稀土镧和铈对大豆蛋白质含量和氨基酸组成的影响及营养评价

Effects of Foliar Application of Lanthanum and Cerium on Protein Content and Amino Acid Composition of Soybeans and Nutritional Evaluation

研究稀土镧、铈对大豆蛋白质含量和氨基酸组分的影响,并对其营养价值进行评价。实验选用稀土镧、稀土铈及镧铈混合稀土,每组设3个质量浓度梯度。以盆栽方式种植,在苗期和初花期叶面喷施稀土溶液。成熟期取大豆籽粒,采用近红外谷物分析仪和氨基酸自动分析仪分别测定籽粒蛋白质含量与氨基酸的组分。并通过计算蛋白质的氨基酸评分(amino acid score,AAS)、化学评分、氨基酸比值系数分(score of ratio coefficient of amino acid,SRCAA)和必需氨基酸指数(essential amino acid index,EAAI),对大豆籽粒蛋白质的营养价值进行评价。结果表明,喷施稀土溶液可显著增加蛋白质的含量,最高较对照组(CK)增加5.17%。经稀土处理后大豆籽粒中必需氨基酸占总氨基酸比例达32.89%～35.17%,除La10外均显著高于CK,且AAS分析表明,各组中除La10第1限制氨基酸为缬氨酸外,其他处理均为蛋氨酸和胱氨酸。在60 mg/L CeCl_3处理下AAS、SRCAA与EAAI分别为94.05、84.08、82.46,均为各组最高,而当稀土溶液质量浓度过高时营养价值评分有所降低。上述结果表明,在苗期和初花期喷施适宜质量浓度的稀土溶液可以提高大豆蛋白的营养价值水平。

In this work, we aimed to study the effect of foliar application of rare earth elements on protein content and amino acid composition of soybeans and to evaluate the nutritional quality of soybean protein. In this pot experiment, LaCl3, CeCl3 and LaCl3 + CeCl3 solutions of three different concentrations were sprayed on soybean leaves in the seedling and early flowering stages. Ripe seeds were harvested for the determination of protein content using a near-infrared grain analyzer. An automatic amino acid analyzer was used to determine amino acid compositions. The protein nutritional quality of soybean seeds was evaluated by calculating amino acid score(AAS), chemical score(CS), score of ratio coefficient of amino acid(SRCAA) and essential amino acid index(EAAI). The results showed that foliar application of rare earth elements could significantly increase the content of protein, with a maximum increment of 5.17% as compared with control group. The ratio of essential to total amino acids in the different experimental groups was between 32.89% and 35.17%, which was significantly higher in all the experimental groups except for La10 than in the control group. According to AAS values,the first limiting amino acid in the La10 group was valine, while the first limiting amino acids in all other groups were methionine and cystine. The AAS, SRCAA, and EAAI in the 60 mg/L CeCl3 treatment group were 94.05, 84.08 and 82.46,respectively, higher than those in all other groups. On the other hand, the nutritional quality of soybean protein decreased at higher concentration of rare earth elements. The above results show that in the seedling and early flowering stages, foliar application of rare earth elements at the appropriate concentrations can improve the nutritional quality of soybean seeds.