Accelerated solvent extraction (ASE) of bioactive compounds from blueberry pomace

Tijekom prerade borovnice u sok, nusproizvod (otpad) koji zaostane predstavlja vrijedan alternativni izvor različitih bioaktivnih spojeva. U novije se vrijeme istražuju ekološki prihvatljive metode ekstrakcije ovih spojeva iz različitih nusproizvoda kako bi se prerada i proizvodnja približile održivom konceptu. Stoga je cilj ovog rada bio ispitati mogućnost primjene ubrzane ekstrakcije otapalima pri povišenom tlaku (ASE ekstrakcija) uz vodu kao otapalo u vrednovanju nusproizvoda borovnice Vaccinium myrtillus L. zaostalog nakon proizvodnje soka. ASE ekstrakcija je provedena variranjem statičkog vremena ekstrakcije (5, 10, 15 min), temperature (40 °C, 80 °C, 120 °C) te broja ciklusa (1, 2, 3). U dobivenim ekstraktima provedena je HPLC-DAD analiza s ciljem određivanja sastavnica fenolnih spojeva. Ukupno su identificirane i kvantificirane tri strukture flavonoida (katehin, kvercetin-3-rutinozid i kvercetin-3-galaktozid) te četiri strukture hidroksicimetnih kiselina (klorogenska, kafeinska, p-kumarinska i ferulinska). Dobiveni rezultati pokazuju da su derivati kvercetina dominantni polifenolni spojevi nusproizvoda borovnice (62 %). Multivarijantnom statističkom analizom utvrđeni su optimalni parametri provedbe ASE ekstrakcije s ciljem najvećeg prinosa fenolnih spojeva kako slijedi: za ukupne fenole i hidroksicimetne kiseline - temperatura 40 °C, statičko vrijeme 5 min kroz jedan ciklus, za flavonoide također statičko vrijeme 5 min kroz jedan ciklus, ali uz temperaturu 59,74 °C (p≤0,05).Blueberry pomace, retained during blueberry juice production, represents a valuable alternative source of various bioactive compounds (BACs). More recently, green extraction methods, based on the concept to be environmentally sustainable, have been developed to extract BACs from various fruit by-products. Therefore, the aim of this paper was to evaluate the use of green extraction procedure such as Accelerated Solvent Extraction (ASE) in the valorisation of the pomace generated from Vaccinium myrtillus L. after pressing the juice. ASE was performed with water as a solvent by varying the static extraction time (5, 10, 15 min), temperature (40 °C, 80 °C, 120 °C) and the number of cycles (1, 2, 3). HPLC-DAD analysis was performed in order to profile phenolic compounds from blueberry pomace aquaeous extracts. Total of three flavonoids (catechin, quercetin 3-rutinoside and quercetin-3-galactoside) and four hydroxycinnamic acids (chlorogenic, caffeic, p-coumaric and ferulic) were identified and quantified. Obtained results revealed that quercetin derivatives were predominant (62 %) polyphenolic compounds found in the blueberry pomace extracts. In order to optimize ASE parameters with highest BACs yields, a multivariate statistical analysis was performed. The optimum ASE parameters were found as follows: for total phenols and hydroxycinnamic acids – temperature 40 °C, static time 5 min with one cycle, while for flavonoids - static time 5 min with one cycle and temperature 59.74 °C (p≤0.05)