Effect of Toasting on Quality and Sensory Attributes of Oat Flakes and Brazil Nuts Intended for Use in Functional Muesli

This study evaluated the effects of toasting temperature and time on the sensory characteristics, moisture content, lipid stability, total phenolic content, and antioxidant capacity of gluten-free oat flakes and Brazil nuts ( Bertholletia excelsa ) to determine optimal processing conditions. Oat flakes were toasted at 120.0, 150.0, and 180.0 ± 0.5°C, and Brazil nuts at 120.0, 130.0, 140.0, and 150.0 ± 0.5°C for 5, 10, 15, and 20 min. Toasting significantly affected sensory quality (p < 0.05). Based on all quality measurements and sensory attribute scores, the best overall results were obtained at 180.0 ± 0.5°C for 5 min for oat flakes and 140.0 ± 0.5°C for 10 min for Brazil nuts. Moisture content decreased with increasing temperature and time, reaching optimal levels of 3-5% for oat flakes and 0.5-0.8% for Brazil nuts. In Brazil nuts, peroxide values increased from 1.12 to 3.75 meq O 2 kg⁻ 1 oil, indicating accelerated lipid oxidation under excessive heating. Toasting also increased total phenolic content from 0.070 to 0.448 mg GAE/g in oats and from 0.487 to 1.171 mg GAE/g in Brazil nuts, while enhancing DPPH and ABTS radical scavenging activities. Controlled toasting is therefore essential for producing functional muesli with high sensory quality, improved antioxidant properties, and good storage stability.