Exploring the application of foam blanket drying: technological and functional analysis of soluble coffee

Coffee is one of the most consumed drinks worldwide and represents a significant product. Studies attribute health benefits to its consumption, most of which are linked to its antioxidant properties. The instant coffee segment has been growing significantly in recent years, with demand emerging for alternative technologies capable of satisfying consumer demand for healthy and functional products. Therefore, the objective was to evaluate the feasibility of producing a powdered coffee model, of the soluble type, using the foam blanket drying technique, using coffee drinks produced from light roast Robusta coffee beans (LR) and medium (MR), prepared in an Aeropress Coffee Maker and characterized them in terms of phenolic content (Folin-Ciocalteu method) and antioxidant activity (DPPH, FRAP and ORAC methods). For the foamed system, the coffee was mixed with 2% albumin powder and 1% carboxymethyl cellulose per 100 mL and stirred until stabilization and then dried at 68°C until the release of the porous film. The apparent density of the powders was low (LR: 0.247 ± 0.03 and MR: 0.266 ± 0.03g/mL), similar to commercial coffees, being an important variable in packaging sizing. The LR sample presented a higher phenolic profile (119.7±5.90 mg %GAE) and antioxidant activity (DPPH:18.2±0.18 µmolTE/g; FRAP:0.98±0.03 µmol Fe2SO4/g; ORAC:67.62±1.93 µmolTE/g) when compared to MR (Total Phenolic: 40.41±0.98 mg %GAE; DPPH:11.02±0.51 µmol TE/g; FRAP: 0.35±0.01 µmol Fe2SO4/g; ORAC:42.74±1.06 µmol TE/g), with a drop observed in liquid bases, before the drying process for both. It is suggested that MR phenolics may have been integrated into melanoidins in the initial stages of the process and subsequently underwent partial oxidation to other products and subsequent degradation. Therefore, it appears that the foam blanket drying process is viable for obtaining powdered coffee, with technological properties such as apparent density similar to the conventional one and significant functional properties in the final product