Wang Kun, Gao Yongjiao, Zhao Jing, Wu Yue, Sun Jingchen, Niu Guangcai, Zuo Feng, Zheng Xiqun
College of Food Science, Heilongjiang Bayi Agricultural University, Daqing, China.
National Coarse Cereals Engineering Research Center, Daqing, China.
Front Nutr. 2022 Oct 12;9:1017765. doi: 10.3389/fnut.2022.1017765. eCollection 2022.
The nutritional value and bioactivity of black beans are enhanced when fermented as tempeh, but their bioaccessibility and bioactivity after ingestion remain unclear. In this study, black bean tempeh and unfermented black beans were digested and changes in protein degradation, phenolic compound release, angiotensin I-converting enzyme (ACE)-inhibitory activity, and antioxidant activity between the two groups were compared. We observed that the soluble protein content of digested black bean tempeh was generally significantly higher than that of digested unfermented black beans at the same digestion stage ( 0.05). The degree of protein hydrolysis and the content of <10 kDa peptides were also significantly higher in the digested black bean tempeh than in digested unfermented black beans ( < 0.05). SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and reversed-phase high-performance liquid chromatography (RP-HPLC) analysis showed that most macromolecular proteins in tempeh had been degraded during fermentation and more of the small peptides were released from black bean tempeh during digestion, respectively. Compared to that of the unfermented black beans, the level of ACE inhibition of black bean tempeh was lower, but this significantly increased to 82.51% following digestion, closing the gap with unfermented black beans. In addition, the total respective levels of phenolics, flavonoids, and proanthocyanidins released from black bean tempeh were 1.21, 1.40, and 1.55 times those of unfermented black beans following digestion, respectively. Antioxidant activity was also significantly higher in digested black bean tempeh than in digested unfermented black beans and showed a positive correlation with phenolic compound contents ( < 0.05). The results of this study proved that, compared to unfermented black beans, black bean tempeh retained protein and phenolic compound bioaccessibility and antioxidant activity and showed an improved ACE-inhibitory activity even after consumption.
黑豆发酵制成天培后，其营养价值和生物活性会得到提升，但其摄入后的生物可及性和生物活性仍不明确。在本研究中，对黑豆天培和未发酵黑豆进行消化，并比较了两组之间蛋白质降解、酚类化合物释放、血管紧张素I转换酶（ACE）抑制活性和抗氧化活性的变化。我们观察到，在相同消化阶段，消化后的黑豆天培的可溶性蛋白质含量通常显著高于消化后的未发酵黑豆（P<0.05）。消化后的黑豆天培的蛋白质水解程度和<10 kDa肽的含量也显著高于消化后的未发酵黑豆（P<0.05）。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和反相高效液相色谱（RP-HPLC）分析表明，天培中的大多数大分子蛋白质在发酵过程中已被降解，并且在消化过程中黑豆天培释放出更多的小肽。与未发酵黑豆相比，黑豆天培的ACE抑制水平较低，但消化后这一水平显著提高至82.51%，与未发酵黑豆的差距缩小。此外，消化后黑豆天培释放的酚类、黄酮类和原花青素的总量分别是未发酵黑豆的1.21、1.40和1.55倍。消化后的黑豆天培的抗氧化活性也显著高于消化后的未发酵黑豆，并且与酚类化合物含量呈正相关（P<0.05）。本研究结果证明，与未发酵黑豆相比，黑豆天培保留了蛋白质和酚类化合物的生物可及性以及抗氧化活性，并且即使在食用后也表现出改善的ACE抑制活性。
