The potential of green coffee in alginate delivery systems for encapsulation of rosemary (Rosmarinus officinalis L.) and dandelion (Taraxacum officinale L.) polyphenols

Ružmarin (Rosmarinus officinalis L.) i maslačak (Taraxacum officinale L.) su ljekovite biljne vrste široko rasprostranjene na području Hrvatske, a od davnina se koriste u tradicionalnoj medicini za liječenje različitih oboljenja zahvaljujući svom bogatom bioaktivnom sastavu, posebice polifenolnim spojevima. Budući da polifenolni profil maslačka još uvijek nije dovoljno istražen, a podaci o inkapsulaciji polifenolnih spojeva ružmarina i maslačka su limitirani, cilj ovog rada bio je karakterizirati polifenolne ekstrakte ružmarina i maslačka spektrofotometrijskim metodama te iste imobilizirati u različite sustave nosača na bazi alginata primjenom ionskog geliranja. Za inkapsulaciju polifenola ružmarina (R) i maslačka (M) korišten je alginat (A) te njegove kombinacije s izolatima proteina sirutke (A-IPS) te zelenom kavom (A-ZK), s naglaskom na ispitivanju potencijala zelene kave kao novog materijala za inkapsulaciju. Dobivenim hidrogel česticama određen je udjel vode, fizikalne i morfološke karakteristike, inkapsulacijska učinkovitost polifenola i sposobnost zadržavanja antioksidacijskog kapaciteta, kao i kinetika otpuštanja polifenola i antioksidacijskog kapaciteta iz hidrogel čestica u simuliranim gastrointestinalnim uvjetima. Analiza ekstrakata ružmarina i lista maslačka pokazala je da je udjel ukupnih polifenola, hidroksicimetnih kiselina te antioksidacijski kapacitet bio veći u ekstraktu ružmarina. Kod obje biljne vrste, dodatak izolata proteina sirutke u alginat rezultirao je smanjenjem veličine hidrogel čestica, dok je dodatak zelene kave uzrokovao povećanje veličine čestica. Dodatak izolata proteina sirutke i zelene kave u alginatni gel rezultirao je povećanjem inkapsulacijske učinkovitosti ukupnih polifenola, hidroksicimetnih kiselina te povećanjem stupnja zadržavanja antioksidacijskog kapaciteta, pri čemu se dodatak izolata proteina sirutke pokazao najučinkovitijim (npr. % imobilizacije ukupnih polifenola za A-IPS iznosio je 94,33% za R i 90,15% za M). Najbolji profil otpuštanja svih ispitivanih parametara imao je sustav A-ZK, gdje je otpuštanje ukupnih polifenola i hidroksicimetnih kiselina, u obje biljne vrste, bilo kontinuirano kroz svih 140 minuta u gastrointestinalnim uvjetima. Zelena kava, kao novi materijal u sustavu nosača, pokazala je velik potencijal za inkapsulaciju polifenola ljekovitog bilja.Rosemary (Rosmarinus officinalis L.) and dandelion (Taraxacum officinale L.) are medicinal herbs widely spread in Croatia, and they have been used for years in traditional medicine for healing various diseases due to their rich bioactive composition, especially polyphenolic compounds. Since the polyphenol profile of dandelion has still not been sufficiently investigated, and data on encapsulation of rosemary and dandelion polyphenols is lacking, the aim of this study was to characterize rosemary and dandelion polyphenolic extracts by spectrophotometric methods and immobilize the extracts in various alginate-based delivery systems using ionic gelation. As a carrier for the encapsulation of polyphenols from rosemary (R) and dandelion (D) alginate (A) and its combination with whey protein isolates (A-WPI) and green coffee (A-GC) was used, with emphasis on the evaluation of a potential of green coffee as a new encapsulation material. Obtained hydrogel beads were investigated for water content, physical and morphological characteristics, encapsulation efficiency of polyphenols and retained antioxidant capacity, and for release profile of polyphenols and antioxidant capacity from hydrogel beads in simulated gastrointestinal conditions. The analysis of rosemary and dandelion leaf extracts showed that the content of total polyphenols, hydroxycinnamic acids and antioxidant capacity was higher in rosemary extract. In both herbal species, the addition of whey protein isolates in alginate resulted with size reduction of hydrogel beads, while the addition of green coffee resulted in increase of particle size. The addition of whey protein isolates and green coffee in alginate gel resulted in higher encapsulation efficiency of total polyphenols, hydroxycinnamic acids and higher retention of antioxidant capacity, whereby the addition of whey protein isolates was the most efficient (e.g. % of total polyphenols immobilization for A-WPI was 94,33% for R and 90,15% for D). The best release profile of all tested parameters was determined in system A-GC, where the release of total polyphenols and hydroxycinnamic acids, in both herbal species, was continuous through all 140 minutes in gastrointestinal conditions. Green coffee, as a new carrier material, has shown a great potential for encapsulation of polyphenol from medicinal herbs