A hybrid process for increasing the shelf life of elderberry juice

Elderberry juice has been used as a nutraceutical product for influenza treatment. Microbial contamination and the polyphenol-degrading enzymes such as polyphenol oxidase (PPO) and peroxidase (POD) are the primary contributors to decrease polyphenols bioactivity in elderberry juice over time. As an alternative sterilization technique to thermal pasteurization, which damages polyphenols, we trailed a protocol combining high-pressure carbon dioxide (HPCO2), mechanical blending, and natural additives. HPCO2 regime of 18 MPa, 45 °C for 90 min inactivated bacteria, yeasts, and molds completely, but had a minimal impact on PPO or POD activity. A subsequent hybrid process comprised of blending and addition of 0.35 M citrate buffer, followed by 15 min HPCO2 treatment proved to be an efficient approach to complete inactivation of microorganisms and enzymes along with enhancing polyphenolic profile and sensorial characteristics of elderberry juice. This low-temperature process is effective for extending the shelf-life of elderberry juice and other polyphenolic-rich nutraceuticals.