Preservation of saffron floral bio-residues by hot air convection

• 110 and 125 °C negatively affect to the quality of saffron floral bio-residues.
• 70 and 90 °C are selected as the best drying temperatures.
• The treatment duration at 70 °C is double than those of 90 °C.
• Phenolics are stable at 70 and 90 °C combined with 2, 4, 6 and 8 ms−1.
• A better color and phenolic content is found at 90 °C with 2, 4 and 6 ms−1.

Large amounts of floral bio-residues are wasted in saffron spice production, which need to be stabilized because of how quickly they deteriorate. These bio-residues are rich in phenolic compounds, and the aim of this study was to evaluate the effect of drying temperatures and air flows on their color and phenolic composition. Anthocyanins and flavonols were degraded at 110 and 125 °C. The best drying temperatures were 70 and 90 °C for maintaining their physicochemical quality. The duration at 70 °C was double than that of 90 °C. Anthocyanins and flavonols were stable at 70 and 90 °C with 2, 4, 6 and 8 m s−1. Dehydrations at 90 °C with 2, 4 and 6 m s−1 were the most appropriate, due to a better color and greater similarity to control samples for their flavonols and anthocyanins.