Department of Chemistry, Faculty of Science, Okayama University of Science, Ridaicho, Kita-ku, Okayama 700-0005, Japan.
Department of Chemistry, Faculty of Science, Okayama University of Science, Ridaicho, Kita-ku, Okayama 700-0005, Japan.
Int J Biol Macromol. 2020 Apr 15;149:1077-1083. doi: 10.1016/j.ijbiomac.2020.02.025. Epub 2020 Feb 5.
Soybean, one of the most abundant plants, has been cultivated around the world as a familiar crop. Especially, most of the soybean is globally used as a crop to obtain the oil. The degreased soybean contains a lot of protein in it. The part of the degreased soybean is used for the food of human consumption and livestock feed, however most of this are discarded as industrial waste throughout the world. Therefore, we demonstrated the preparation of bioplastics consisting of soy protein. Although the soy protein without the cross-linking reaction by formaldehyde (HCHO) was collapsed in water, bioplastics were stable in water. Additionally, the bending strength of the bioplastic increased with the HCHO concentration and showed the maximum value of approximately 35 MPa at a 1% HCHO concentration. Surprisingly, this bending strength value was the same as that of polyethylene. In contrast, the infrared spectra indicated the formation of methylene cross-linking between the basic amino acids, such as lysine and arginine. Finally, we estimated the biodegradable property of the bioplastic by pronase, one of the proteolytic enzymes. As a result, this bioplastic showed the weight loss of approximately 30% after the incubation time of 6 days. These results suggested that the bioplastic consisting of soy protein possesses a biodegradable property. Therefore, the bioplastic consisting of soybean may have the potential to be used as a biodegradable material, such as agricultural materials, industrial parts, and disposable items.
大豆是世界上最丰富的植物之一，作为一种常见的作物在全球范围内被种植。特别是，全球大部分大豆都被用作作物来获取油脂。脱脂大豆中含有大量蛋白质。脱脂大豆的一部分被用于人类食用和牲畜饲料，但在全世界，大部分都被当作工业废料丢弃。因此，我们展示了由大豆蛋白制成的生物塑料的制备方法。尽管未经甲醛（HCHO）交联反应的大豆蛋白在水中会塌陷，但生物塑料在水中是稳定的。此外，生物塑料的弯曲强度随着 HCHO 浓度的增加而增加，并在 1% HCHO 浓度下显示出约 35 MPa 的最大值。令人惊讶的是，这个弯曲强度值与聚乙烯的相同。相比之下，红外光谱表明碱性氨基酸（如赖氨酸和精氨酸）之间形成了亚甲基交联。最后，我们用一种蛋白水解酶——蛋白酶来估计生物塑料的可生物降解性。结果表明，这种生物塑料在孵育 6 天后的重量损失约为 30%。这些结果表明，由大豆蛋白制成的生物塑料具有可生物降解性。因此，由大豆蛋白制成的生物塑料可能具有作为可生物降解材料的潜力，如农业材料、工业部件和一次性用品。
