Germination-Induced Changes in the Nutritional, Bioactive, and Digestive Properties of Lima Bean (Phaseolus lunatus L.)

Abstract

(1) Background: Lima beans (Phaseolus lunatus L.) are underutilized legumes rich in nutrients; however, they are limited by the presence of antinutritional content. In this study, we evaluated the effects of a low-cost germination treatment on the nutritional composition, antinutrient content, and digestibility of whole lima beans. (2) Methods: unlike previous studies focused on common legumes or isolated proteins, this work adopted a whole-seed approach and integrated multiple parameters to provide a comprehensive evaluation. (3) Results: The total polyphenol and flavonoid contents increased significantly, by 215.57 mg GAE/g and 71.84 mg RE/g, respectively, at 72 h of germination (p < 0.05). Antioxidant activity nearly doubled compared to raw beans, while the tannins and phytic acid content decreased significantly (p < 0.05). SDS-PAGE showed that germination enhanced digestibility by breaking down high-molecular-weight proteins into smaller fragments (15-30 kDa). Notably, samples germinated for 12-48 h showed higher digestibility after 2-3 h of limited proteolysis. (4) Conclusions: these findings indicate that germination effectively reduces antinutritional factors and improves digestibility, making processed lima beans a promising nutrient-dense ingredient for food formulations.

Keywords: antinutrient; antioxidant activities; germination; lima bean; limited proteolysis profile.

Figure 1

Preparation process and appearance changes of germinated lima beans—0–72 h: germinated lima beans during 0, 12, 24, 36, 48, 60, and 72 h.

Figure 2

Non-reducing SDS-PAGE profiles and densitometric analysis of lima bean proteins during germination (0–72 h) under limited in vitro proteolysis. (A): Representative non-reducing SDS-PAGE gel images of lima bean proteins subjected to germination (0–72 h) and limited in vitro proteolysis (1–4 h). (B): Densitometric quantification of SDS-PAGE bands using ImageJ software. Integrated density (IntDen) values were calculated based on fixed rectangular areas for three molecular weight ranges (75 kDa, 15–30 kDa, and <15 kDa) across different germination time points. Data are expressed in arbitrary units.

Figure 3

Digestibility of lima beans under different germination times with limited proteolysis (1–4 h).

Figure 4

Heat map representing the Pearson correlation between all variables.