江连洲, 冉安琪, 贾子璇, 刘季善, 李杨, 王中江. 不同贮藏期大豆蛋白对千页豆腐品质的影响[J]. 农业工程学报, 2019, 35(20): 311-318. DOI: 10.11975/j.issn.1002-6819.2019.20.038
    引用本文: 江连洲, 冉安琪, 贾子璇, 刘季善, 李杨, 王中江. 不同贮藏期大豆蛋白对千页豆腐品质的影响[J]. 农业工程学报, 2019, 35(20): 311-318. DOI: 10.11975/j.issn.1002-6819.2019.20.038
    Jiang Lianzhou, Ran Anqi, Jia Zixuan, Liu Jishan, Li Yang, Wang Zhongjiang. Effect of soy protein on the quality of Qianye tofu in different storage periods[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2019, 35(20): 311-318. DOI: 10.11975/j.issn.1002-6819.2019.20.038
    Citation: Jiang Lianzhou, Ran Anqi, Jia Zixuan, Liu Jishan, Li Yang, Wang Zhongjiang. Effect of soy protein on the quality of Qianye tofu in different storage periods[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2019, 35(20): 311-318. DOI: 10.11975/j.issn.1002-6819.2019.20.038

    不同贮藏期大豆蛋白对千页豆腐品质的影响

    Effect of soy protein on the quality of Qianye tofu in different storage periods

    • 摘要: 为了研究不同贮藏期大豆分离蛋白(soy protein isolate,SPI)对千页豆腐品质的影响,该文首先研究了贮藏期对大豆分离蛋白结构的影响,进而探讨贮藏期对大豆蛋白制备千页豆腐的品质的影响。对不同贮藏期的大豆蛋白分别采用了凝胶质构特性、感官评价、羰基含量、大豆蛋白亚基以及巯基的测定,并采用拉曼光谱对大豆蛋白二级结构、二硫键构型以及侧链结构进行了分析,同时采用扫描电镜观察千页豆腐的微结构。结果表明:随着贮藏期的延长,千页豆腐的感官评价变差,由88分降低至44分;其凝胶网络结构逐渐疏松;大豆蛋白羰基含量逐渐上升;巯基含量逐渐下降;二级结构含量改变;凝胶硬度呈下降趋势,硬度值低于234 g时,将无法达到千页豆腐的质量要求。这表明在贮藏期内SPI发生了氧化,导致大豆蛋白质结构发生改变,使其凝胶性质下降。

       

      Abstract: In this paper, the effects of different storage periods on the structure of soy protein isolate (SPI) were studied, and the effects of storage period on the quality of Qianyetofu were discussed. The content, subunit, sulfhydryl group, gel texture and sensory evaluation were determined for SPI in different storage periods, and the SPI secondary structure, disulfide bond configuration and side chain structure were analyzed by Raman spectroscopy. The measurement was carried out, and the microstructure of Qianyetofu was observed by scanning electron microscopy. The results showed that with the prolongation of storage period, the content of SPI carbonyl increased gradually; the content of disulfide bond in free sulfhydryl group and total sulfhydryl group decreased gradually; the content of secondary structure changed; the hardness of gel showed a downward trend. The sensory evaluation of Qianyetofu deteriorated in terms of taste, color and flavor; the gel network structure became looser, the degree of crosslinking decreased and the network structure was rough. This indicate that the SPI has undergone an oxidation reaction during the storage period, resulting in a change in the structure of the soybean protein, which ultimately reduces the gel properties. According to Raman spectroscopy, the analysis of soy protein isolates in different storage periods showed that the α-helix and β-sheet configurations were higher during the storage period of 0-18 days, and the intermolecular disulfide bonds were converted into intramolecular disulfide bonds. During the storage period of 18-30 days, the random coil configuration increased significantly, and the disulfide bond was converted from intramolecular to intramolecular. At this time, the secondary structure of soy protein was loose and the protein gel strength was low. During the whole storage process, the carbonyl content increased gradually, SPI may react during storage to produce reactive oxygen species or free radicals, which attack proteins, causing breakage of the main peptide chain or oxidation of side chain groups, resulting in elevated carbonyl content, protein carbonylation leading to changes in protein structure, the content of sulfhydryl groups and disulfide bonds decreased gradually, oxidation can change the redox state of cysteine in proteins and the equilibrium constant of thiol/disulfide bond interactions, thereby changing distribution of sulfhydryl and disulfide bonds in proteins, and the subunits of 65, 62, 57 and 20 kDa belonged to the bands, it indicates that long-term storage leads to the formation of insoluble high molecular weight oxidized aggregates of soy protein, making them unable to enter the electrophoresis gel, and non-disulfide bonds participate in the formation of oxidized aggregates, which were related to the large aggregate formed by oxidative attack of SPI. Observing the combination of the microstructure of Qianyetofu and the sensory evaluation of texture characteristics, it is concluded that the soy protein is oxidized and attacked to form oxidized aggregates, which affects the processing characteristics of the protein, which is the reason for the decrease of gel strength and poor taste. This indicates that the SPI has undergone an oxidation reaction during the storage period, resulting in a change in the structure of the soybean protein and a decrease in its gel properties.

       

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