- Email: [email protected]
The effect of iodine salts on lipid oxidation and changes in nutritive value of protein in stored processed meats
Meat Science 92 (2012) 139–143
Contents lists available at SciVerse ScienceDirect
Meat Science journal homepage: www.elsevier.com/locate/meatsci
The effect of iodine salts on lipid oxidation and changes in nutritive value of protein in stored processed meats Marzanna Hęś ⁎, Katarzyna Waszkowiak, Krystyna Szymandera-Buszka Department of Food Service and Catering, Poznań University of Life Sciences, 60-624 Poznań, Poland
a r t i c l e
i n f o
Article history: Received 26 January 2012 Accepted 19 April 2012 Keywords: Meat Iodine salts Lipid oxidation Lysine Methionine Protein digestibility
a b s t r a c t The aim was to assess the effect of iodine salts (KI or KIO3) on lipid oxidation as well as changes in the availability of lysine and methionine and protein digestibility in frozen-stored processed meats. Three types of iodine salt carriers were used: table salt, wheat fiber and soy protein isolate. The results showed no catalytic effect of iodine salts on lipid oxidation in stored processed meats. The application of a protein isolate and wheat fiber resulted in the inhibition of lipid oxidation in meatballs. During storage of meat products the contents of available lysine and methionine as well as protein digestibility were decreased. The utilization of wheat fiber as an iodine salt carrier had a significant effect on the reduction of lysine losses. No protective properties were found for the wheat fiber or soy protein isolate towards methionine. © 2012 Elsevier Ltd. All rights reserved.
1. Introduction Iodine deficiency disorders remain a public health problem in many countries (WHO/UNICEF/ICCIDD, 2007). The most common method to prevent iodine deficiencies, the element being an essential trace element in human metabolism, is to iodize table salt. An addition of potassium iodide or iodate to table salt guarantees an increased intake of iodine by the entire population (Longvah et al., 2012; Szybiński, 2010). In spite of the beneficial action of iodized salt it should not be consumed in amounts higher than 5 g, equivalent to 2 g of Na, a day (WHO, 2006, 2007). Excess salt in the diet may lead to arterial hypertension and atherosclerosis. Recommended limitation of table salt intake may result in a considerable reduction of effectiveness of iodine deficiency prevention (Szybiński, 2010). Thus, it is necessary to seek alternative iodine carriers. The application of high-protein and fiber preparations is being investigated. Waszkowiak and SzymanderaBuszka (2008) showed that wheat dietary fiber and soy isolate applied as carries of KI and KIO3 limited iodine changes in fortified meat products compared with iodized table salt. Oxidation processes in meat during long frozen storage are major causes of deteriorating quality. They are responsible for the degradation of aroma, taste, texture and consistency, as well as decreases of nutritive value (Gray, Gomaa, & Buckley, 1996; Pokorn , 1990). A deterioration of
nutritive value may be a consequence of interactions between lipid oxidation products and protein. Iodine possesses oxidizing properties when in the atomic form (Guerra, Silva, Vieira, de Almeida, & Soares Fontes, 2007; GutierrezCorrea, 1999). Potassium iodide and iodate in iodized table salt are changed by redox reactions during food processing and storage (Winger, König, & House, 2008). Table salt can also affect lipid oxidation in meat and processed meats (O'Neill, Galvin, Morrissey, & Buckley, 1999; Rhee & Ziprin, 2001; Sakai, Munasinghe, Kashimura, Sugamoto, & Kawahara, 2004; Sallam & Samejima, 2004), mechanisms suggested to explain it include: iron ions may be displaced by sodium ions from macromolecules (e.g. myoglobin) and catalyze lipid oxidation; metal ions (particularly divalent) could contaminate table salt. Moreover, table salt has the ability to reduce the activity of antioxidant enzymes (O'Neill et al., 1999; Salminen, Estevez, Kivikari, & Heinonen, 2006). The aim of this study was to determine the effect of iodine salts (KI or KIO3) added to three carriers (i.e. table salt, a wheat fiber preparation, and a soy protein isolate) on lipid oxidation, the availability of lysine and methionine and protein digestibility in frozen-stored meat products.
2. Materials and methods 2.1. Chemicals
⁎ Corresponding author at: Department of Food Service and Catering, Poznań University of Life Sciences, ul. Wojska Polskiego 31, 60-624 Poznań, Poland. Tel.: +48 618487331; fax: +48 618487430. E-mail address: [email protected] (M. Hęś). 0309-1740/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2012.04.025
All chemicals and solvents used were of analytical grade. 2-Thiobarbituric acid, agar, octan-2-ol, sodium hydrogen carbonate, 2,4,6-trinitrobenzenesulphonic acid (picrylsulfinic acid), DL-lysine monohydrochloride, pancreatopeptidase, pepsin, trypsin, glycine, sodium nitroprusside, and DL-methionine were purchased from Sigma-Aldrich
140
M. Hęś et al. / Meat Science 92 (2012) 139–143
(Poznań, Poland). Hydrochloric acid and diethyl ether were purchased from POCh (Gliwice, Poland). 2.2. Iodination process Three types of iodine salt carriers were used: table salt (Salt Mine Solino, Inowrocław, Poland), a wheat fiber (Vitacel 400) and a soy protein isolate (Kulinaria S.A., Tychy, Poland). The iodination process of the wheat fiber and the soy protein isolate consisted of soaking in solutions of potassium iodide or iodate on Petri dishes for approx. 30 min at room temperature with limited access to light, until the solution was completely absorbed. The iodized carriers were freeze-dried. A spray mixing method (Diosady, Alberti, Mannar, & Stone, 1997) was used for table salt iodination. Ten milliliters of iodine solution (3 g KI l − 1or 3.9 g KI l − 1) was spread on 1 kg of table salt during constant blending using a Homogeniser 2094 (Foss Tecator, Sweden). The iodized table salt was freeze-dried. The amount and concentration of potassium iodide and potassium iodate used in the iodination processes were selected to meet the iodine content in iodized table salt commercially available in the Polish market, i.e. approximately 30 mg KI kg − 1 or 39 mg KIO3 kg − 1.
