rotating. A completely clear solution is obtained by heating. After cooling, this solution was transferred to a 100 ml balloon and until it reached volume (Kalay and Bevis 2003; Eboh et al. 2006). Heavy metals were measured by atomic absorption using Perkin Elmer 4100. To measure heavy metals, first to 10 ml of the digested solution, 5 ml of 5% ammonium pyrrolidine carbamate solution was added and then the sample was shaken by a shaker for 20 min until the elements were complexed in metallic organic form in solution. Then 2 ml of methyl isobutyl ketone was added to the solution and mixed for 30 min. After 10 min, the samples were centrifuged at 2500 rpm and the elements were transferred to the organic phase. After adjusting the furnace and EDL system (source of cathode ray production) of the device and optimizing the atomic absorption device, the calibration curve of these elements was plotted by Win Lab 32 software with the help of their standards and the modifiers of palladium and then the concentration of heavy metals in ready solutions measured (Olowu et al. 2010).

Statistical analysis of data

In this study, data analysis was performed using SPSS software. The mean of treatments was compared using t-test and the presence or absence of significant differences was determined at the level of 5%. Excel 2003 software was used to draw the Figures.

The percentage of ash during the 6th and 9th months after canning process was lower than the control sample. The highest percentage of ash was observed in the 11th month of the experiment. Statistical analysis of the data showed that there was a significant difference between all experimental treatments (p<0.05).

The results of measuring the concentration of heavy metals in fresh and canned tuna fillets after 6, 9 and 11 months after production are shown in the following Figures 3-6:

The Figure 3 showed that the iron concentration in canned fish in the 6th month of the experiment was higher than other experimental samples. The lowest content of iron was observed in the control sample. The results showed a significant difference between all experimental treatments (p<0.05).

The results of present study in Figure 4 showed there was a significant difference between the concentration of zinc in all experimental treatments (p<0.05). The highest was observed in the 9th month with a concentration of 10.83 (mg / kg) and the lowest was observed in the 11th month of the experiment with a concentration of 5.73 (mg / kg).

The results of the experiment in Figure 5 showed that the concentration of copper in canned tuna fillets over time significantly increased (p<0.05). The concentration of this element in the control treatment was higher than the 6th month of the experiment, but it found significantly lower than other experimental treatments. The highest copper content was observed in canned fish in the 11th month of the experiment (p<0.05).

According to the following Figure 6, it can be stated that the concentration of mercury in the 9th and 11th months after canning comparing to the 6th month storage increased, but this increase in concentration was significantly different comparing to the other samples in control and 6 th month storage (p<0.05).

The results showed that decrease the moisture content (%52.5) in the control treatment to %50.33 in the 9-month storage treatment led to an increase in fat content from %14.91 in the control to %18.1 and a decrease ash content from %1.11 in the control to %0. 63 in treatment 9 months storage.

The concentrations of iron, copper and mercury in the control treatment from 11.03, 7.11, 1.71, 0.03 mg / kg, respectively, increased to 22.06, 10.83, 2.76 and 0.04 mg / kg for 9 months storage treatment. This indicated that the remaining elements in the ash of the samples should be reduced after 9 months of storage.

The comparison the moisture contents in treatments of control and 11 and 6 months of storage, shown that because the amount of moisture has increased, the amount of ash has also increased, while the comparison of moisture in treatments of control and 9 months of storage showed that because moisture content was low, the ash content had also been decreased. The among the tested elements, the amounts of iron and zinc in the 6-month treatment had increased, but the amount of copper decreased and the amount of mercury did not change.

In this study, the average concentration of mercury obtained in all samples was lower than the global standard, which was 0.5 mg /kg. Gochfeld and Burger (2004) evaluated 168 canned tuna in terms of mercury concentration. Their results showed that the average total mercury content in tuna fish was 0.456 mg/kg and they stated that the total mercury content was 25% higher than the world standard. The maximum concentration of mercury obtained in their report was 0.956 mg/kg. Emami Khansari et al. (2002) stated that the amount of mercury in a sample of canned food investigated in Iran was less than the standard. Although in the present study, the concentration of mercury in canned tuna increased over time, but its amount was lower than the values of international standards, and obtained results of present study were in line with the results obtained from the study of other researchers.

