with the collaboration of Iranian Food Science and Technology Association (IFSTA)

Document Type : Research Article

Authors

1 Department of Food Science and Technology, Faculty of Agriculture, Shiraz University, Shiraz, Iran.

2 Sea Food Processing Research Group, Faculty of Agriculture, Shiraz University, Shiraz, Iran.

3 Department of Biochemistry, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.

Abstract

Introduction: Proteins play a fundamental role in biological systems and are often sensitive against organic solvents, heat and other damaging factors. Proteins are the basic component of food formulations and enhancement the functional characteristics and stability of the proteins has always been the main goal of food industry engineers. One of the natural ways used for protein modifications is Maillard reaction. Maillard reaction as a result of covalent binding between the available amino groups of the proteins and carbonyl containing moiety of the polysaccharides, causes a loss in free amino group content of the mixture. Protein- polysaccharide hybrids, as a result of dry heating of two biopolymers mixture under controlled reaction conditions, cause the emergence of conjugates with novel functionalities. Much research has shown that conjugation can increase thermal stability and functional characteristics of food proteins and also reduce the allergenicity of suspected proteins. Although many studies have been conducted on the effects of conjugation on functional properties of proteins, the impacts of conjugation on proteins behavior after food processing have been less investigated. So, in this paper the influences of Maillard reaction on functional properties of soy proteins have been investigated. In addition, characteristics of conjugated proteins after pasteurization treatment was also studied. Materials and methods: Construction of protein- polysaccharide conjugates was done in several steps. First, soy proteins and dextran were mixed with phosphate buffer (0.1 M, pH: 8.5) and 1 to 4 ratio of protein to polysaccharide. After mixing and incubating at ambient temperature for some hours, solutions were frozen at –80 ℃ and freeze dried. Then the lyophilized powder was incubated at different times, at 60℃, under the 79 percent relative humidity in presence of saturated KBr. For each treatment a non conjugated sample was prepared in the exact same condition. Conjugation of proteins to polysaccharides was monitored by SDS-PAGE electrophoresis, browning intensity measurement and UV absorbance analysis. SDS-PAGE was conducted according to Laemmli procedure using a discontinuous buffer system. A vertical gel electrophoresis unit was used with 3% acrylamide stacking gel and 10% acrylamide running gel. Evaluation of the color changes as an indicator of grafting intensity was investigated by monitoring absorption at a wavelength of 420 nm. To investigate the UV absorption of conjugated proteins, the samples were diluted with SDS (Sodium dodecyl sulfate) solution and the absorption was read by a UV-visible spectrophotometer at 294 nm. The impact of modification on characteristics of soy proteins was monitored by examining the functional properties changes of protein samples. In the last stage soy drinks were prepared from conjugated and non conjugated proteins then the prepared beverages were subjected to thermal processing conditions and the influences of Maillard conjugation on the stability of soy drinks was monitored over time. Results and Discussion: SDS-PAGE electrophoresis profile showed that proteins-polysaccharide conjugates were formed. As a result of conjugation, the protein-dextran covalent binding occurs, leads to the formation of higher molecular weight components, resulting in its accumulation on the top of the separating gel. When heating time increased a wider and higher molecular weight bands appeared near the top of the running gel however they were not observed in the native soy pattern. Covalent linkage between amino group of proteins and carbonyl group of polysaccharides causes a color changes from light yellow to brown, browning intensity results showed that the even during early incubation time, a significant absorption was observed at 420 nm compared to the control samples. UV absorption results showed similar trend of changes in browning intensity measurement. Increasing UV absorption is due to the intermediate Maillard reaction products (MRP). Increasing UV absorption with increasing heating time indicates the fact that Maillard reaction products (MRP) formation are more favorable in the long incubation time. Data of UV absorption are a good evidence for SDS-PAGE and browning intensity results. Functional properties results indicated that grafted proteins had better functional properties. The storage stability of soy drinks prepared from conjugated proteins was significantly higher than the samples prepared from non conjugated proteins. Stability of beverages after thermal processing and during storage is one of the most important features of protein drinks and many efforts have been made to develop mentioned characteristics. Stability of soy drinks produced from the conjugated proteins was significantly higher than those prepared from non conjugated soy proteins. Functional characterization of proteins is dependent on several factors, the majority of soy drink composed of proteins that could be denaturated by heating applied during thermal processing, as the results showed conjugation with dextran caused an increase in denaturation temperature of soy proteins which enhance the resistance of proteins during thermal processing treatment. In addition, the solubility and emulsifying properties of soy proteins increased with conjugation which can be a good reason for improvement the relation between protein and surrounding water molecules and therefore increases the protein storage stability. It can be concluded that Maillard reaction could be applied as a means to prepare soy proteins–dextran conjugates with better functional properties and more stable during processing and storage.

