1. 华南理工大学轻工与食品学院，广东 广州 510640 2. Department of Chemical Engineering, Faculty of Engineering, Monash University, Clayton, VIC 3800, Australia
Effects of Pulsed Electric Fields and Heat Treatments on SPI Structure Analyzed by FTIR
LIU Yan-yan1, ZENG Xin-an1*，CHEN Xiao-dong2
1. College of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510640, China 2. Department of Chemical Engineering, Faculty of Engineering, Monash University, Clayton, VIC 3800, Australia
Abstract：The effects of pulsed electric field (PEF) under 50 kV·cm-1 as well as heat treatments on the secondary structure of soy protein isolate (SPI) were investigated by Fourier transform infrared (FTIR) method in the present paper. A set of self-designed and made PEF equipment was used. It was demonstrated from the FTIR spectra that the PEF treatment under 50 kV·cm-1 had induced the increase in hydrogen bonds amidst in the intermolecule and intramolecule of SPI, and the increase in C—O—O bonds stretch vibration and the PO or P—O—C stretch vibration, which is positive relative to the increase in the time of PEF treatment. It was shown that after PEF treatment, the ratio of α-helix and β-sheet structure in SPI was decreased by 5.9% and 0.7%, respectively. On the other hand, the ratio of β-turn and side chain vibration structure was obviously increased by 7.5% and 9.6% at the treatment time of 1 600 μs, respectively. Comparatively the effect of heat treatments with 90 ℃ for 30 min on the C—O—O bonds stretch vibration and the PO or P—O—C stretch vibration is more evident, but the effect of which on the secondary structure of SPI is less. So it is concluded that the effect mechanism of PEF and HT on SPI structure is significantly different.
Key words：Pulsed electric field (PEF);Heat treatment(HT);Soy protein isolate(SPI);Fourier transform infrared (FTIR);Secondary structure of protein
[1] Olga Martín-Belloso, Pedro Elez-Martínez. Emerging Technologies for Food Processing, 2005, 8: 183. [2] Han Zhong, Zeng Xinan, Yu Shujuan, et al. Innovative Food Science and Emerging Technologies, 2009, 10: 481. [3] Zeng Xinan, Yu Shujuan, Zhang Lu, et al. Innovative Food Science & Emerging Technologies, 2008, 9(4): 463. [4] Nagano T, Hirotsuka M, Mori H. Journal of Agricultural and Food Chemistry, 1992, 40: 941. [5] Andreas Barth. Biochimicaet Biophysica Acta, 2007, 1767: 1073. [6] Schmidt V, Giacomelli C, Soldi V. Polymer Degradation and Stability, 2005, 87: 25. [7] Mamun A Monsoor. Carbohydrate Polymers, 2005, 61: 362. [8] Barreto P L M, Pires A T N, Soldi V. Polymer Degradation and Stability, 2003, 79: 147. [9] Preeti Lodha, Anil N Netravali. Industrial Crops and Products, 2005, 21: 49. [10] Zhao Xiaoyan, Chen Fusheng, Xue Wentong, et al. Food Hydrocolloids，2008, 22: 568. [11] Tang Chuanhe, Ma Chingyung. LWT-Food Science and Technology, 2009, 42: 606. [12] Carbonaro M, Grant G, Cappelloni M. Journal of the Science of Food and Agriculture, 2005, 85: 65. [13] Michael Jackson, Michael G Sowa, Henry H Mantsch. Biophysical Chemistry, 1997, 68: 109. [14] Shanmugam Neviliappan, Lim Fang Kan, Tan Tiang Lee Walter, et al. Gynecologic Oncology, 2002, 85: 170. [15] Byler D M, Susi H. Biopolymers, 1986, 25: 469. [16] Preeti Lodha, Anil N Netravali. Composites Science and Technology, 2005, 65: 1211. [17] Sureka Weerakoon Ellepola, Siu Mei Choi, Ma Ching Yung. International Journal of Biological Macromolecules, 2005, 37: 12. [18] Jackson M，Mantsch H. Biochimica et Biophysica Acta, 1992, 1118: 139.
