Elderberries, a rich source of polyphenols, have a high potential as a source of nutraceutical compounds for use in the treatment of influenza infection. However, due to insufficient extraction and limited stability of active compounds during processing, elderberries remain an underutilised resource. Thermal treatments, the most common pasteurisation method, used to prevent microbial contamination and the intrinsic polyphenol-degrading enzymes have a detrimental impact on thermo-labile active compounds and sensorial characteristics of food products. Moreover, microorganisms and polyphenol oxidase (PPO) and peroxidase (POD) found in elderberry juice can substantively decrease the bioactivity over time. Therefore, this project aims to develop a low-temperature process to increase the extraction and preserve the activity of the thermosensitive compounds, while promoting safety and shelf life.
As an alternative sterilisation technique to high-temperature pasteurisation, a non-thermal process was designed with the aim of simultaneous inactivation of microorganisms and degradative enzymes. The process composed of blending elderberry fruit followed by a short high-pressure carbon dioxide (HPCO2) regimen in the presence of natural inhibitors such as citrate buffer. Also, this process enhanced the extraction and the stability of anthocyanin, the main antiviral compound in elderberry.
Moreover, understanding elderberry’s mechanism of action in inhibiting influenza infection is a prerequisite for studying the impact of the processing on its anti-influenza activity. In this comprehensive report, elderberries’ mechanism of action is elucidated. Elderberry showed potent antiviral activity by a therapeutic index of 12 ± 1.3 against influenza infection. Moreover, inhibition by elderberry was stronger against the late stage influenza cycle than the early stage. The action of elderberry is both direct – suppressing viral entry, the post-infection phase, and viral transmission from cell to cell, and indirect – by modulating the release of cytokines such as IL-6, IL-8, and TNF. These data support the application of Sambucus nigra berries as nutraceuticals for the management of influenza infection. Treatment with cyn 3-glu endorses bioactive properties of this compound in elderberry that at least partly modulates its antiviral activity.
Thus, the developed process represents a high-utility non-thermal approach for manufacturing heat-labile elderberry products with enhanced therapeutic benefits, improved sensorial attributes, and prolonged shelf life. It also has a high potential for pasteurisation of other juices and nutraceuticals that are rich sources of polyphenols.