Anthocyanins from Java Plum Fruits (<i>Syzygium cumini</i>) and Their Stability in Various pHs

Anthocyanins exhibit exciting colours in plants. Java plum fruit (Syzygium cumini) is considered a non-conventional and rarely consumed fruit with high levels of anthocyanins. This study was conducted to extract, purify, and characterise anthocyanins from dried Java plum fruits. The stability of anthocyanins was also studied. Anthocyanins in this study were extracted from dried Java plum fruits using acidified water (0.01% HCl, v/v) as a sustainable solvent. The crude extracts were loaded into a solid phase extraction (SPE) column packed with Amberlite-XAD-7HP with sequential elution. The ethanol solution was then analysed and characterised using UV-Vis spectrophotometry and Liquid Chromatography-Mass Spectrometry (LC-MS) to confirm the anthocyanins profiles present in the extracts; Anthocyanins extracted from Java plum fruits were identified as cyanidin-3-O-glucoside ([M+] m/z of 449.3), delphinidin-3-O-glucoside ([M+] m/z of 465.3), and petunidin-3-O-glucoside ([M+] m/z of 479.3). Total monomeric anthocyanin content (TMAC) was 0.13 mg/mL (cyanidin-3-O-glucoside eq.). Anthocyanins show various colours depending on the pH of the solution. Anthocyanins are stable at acidic pH and start degrading at neutral to alkaline pH. The suggested application of highly coloured anthocyanins extracted from dried Java plum is as natural colorants in foods, beverages, textiles, cosmetics etc.