Coating spent coffee grounds with whey protein: A valorization study

Food and dairy industry are now considering waste streams as important actors in the transition to sustainable manufacture. It is crucial to develop cost-effective processing alternatives for the utilization of such streams that not only creates value from waste materials but also reduces the environmental impact. In this work, we studied the valorization of spent coffee ground (SCG), a rich source of fatty acids, amino acids, polyphenols, minerals, and polysaccharides. Our objective is to evaluate the structural properties of a powder obtained by spray drying containing different percentages of whey protein concentrated. Different percentages of SCG (4–16%) were mixed (2500 rpm for 5min) with concentrated whey (total solids 39%). Afterward, the mixture was spray dried using an inlet temperature of 170°C. The moisture content and water activity of obtained powder were 3.25 ± 0.18 and 0.252 ± 0.01, while the bulk density was 0.495 ± 0.10 g/cm3, showing a significant correlation (P \u3c 0.05) with the particle size (43.87 μm). This observation is due to the fact that small particles can occupy spaces between large particles, increasing the apparent density of the system. Such an effect was confirmed by Scanning electron microscope. Moisture-sorption isotherms were determined (17–45°C) and the moisture content at the monolayer was between 0.043 and 0.086 kg of water/g dry basis, and the isosteric heat was 27.65 kJ/mol, which decreased as a function of the increase in moisture content. On the other hand, some amino acids were determinate in the powder samples phenylalanine (135.97), lysine (68.91), leucine (406.12), isoleucine (613.07) and proline (192.79) all in mg/100g. In general, the addition of whey concentrated as a coating medium for SCG particles shows great potential for the fortification of dairy products