diethyl ether and the absorbance of the remaining yellow solution of ε-TNP-lysine was measured at 415 nm. Pure DL-lysine monohydrochloride was used as a standard. Available methionine contents were determined by chemical methods after hydrolysis (Pieniążek, Rakowska, Szkiłłądziowa, & Grabarek, 1975). The proteins were hydrolyzed with pancreatopeptidase. After hydrolysis the hydrolysate was reacted with sodium nitroprusside as described by McCarthy and Sullivan (1941) and the absorbance at 520 nm of the complex was measured (Specord 40). Pure DL-methionine was used as a standard. Lysine and methionine content was expressed as mg per 100 g of protein. Determination of protein digestibility in vitro was carried out by the method of Sheffner, Eckfeldt, and Spector (1956) with the use of pepsin and trypsin. 2.5. Statistical analysis Statistical analyses were performed with STATISTICA Version 7 (StatSoft). The analyses of variance (ANOVA) was applied as well as Tukey's multiple test (P = 0.05).
2.3. Meat product preparation and storage
3. Results and discussion
The carriers were used in the production of meatballs from ground pork. Pork (best end of neck) was ground in a meat grinder (mesh size of 3 mm) and mixed with ingredients specified by the formulation. The meat batter was divided into four portions and the following additives (% of meat batter) were blended in:
Results showed no catalyzing effect of iodine salt on lipid autooxidation processes in stored processed meats. Differences in peroxide as well as TBARS values were non-significant between samples with iodized and non-iodized salt after 60 and 105-days of storage for KI and KIO3, respectively (Tables 1 and 2). The application of soy protein isolate and a wheat fiber preparation as iodine carriers resulted in inhibition of lipid oxidation in meatballs (Tables 1 and 2). The greater effect was observed with soy protein isolate because of its inhibition against primary oxidation products (peroxides) as well as secondary ones (TBARS). The effect could have resulted from the antioxidant properties of both iodine carriers. It was found previously that a soy protein isolate could directly limit lipid oxidation by acting as an antioxidant. Its antioxidant properties in frozen pork meatballs and raw sausage were shown by Korczak, Hęś, Gramza, and Jędrusek-Golińska (2004) and Pyrcz, Hęś, Kowalski, and Korczak (2007). The results of iodine retention, carried out simultaneously (Waszkowiak & Szymandera-Buszka, 2008), showed that soy protein isolate significantly decreased iodine losses during frozen storage of steamed meatballs, particularly in products fortified with the less stable KI. It suggests that thanks to the antioxidant properties of soy
1) 2) 3) 4)
Iodized table salt (2%) Iodized wheat fiber (2%) and non-iodized table salt (2%) Iodized soy isolate (2%) and non-iodized table salt (2%) Non-iodized table salt (2%) — control sample.
The wheat fiber and soy isolate were added to the batter in the hydrated form at 1:6 and 1:3, respectively. The hydration rate of carriers was selected by sensory analysis of the products (Jędrusek-Golińska & Szymandera-Buszka, 2007). After thorough mixing of the additives (approx. 10 min) using a Homogeniser 2094, the meatballs were formed. In order to maintain uniform conditions during thermal processing, the formed meat products had similar weights (approx. 50 g) and shape (spherical). Meatballs were steamed for 16 min at 100 °C using a convection oven (CCC series, Rational, Germany) and stored (−18 °C) in polyethylene bags for 150 days. 2.4. Analytical methods The extent of lipid oxidation was determined periodically based on measurements of peroxide values by iodometry (PN-ISO 3960, 1996) and TBARS (2-thiobarbituric acid reactive substances) content by distillation method (Pikul, Leszczyński, & Kummerow, 1989). Results are expressed as mg malondialdehyde(MDA)/kg products. The effect of lipid oxidation on proteins was characterized by changes in available lysine and methionine as well as protein digestibility in vitro. Available lysine was determined by the method of Hall, Trinder, and Givens (1973). Briefly, the meat sample was ground to a very fine powder, which was suspended in an agar solution (0.1%) with 3 drops of octan-2-ol and the suspension was mixed with a sodium hydrogen carbonate solution (1 M). A solution of trinitrobenzenesulphonic acid (1%) was added. It reacted with the free epsilon-amino groups in lysine within the intact protein. Then ε-trinitrophenyllysine (ε-TNPlysine) was released by hydrolysis with hydrochloric acid. Interfering substances, such as free picric acid, were removed by extraction into
Table 1 Changes in peroxide value (meq O2/kg fat) in frozen meatballs with addition of potassium iodide or iodate carries. Storage time Kind of addition (days) Iodized soy isolate Iodized Iodized wheat fiber and non-iodized table and non-iodized table table salt salt salt
Noniodized table salt
Addition of potassium iodide carriers 1 1.20a 1.49b 60 2.12a 2.19a 105 2.89b 2.50a 150 3.27b 2.97a
1.66b 2.14a 2.38a 2.93a
1.57b 2.00a 2.99b 3.37b
Addition of potassium iodate carries 1 1.54c 0.99a 60 3.28b 3.24b 105 3.95b 3.15a 150 3.65b 2.99a
1.19b 3.15b 3.00a 3.15a
0.97a 2.59a 3.93b 3.56b
Mean values (n = 3) with different letters in the same row are significantly different (one-way ANOVA and Tukey's test, p b 0.05).
M. Hęś et al. / Meat Science 92 (2012) 139–143
141
Table 2 Changes in TBARS value (mg MDA/kg products) in frozen meatballs with addition of potassium iodide or iodate carries. Storage time Kind of addition (days) Iodized soy isolate Iodized Iodized wheat fiber and non-iodized table and non-iodized table table salt salt salt
Noniodized table salt
Addition of potassium iodide carriers 1 1.13a 1.42b 60 1.10b 1.08b 105 0.84b 0.55a 150 1.06b 1.02b
1.04a 0.71a 0.62a 0.74a
1.37b 1.16b 0.76b 0.97b
Addition of potassium iodate carries 1 2.95d 2.31c 60 1.74b 1.73b 105 1.56c 1.00a 150 3.13c 2.74b
1.38a 1.18a 1.24b 2.08a
1.81b 2.93c 1.66c 2.98c
Fig. 2. Change of available lysine content in frozen meatballs with potassium iodate carriers.
