Measurement of Nitrate Residues in Tomato and Pomegranate Fruits and their Products using the High Performance Liquid Chromatography Method.

Document Type : Complete scientific research article

Authors

1 Graduate student, Department of Food Science and Technology, Fasa Branch, Islamic Azad University, Fasa, Iran

2 Assistant Professor, Department of Food Science and Technology, Fasa Branch, Islamic Azad University, Fasa, Iran,

Abstract

Background and Objectives: Nitrate is the most important source of nitrogen in plants. The market demand has led to the use of chemical fertilizers which results in the increase of nitrate composition of the soil. Most plant organs are able to regenerate nitrate but the increase of this element in the plant causes accumulation in its parts. Excess nitrate intake in the body through food products can cause health hazards. Tomatoes and pomegranates are two products that in addition to being eaten fresh, are also used as paste, dried and juice. Therefore do to the importance of nitrate and nitrite content in the safety of these products, measurement of nitrate in these products and the effect of heating and drying processes was investigated in this study.
Materials & Methods: Tomato and pomegranate samples were gathered from the fields and gardens of Marvdasht, Arsenjan, Shiraz and Fasa in the Fars province. Nitrate levels were determined by HPLC. The correlation between nitrate content and sample size, pH and moisture content was also investigated. In the next step, the processes of cooking and preparing paste, drying and dehydration were performed on the samples and the residual nitrate concentration in the samples was re-measured.
Results: The results showed that the highest amount of nitrate content in tomatoes were from Kazeroon and Shiraz cities with the amount of 27.7 and 25 kg/mg wet weight. A correlation was observed between nitrate and pH in tomatoes. The highest concentration of nitrate concentration was in pomegranate fruit related to samples of Fasa and Shiraz regions with 6.1 and 5.8 mg/kg weight wet, respectively. There was a correlation between the volumes of pomegranate samples with nitrate. The amount of nitrate in tomato juice sample was higher than dried tomato sample, and tomato paste had the lowest amount of nitrate. There was no significant difference between the amount of nitrate in pomegranate juice and raw pomegranate, while the amount of nitrate in pomegranate paste and dried pomegranate was decreased.
Conclusion: According to the world standards, the nitrate content in all samples gathered in the Fars province were not high and in the safe limits 120 mg/kg wet weight. It was also determined that the nitrate content in the processed samples were much lower than the raw samples. Nitrate was decreased up to 86 percent in samples that were heated, such as tomato paste and pomegranate paste, while in the tomato juice samples nitrate did not show much decrease (37 percent) due to the solubility of nitrate in water. Proper farm management in fertilizing and proper processing of these products can help reduce nitrate content in products.

Keywords


  1. Malakouti, M.J., and Baba Akbar, M. 2004. The need to increase the efficiency of nitrogen fertilizers in the country, the first part of definitions and practical examples. Publication No. 425. Soil and Water Research Institute, Sana publications, Tehran, Iran. (In Persian).
  2. Laue, W., Thiemann, M., Scheibler, E., and Wiegand, K.W. 2006. Nitrates and Nitrites. Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH. Weinheim, Germany.
  3. Mosier, A., Syers, J.K., and Freney, J.R. 2013. Agriculture and the nitrogen cycle: assessing the impacts of fertilizer use on food production and the environment. Island Press. Washington DC, USA.
  4. Lorenz, O.A. 1978. Potential nitrate levels in edible plant parts. In: D.R .Nielsen and J.G. MacDonald (eds), Nitrogen in environment. 2nd ed. Academic Press. New York. p. 210-20.
  5. Malakouti, M.J. 2010. The relationship between optimal fertilizer consumption and production of healthy agricultural products. J Crop Ecophys. 4:16.133-150 (In Persian)
  6. MirMohammad-Makki, F., and Ziarati, P. 2015. Nitrate and nitrite in fresh tomato and tomato derived products Biomed pharmacol.8:1. 115-22.

7.Simion, V., Campeanu, G.H., Vasile, G., Artimon, M., Catana, L., and Negoita. M. 2008. Nitrate and nitrite accumulation in tomatoes and derived products. Roum. Biotech. Lett. 13:4. 3785-90.

8.El-Nahhal, Y. 2018. Nitrate residues in fruits, vegetables and bread samples and their health consequences. Health.10:4. 487-501.

9.Zamrik, M.A. 2013. Determination of nitrate and nitrite contents in tomato and processed tomato products in Syrian market. Int .J. Pharm Sci. Rev Res. 19:1. 1-5.

10.Brickell, C. and Joyce, D. 1996. Royal Horticultural Society: Pruning & training. Dorling & Kindersley. London, UK.

11.AOAC. 1990. Moisture in dried fruits. Official method 934.06.

