Abstract：Rice aging during storage leads to a decline in eating quality, and protein changes are the underlying reasons. Glutelin is the main protein in rice. Raman and infrared spectroscopy were used to characterize the changes in glutelin during aging, and the differences in functional properties were compared, which was helpful to clarify the mechanism of rice aging. Raman spectroscopy showed that the normalized Raman intensities of aged rice glutelin at 1 665 and 1 218 cm-1 were 1.01 and 0.25, significantly lower than fresh rice glutelin, indicating a decreased α-helix in glutelin after rice aging. The disulfide bonds (the peak intensities at 516 and 527 cm-1 were 0.45 and 0.42 respectively), sulfoxides (the peak intensity at 1 035 cm-1 was 0.48) and sulfones (the peak intensities at 1 124, 1 152, 1 159, 1 316 and 1 334 cm-1 were 0.47, 0.22, 0.26, 0.50 and 0.63, respectively) of the aged rice glutelin were significantly higher than those of the fresh rice glutelin, indicating the obvious oxidation of sulfur-containing amino acid residues. The intensity ratio of Fermi resonance at 857/830 cm-1 of tyrosine in aged rice glutelin was 1.68, which was larger than fresh rice glutelin, indicating more exposed tyrosine residues in glutelin after aging. The Raman intensity of the tryptophan indole ring near 751 cm-1 of aged rice glutelin was 0.20, which was significantly higher than the intensity of 0.14 for the tryptophan indole ring of fresh rice glutelin, indicating more buried tryptophan residues after aging. The O—H stretching strength of the aged rice glutelin at 3 423 cm-1 was 0.05, which was significantly higher than that of the fresh rice glutelin of 0.02, indicating that the degree of intermolecular bonding was increased association between glutelin and starch strengthened. Except for the peak intensities of tyrosine Fermi resonance and sulfone at 1 333 and 1 152 cm-1 were not higher, the Raman intensities of fresh rice glutelin-aged at other peaks were higher than those of aged rice glutelin, which indicates that the oxidation degree of fresh rice glutelin-aged is high. Infrared spectroscopy showed that the absorption peaks of sulfur oxides at 1 153, 1 078 and 1 026 cm-1 in aged rice glutelin and fresh rice glutelin-aged increased, further supporting the oxidation of glutelin after aging. Compared with the functional properties of fresh rice glutelin, the solubility, water holding capacity, emulsifying properties and emulsifying stability of aged rice glutelin were significantly reduced, while oil holding capacity increased, which supported the obvious oxidation of aged rice glutelin. The solubility (except for pH 9), water holding capacity and emulsifying properties of fresh rice glutelin-aged were lower than those of aged rice glutelin, and its oil holding capacity was higher, which indicated that glutelin had a higher degree of oxidation when it was extracted from fresh rice and aged alone. The changes in the functional properties of glutelin after aging supported the oxidative changes shown by Raman and infrared spectroscopies, which provides new evidence for clarifying the roles of protein in aging deterioration of rice quality, and provides a basis for controlling the deterioration of rice aging and reducing post-harvest losses.
宁俊帆，郭玉宝，宋 睿，朱世民，董 鹏. 稻米陈化中谷蛋白变化光谱解析及其对功能性质的影响[J]. 光谱学与光谱分析, 2021, 41(11): 3431-3437.
NING Jun-fan, GUO Yu-bao, SONG Rui, ZHU Shi-min, DONG Peng. Spectral Analysis of Glutelin Changes During Rice Aging and Its Effects on Glutelin Functional Properties. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(11): 3431-3437.
[1] GE Zhi-wen, GAO Yu-long, FANG Yong, et al(葛志文, 高瑀珑, 方 勇, 等). Cereals & Oils(粮食与油脂), 2019, 32(2): 7.
[2] ZHOU Xian-qing, ZHU Fang-qing, ZHANG Yu-rong, et al(周显青, 祝方清, 张玉荣, 等). Journal of the Chinese Cereals and Oils Association(中国粮油学报), 2020, 35(12): 108.
[3] WU Wei, WU Xiao-juan(吴 伟, 吴晓娟). Journal of the Chinese Cereals and Oils Association(中国粮油学报), 2018, 33(10): 104.
[4] Guo Yubao, Cai Weirong, Tu Kang, et al. Journal of Agricultural and Food Chemistry, 2013, 61(1): 185.
[5] WU Wei, YE Jian-fen, CAI Yong-jian, et al(吴 伟, 叶建芬, 蔡勇建, 等). Food and Machinery(食品与机械), 2015, 31(5): 165.
[6] Villareal R M, Resurreccion A P, Suzuki L B, et al. Starch-Starke, 2010, 26(3): 88.
[7] WU Wei, WU Xiao-juan, CAI Yong-jian, et al(吴 伟, 吴晓娟, 蔡勇建, 等). Journal of the Chinese Cereals and Oils Association(中国粮油学报), 2017, 32(7): 98.
[8] Xue Lianjing, Chen Yang, Li Pingzhang. Journal of Food Science, 2016, 81(10-12): 2337.
[9] SHI Jia-yi, ZHANG Tai, LIANG Fu-qiang, et al(石嘉怿, 张 太, 梁富强, 等). Science and Technology of Food Industry(食品工业科技), 2021, 42(6): 29.
[10] Khang N Tran, Torsten Witt, Michael J Gidley, et al. Food Chemistry, 2018, 253(1): 221.
[11] ZHAO Ying, LI Ming, WANG Xiao-long, et al(赵 迎, 李 明, 王小龙, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2019, 39(5): 1468.
[12] Zhou Z, Robards K, Helliwell S, et al. Food Research International, 2010, 43(3): 709.
[13] GAO Ying, DAI Lian-kui, ZHU Hua-dong, et al(高 颖, 戴连奎, 朱华东, 等). Chinese Journal of Analytical Chemistry(分析化学), 2019, 47(1): 67.
[14] CHEN Jia-yi, ZHONG Jun-zhen, LIU Cheng-mei(陈嘉懿, 钟俊桢, 刘成梅). Modern Food Science and Technology(现代食品科技), 2015, 31(10): 241.
[15] LIU Shan-shan, CHEN Ji-wang, CHEN Lu, et al(刘珊珊, 陈季旺, 陈 露, 等). Journal of the Chinese Cereals and Oils Association(中国粮油学报), 2015, 30(4): 33.
[16] DU Xiao-lin, WANG Yu-min(杜晓林，王玉民). Multivariate Statistical Analysis and SAS(多元统计分析与SAS). Beijing: China Agriculture Press(北京：中国农业出版社), 2014, 185.
[17] Ellepola S W, Choi S M, Phillips D L, et al. Journal of Cereal Science, 2005, 43(1): 85.
[18] Li-Chan E C Y. Trends in Food Science & Technology, 1996, 71(7): 361.
[19] Shao J H, Zou Y F, Xu X L, et al. Food Research International, 2011, 44(9): 2955.
[20] ZHANG You-jie(张友杰). Spectrum Analysis of Organic Compounds and Drugs(有机化合物及药物波谱分析). Wuhan: Central China Normal University Press(武汉：华中师范大学出版社), 2008. 113.
[21] Guo Y, Diao M, Tu K, et al. International Journal of Food Properties, 2018, 20(Supl.3), S2969.
