Effect of Microwave-Assisted Processing of Acorn Flour on Muffin Quality

The aim of this study was to evaluate the impact of microwave treatment on the physical properties and bioactive compound content of acorn flour and its subsequent effects on the quality of muffins. Acorn flour, both dry and hydrated (flour-to-water mixture = 1:1, w/v), was subjected to microwave processing at varying power levels (925, 1295, and 1850 W) and exposure times (0.5, 1.0, 1.5, 2.0, and 3.0 min). The treated flour was incorporated into composite wheat–acorn muffins, which were analyzed for key physical attributes, including volume, porosity, crumb firmness, and color. In addition, the chemical composition of the muffins was assessed, with a particular focus on antioxidant activity and the content of bioactive compounds such as total free phenolics, flavonoids, and tannins. The results indicated that microwave treatment significantly influenced the antioxidant potential and technological properties of acorn flour-based muffins. Microwave treatment at 925 W for 3 min or 1295 W for 1.5 min under moist conditions resulted in muffins with enhanced antioxidant capacity (e.g., an increase in total free phenolics by up to 61.4% and flavonoids by up to 135.9%, and a reduction in tannin content by up to 38.2%), as well as improved volume and sensory acceptance. However, high-power treatment (1850 W) negatively affected muffin volume, porosity, and firmness. These findings emphasize the effectiveness of controlled microwave processing in improving both the nutritional and technological qualities of bakery products enriched with acorn flour.