Extraction of phenolic compounds from bilberry (Vaccinium myrtillus L.) press residue: Effects on phenolic composition and cell proliferation

•Phenolic compounds in bilberry press residue were extracted using hot water.•The yields were highest at high temperature (80 °C) and short duration (4-15 min).•Anthocyanins, flavonols and cinnamic acids were characterized and quantified.•Bilberry press residue extracts had promising antiproliferative effects.•Extracts obtained at high temperatures showed the strongest antiproliferation.

The press residue after industrial juice production from bilberry (Vaccinium myrtillus L.) contained high concentration of polyphenols, a group of compounds with possible health benefits. The effects of temperature (22-100 °C) and duration (4-45 min) utilized in aqueous extraction of phenolic compounds from the press residue were studied. The yield of anthocyanins in the extracts increased with temperature and extraction time up to a point, and then declined. The recovery of flavonols and cinnamic acid containing compounds in the extracts increased with increasing temperature and reached 97% and 63%, respectively. Extraction at 80 °C for 15 min and 100 °C for 4 min gave the highest retrieval of both total phenolics (TP) and total monomeric anthocyanins (TMA), 37% and 67-68%, respectively. Extracts obtained at high extraction temperatures showed a stronger inhibition of cell proliferation of three colon cancer cell lines (Caco-2, HT-29, and HCT 116) than extracts obtained at lower temperatures.