Mean values (n = 3) with different letters in the same row are significantly different (one-way ANOVA and Tukey's test, p b 0.05).
proteins both lipid and iodine salts' oxidation may be limited. Górecka, Korczak, Konieczny, Hęś, and Flaczyk (2005) and Stachowiak and Górecka (2000) described some properties of dietary fiber such as its water holding capacity and ability to bind bile acid salts and cholesterol, as well as its cation exchange capacity. These properties could have limited lipid oxidation in meat because as a result of water immobilization molecules have less potential to move and reaction is less likely, while binding of cholesterol and lipid reduces oxidation. Cation exchange may be also important for reduction of lipid oxidation, by binding metal ions, e.g. iron. During storage of steamed meatballs the content of available lysine was decreased (Figs. 1 and 2). The meatballs iodized with KI were characterized by higher contents of available lysine than those iodized with KIO3 during the entire 5-month storage period. The highest losses of lysine were found in meatballs with soy protein isolate impregnated with iodine salts. After 150-day storage meatballs with soy isolate and KI or KIO3 had losses of 51% and 63%, respectively. In samples containing table salt iodized with KI and KIO3 the availability of lysine decreased by 34% and 56%, respectively, while in the control (non-iodized salt) it was almost 50% (Figs. 1 and 2). The lowest losses of available lysine (by approx. 22%) were observed with the wheat fiber impregnated with KI. The nutritive value of protein was also assessed by monitoring of changes in available methionine (Figs. 3 and 4). Throughout the period of storage the highest, and statistically significant losses of methionine were found in the sample with table salt iodized with KIO3, amounting
Fig. 1. Change of available lysine content in frozen meatballs with potassium iodide carriers.
to 23% in relation to the initial content. In the other samples losses of methionine were non-significant. A reduction in contents of available lysine may be connected with changes occurring in the lipid fraction, leading to blocking of the ε-amino groups of protein. Losses of methionine may have been caused by oxidation reactions, which lead to the formation of methionine sulfoxide or even sulfone (Davídek, Janíček, & Pokorný, 1983). The phenomenon of blocking of active protein groups by products of lipid oxidation was investigated by Pokorný and Davídek (1979), who showed that the reactions of protein cross-linking, amino acid oxidation and the transformation of their amino groups into imino groups are initiated by hydroperoxides. In turn, hexanal, similarly to other aldehydes, may initiate protein cross-linking as well as blocking and transformation of functional groups. Aldehydes, when reacting with the sulfhydryl group of cysteine, form thioacetal; when binding with the amino group of lysine, they form Schiff bases (Esterbauer, Schaur, & Zollner, 1991; Pokorný & Davídek, 1979). The rates of the aldehyde reactions were much lower than those of the hydroperoxides. Hydroperoxides may react rapidly with proteins even at room temperature (Pokorný & Kołakowska, 2003). The five-month storage of samples with addition of iodine salts had a slight negative effect on protein digestibility. The highest and statically significant changes in digestibility were observed for samples with the wheat fiber preparation impregnated with both forms of iodine salts (6–7%) (Figs. 5 and 6). The destructive effect of lipid oxidation products on protein digestibility as well as available lysine
Fig. 3. Change of available methionine content in frozen meatballs with potassium iodide carriers.
142
M. Hęś et al. / Meat Science 92 (2012) 139–143
Fig. 4. Change of available methionine content in frozen meatballs with potassium iodate carriers.
and methionine contents in frozen pork meatballs was also found by Korczak et al. (2004) and Hęś, Korczak, and Gramza (2007).
4. Conclusion The results on iodine stability described previously (Waszkowiak & Szymandera-Buszka, 2008) showed that soy protein isolate and a wheat fiber preparation may be successfully used as carriers of iodine salts in processed meats. The alternative iodine salt carriers suggested offer potential against iodine deficiencies and at the same time makes it possible to reduce the amount of table salt consumed in the diet. The results indicated that both carriers are also be able to stabilize the nutritive value of fortified meat products, i.e. lipid and protein quality. The application of high-protein and fiber preparations as iodine carriers may have inhibited lipid oxidation (Peña-Ramos & Xiong, 2003; Saura-Calixto, 1998, 2003). Wheat fiber is recommended to produce novel and safe meat products possessing good nutritive value, both due to its probiotic attributes and protective properties against lysine losses. It offers an opportunity to develop the market of high quality food fortified with iodine.
Acknowledgment The study was financed by the Ministry of Science and Higher Education in 2006–2008, research project number N312 027 31/2058.
Fig. 5. Effect of potassium iodide carriers on reduction of protein digestibility in meatballs after a 5-month frozen storage (initial digestibility of sample is equal to 100%). Mean values with different letters (a, b, c) differ statistically between bars (pb 0.05).
Fig. 6. Effect of potassium iodate carriers on reduction of protein digestibility in meatballs after a 5-month frozen storage (initial digestibility of sample is equal to 100%). Mean values with different letters (a, b) differ statistically between bars (pb 0.05).
