Pumpkin powder with co-products seeds and peel: effect on the physicochemical and functional properties by spray drying

• Pumpkin and its co-products (seeds and peel) are a rich source of bioactive compounds. • A stable mixture of whole pumpkin powder with bioactive compounds and antioxidant properties was obtained. • By using agro-industrial waste from pumpkin, added value is generated within the framework of the circular economy model. • The pumpkin powder mixture has potential use in new food matrices for the industrial sector. The incorporation of pumpkin co-products (peel and seed) rich in phenolic and fat-soluble bioactive compounds, together with its pulp, allowed the development of a new pumpkin powder mixture (PPM) by spray drying (SD). The main factors that can affect its physicochemical and techno-functional quality and bioactive compounds are: inlet air temperature (IAT), outlet air temperature (OAT), atomizing disk speed (ADS), and carrier agent concentration (Maltodextrin, MD). The aim of the study was to evaluate the influence of these factors on moisture content (X m ), water activity (a w ), volume mean diameter (D [4;3] ), CIE-L*a*b* color, cold water solubility (CWS), oil absorption capacity (OAC), total phenols (TP), antioxidant capacity by DPPH • and ABTS +• , β-carotene (β-car), and α-tocopherol (α-toc) of the PPM. The response surface methodology with a central composite design was used for optimization. SD conditions were significant ( p < 0.05) in the evaluated variables, excluding a w , L*, and b*. The optimal conditions were achieved: IAT: 172.3 °C, OAT: 81.6 °C, ADS: 23,893 rpm and MD: 4.0 %. PPM was obtained with X m : 6.9 % db (dry basis) ± 0.7, CWS: 89.8 ± 1.2 %, OAC: 0.47 ± 0.00 g oil/g db, TP: 450.3 ± 23.3 mg gallic acid equivalent (GAE)/100 g db, DPPH • : 1090.4 ± 78.1 µmol Trolox Eq ​​(TE)/100 g db and ABTS •+ : 817.0 ± 52.2 µmol TE/100 g db, 21.0 ± 1.5 mg β-car/100 g db, and 1.3 ± 0.3 mg α-toc/100 g db. The quadratic regression method allowed optimizing the SD conditions to obtain a PPM with the best quality characteristics and functional properties.