Design and evaluation of microencapsulated systems containing extract of whole green coffee fruit rich in phenolic acids

The optimal conditions to microencapsulate green coffee (Coffea canephora) fruit extract (GCFE) by spray drying using a maltodextrin (MD)-gum Arabic (GA) mixture as carrier material were selected. For this purpose, a Central Composite Rotational Design was applied to investigate the combined effects of the MD percentage in the mixture and the extract-to-carrier agent mass ratio (mE/mC) as the independent variables. These effects were modelled by second-order polynomial models on several responses, namely process yield, encapsulation efficiency, water activity, losses of reducing capacity, caffeic acid, caffeine, trigonelline, 5-O-caffeoilquinic acid (5-CQA) from microcapsules (MCs) and 5-CQA retention after 180-days storage. The statistically significant effects were then submitted to more in-depth analysis by Response Surface Methodology. The highest process yield was obtained using a MD percentage of 80% and a mE/mC ratio of 1:1.5 (w/w). Both microencapsulated and non-encapsulated GCFE showed good stability during the accelerated stability study performed at 40 °C for 180 days. Surface morphology and particle size distribution of GCFE-loaded MCs were shown to be suitable for use in the food industry.