Spectral Characteristic, Storage Stability and Antioxidant Properties of Anthocyanin Extracts from Flowers of Butterfly Pea (Clitoria ternatea L.)

Abstract

Anthocyanins from flowers of the butterfly pea (Clitoria ternatea L.) are promising edible blue food colorants. Food processing often faces extreme pHs and temperatures, which greatly affects the color and nutritional values of anthocyanins. This study explored the color, spectra, storage stability, and antioxidant properties of C. ternatea anthocyanin extract (CTAE) at different pHs. The color and absorption spectra of CTAEs at a pH of 0.5–13 were shown, with their underlying structures analyzed. Then, the storage stability of CTAEs were explored under a combination of pHs and temperatures. The stability of CTAE declines with the increase in temperature, and it can be stored stably for months at 4 °C. CTAEs also bear much resistance to acidic and alkaline conditions but exhibit higher thermal stability at pH 7 (blue) than at pH 0.5 (magenta) or pH 10 (blue-green), which is a great advantage in food making. Antioxidant abilities for flower extracts from the butterfly pea were high at pH 4–7, as assessed by DPPH free radical scavenging assays, and decreased sharply when the pH value exceeded 7. The above results provide a theoretical basis for the application of butterfly pea flowers and imply their great prospect in the food industry.

Colorful and health improving Chinese steamed bread fortified by anthocyanin‐rich extract of butterfly pea flower

“…Tenatins are the main polyacylated anthocyanins of CT flowers, and are relatively stable in acidic and neutral conditions (Vuong & Hongsprabhas, 2021). The anthocyanin stability of five materials was ranked as CT flower > purple sweet potato > red cabbage > grape skin > eggplant peel (Fu et al, 2021). However, anthocyanins might be degraded during heat processing due to the deglycosylation, deacylation, oxidation, and cleavage of covalent bonds (Fu et al, 2021; Gamage et al, 2021; Patras et al, 2010).…”

“…The anthocyanin stability of five materials was ranked as CT flower > purple sweet potato > red cabbage > grape skin > eggplant peel (Fu et al, 2021). However, anthocyanins might be degraded during heat processing due to the deglycosylation, deacylation, oxidation, and cleavage of covalent bonds (Fu et al, 2021; Gamage et al, 2021; Patras et al, 2010). The thermal degradation of anthocyanidins was also found in this study, which CSB had less TAC than the dough.…”

“…In this study, BPFE prepared had 31,555 μg FAE/g of FPC, 9917 μg TE/g of DPPH scavenging capacity, and 169,872 μg TE/g (DB) of reducing power. Fu et al (2021) reported that flower extracts of CT had high DPPH radical scavenging activity at pH 4.0–7.0, but the radical scavenging activity decreased sharply at pH > 7.0. Results in Table 1 exhibited that FPC and antioxidant capacities of the CSB significantly increased with the increase of the BPFE level.…”

“…Anthocyanin appears in red, purple, violet and blue colors, depending on the pH value of medium. Fu et al (2021) reported that the anthocyanin extract of CT was most stable under pH 4.0–8.0. Moreover, the extract underwent its color from magenta to purple, blue, green, and yellow when pH value increased from 0.5 to 13.…”

A green-PAD array combined with chemometrics for pH measurements

“…50 The extracts of red cabbage and butterfly pea flower were previously employed as pH indicators since the solution acidity influences their color, and this is due to the reversible structural transformation of the anthocyanins that lead to color changes. [48][49][50] A comparison with the color palette at various pHs of the PADs of 100% RC and 100% BPF with those previously reported 48 for aqueous extracts of red cabbage and butterfly pea flower 50 was performed, confirming the correct preparation of the solutions and the preservation of the anthocyanins.…”