Postharvest drying is a critical procedure that determines storage safety and the nutritional stability of maize grains. This study evaluated the effects of eight drying conditions, including open-sun, greenhouse, freeze-drying, 200 W microwave, 200 W + 60 °C hybrid, and convective drying at 40, 60, and 80 °C, on the biochemical composition and fatty acid profile of three maize cultivars (ADA 13.4, Pioneer-P1921, and Dekalb-DKC6589). Artificial neural networks (ANNs) were also used to predict the temporal dynamics of mass-loss kinetics. Significant differences were observed among drying methods and cultivars (p ≤ 0.01). Freeze-drying preserved the highest oil (up to 52.0 g/kg), amylopectin (731.8 g/kg), and total starch (750.5 g/kg) contents, whereas microwave and hybrid drying reduced oil to 24.9-25.6 g/kg and caused significant protein losses. Greenhouse drying retained relatively high protein (86.4-89.5 g/kg) and amylose (290-320 g/kg) levels, indicating its potential as an energy-saving alternative. In terms of fatty acid stability, freeze-drying and low-temperature drying were the most suitable methods for preserving the relative unsaturated fatty acid profile; for example, freeze-drying in Dekalb-DKC6589 retained 608.4 g/kg linoleic acid and 234.4 g/kg oleic acid, whereas high-temperature treatments increased the relative proportion of saturated fatty acids (palmitic + stearic, 120-140 g/kg), likely because unsaturated fatty acids were more susceptible to oxidative degradation under severe drying conditions. Mineral losses were more evident under high-temperature drying; for instance, in ADA 13.4 dried at 80 °C, Ca and Zn decreased to 196.9 and 16.15 mg/kg, respectively, while freeze-drying preserved relatively high Fe and Zn contents in Pioneer-P1921 (49.93 and 47.83 mg/kg, respectively). ANN models showed high predictive performance for relatively stable drying conditions such as greenhouse and convective drying (R 2 > 0.96), but lower accuracy for rapid microwave-assisted processes (R 2 < 0.80) because of stochastic moisture loss. Overall, the results highlight a trade-off between processing speed and nutritional quality, suggesting that greenhouse and low-temperature drying offer promising alternatives, while drying protocols should be optimized according to cultivar-specific responses. • Drying methods significantly affected maize biochemical composition. • Low-temperature drying preserved amylopectin and total starch. • Microwave drying reduced time but increased biochemical degradation. • High-temperature drying increased resistant starch formation. • ANN models successfully predicted maize drying behavior.
Çetin et al. (Fri,) studied this question.