Unlocking the potential of American elderberry : drying techniques to protect its bioactive potential (Sambucus nigra subsp. canadensis)
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The American elderberry (Sambucus nigra subsp. canadensis) belongs to the family Viburnaceae, is a small dark purple fruit. The fruit naturally proliferates across eastern North America, and its cultivation in the USA is on the rise due to its value as a dietary supplement. While the European elderberry (Sambucus nigra subsp. nigra) has undergone extensive research and commercialization, American elderberries' cultivation and commercial utilization is still nascent. The chemistry of the two species is distinct: American elderberries have over 75 percent acylated anthocyanins, which contribute to color stability, while European elderberries predominantly contain non-acylated anthocyanins. The technological applications of American elderberries are mainly confined to products like jams, jellies, syrups, juice, and wine. Hence, this study aims to process American elderberry juice and pomace extract by spray drying using soy protein isolate (SPI) and tapioca starch (TS). The spray dried juice and pomace extract particles were evaluated for their physical and bioactive properties. Further, an in vitro gastrointestinal digestion assay was performed to understand the bioavailability. The findings show that an efficient spray drying process was established, since the solids recovery was greater than 60 percent. Further, particles obtained using SPI exhibited higher solubility (60 percent-64 percent), lower porosity (69 percent- 70 percent), and better flowability (22 percent Carr index, 1.29 Hausner ratio). On the other hand, particles produced using TS showed significantly higher total polyphenol content (42-49 mg gallic acid equivalent/g sample), proanthocyanidin content (0.76-2.86 mg proanthocyanidin-B2/g sample), and anthocyanins (7.86-33.80 mg/g sample) for both elderberry juice and pomace extract, compared to SPI-derived particles. Further, the in vitro bioaccessibility assay showed that particles of encapsulated elderberry juice or pomace extract with SPI had higher bioaccessibility compared to non-encapsulated elderberry juice or TS-derived particles. Since soy-based ingredients are considered as one of the commonly found allergic products by FDA, the next study evaluated proso millet as an alternative drying aid and compared with the established pea protein isolate. Alternative drying techniques were used to preserve elderberries and the findings showed that both spray and freeze-dried particles had lower water activity ([less than] 0.2) and preserved high amounts total polyphenols, anthocyanins and antioxidant capacity compared to vacuum drying. Spray dried elderberry juice with proso millet exhibited significantly high amounts of total polyphenols (31.98mg GAE/mg sample), and anthocyanins (3474 mg/100 g sample) among all experimental groups. This shows that, Proso millet, despite having lower protein content (12 percent), compared to pea protein isolate (84 percent) still exhibited high sorption of elderberry polyphenols. Therefore, from these studies, we demonstrate that spray-dried elderberry particles are a convenient and versatile way to deliver polyphenols from underutilized American elderberries for various food applications. These findings provide an industry-friendly technological solution for creating value-added ingredients in the emerging market of elderberry.
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M.S.