Phenolic compounds and antioxidant activity of two bean cultivars (Phaseolus vulgaris L.) submitted to cooking

In vitro protein digestibility and biochemical characteristics of soaked, boiled and fermented soybeans

Protein digestibility of soybean obtained from the main manufacturing steps for natto, such as soaking (soaked soybeans 'S'), boiling (boiled soybeans 'B'), and fermentation (fermented soybeans 'F'), was examined in this study. Biochemical indices for the processed soybeans from each manufacturing step and those digested fractions by simulated in vitro gastrointestinal digestion were also evaluated. The result showed a significant (P < 0.05) increase in the protein digestibility of B (48.71 ± 0.04%) and F (50.21 ± 0.45%) compared to that of S (20.58 ± 0.25%), accompanying the accumulation of small protein sub-fractions and essential amino acids. Besides, antioxidant activity indices of all digested fractions increased around two to fourfold at the end of the simulated digestion. F showed a consistently increasing trend when the digestion stage progressed and maximum values overall at the final digestion stage.  Soybeans from fermentation step showed higher protein digestibility and indispensable amino acids as well as potential bioactivities than those from boiling and soaking step. The results demonstrated that manufacturing steps improved nutritional values of soybean protein, such as bioavailability of amino acids and certain bioactivities.

Characterization of Soaking Process' Impact in Common Beans Phenolic Composition: Contribute from the Unexplored Portuguese Germplasm

Despite the common beans' nutritional and phytochemical value, in Portugal its consumption decreased more than 50% in the last decade. The present study aimed to characterize phenolic composition of the Portuguese traditional varieties and corresponding soaked seed fractions (including soaking water). With such purpose, the phenolic composition (total content of soluble phenolics, flavonoids, and proanthocyanidins) and in vitro antioxidant activity were evaluated in the raw whole flour of 31 Portuguese common bean varieties. The phenolic composition of the soaked fractions was respectively compared to the raw flour. Phenolic compounds' identification and relative quantification were achieved by UPLC-TripleTOF-MS for one representative variety and their fractions. The highest phenolic content was found in colored varieties and the brown market class highlighted as the richest one. The loss of phenolic compounds to the soaking water was highly dependent on variety. The predominant phenolic compounds' classes were flavan-3-ols (soaking water and coats), flavonols (coats), and phenolic acids (cotyledons). This characterization study showed the diversity on the phenolic composition of Portuguese varieties and the need to adjust the soaking and peeling processes to the variety (considering the possible loss of potential health promoter compounds, e.g., phenolic compounds).