Identification and Characterization of a-Glucosidase Inhibition Flavonol Glycosides from Jack Bean (Canavalia ensiformis (L.) DC

Potential of White Jack Bean (Canavalia ensiformis L. DC) Kefir as a Microencapsulated Antioxidant

Oxidative stress plays a major role in the pathogenesis and progression of noncommunicable diseases. Kefir is a fermented food that has been reported to repress oxidative stress. This study aimed to assess the antioxidant activity, bioactive composition, and encapsulation efficiency of white jack bean (WJB) kefir. The following procedures were conducted: WJB was prepared and converted into juice using water solvent. The sterilized WJB juice was then fermented with kefir grain (10%) for 24∼72 h. Every 24 h, the kefir was evaluated for antioxidant activity, and the dominant bioactive component suspected to be the source of the antioxidant activity was identified. The final stage was the encapsulation process. WJB kefir showed high antioxidant activity, inhibiting DPPH radicals by 90.51±4.73% and ABTS radicals by 86.63±2.34% after 72 h of fermentation. WJB kefir contained 0.35±0.01 mg GAE/g total phenolics and 0.08 mg/g total flavonoids. The LC/MS identification suggested that the bioactive antioxidant components of the WJB kefir were from the alkaloid, saponin, phenolic, and flavonoid groups. The encapsulation with maltodextrin using freeze drying resulted in microencapsulation of WJB kefir with a particle size of 6.42±0.13 μm. The encapsulation efficiency was 79.61%, and the IC50 value was 32.62 ppm. The encapsulation method was able to maintain the antioxidant stability of the kefir and extend its shelf life. WJB kefir, a nondairy, lactose-free kefir, can be used as an antioxidant functional food.

Thermal Stability of Anisoyl Kaempferol Glycosides in Jack Bean (Canavalia ensiformis (L.) DC) and Their Effect on α-Glucosidase Inhibition

Kaempferol glycosides are functional components of jack bean. The chemical stability of kaempferol glycosides under simulated food processing conditions was evaluated in this study by subjecting the methanol extract and each compound to heat treatment. During the heat treatment, rearrangement of the anisoyl group on the rhamnose moiety of the kaempferol glycoside was observed, followed by hydrolysis upon long-term heat treatment. One of the two regioisomers produced under heating conditions showed higher α-glucosidase inhibitory activity than the dominant anisoyl kaempferol glycoside. This rearrangement reaction was also observed upon the heat treatment of methyl-3-O-anisoyl-rhamnose, with the rearrangement from the 3-position to the 2-position occurring preferentially. The approach adopted in this study can be used to design appropriate food processing conditions, which, in turn, will increase the functional value of foods.