In another study, the concentration of mercury in the analyzed canned fish was 146.65 ppb, which was lower than the global standards of EPA and FDA, which stated that the permissible amount was 1 μg per g (Salar Amoli and Isfahani 2010) which was consistent with the results of this study. Research on the concentration of heavy metals in canned tuna has results with different yield. Accumulation of heavy metals in fish muscle varies according to ecological and biological conditions as well as metabolic activities of fish (Canli and Atli 2002). Study of Ikem and Egiebor (2005) showed, the concentration of copper metal in the analyzed canned fish was less than the MAFF standard, which was consistent with the results of present study.

Velayatzadeh et al. (2010) investigated the heavy metals in some canned tuna in Iran. Their results showed that the highest amount of iron was 7.63 ± 0.04 mg and 5.36 ± 0.82 mg /kg and the lowest amount of iron was 4.29 ± 0.45 and 2.84 ± 0.42 mg /kg. In the present study, the concentrations of zinc and iron in canned fish showed a significant increase comparing to the fresh samples. Zinc accumulates mainly in the bones and skin, but is also found in significant amounts in the liver, gills and kidneys (Ismaili Sari 2002). The place of absorption and the mechanism of its transfer to the fish body depends on factors such as the chemical form of the metal (ionic or its salts).

The canning process can change the concentration of heavy metals in the product. Atta, El-Sebaie et al. (1993) reported that the concentration of some heavy metals decreased during the cooking and frying process. A study by Ezzatpanah et al. (2010) found showed that canning steps, including defrosting, baking, and sterilization, significantly reduced the concentration of heavy metals. In a recent study, the copper content in canned tuna in the 6th month of the experiment and the amount of zinc in the 11th month of the experiment was significantly reduced comparing to the fresh sample (p<0.05).

Iron content had the highest among other elements measured in fresh and canned tuna fillets, while mercury was the lowest concentration in the samples. These findings were consistent with other researchers' findings which the element iron had the highest concentration in different organs of the fish (Mahboob et al. 2016), which was in agreed with present study results.

According to study results of Celik and Oehlenschlager (2007), the lowest and highest levels of zinc in canned fish tested in Turkey were in the range of 33.8 - 556 μg/g. The level of this element in Black Sea fish samples, Turkey, was in the range of 52.9-40.32 μg/g (Tuzen 2003). One of the reasons for the different amounts of heavy metals in canned fish in different countries was the difference in the environmental conditions of ecosystems and the type of fish species.

The high slightly content of metals in Iranian the canned fish in this study may be due to environmental pollution and raw materials or due to secondary pollution due to improper handling of raw materials, containers and processing steps on land and / or at sea.

The concentrations of the heavy metals iron, zinc, copper and mercury in canned tuna fish were higher than in fresh tuna fillets, but because that these amounts were less than the permitted levels and international standards, its limited consumption will not be harmful for human consumption. On the other hand, due to the accumulation and transfer of these metals to the human body and its destructive effects on health, we must find a way to minimize the concentration of these metals in produced products. Because of water content and analytical issues changed, the concentrations of heavy and toxic elements changed in canned tuna fish. Therefore, because these products are widely consumed, it is desirable that appropriate control programs be presented by the competent authorities at the community level. In addition, continuous monitoring on mercury concentrations in tuna products is essential for food safety.

- Ethical Approval and Consent to participate

Not applicable

- Consent for publication

Not applicable

- Availability of data and materials

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

- Competing interests

The authors declare that they have no conflicts of interest.

- Funding

This work supported by Behbahan Khatam Alanbia University of Technology.

- Authors' contributions

FB analyzed samples in laboratory. AA performed the design examination of the project and was a major contributor in edit the manuscript and was supervisor.

- Acknowledgements

The authors thanks to Dean of Behbahan Khatam Alanbia University of Technology for supporting this research work.