Keywords

Aminlari, M., Ramezani, R., and Jadidi, F., 2005. Effect of Maillard-based conjugation with dextran on the functional properties of lysozyme and casein. J Sci Food Agric. 85: 2617–2624.
Ajandouz, E, Desseaux, V, Tazi, S. and Puigserver, A, 2008, Effects of temperature and pH on the kinetics of caramelisation, protein cross-linking and Maillard reactions in aqueous model systems, Food Chemistry, 107: 1244–1252
Alahdad, z., Ramezani, R., Aminlari, M., and Majzoobi. M., 2009. Preparation and Properties of Dextran Sulfate-Lysozyme Conjugate. J.Agric.Food Chem. 57: 6449–6454.
Babiker, E., Hiroyuki, A., Matsudomi, N., Iwata, H., Ogawa, T., Bando, N., and Kato, A. 1998. Effect of Polysaccharide Conjugation or Transglutaminase Treatment on the allergenicity and functional properties of soy protein. J.Agric. Food Chem, 46: 866-871.
Boostani, S., Aminlari, M., Moosavi-nasab, M., Niakosari, M., Mesbahi, GH. 2016. Optimizing the glycation extent of SPI-dextran conjugates produced by different Maillard reaction conditions. Iranian Food Science and Technology Research Journal. 12: 526-532.
Boostani, S., Aminlari, M., Moosavi-nasab, M., Niakosari, M., Mesbahi, GH. 2016. Physicochemical and functional properties of acid precipitated soy proteinsmaltodextrin conjugates. Iranian Food Science and Technology Research Journal. 12: 453-462.
Chiu, T., Chen,M., and Chang, H, 2009. Comparisons of emulsifying properties of maillard reaction products conjugated by green, red seaweeds and various commercial proteins. Food Hydrocolloids, 23: 2270–2277.
Diftis, N. and Kiosseoglou, V. 2006. Stability against heat-induced aggregation of emulsions prepared with a dry-heated soy protein isolate–dextran mixture. Food Hydrocolloids. 20: 787–792.
Damodaran, S. (1996). Amino Acids, Peptides and Proteins. In: Food Chemistry, 3rd ed.; Fennema, O. R., Ed.; Dekker: New York, 321-330.
Dickinson, E., 2003. Hydrocolloids at interfaces and the influence on the properties of dispersed systems. Food Hydrocolloids, 17: 25–39.
Endres, J. G., 2001. Soy Protein Products Characteristics, Nutritional Aspects, and Utilization. AOAC Press, Champaign IL. 16-30.
Jinapong, N., Suphantharika, M., Jamnong, P., 2008. Production of instant soymilk powders by ultrafiltration, spray drying and fluidized bed agglomeration, Journal of Food Engineering 84: 194–205.
Kato, A., Shimokawa, K., and Kobayashi, K, 1991. Improvement of the Functional Properties of Insoluble Gluten by Pronase Digestion Followed by Dextran Conjugation. J. Agric. Food Chem., 39: 1053-1058.
Kato, A., 2002. Industrial applications of Maillard-type protein- polysaccharide conjugates. Food Sci Tech Res., 8: 193-199.
Laemmli, U. K., 1970. Cleavage of structural proteins during the assembly of head of bacteriophage T4. Nature, 227: 680-685.
Li, Y., Lu, F, Luo, C, Chen, Z, Mao, J, Shoemaker, C, Zhong, F, 2009, Functional properties of the Maillard reaction products of rice protein with sugar, Food Chemistry, 117, 69–74
Lertittikul, W, Benjakul, S. and Tanaka, M, 2007, Characteristics and antioxidative activity of Maillard reaction products from a porcine plasma protein–glucose model system as influenced by Ph, Food Chemistry, 100: 669–677
Li, Y, Zhong, F, Ji, W, Yokoyama, W, Shoemaker, C. F, Zhu, S, Xia, W, 2013, Functional properties of Maillard reaction products of rice protein hydrolysates with mono, oligo and polysaccharides, Food Hydrocolloids, 30: 53-60.
Liu, Y., Zhao, G., Zhao, M., Ren, J. and Yang, B., 2012. Improvement of functional properties of peanut protein isolate by conjugation with dextran through Maillard reaction. Food Chem., 131: 901-906.
Mu, L., Zhao, M., Yang B., Zhao, H., Cui, C., Zhao, Q., 2010. Effect of ultrasonic treatment on the graft reaction between soy protein isolate and gum acacia and on the physicochemical properties of conjugates. J. Agric. Food Chem, 58: 4494–4499.
Millqvist-Fureby, A., Elofsson, U., and Bergenstahl, B., 2001. Surface composition of spray-dried milk protein-stabilised emulsions in relation to pre-heat treatment of proteins. Colloids and Surfaces B: Biointerfaces, 21: 47–58.
Pearce, K. M. and Kinsella, J. E. 1978. Emulsifying properties of proteins: evaluation of a turbidimeric technique. Journal of Agricultural and Food Chemistry, 26: 716-723.
Qi, J., Yang, X. and Liao, J. 2009. Improvement of functional properties of acid-precipitated soy protein by the attachment of dextran through Maillard reaction, INT J Food Sci Technol., 44: 2296–2302.
Toure1, A., Zhang, X., Tolno, M., Xia, L., Xueming, X. 2009. Preparation of soybean protein isolate (SPI) drinks using ginger essential oil and oleoresin as flavouring agents. As. J. Food Ag-Ind, 2: 72-79
Usui, M., Tamura, H., Nakamura, K., Ogawa, T., Muroshita, M., Azakami, H., Kanuma, S., and Kato, A, 2004. Enhanced bactericidal action and masking of allergen structure of soy protein by attachment of chitosan through Maillard-type protein-polysaccharide conjugation. Nahrung/Food, 48: 69 – 72.
Xu , C.H., Yang, X.Q., Yu , S.J., Qi, J.R., Guo, R., Sun, W.W., Yao, Y.J., and Zhao, M.M., 2010, The effect of glycosylation with dextran chains of differing lengths on the thermal aggregation of β-conglycinin and glycinin, Food Res Int, 43: 2270–2276.
Yadav, M.P., Strahan, G.D., Mukhopadhyay, S., Hotchkiss, A.T., Hicks, K.B., (2012) Formation of corn fiber gumemilk protein conjugates and their molecular characterization, Food Hydrocolloids, 26, 326-333
CAPTCHA Image