12.Institute of Standards and Industrial Research of Iran. 2007. Canned Tomato Paste Features and Test Methods. ISIRI no 761. Karaj: ISIRI. (In Persian).

13.Institute of Standards and Industrial Research of Iran.1988. Fruits and Vegetables- pH measurement in products butter (margarine)- specifications. ISIRI no 4404. Karaj: ISIRI. (In Persian)

14.Rahmani, H.R. 2006. Investigation of nitrate status in soil, water and plant of Isfahan vegetable lands Environ. Sci. 11: 1. 23-34. (In Persian)

15.Pourmoghim, M., Khosh Tinat, Kh, Sadegh Maki, A., Kamili Fotud, R, Golestan, B., Pir Ali, M. 2010. Determination of nitrate content in lettuce, tomatoes and potatoes supplied in Tehran's Tareh Bar Square by HPLC method. Iranian J. Nutr. Sci. Food Tech. 5: 1. 63-70. (In Persian)

16.Pirsaheb, M., Rahimiyan, S., Pasdar, Y. 2012. The amount of nitrate and nitrite in vegetables and summer vegetables consumed in Kermanshah. J. of Kermanshah University of Medical Sciences 16: 1. 76-83. (In Persian)

17.Sadeghi, A., Almasi, A., Dehem, M., Azizi, A., and Ghayebzadeh, M. 2014. Investigation of the effect of vegetable drying and frying processes on nitrite and nitrate levels. IJHE. 7: 4. 491-498. (In Persian).

18.Asadi, S., and Fazeli, F. 2020. Nitrate contents of some highly consumed products on sale in wholesale fruit and vegetable markets in spring and winter in district 4, Tehran, Iran. Journal of school of public health and institute of public health research. 18:1. 111-120. (In Persian)

19.FAO/WHO. 2013. Nitrate (and potential endogenous formation of N-nitroso compounds) In: WHO Food Additive series World Health Organization, 50.

20.Santamaria, P. 2006. Nitrate in vegetables: toxicity, content, intake and EC regulation. J. Sci. Food Agri. 86:1. 10–17.

21.Institute of Standards and Industrial Research of Iran. 2013. Maximum nitrate residue limit in agricultural products. ISIRI no 16596. Karaj: ISIRI. (In Persian)

22.Haft Baradar, S.H., Malakoti, M.J., and Koshghoftarmanesh, A. 2018. Nitrate risk assessment in edible organs of some agricultural products of Isfahan province. Appl. Soil Res. 6:1. 1-12. (In Persian)

23.Keshavarz, M., Mazloomi, S.M., Babajafari, S. 2015.The effect of home cooking method and refrigeration processes on the level of nitrate and nitrite in spinach. JHSSS. 3:3.88-93.

24.Ghorbani Dehkordi, A., Mashayek, K., and Kamkar, B. 2015. Effect of foliar application of sucrose on nitrate and salicylic acid on yield and yield components of Super tomato plant. Res Crop Ecosyst. 2: 1.43-52 (in Persian).

25.Özdestan, Ö., and Üren, A. 2011. Effects boiling parameters on the levels of nitrate, nitrite and color values of wild Radish (Raphanus raphanistrum). GIDA. 36: 193-200.

26.Ezeagu, I.E. and Fafunso, M.A. 1995. Effect of wilting and processing on the nitrate and nitrite contents of some Nigerian leaf vegetables. Nut. and Health.10:3. 269-75.

27.Shahbazzadeghan, S., Hashemi Majd, K.V., and Shabazi, B. 2010. Measurement of nitrate concentration in vegetables and fruits supplied in Ardabil. J. of Ardabil University of Medical Sciences. 10: 1. 38-47. (In Persian)

28.Tadayon, M.S. 2004. Pomegranate nutrition technical instructions. Fars Province Agricultural and Natural Resources Research and Training Center. Soil and Water Research Institute. 2: 1-57.

29.Hosseini, M., Zamani, Z., Savaghi, G.H.R., and Tabatabai, Z. 2014. Effect of urea and manure on leaf nutrient concentration, yield and quality of pomegranate fruit. JOPPR. 20: 2.1-18. (In Persian)

30.Hord, N.G., Tang, Y., and Bryan, N.S. 2009. Food sources of nitrates and nitrites: the physiologic context for potential health benefits. Am. J. Clin, Nut. 90:1. 1-10.

31.Roelofs, E.J., Smith-Ryan, A.E., Trexler, E.T., Hirsch, K.R., and Mock, M.G. 2017. Effects of pomegranate extract on blood flow and vessel diameter after high-intensity exercise in young, healthy adults. Eur. J. Sport Sci. 17: 3. 317-325.