- Authors' information

Not applicable.

Ikem A, Egiebor NO. (2005). Assessment of trace elements in canned fishes (mackerel, tuna, salmon, sardines and herrings) marketed in Georgia and Alabama (USA). J of Food Comp and Anal 18(8), 771-787. https://doi.org/10.1016/j.jfca.2004.11.002.
Selmi S, Monser L, Sadok S. (2008). The influence of local canning process and storage on pelagic fish from Tunisia: fatty acid profiles and quality indicators. J of Food Process and Preserv 32(3): 443-457. https://doi.org/10.1111/j.1745-4549.2008.00189.x.
Bonyadian M, Moshtaghi H, Nematellahi A, Naghavi Z. (2012). Investigation of heavy metals of lead, tin, copper and cadmium in canned fish produced in Iran. J of Food Sci and Technol 27.
Cheung RY, Chan KM. (1999). Metal concentrations in tissues of rabbitfish (Siganus oramin) collected from Tolo Harbour and Victoria Harbour in Hong Kong. Marine Pollu Bull 39(1-12), 234-238. https://doi.org/10.1016/S0025-326X(98)00207-0.
Velayatzadeh M, Askari Sari A, (2014). Accumulation of heavy metals mercury, cadmium, tin, nickel, zinc and iron in canned tuna samples in Khuzestan province. J of Food Hygiene, 4( 3,15): 80-33.
Velayatzadeh M, Askari Sari A, Beheshti M, Hosseini M, Mahjoub S, (2010). Investigation and comparison of accumulation of heavy metals in canned tuna in Shushtar, Isfahan and Hamedan. J of Marine Biol 2(1): 74-71.
Rahimi A, Fadaei Fard F, Karimi M, Shakarian A, Garshasbi Sh. (2014). Determination of arsenic concentration in canned tuna supplied in Isfahan and Shahrekord. J of Fisher Islamic Azad Uni, Azadshahr Branch, 8 (1): 42-37.
Ghazi Khansari M, Afshar M. (1996). Determination of heavy metals (lead, cadmium and zinc) in the waters of the Persian Gulf. Seminar of Iranian Toxicology and Poison Association, School of Medicine, Tehran University of Medical Sciences, Iran.
Lashkari Moghadam N, Rabbani M, Ahmadi Panahi H, (2010). Investigation of heavy metals (zinc, cobalt, nickel and cadmium) in canned tuna and its oil. J of Marine Sci and Technol Res 3(2): 84-78.
Emami Khansari F, Ghazi Khansari M, Abdollahi M, (2002). Investigation of heavy metals in canned tuna. J of the School of Heal and the Ins of Heal Res, 1 (3): 8-1.
Food and Agricultural Organization (FAO). (2003). (.Heavy Metal Regulations–Faolex. Legal Notice. No 66.
Qomi Behbahani, Javaheri Baboli M. (2014).Comparison of the effect of fillers on some quality indicators of canned mead (Liza klunzingeri). J of Fisher 67(3): 393-403.
Naseri IM, Rezaei M, Moieni S, Hosseini H, Eskandari S. (2011). Effects of Different Filling Media on the Oxidation and Lipid Quality of Canned Silver Carp (Hypophthalmichthys molitrix). Int J of Food Sci and Technol 46, 1149–1156. https://doi.org/10.1111/J.1365-2621.2011.02608.X.
Aberoumand A. Baesi F. (2018). Studies on relationship between body length, weight and elements contents in fish Chirocentrus Nudusswainson (1839) In Iran. Potravinarstvo Slovak J. of Food Sci. 12, 1, 756-761doi:https://doi.org/10.5219/987.
Ezzatpanah H, Ganjavi M, Givianrad MH, Shams A. (2010). Effect of canned tuna fish processing steps on lead and cadmium of Iranian tuna fish. J of Food Chem 118: 525–528. https://doi.org/10.1016/j.foodchem.2009.05.018.
Castro-González MI, Méndez-Armenta M. (2008). Heavy metals: Implications associated to fish consumption. Environ Toxicol Pharmacol 26 , 263-271. https://doi.org/ 10/cjxr78.