References Davídek, J., Janíček, G., & Pokorný, J. (1983). Chemie potravin (pp. 462–485). Praha: SNTL/ALFA. Diosady, L. L., Alberti, J. O., Mannar, M. G. V., & Stone, T. G. (1997). Stability of iodine in iodized salt used for correction of iodine-deficiency disorders. Food and Nutrition Bulletin, 18(4), 388–397. Esterbauer, H., Schaur, R. J., & Zollner, H. (1991). Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes. Free Radical Biology & Medicine, 11, 81–128. Górecka, D., Korczak, J., Konieczny, P., Hęś, M., & Flaczyk, E. (2005). Adsorption of bile acids by cereal products. Cereal Foods World, 50(4), 176–178. Gray, J. I., Gomaa, E. A., & Buckley, D. J. (1996). Oxidative quality and shelf life of meats. Meat Science, 43, 111–123. Guerra, W., Silva, H., Vieira, Mauro, de Almeida, M. V., & Soares Fontes, A. P. (2007). Synthesis and characterization of novel platinum(IV) complex from its platinum(II) analogue using molecular iodine as an oxidizing agent: An interesting synthetic route for the preparation of new platinum complexes. Química Nova, 30, 235–238. Gutierrez-Correa, J. (1999). Inactivation of myocardial dihydrolipoamide dehydrogenase by myeloperoxidase systems: Effect of hallides, nitrite and thiol compounds. Free Radical Research, 2, 105–117. Hall, R. J., Trinder, N., & Givens, D. I. (1973). Observations on the use of 2,4,6-trinitrobenzenesulphonic acid for the determination of available lysine in animal protein concentrates. Analyst, 98, 673–686. Hęś, M., Korczak, J., & Gramza, A. (2007). Changes of lipid oxidation degrees and their influence on protein nutritive value of frozen meat products. Polish Journal of Food and Nutrition Sciences, 57(3), 323–328. Jędrusek-Golińska, A., & Szymandera-Buszka, K. (2007). Consumer desirability of pork meat products with an addition of preparations being carriers of iodine. Polish Journal of Human Nutrition and Metabolism, 34(1/2), 779–782. Korczak, J., Hęś, M., Gramza, A., & Jędrusek-Golińska, A. (2004). Influence of fat oxidation on the stability of lysine and protein digestibility in frozen meat products. Electronic Journal of Polish Agricultural Universities, 7, 1–13. Longvah, T., Toteja, G. S., Bulliyya, G., Raghuvanshi, R. S., Jain, S., Rao, V., et al. (2012). Stability of added iodine in different Indian cooking processes. Food Chemistry, 130, 953–959. McCarthy, T. E., & Sullivan, M. X. (1941). A new and highly specific colorimetric test for methionine. Journal of Biological Chemistry, 141, 871–876. O'Neill, L. M., Galvin, K., Morrissey, P. A., & Buckley, D. J. (1999). Effect of carnosine, salt and dietary vitamin E on the oxidative stability of chicken meat. Meat Science, 52, 89–94. Peña-Ramos, E. A., & Xiong, Y. L. (2003). Whey and soy protein hydrolysates inhibit lipid oxidation in cooked pork patties. Meat Science, 64, 250–263. Pieniążek, D., Rakowska, M., Szkiłłądziowa, W., & Grabarek, Z. (1975). Estimation of available methionine and cysteine in proteins of food products by in vivo and in vitro methods. British Journal of Nutrition, 34, 175–190. Pikul, J., Leszczyński, E., & Kummerow, F. A. (1989). Evaluation of three modified TBA methods for measuring lipid oxidation in chicken meat. Journal of Agricultural and Food Chemistry, 37, 1309–1313. PN-ISO 3960 (1996). Animal and vegetable oils and fats. Determination of peroxide value (in Polish). Pokorn , J. (1990). Effect of lipid degradation on taste and odor of foods. Nahrung, 34, 887–897. Pokorný, J., & Davídek, J. (1979). Influence in interactions of proteins with oxidized lipids on nutrition and sensory value of food. Acta Alimentaria Polonica, 5, 87–95. Pokorný, J., & Kołakowska, A. (2003). Lipid–protein and lipid–saccharide interactions. In Z. E. Sikorski, & A. Kołakowska (Eds.), Chemical and functional properties of food lipids (pp. 346–351). New York: CRC Press. Pyrcz, J., Hęś, M., Kowalski, R., & Korczak, J. (2007). Einfluss ausgewählter antioxidantien auf die qualität von rohwurst. Fleischwirtschaft, 9, 115–118 (in German). Rhee, K. S., & Ziprin, Y. A. (2001). Pro-oxidative effects of NaCl in microbial growthcontrolled and uncontrolled beef and chicken. Meat Science, 57, 105–112.
M. Hęś et al. / Meat Science 92 (2012) 139–143 Sakai, T., Munasinghe, D. M. S., Kashimura, M., Sugamoto, K., & Kawahara, S. (2004). Effect of NaCl on lipid peroxidation-derived aldehyde, 4-hydroxy-2-nonenal formation in minced pork and beef. Meat Science, 66, 789–792. Sallam, K. I., & Samejima, K. (2004). Microbiological and chemical quality of ground beef treated with sodium lactate and sodium chloride during refrigerated storage. Lebensmittel-Wissenschaft und Technologie, 37, 865–866. Salminen, H., Estevez, M., Kivikari, R., & Heinonen, M. (2006). Inhibition of protein and lipid oxidation by rapeseed, camelina and soy meal on cooked pork meat patties. European Food Research and Technology, 4, 89–94. Saura-Calixto, F. (1998). Antioxidant dietary fibre product: A new concept and a potential food ingredient. Journal of Agricultural and Food Chemistry, 46, 4303–4306. Saura-Calixto, F. (2003). Antioxidant dietary fibre. Electronic Journal of Environmental, Agricultural and Food Chemistry, 2(1), 1–4. Sheffner, A. L., Eckfeldt, G. A., & Spector, H. (1956). The pepsin-digest-residue (PDR) amino acid index of net protein utilization. The Journal of Nutrition, 60, 105–120. Stachowiak, J., & Górecka, D. (2000). Sorption of selenium by selected cereal bran. Polish Journal of Food and Nutrition Sciences, 9(50), 4, 27–4, 30.
143
Szybiński, Z. (2010). Iodine-deficiency prophylaxis and the restriction of salt consumption — A 21st century challenge. Polish Journal of Endocrinology, 61(1), 135–140. Waszkowiak, K., & Szymandera-Buszka, K. (2008). The application of wheat fibre and soy isolate impregnated with iodine salts to fortify processed meats. Meat Science, 80, 1340–1344. WHO (2006). Report of a WHO forum and technical meeting on reducing salt intake in the population. Paris: World Health Organization. WHO (2007). Report of a WHO expert consultation on salt as a vehicle for fortification. Luxembourg: World Health Organization. WHO/UNICEF/ICCIDD (2007). Assessment of iodine deficiency disorders and monitoring their elimination: A guide for programme managers (3rd ed.). Geneva: World Health Organization. Winger, R. J., König, J., & House, D. A. (2008). Technological issues associated with iodine fortification of foods. Trends in Food Science & Technology, 19, 94–101.
