Optimizing quality, functionality, and safety of Palmyrah palm (Borassus flabellifer Linn.) pulp powder via steaming and hot-air drying

• Steaming and hot-air drying markedly affected Palmyrah palm pulp powder quality. • Drying at 50°C without steaming retained the highest bioactive compound contents. • Steaming reduced browning and HMF formation but lowered antioxidant retention. • Steamed powders exhibited improved solubility, swelling capacity, and bulk density. • All dried powders were microbiologically safe and suitable for functional food use. Palmyrah palm ( Borassus flabellifer Linn.) pulp is a nutrient-rich tropical fruit containing abundant carbohydrates, vitamins, minerals, and bioactive compounds; however, its high moisture content (∼91 %) limits shelf life and industrial utilization. This study investigated the effects of steaming pretreatment and hot-air drying temperatures (50, 60, and 70°C) on the quality, functional characteristics, and microbial safety of Palmyrah palm pulp powder. Drying decreased moisture content from 91.18-91.93% to 9.35-9.77% and water activity from 0.86-0.92 to 0.52-0.55, ensuring safe storage. Steaming pretreatment minimized color browning and hydroxymethylfurfural formation but slightly reduced phenolic retention. Non-steamed pulp dried at 50°C exhibited the highest total phenolics (167.30 mg GAE/100 g), flavonoids (515.92 mg CE/100 g), carotenoids (12.17 mg/100 g), and ascorbic acid (8.82 mg/100 g), together with superior antioxidant activities measured by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, FRAP (ferric reducing antioxidant power), and ABTS • ⁺ (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization) assays. In contrast, steamed pulp dried at 50°C showed enhanced solubility (5.37%) and swelling capacity (282.90%). All dried samples were microbiologically safe. Overall, hot-air drying at 50°C following steaming pretreatment yielded high-quality Palmyrah palm pulp powder with excellent rehydration and dispersibility, suitable for use in instant foods, Thai desserts, and functional food formulations.