Sarmiento AM, DelValls A, Nieto JM, Salamanca MJ, Caraballo MA. (2011). Toxicity and potential risk assessment of a river polluted by acid mine drainage in the Iberian Pyrite Belt (SW Spain). Sci Total Environ 409: 4763-4771. https://doi.org/10/dxxvsh.
Olmedo P, Pla A, Hernández AF, Barbier F, Ayouni L, Gil F. (2013). Determination of toxic elements (mercury, cadmium, lead, tin and arsenic) in fish and shellfish samples. Risk assessment for the consumers. Environ Int 59: 63-72. https://doi.org/10/f5cwfd.
AOAC Association of Official Analytical Chemists. (2005). International. Official methods of analysis. 18th ed. Maryland: AOAC International.
Kalay G, Bevis CR. (2003). Structure and physical property relationships in processed polybutene‐1. J of Appl Polymer Sci 88(3): 814-824. https://doi.org/10.1002/app.11639.
Eboh L, Mepba HD, Ekpo MB. (2006). Heavy metal contaminants and processing effects on the composition, storage stability and fatty acid profiles of five common commercially available fish species in Oron Local Government, Nigeria. Food Chem 97(3), 490-497. https://doi.org/10.1016/j.foodchem.2005.05.041.
Olowu RA, Ayejuyo OO, Adewuyi GO, Adejoro IA, Denloye AAB, Babatunde AO, Ogundajo, AL. (2010). Determination of heavy metals in fish tissues, water and sediment from Epe and Badagry Lagoons, Lagos, Nigeria. E-J of Chem 7(1): 215-221. https://doi.org/10.1155/2010/676434.
Gochfeld M, Burger J. (2004). Mercury in canned tuna: white versus light and temporal variation. Environ Res 96(3), 239-249. https://doi.org/10.1016/j.envres.2003.12.001.
Salar Amoli J, Ali Isfahani I. (2010). Determination of total mercury and the effect of reducing agent and sample weight on it in tuna cans by hydride generator-atomic absorption method (HG-AAS). J of Vet Res 63 (5): 331-335.
Canli M, Atli G. (2002).The relationships between heavy metal (Cd, Cr, Cu, Fe, Pb, Zn) levels and the size of six Mediterranean fish species. Environ pollu. 121(1), 129-136. https://doi.org/10.1016/s0269-7491(02)00194-x.
Ismaili Sari AS. (2002). Pollutants, health and standard in the environment, Tehran, Naghsh Mehr Publications, PP.184-189.
Atta MB, El-Sebaie LA, Noaman MA, Kassab HE. (1993). The effect of cooking on the content of heavy metals in fish (Tilapia nilotica). Food Chem 58(1-2), 1-4. https://doi.org/10.1016/0308-8146(95)00205-7.
Mahboob S, Kausar S, Jabeen F, Sultana S, Sultana T, Al-Ghanim KA, Ahmed Z. (2016). Effect of heavy metals on liver, kidney, gills and muscles of Cyprinus carpio and Wallago attu inhabited in the Indus. Brazilian Arch of Biol and Technol 59. https://doi.org/10.1590/1678-4324-2016150275.
Celik U, Oehlenschläger J. (2007).High contents of cadmium, lead, zinc and copper in popular fishery products sold in Turkish supermarkets. Food Cont 18(3), 258-261.
Tuzen M. (2003). Determination of heavy metals in fish samples of the middle Black Sea (Turkey) by graphite furnace atomic absorption spectrometry. Food Chem 80(1): 119-123. https://doi.org/10.1016/S0308-8146(02)00264-9.

No competing interests reported.

Download PDF

Version 1

posted

You are reading this latest preprint version

Spectrometric method for determination of inorganic metals (Iron, zinc, copper and mercury) in fresh and canned Thunnus tonggol

Status:

Version 1

Abstract

Figures

Introduction

Materials And Methods

Results and Discussion

Conclusions

Declarations

References

Additional Declarations

Status:

Version 1