Contents lists available at SciVerse ScienceDirect
Meat Science journal homepage: www.elsevier.com/locate/meatsci
The effect of iodine salts on lipid oxidation and changes in nutritive value of protein in stored processed meats Marzanna Hęś ⁎, Katarzyna Waszkowiak, Krystyna Szymandera-Buszka Department of Food Service and Catering, Poznań University of Life Sciences, 60-624 Poznań, Poland
a r t i c l e
i n f o
Article history: Received 26 January 2012 Accepted 19 April 2012 Keywords: Meat Iodine salts Lipid oxidation Lysine Methionine Protein digestibility
a b s t r a c t The aim was to assess the effect of iodine salts (KI or KIO3) on lipid oxidation as well as changes in the availability of lysine and methionine and protein digestibility in frozen-stored processed meats. Three types of iodine salt carriers were used: table salt, wheat fiber and soy protein isolate. The results showed no catalytic effect of iodine salts on lipid oxidation in stored processed meats. The application of a protein isolate and wheat fiber resulted in the inhibition of lipid oxidation in meatballs. During storage of meat products the contents of available lysine and methionine as well as protein digestibility were decreased. The utilization of wheat fiber as an iodine salt carrier had a significant effect on the reduction of lysine losses. No protective properties were found for the wheat fiber or soy protein isolate towards methionine. © 2012 Elsevier Ltd. All rights reserved.
1. Introduction Iodine deficiency disorders remain a public health problem in many countries (WHO/UNICEF/ICCIDD, 2007). The most common method to prevent iodine deficiencies, the element being an essential trace element in human metabolism, is to iodize table salt. An addition of potassium iodide or iodate to table salt guarantees an increased intake of iodine by the entire population (Longvah et al., 2012; Szybiński, 2010). In spite of the beneficial action of iodized salt it should not be consumed in amounts higher than 5 g, equivalent to 2 g of Na, a day (WHO, 2006, 2007). Excess salt in the diet may lead to arterial hypertension and atherosclerosis. Recommended limitation of table salt intake may result in a considerable reduction of effectiveness of iodine deficiency prevention (Szybiński, 2010). Thus, it is necessary to seek alternative iodine carriers. The application of high-protein and fiber preparations is being investigated. Waszkowiak and SzymanderaBuszka (2008) showed that wheat dietary fiber and soy isolate applied as carries of KI and KIO3 limited iodine changes in fortified meat products compared with iodized table salt. Oxidation processes in meat during long frozen storage are major causes of deteriorating quality. They are responsible for the degradation of aroma, taste, texture and consistency, as well as decreases of nutritive value (Gray, Gomaa, & Buckley, 1996; Pokorn , 1990). A deterioration of
nutritive value may be a consequence of interactions between lipid oxidation products and protein. Iodine possesses oxidizing properties when in the atomic form (Guerra, Silva, Vieira, de Almeida, & Soares Fontes, 2007; GutierrezCorrea, 1999). Potassium iodide and iodate in iodized table salt are changed by redox reactions during food processing and storage (Winger, König, & House, 2008). Table salt can also affect lipid oxidation in meat and processed meats (O'Neill, Galvin, Morrissey, & Buckley, 1999; Rhee & Ziprin, 2001; Sakai, Munasinghe, Kashimura, Sugamoto, & Kawahara, 2004; Sallam & Samejima, 2004), mechanisms suggested to explain it include: iron ions may be displaced by sodium ions from macromolecules (e.g. myoglobin) and catalyze lipid oxidation; metal ions (particularly divalent) could contaminate table salt. Moreover, table salt has the ability to reduce the activity of antioxidant enzymes (O'Neill et al., 1999; Salminen, Estevez, Kivikari, & Heinonen, 2006). The aim of this study was to determine the effect of iodine salts (KI or KIO3) added to three carriers (i.e. table salt, a wheat fiber preparation, and a soy protein isolate) on lipid oxidation, the availability of lysine and methionine and protein digestibility in frozen-stored meat products.
2. Materials and methods 2.1. Chemicals
⁎ Corresponding author at: Department of Food Service and Catering, Poznań University of Life Sciences, ul. Wojska Polskiego 31, 60-624 Poznań, Poland. Tel.: +48 618487331; fax: +48 618487430. E-mail address: [email protected] (M. Hęś). 0309-1740/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2012.04.025
All chemicals and solvents used were of analytical grade. 2-Thiobarbituric acid, agar, octan-2-ol, sodium hydrogen carbonate, 2,4,6-trinitrobenzenesulphonic acid (picrylsulfinic acid), DL-lysine monohydrochloride, pancreatopeptidase, pepsin, trypsin, glycine, sodium nitroprusside, and DL-methionine were purchased from Sigma-Aldrich
140
M. Hęś et al. / Meat Science 92 (2012) 139–143
(Poznań, Poland). Hydrochloric acid and diethyl ether were purchased from POCh (Gliwice, Poland). 2.2. Iodination process Three types of iodine salt carriers were used: table salt (Salt Mine Solino, Inowrocław, Poland), a wheat fiber (Vitacel 400) and a soy protein isolate (Kulinaria S.A., Tychy, Poland). The iodination process of the wheat fiber and the soy protein isolate consisted of soaking in solutions of potassium iodide or iodate on Petri dishes for approx. 30 min at room temperature with limited access to light, until the solution was completely absorbed. The iodized carriers were freeze-dried. A spray mixing method (Diosady, Alberti, Mannar, & Stone, 1997) was used for table salt iodination. Ten milliliters of iodine solution (3 g KI l − 1or 3.9 g KI l − 1) was spread on 1 kg of table salt during constant blending using a Homogeniser 2094 (Foss Tecator, Sweden). The iodized table salt was freeze-dried. The amount and concentration of potassium iodide and potassium iodate used in the iodination processes were selected to meet the iodine content in iodized table salt commercially available in the Polish market, i.e. approximately 30 mg KI kg − 1 or 39 mg KIO3 kg − 1.
diethyl ether and the absorbance of the remaining yellow solution of ε-TNP-lysine was measured at 415 nm. Pure DL-lysine monohydrochloride was used as a standard. Available methionine contents were determined by chemical methods after hydrolysis (Pieniążek, Rakowska, Szkiłłądziowa, & Grabarek, 1975). The proteins were hydrolyzed with pancreatopeptidase. After hydrolysis the hydrolysate was reacted with sodium nitroprusside as described by McCarthy and Sullivan (1941) and the absorbance at 520 nm of the complex was measured (Specord 40). Pure DL-methionine was used as a standard. Lysine and methionine content was expressed as mg per 100 g of protein. Determination of protein digestibility in vitro was carried out by the method of Sheffner, Eckfeldt, and Spector (1956) with the use of pepsin and trypsin. 2.5. Statistical analysis Statistical analyses were performed with STATISTICA Version 7 (StatSoft). The analyses of variance (ANOVA) was applied as well as Tukey's multiple test (P = 0.05).
