Abstract Rice bran (RB) is an important by-product from the rice production with a high valorization potential. The aim of the present work was to explore this potential by considering combined protein and phenolic fractions and enzymatic hydrolysis. The influence of different protocols in the recovery/fractioning of protein were evaluated, including defatting procedures, in rice brans from two very different locations: Portugal and Colombia. The different protein fractions achieved were characterized. Proteins were further hydrolyzed using trypsin and their hydrolysates were characterized in terms of degree of hydrolysis and peptide size. Moreover, the total phenolic content (TPC) and phenolic compounds’ profile on extracted fractions and hydrolysates of RB from Portugal and Colombia were determined. The functional potential was assessed in terms of antioxidant and antihypertensive activities. Though the protein concentrates had already significant potential bioactivities, protein hydrolysates showed that the TPC, antioxidant and antihypertensive activities significantly increased with the digestion by trypsin. Hydrolysates of RB from Portugal presented a higher antioxidant and hypertensive activities in comparison with hydrolysates of RB from Colombia, moreover it presented a higher content of TPC. This study indicated that the exploitation potential of rice bran can be increased with simple fractioning procedures, that combined protein/phenolic fractions are important to deliver functionality and that hydrolysis can be a relevant tool to release that functionality. Furthermore, regional differences in rice bran composition are also important factors to consider. Overall, this knowledge can be used to increase the industrial potential of valorization for this by-product.

中文翻译：

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大米副产品的价值化：具有生物活性潜力的蛋白质-酚类组分

摘要 米糠（RB）是水稻生产的重要副产品，具有很高的增值潜力。本工作的目的是通过考虑组合的蛋白质和酚类组分以及酶促水解来探索这种潜力。在来自两个非常不同的地方：葡萄牙和哥伦比亚的米糠中，评估了不同方案对蛋白质回收/分级的影响，包括脱脂程序。对获得的不同蛋白质级分进行表征。使用胰蛋白酶进一步水解蛋白质，并根据水解程度和肽大小对它们的水解产物进行表征。此外，还测定了来自葡萄牙和哥伦比亚的 RB 提取馏分和水解物的总酚含量 (TPC) 和酚类化合物的分布。根据抗氧化和抗高血压活性评估功能潜力。虽然蛋白质浓缩物已经具有显着的潜在生物活性，但蛋白质水解物表明，随着胰蛋白酶的消化，TPC、抗氧化和抗高血压活性显着增加。与哥伦比亚RB水解产物相比，葡萄牙RB水解产物具有更高的抗氧化和抗高血压活性，而且TPC含量更高。这项研究表明，米糠的开发潜力可以通过简单的分级程序来增加，蛋白质/酚类组分的组合对于提供功能很重要，水解可以成为释放该功能的相关工具。此外，米糠成分的地区差异也是需要考虑的重要因素。总体而言，这些知识可用于提高该副产品的工业价值。