Black bean anthocyanin-rich extracts as food colorants: Physicochemical stability and antidiabetes potential

- Extraction of anthocyanins from black bean coats was optimized using RSM.
- Black bean anthocyanins rich extracts presented good shelf-life stability.
- Black bean anthocyanins inhibit α-glucosidase, α-amylase, DPP-IV and glucose uptake.
- Black bean anthocyanins have technological functionality and antidiabetes potential.
- Anthocyanins from black beans are natural-source colorants for the food industry.

Black beans contain anthocyanins that could be used as colorants in foods with associated health benefits. The objective was to optimize anthocyanins extraction from black bean coats and evaluate their physicochemical stability and antidiabetes potential. Optimal extraction conditions were 24% ethanol, 1:40 solid-to-liquid ratio and 29 °C (P < 0.0001). Three anthocyanins were identified by MS ions, delphinidin-3-O-glucoside (465.1 m/z), petunidin-3-O-glucoside (479.1 m/z) and malvidin-3-O-glucoside (493.1 m/z). A total of 32 mg of anthocyanins were quantified per gram of dry extract. Bean anthocyanins were stable at pH 2.5 and low-temperature 4 °C (89.6%), with an extrapolated half-life of 277 days. Anthocyanin-rich extracts inhibited α-glucosidase (37.8%), α-amylase (35.6%), dipeptidyl peptidase-IV (34.4%), reactive oxygen species (81.6%), and decreased glucose uptake. Black bean coats are a good source of anthocyanins and other phenolics with the potential to be used as natural-source food colorants with exceptional antidiabetes potential.