2.3. Meat product preparation and storage
3. Results and discussion
The carriers were used in the production of meatballs from ground pork. Pork (best end of neck) was ground in a meat grinder (mesh size of 3 mm) and mixed with ingredients specified by the formulation. The meat batter was divided into four portions and the following additives (% of meat batter) were blended in:
Results showed no catalyzing effect of iodine salt on lipid autooxidation processes in stored processed meats. Differences in peroxide as well as TBARS values were non-significant between samples with iodized and non-iodized salt after 60 and 105-days of storage for KI and KIO3, respectively (Tables 1 and 2). The application of soy protein isolate and a wheat fiber preparation as iodine carriers resulted in inhibition of lipid oxidation in meatballs (Tables 1 and 2). The greater effect was observed with soy protein isolate because of its inhibition against primary oxidation products (peroxides) as well as secondary ones (TBARS). The effect could have resulted from the antioxidant properties of both iodine carriers. It was found previously that a soy protein isolate could directly limit lipid oxidation by acting as an antioxidant. Its antioxidant properties in frozen pork meatballs and raw sausage were shown by Korczak, Hęś, Gramza, and Jędrusek-Golińska (2004) and Pyrcz, Hęś, Kowalski, and Korczak (2007). The results of iodine retention, carried out simultaneously (Waszkowiak & Szymandera-Buszka, 2008), showed that soy protein isolate significantly decreased iodine losses during frozen storage of steamed meatballs, particularly in products fortified with the less stable KI. It suggests that thanks to the antioxidant properties of soy
1) 2) 3) 4)
Iodized table salt (2%) Iodized wheat fiber (2%) and non-iodized table salt (2%) Iodized soy isolate (2%) and non-iodized table salt (2%) Non-iodized table salt (2%) — control sample.
The wheat fiber and soy isolate were added to the batter in the hydrated form at 1:6 and 1:3, respectively. The hydration rate of carriers was selected by sensory analysis of the products (Jędrusek-Golińska & Szymandera-Buszka, 2007). After thorough mixing of the additives (approx. 10 min) using a Homogeniser 2094, the meatballs were formed. In order to maintain uniform conditions during thermal processing, the formed meat products had similar weights (approx. 50 g) and shape (spherical). Meatballs were steamed for 16 min at 100 °C using a convection oven (CCC series, Rational, Germany) and stored (−18 °C) in polyethylene bags for 150 days. 2.4. Analytical methods The extent of lipid oxidation was determined periodically based on measurements of peroxide values by iodometry (PN-ISO 3960, 1996) and TBARS (2-thiobarbituric acid reactive substances) content by distillation method (Pikul, Leszczyński, & Kummerow, 1989). Results are expressed as mg malondialdehyde(MDA)/kg products. The effect of lipid oxidation on proteins was characterized by changes in available lysine and methionine as well as protein digestibility in vitro. Available lysine was determined by the method of Hall, Trinder, and Givens (1973). Briefly, the meat sample was ground to a very fine powder, which was suspended in an agar solution (0.1%) with 3 drops of octan-2-ol and the suspension was mixed with a sodium hydrogen carbonate solution (1 M). A solution of trinitrobenzenesulphonic acid (1%) was added. It reacted with the free epsilon-amino groups in lysine within the intact protein. Then ε-trinitrophenyllysine (ε-TNPlysine) was released by hydrolysis with hydrochloric acid. Interfering substances, such as free picric acid, were removed by extraction into
Table 1 Changes in peroxide value (meq O2/kg fat) in frozen meatballs with addition of potassium iodide or iodate carries. Storage time Kind of addition (days) Iodized soy isolate Iodized Iodized wheat fiber and non-iodized table and non-iodized table table salt salt salt
Noniodized table salt
Addition of potassium iodide carriers 1 1.20a 1.49b 60 2.12a 2.19a 105 2.89b 2.50a 150 3.27b 2.97a
1.66b 2.14a 2.38a 2.93a
1.57b 2.00a 2.99b 3.37b
Addition of potassium iodate carries 1 1.54c 0.99a 60 3.28b 3.24b 105 3.95b 3.15a 150 3.65b 2.99a
1.19b 3.15b 3.00a 3.15a
0.97a 2.59a 3.93b 3.56b
Mean values (n = 3) with different letters in the same row are significantly different (one-way ANOVA and Tukey's test, p b 0.05).
M. Hęś et al. / Meat Science 92 (2012) 139–143
141
Table 2 Changes in TBARS value (mg MDA/kg products) in frozen meatballs with addition of potassium iodide or iodate carries. Storage time Kind of addition (days) Iodized soy isolate Iodized Iodized wheat fiber and non-iodized table and non-iodized table table salt salt salt
Noniodized table salt
Addition of potassium iodide carriers 1 1.13a 1.42b 60 1.10b 1.08b 105 0.84b 0.55a 150 1.06b 1.02b
1.04a 0.71a 0.62a 0.74a
1.37b 1.16b 0.76b 0.97b
Addition of potassium iodate carries 1 2.95d 2.31c 60 1.74b 1.73b 105 1.56c 1.00a 150 3.13c 2.74b
1.38a 1.18a 1.24b 2.08a
1.81b 2.93c 1.66c 2.98c
Fig. 2. Change of available lysine content in frozen meatballs with potassium iodate carriers.
