Acrylamide and HMF occurrence and bioaccessibility in instant coffee and coffee substitutes. A study on isolated and milk-combined beverages

This research evaluated the occurrence and bioaccessibility of acrylamide and HMF in commercial instant coffees (IC) and coffee substitutes (CS), considering both isolated consumption and combination with milk. There were no significant differences in acrylamide content between IC and CS samples (median: 589 vs. 671 mu g/kg), but higher variability was reported for CS, probably due to their varied composition (roasted cereals, nuts, honey, dehydrated fruits, and/or chicory). Acrylamide level were always below the EU benchmark for each category. HMF contents were similar between both groups (1354-5127 mg/kg for IC and 735-7134 mg/kg for CS; median: 2890 vs. 2960 mg/kg), with no clear ingredient relationship. Since IC consumption by the Spanish population is ten times higher than that of CS, exposure to acrylamide and HMF was higher from IC (6.8 vs. 1.07 ng/kg body weight/day for acrylamide; 39.1 vs. 4.2 mu g/kg body weight/day for HMF). The standardized in vitro gastrointestinal digestion protocol (INFOGEST) was used. The gastrointestinal process reduced the bioaccessibility of acrylamide up to 27.2 % in IC and to 22.4% in CS, regardless of the presence of milk. HMF bioaccessibility from IC significantly dropped after the gastrointestinal digestion, whereas it greatly increased for CS. The presence of milk did not affect HMF bioaccessibility. These results highlight the importance of assessing food bioaccessibility in typical consumption scenarios, providing a holistic view and a realistic evaluation of the potential risks associated with acrylamide and HMF exposure in the diet.