Characterization and Optimization of Extrusion Cooking for the Manufacture of Third-Generation Snacks with Winter Squash (Cucurbita moschata D.) Flour

The aim of this work was to study the effects of barrel temperature (BT, 93.5-140.5 degrees C), feed moisture (FM, 21.3-34.7%), and winter squash flour content (SFC, 0.43-15.6%) on physicochemical properties of microwave-expanded third-generation snack foods obtained by extrusion. Physicochemical properties used for optimization were expansion index (EI), penetration force (PF), specific mechanical energy (SME), and total color difference (Delta E). Response surface methodology was used for the analysis of data. The highest values of EI and lowest values of PF were found at high BT and low FM. The lowest values of SME were obtained at high levels of FM throughout the range of BT and SFC, whereas the highest values of Delta E were obtained at high SFC and low FM. Increasing levels of SFC increased Delta E values. whereas EI and SME values decreased. The best processing conditions (EI > 6.0, PE < 9.5 N, SME < 172 kJ/kg, and Delta E < 18) were found in the range of BT, 122-141 degrees C; FM, 24.7-29.5%; and SFC, 0-10.9%. Under optimal process conditions, the retention of total carotenoids was higher than 60%. It is possible to manufacture third-generation snack foods with good physicochemical properties, which could bring a health benefit because of the presence of carotenoids and dietary fiber in winter squash flour.