Mean values (n = 3) with different letters in the same row are significantly different (one-way ANOVA and Tukey's test, p b 0.05).
proteins both lipid and iodine salts' oxidation may be limited. Górecka, Korczak, Konieczny, Hęś, and Flaczyk (2005) and Stachowiak and Górecka (2000) described some properties of dietary fiber such as its water holding capacity and ability to bind bile acid salts and cholesterol, as well as its cation exchange capacity. These properties could have limited lipid oxidation in meat because as a result of water immobilization molecules have less potential to move and reaction is less likely, while binding of cholesterol and lipid reduces oxidation. Cation exchange may be also important for reduction of lipid oxidation, by binding metal ions, e.g. iron. During storage of steamed meatballs the content of available lysine was decreased (Figs. 1 and 2). The meatballs iodized with KI were characterized by higher contents of available lysine than those iodized with KIO3 during the entire 5-month storage period. The highest losses of lysine were found in meatballs with soy protein isolate impregnated with iodine salts. After 150-day storage meatballs with soy isolate and KI or KIO3 had losses of 51% and 63%, respectively. In samples containing table salt iodized with KI and KIO3 the availability of lysine decreased by 34% and 56%, respectively, while in the control (non-iodized salt) it was almost 50% (Figs. 1 and 2). The lowest losses of available lysine (by approx. 22%) were observed with the wheat fiber impregnated with KI. The nutritive value of protein was also assessed by monitoring of changes in available methionine (Figs. 3 and 4). Throughout the period of storage the highest, and statistically significant losses of methionine were found in the sample with table salt iodized with KIO3, amounting
Fig. 1. Change of available lysine content in frozen meatballs with potassium iodide carriers.
to 23% in relation to the initial content. In the other samples losses of methionine were non-significant. A reduction in contents of available lysine may be connected with changes occurring in the lipid fraction, leading to blocking of the ε-amino groups of protein. Losses of methionine may have been caused by oxidation reactions, which lead to the formation of methionine sulfoxide or even sulfone (Davídek, Janíček, & Pokorný, 1983). The phenomenon of blocking of active protein groups by products of lipid oxidation was investigated by Pokorný and Davídek (1979), who showed that the reactions of protein cross-linking, amino acid oxidation and the transformation of their amino groups into imino groups are initiated by hydroperoxides. In turn, hexanal, similarly to other aldehydes, may initiate protein cross-linking as well as blocking and transformation of functional groups. Aldehydes, when reacting with the sulfhydryl group of cysteine, form thioacetal; when binding with the amino group of lysine, they form Schiff bases (Esterbauer, Schaur, & Zollner, 1991; Pokorný & Davídek, 1979). The rates of the aldehyde reactions were much lower than those of the hydroperoxides. Hydroperoxides may react rapidly with proteins even at room temperature (Pokorný & Kołakowska, 2003). The five-month storage of samples with addition of iodine salts had a slight negative effect on protein digestibility. The highest and statically significant changes in digestibility were observed for samples with the wheat fiber preparation impregnated with both forms of iodine salts (6–7%) (Figs. 5 and 6). The destructive effect of lipid oxidation products on protein digestibility as well as available lysine
Fig. 3. Change of available methionine content in frozen meatballs with potassium iodide carriers.
142
M. Hęś et al. / Meat Science 92 (2012) 139–143
Fig. 4. Change of available methionine content in frozen meatballs with potassium iodate carriers.
and methionine contents in frozen pork meatballs was also found by Korczak et al. (2004) and Hęś, Korczak, and Gramza (2007).
4. Conclusion The results on iodine stability described previously (Waszkowiak & Szymandera-Buszka, 2008) showed that soy protein isolate and a wheat fiber preparation may be successfully used as carriers of iodine salts in processed meats. The alternative iodine salt carriers suggested offer potential against iodine deficiencies and at the same time makes it possible to reduce the amount of table salt consumed in the diet. The results indicated that both carriers are also be able to stabilize the nutritive value of fortified meat products, i.e. lipid and protein quality. The application of high-protein and fiber preparations as iodine carriers may have inhibited lipid oxidation (Peña-Ramos & Xiong, 2003; Saura-Calixto, 1998, 2003). Wheat fiber is recommended to produce novel and safe meat products possessing good nutritive value, both due to its probiotic attributes and protective properties against lysine losses. It offers an opportunity to develop the market of high quality food fortified with iodine.
Acknowledgment The study was financed by the Ministry of Science and Higher Education in 2006–2008, research project number N312 027 31/2058.
Fig. 5. Effect of potassium iodide carriers on reduction of protein digestibility in meatballs after a 5-month frozen storage (initial digestibility of sample is equal to 100%). Mean values with different letters (a, b, c) differ statistically between bars (pb 0.05).
Fig. 6. Effect of potassium iodate carriers on reduction of protein digestibility in meatballs after a 5-month frozen storage (initial digestibility of sample is equal to 100%). Mean values with different letters (a, b) differ statistically between bars (pb 0.05).
