Freeze-dried coconut press cake powder (CPP),
43% w/w protein, was used to investigate the heat-induced gelation by heating
in rheometer to
75℃ in a wide range of pH values, from 4 to 9. Low strain oscillatory method
applied the measure visco-elastic propertieson 15% w/w CPP. The gel strength
was also assessed by a texture analyzer. SDS-PAGE electrophoresis was conducted
to identify the proteins evolved in the gel network structure and the gel
micro-structure was also evaluated. At low pH, the CPP proteins formed soft
(elastic modulus <100 Pa) particulate gels prone to syneresis, with
aggregate size of the order of 4.2 micrometers. In the alkaline region,
homogenous gels were induced by heating. Gel strength started to increase
dramatically from 64℃ to
67℃, for pH 9 and pH 8 respectively, reaching the maximum gel elastic modulus
over 1000 Pa at pH 9. The SDS-PAGE showed that the polypeptide sub-unities at
24, 32 - 34 and 53 kDa were the most prominent in gelation.
References
[1]
Cavallieri, A., Garcez, M., Takeuchi, K. and Cunha, R. (2010) Heat-Induced Gels of Soy Protein and j-Carrageenan at Different pH Values. International Journal of Food Science and Technology, 45, 1130-1137. http://dx.doi.org/10.1111/j.1365-2621.2010.02247.x
[2]
Clark, A., Kavanagh, G. and Murphy, S. (2001) Globular Protein Gelation—Theory and Experiment. Food Hydrocolloids, 15, 383-400. http://dx.doi.org/10.1016/S0268-005X(01)00042-X
[3]
Foegeding, E. and Davis, J. (2011) Food Protein Functionality: A Comprehensive Approach. Food Hydrocolloids, 25, 1853-1864. http://dx.doi.org/10.1016/j.foodhyd.2011.05.008
[4]
Nicolai, T. and Durand, D. (2013) Controlled Food Protein Aggregation for New Functionality. Current Opinion in Colloid & Interface Science, 18, 249-256. http://dx.doi.org/10.1016/j.cocis.2013.03.001
[5]
He, J., Mu, T., Guo, X., Zhu, S., Azuma, N. and Kanno, C. (2013) Comparison of the Gel-Forming Ability and Gel Properties of α-Lactalbumin, Lysozyme and Myoglobin in the Presence of β-Lactoglobulin under High Pressure. Food Hydrocolloids, 33, 415-424. http://dx.doi.org/10.1016/j.foodhyd.2013.04.010
[6]
Li, X., Li, Y. and Hua, Y. (2007) Effect of Concentration, Ionic Strength and Freeze-Drying on the Heat-Induced Aggregation of Soy Proteins. Food Chemistry, 104, 1410-1417. http://dx.doi.org/10.1016/j.foodchem.2007.02.003
[7]
Sun, X. and Arntfield, S. (2011) Gelation Properties of Salt-Extracted Pea Protein Isolate Induced by Heat Treatment: Effect of Heating and Cooling rate. Food Chemistry, 124, 1011-1016. http://dx.doi.org/10.1016/j.foodchem.2010.07.063
[8]
Gosal, W. and Ross, S. (2000) Globular Protein Gelation. Current Opinion in Colloid & Interface Science, 5, 188-194. http://dx.doi.org/10.1016/S1359-0294(00)00057-1
[9]
Angelia, M., Garcia, R., Caldo, K., Prak, K., Utsumi, S. and Tecson, E. (2010) Physicochemical and Functional Characterization of Cocosin, the Coconut 11S Globulin. Food Science and Technology Research, 16, 225-232. http://dx.doi.org/10.3136/fstr.16.225
[10]
Chambal, B., Bergenstahl, B. and Dejmek, P. (2012) Edible Proteins from Coconut Milk Press Cake; One Step Alkaline Extraction and Characterization by Electrophoresis and Mass Spectrometry. Food Research International, 47, 146151. http://dx.doi.org/10.1016/j.foodres.2011.04.036
[11]
Foegeding, E., Gwartney, E. and Errington, A. (1998) Functional Properties of Whey Proteins in Forming Networks. 145-157.
[12]
Ikeda, S. and Nishinari, K. (2001) Structural Changes during Heat-Induced Gelation of Globular Protein Dispersions. Biopolymers, 59, 87-102.
[13]
Linden, E. and Venema, P. (2007) Self-Assembly and Aggregation of Proteins. Current Opinion in Colloid & Interface Science, 12, 158-165. http://dx.doi.org/10.1016/j.cocis.2007.07.010
[14]
Chambal, B., Bergenstahl, B. and Dejmek, P. (2013) Coconut Press Cake Alkaline Extract—Protein Solubility and Emulsification Properties. Food and Nutrition Sciences, 4, 29-37. http://dx.doi.org/10.4236/fns.2013.49A2005
[15]
Garcia, R., Arocena, R., Laurena, A. and Tecson-Mendoza, E. (2005) 11S and 7S Globulins of Coconut (Cocos nucifera L.): Purification and Characterization. Journal of Agricultural and Food Chemistry, 53, 1734-1739. http://dx.doi.org/10.1021/jf0402173
[16]
Tangsuphoom, N. and Coupland, J. (2009) Effect of Surface-Active Stablizers on the Surface Properties of Coconut Milk Emulsions. Food Hydrocolloids, 23, 1801-1809. http://dx.doi.org/10.1016/j.foodhyd.2008.12.002
[17]
Renkema, J.M.S. and Van Vliet, T. (2002) Heat-Induced Gel Formation by Soy Proteins at Neutral pH. Journal of Agricultural and Food Chemistry, 50, 1569-1573. http://dx.doi.org/10.1021/jf010763l
