Effects of Process Parameters and Storage on the Quality Characteristics and Formation of Potential Hazardous Maillard Reaction Products in Gluten-Free Chestnut (Castanea sativa Mill.) Biscuits

The aim of this study was to evaluate the effects of baking temperature (170–200 °C), baking time (6–12 min), and chestnut flour: rice flour ratio (1:4, 2:3, 3:2, 4:1) on the formation of Maillard reaction products (MRPs) including acrylamide, 5-hydroxymethylfurfural (HMF), and furan in gluten-free biscuits, as well as to assess the impact of storage (for 3 months at 25 °C in heat-sealed aluminium laminated polyethylene (ALPE) packages) on these compounds and on product quality attributes. Results demonstrated that increasing baking time (6–12 min) led to higher levels of acrylamide (120.85 ± 4.53–508.60 ± 13.72 µg/kg), HMF (6.09 ± 0.80–11.45 ± 0.32 mg/kg), and furan (128.79 ± 15.99–3498.41 ± 12.57 ng/g). When the chestnut flour proportion increased from 20% to 60% under the studied baking conditions, acrylamide, HMF, and furan contents showed an increasing tendency, with maximum values of 508.60 ± 13.72 µg/kg, 11.45 ± 0.32 mg/kg, and 3498.41 ± 12.57 ng/g, respectively. Process parameters affected not only the formation of acrylamide, HMF, and furan, but also total phenolic content, hardness value as well as color, water activity and moisture content of biscuits. Especially with increasing baking temperature, a decreasing trend was observed in total phenolic content, while hardness tended to increase with longer baking time. During storage, acrylamide and HMF levels decreased over time, with the lowest acrylamide content (124.21 ± 4.46 µg/kg) observed in biscuits made solely with rice flour after 90 days. Furan levels also decreased slightly, although not significantly, and HMF was undetectable in all samples after day 7 of storage. Texture analysis revealed an increase in hardness and a decrease in crispness during storage. Following the evaluation of process parameters, optimization was performed to determine the best combination of variables. Overall, both formulation and baking conditions had significant effects on the formation of MRPs and on the bioactive properties of gluten-free biscuits. Higher processing temperatures statistically increased these compounds.