References Davídek, J., Janíček, G., & Pokorný, J. (1983). Chemie potravin (pp. 462–485). Praha: SNTL/ALFA. Diosady, L. L., Alberti, J. O., Mannar, M. G. V., & Stone, T. G. (1997). Stability of iodine in iodized salt used for correction of iodine-deficiency disorders. Food and Nutrition Bulletin, 18(4), 388–397. Esterbauer, H., Schaur, R. J., & Zollner, H. (1991). Chemistry and biochemistry of 4-hydroxynonenal, malonaldehyde and related aldehydes. Free Radical Biology & Medicine, 11, 81–128. Górecka, D., Korczak, J., Konieczny, P., Hęś, M., & Flaczyk, E. (2005). Adsorption of bile acids by cereal products. Cereal Foods World, 50(4), 176–178. Gray, J. I., Gomaa, E. A., & Buckley, D. J. (1996). Oxidative quality and shelf life of meats. Meat Science, 43, 111–123. Guerra, W., Silva, H., Vieira, Mauro, de Almeida, M. V., & Soares Fontes, A. P. (2007). Synthesis and characterization of novel platinum(IV) complex from its platinum(II) analogue using molecular iodine as an oxidizing agent: An interesting synthetic route for the preparation of new platinum complexes. Química Nova, 30, 235–238. Gutierrez-Correa, J. (1999). Inactivation of myocardial dihydrolipoamide dehydrogenase by myeloperoxidase systems: Effect of hallides, nitrite and thiol compounds. Free Radical Research, 2, 105–117. Hall, R. J., Trinder, N., & Givens, D. I. (1973). Observations on the use of 2,4,6-trinitrobenzenesulphonic acid for the determination of available lysine in animal protein concentrates. Analyst, 98, 673–686. Hęś, M., Korczak, J., & Gramza, A. (2007). Changes of lipid oxidation degrees and their influence on protein nutritive value of frozen meat products. Polish Journal of Food and Nutrition Sciences, 57(3), 323–328. Jędrusek-Golińska, A., & Szymandera-Buszka, K. (2007). Consumer desirability of pork meat products with an addition of preparations being carriers of iodine. Polish Journal of Human Nutrition and Metabolism, 34(1/2), 779–782. Korczak, J., Hęś, M., Gramza, A., & Jędrusek-Golińska, A. (2004). Influence of fat oxidation on the stability of lysine and protein digestibility in frozen meat products. Electronic Journal of Polish Agricultural Universities, 7, 1–13. Longvah, T., Toteja, G. S., Bulliyya, G., Raghuvanshi, R. S., Jain, S., Rao, V., et al. (2012). Stability of added iodine in different Indian cooking processes. Food Chemistry, 130, 953–959. McCarthy, T. E., & Sullivan, M. X. (1941). A new and highly specific colorimetric test for methionine. Journal of Biological Chemistry, 141, 871–876. O'Neill, L. M., Galvin, K., Morrissey, P. A., & Buckley, D. J. (1999). Effect of carnosine, salt and dietary vitamin E on the oxidative stability of chicken meat. Meat Science, 52, 89–94. Peña-Ramos, E. A., & Xiong, Y. L. (2003). Whey and soy protein hydrolysates inhibit lipid oxidation in cooked pork patties. Meat Science, 64, 250–263. Pieniążek, D., Rakowska, M., Szkiłłądziowa, W., & Grabarek, Z. (1975). Estimation of available methionine and cysteine in proteins of food products by in vivo and in vitro methods. British Journal of Nutrition, 34, 175–190. Pikul, J., Leszczyński, E., & Kummerow, F. A. (1989). Evaluation of three modified TBA methods for measuring lipid oxidation in chicken meat. Journal of Agricultural and Food Chemistry, 37, 1309–1313. PN-ISO 3960 (1996). Animal and vegetable oils and fats. Determination of peroxide value (in Polish). Pokorn , J. (1990). Effect of lipid degradation on taste and odor of foods. Nahrung, 34, 887–897. Pokorný, J., & Davídek, J. (1979). Influence in interactions of proteins with oxidized lipids on nutrition and sensory value of food. Acta Alimentaria Polonica, 5, 87–95. Pokorný, J., & Kołakowska, A. (2003). Lipid–protein and lipid–saccharide interactions. In Z. E. Sikorski, & A. Kołakowska (Eds.), Chemical and functional properties of food lipids (pp. 346–351). New York: CRC Press. Pyrcz, J., Hęś, M., Kowalski, R., & Korczak, J. (2007). Einfluss ausgewählter antioxidantien auf die qualität von rohwurst. Fleischwirtschaft, 9, 115–118 (in German). Rhee, K. S., & Ziprin, Y. A. (2001). Pro-oxidative effects of NaCl in microbial growthcontrolled and uncontrolled beef and chicken. Meat Science, 57, 105–112.
M. Hęś et al. / Meat Science 92 (2012) 139–143 Sakai, T., Munasinghe, D. M. S., Kashimura, M., Sugamoto, K., & Kawahara, S. (2004). Effect of NaCl on lipid peroxidation-derived aldehyde, 4-hydroxy-2-nonenal formation in minced pork and beef. Meat Science, 66, 789–792. Sallam, K. I., & Samejima, K. (2004). Microbiological and chemical quality of ground beef treated with sodium lactate and sodium chloride during refrigerated storage. Lebensmittel-Wissenschaft und Technologie, 37, 865–866. Salminen, H., Estevez, M., Kivikari, R., & Heinonen, M. (2006). Inhibition of protein and lipid oxidation by rapeseed, camelina and soy meal on cooked pork meat patties. European Food Research and Technology, 4, 89–94. Saura-Calixto, F. (1998). Antioxidant dietary fibre product: A new concept and a potential food ingredient. Journal of Agricultural and Food Chemistry, 46, 4303–4306. Saura-Calixto, F. (2003). Antioxidant dietary fibre. Electronic Journal of Environmental, Agricultural and Food Chemistry, 2(1), 1–4. Sheffner, A. L., Eckfeldt, G. A., & Spector, H. (1956). The pepsin-digest-residue (PDR) amino acid index of net protein utilization. The Journal of Nutrition, 60, 105–120. Stachowiak, J., & Górecka, D. (2000). Sorption of selenium by selected cereal bran. Polish Journal of Food and Nutrition Sciences, 9(50), 4, 27–4, 30.
143
Szybiński, Z. (2010). Iodine-deficiency prophylaxis and the restriction of salt consumption — A 21st century challenge. Polish Journal of Endocrinology, 61(1), 135–140. Waszkowiak, K., & Szymandera-Buszka, K. (2008). The application of wheat fibre and soy isolate impregnated with iodine salts to fortify processed meats. Meat Science, 80, 1340–1344. WHO (2006). Report of a WHO forum and technical meeting on reducing salt intake in the population. Paris: World Health Organization. WHO (2007). Report of a WHO expert consultation on salt as a vehicle for fortification. Luxembourg: World Health Organization. WHO/UNICEF/ICCIDD (2007). Assessment of iodine deficiency disorders and monitoring their elimination: A guide for programme managers (3rd ed.). Geneva: World Health Organization. Winger, R. J., König, J., & House, D. A. (2008). Technological issues associated with iodine fortification of foods. Trends in Food Science & Technology, 19, 94–101.