Colour of reconstituted pomegranate-orange juice blends: impact of amino acid copigmentation.

BACKGROUND: This study investigated the effects of amino acid copigmentation and storage at 20 °C on pomegranate anthocyanins in mixed fruit juices (POJs) prepared from different ratios of pomegranate juice (PJ) and orange juice (OJ). To better simulate industrial production conditions, both PJ and OJ were obtained from concentrates and stored at - 18 °C for 0, 9, and 18 months prior to use, rather than being freshly produced from fruits. While individual anthocyanin profiles were tracked via high-performance liquid chromatography, copigmentation indicators were monitored spectrophotometrically. RESULTS: Asparagine (ASN) significantly reduced the degradation rate of anthocyanins by 1.29-2.49 times compared to the control, depending on the storage duration of the concentrates. The addition of ASN preserved the stability of all individual anthocyanins. However, the polymeric colour ratio increased up to 10.04% after 18 months of storage, indicating enhanced polymerisation of anthocyanins and a consequent decline in their copigmentation capacity with amino acids. CONCLUSION: The findings demonstrate that ASN is an effective copigment to improve the stability of pelargonidin-based anthocyanins and colour preservation in POJs produced from concentrates. Therefore, the use of ASN represents a promising strategy for improving the colour stability of anthocyanins, particularly in POJs. © 2026 Society of Chemical Industry.