Park S K, Hettiarachchy N S, Were L
Department of Food Science, University of Arkansas, Fayetteville, Arkansas 72704, USA.
J Agric Food Chem. 2000 Jul;48(7):3027-31. doi: 10.1021/jf0000272.
Films containing soy protein and wheat gluten were exposed to simulated farmland soil mix over a period of 30 days and monitored for degradation. The simulated farmland soil mix (topsoil/sand/Sunshine compost/vermiculite, 59:6:25:10, wt %) was mixed and stored at ambient humidity (48-55%) and temperature (20-24 degrees C); the soil mix was constantly maintained at 15% moisture by weight. Research focused on evaluating the effectiveness of gluten and cysteine additions on biodegradable behavior in the simulated farmland soil conditions. The four types of films, soy protein (S:G 1:0); soy protein with cysteine addition (S:G 1:0 + CYS); soy protein-wheat gluten (S:G 4:1); and soy protein-wheat gluten with cysteine addition (S:G 4:1 + CYS), were prepared at pH 7. 0 for degradation studies. Soy protein-gluten film rapidly degraded with 50% weight loss in about 10 days and with up to 95% weight loss in 30 days. Tensile strength and elongation of all soy protein-gluten films significantly decreased in 3 days. However, cysteine addition delayed the degradation rate of soy protein-gluten films. Soy protein-wheat gluten film disintegrated after 20 days in the simulated farmland soil environment. These results suggest that wheat gluten and cysteine addition to soy protein-based films could delay degradation rates due to their high disulfide contents.
含有大豆蛋白和小麦面筋的薄膜在模拟农田土壤混合物中暴露30天，并监测其降解情况。模拟农田土壤混合物（表土/沙子/阳光堆肥/蛭石，重量比为59:6:25:10）混合后在环境湿度（48 - 55%）和温度（20 - 24摄氏度）下储存；土壤混合物的重量含水量持续保持在15%。研究重点是评估添加面筋和半胱氨酸对模拟农田土壤条件下生物降解行为的有效性。四种类型的薄膜，大豆蛋白（S:G 1:0）；添加半胱氨酸的大豆蛋白（S:G 1:0 + CYS）；大豆蛋白 - 小麦面筋（S:G 4:1）；以及添加半胱氨酸的大豆蛋白 - 小麦面筋（S:G 4:1 + CYS），在pH 7.0条件下制备用于降解研究。大豆蛋白 - 面筋薄膜在约10天内迅速降解，重量损失50%，在30天内重量损失高达95%。所有大豆蛋白 - 面筋薄膜的拉伸强度和伸长率在3天内显著下降。然而，添加半胱氨酸延缓了大豆蛋白 - 面筋薄膜的降解速率。大豆蛋白 - 小麦面筋薄膜在模拟农田土壤环境中20天后解体。这些结果表明，由于其高含量的二硫键，向大豆蛋白基薄膜中添加小麦面筋和半胱氨酸可能会延缓降解速率。
